AP696A - Draught animal driven electrical power generator. - Google Patents

Abstract

According to the invention there is provided electrical power generating apparatus 10 for use in rural areas not serviced by an electrical power distribution network or grid. The apparatus 10 comprises an electrical generator 22 and a lever 12 for connecting the generator to a draught animal 14 to drive the generator. A speed increasing arrangement 18 and the flat configuration of the generator ensures effective generation to charge a DC battery. An electrical load 28 comprising lights and/or a television set and/or a personal computer is connectable to the battery.

Description

INTRODUCTION AND BACKGROUND

THIS invention relates to electrical power generating apparatus and more particularly to relatively inexpensive apparatus for generating power in remote areas not serviced by an electrical power distribution network or grid.

One solution for generating electrical power in such remote areas, is photovoltaic systems. Although these systems are successful in some areas, they are too expensive and difficult to install and maintain for many very poor and unsophisticated communities. Furthermore, during prolonged overcast periods, they are not effective and there is normally no back-up supply or system for providing electricity over a number of days.

OBJECT OF THE INVENTION

Accordingly it is an object of the present invention to provide an alternative system and method with which the applicants believe the aforementioned disadvantages may at least be alleviated.

AP/P/ 9 6 / 0 0 8 1 3

-1AP.00696

SUMMARY OF THE INVENTION

According to the invention there is provided electrical power generating apparatus, the apparatus comprising an electrical generator; means for, in use, connecting the generator to a draught animal to drive the generator; and DC power storage means connected to an electrical output of the generator and which storage means is connectable to an electrical load.

The electrical generator may provide a DC output voltage via a commutator or may provide an AC output voltage.

The means for connecting the draught animal to the generator may comprise a lever connected to a shaft, the shaft being connected by rotational speed increasing means to an input shaft of the generator.

AP/P/ 9 6 / 0 0 8 1 3

The lever may be marked along its length to indicate suitable regions along its length to connect or yoke different kinds of draught animals such as a donkey or an ox. So, for example, will an ox be connected to the lever in a region thereof closer to the shaft than a donkey.

-2ΑΡ. Ο.Λ·%|β

The rotational speed increasing means may comprise a gear and chain assembly, alternatively it may comprise a belt and pulley assembly, further alternatively it may comprise a gearbox or any other suitable arrangement. The rotational speed increasing means preferably has a speed increasing ratio of in the order of 1:50 or higher.

Θ

A slip friction clutch may be provided between the lever and the input shaft to protect the speed increasing means against too big a torque.

Ό The DC power storage means may comprise a 12V rechargeable lead acid battery.

bJ , The generator may either be a shunt generator or a permanent

Ό magnet generator comprising a commutator to provide a DC output. Alternatively, it may be an alternator with electromagnetic field or a permanent magnet alternator having one or more phase windings.

In the preferred form it is a three phase alternator with a permanent magnet field.

£1800/96 dV

-3The generator may comprise a disc shaped rotor carrying permanent magnets along a periphery thereof and windings of the generator may be provided in slots defined in a stator provided on the other side of an airgap as the rotor.

ΑΡ.ΟΟββδ

The generator is of generally flat design so that the spacing between the airgap and the input shaft is bigger than the axial o

length of the generator. In a preferred form the spacing is at least four times bigger than the axial length of the generator.

The electrical load may, for example, comprise fluorescent lamps 10 and/or a television set and/or a personal computer.

Further according to the invention an electrical power generating system comprises an electrical generator; a draught animal ©

connected to the generator to drive the generator; DC power storage means connected to an electrical output of the generator to

5 be charged thereby; and an electrical load which is connectable to the battery.

ART/ 9 6 / 0 0 8 1 3

-4AP.009*6

According to another aspect of the invention a method of generating electricity comprises the step of utilising a draught animal to drive an electrical power generator.

The method may further comprise the step of charging with the generator DC power storage means which is connectable to an electrical load.

BRIEF DESCRIPTION OF THE DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein: figure 1 is a diagrammatic illustration of part of a rural village comprising an electrical power generating system according to the invention;

figure 2 is a diagrammatic perspective view of a generator forming part of the system;

figure 3 is a section on line III in figure 2;

figure 4 is a diagrammatic perspective view of a peripheral region of a rotor of the generator;

figure 5 is an axial view of part of the rotor, air gap and stator (without windings) of the generator;

AP/P/ 9 6 / 0 0 8 1 3

-5AF,. ⁶ figure 6 is a flattened radially outward view in a direction from the rotor towards the stator, illustrating the windings for a three phase generator; and figure 7 is a block diagram of electrical circuitry connected to an output of the generator.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Electrical power generating apparatus according to the invention is generally designated by the reference numeral 10 in figure 1.

The apparatus 10 comprises a lever 12 connectable at one end thereof to a draught animal 14 and at another end thereof to a shaft

16. Shaft 16 is connected via rotational speed increasing means in the form of a gear and chain arrangement 18 to an input shaft 20 of an electrical power generator 22. The gear and chain

I arrangement is preferably a two-stage arrangement as shown and 5 comprises a slip friction clutch (not shown), to protect the gear and chain arrangement against too big a torque.

As shown in figures 1 and 7 an electrical output 22.1 of the generator is connected to rectifier means in the form of a rectifier

AP/P/ 9 6 / 0 0 8 1 3

-6AP. Ο 0 HI bridge 24. The output of the bridge is connected to a 12V lead acid battery 26 via a regulator 25. The battery 26 is connectable to an electrical load 28.

The gear and chain arrangement 18 is adapted to increase the low 5 speed of rotation in operation of the draught animal 14 of typically to 2 rpm, by a ratio of in the order of 1:50. Accordingly, the shaft 20 will have a rotational speed of 50 - 100 rpm.

The generator 22 is preferably a permanent magnet, three phase AC generator.

IO

The battery 26 is a standard size 12V, 90 Ah battery of the kind designed to handle at least 1500 charge/discharge cycles. Such i batteries have operated in situ in photovoltaic systems for more than 5 years, without noticeable degradation.

APT,' 9 6 / 0 0 8 1 3

The load 28 may comprise a plurality of 12V fluorescent tubes 1 5 and/or a 12V television set (not shown) and/or a personal computer (also not shown), for example.

oGU'ae

As shown in figure 2, the generator 22 comprises a housing 30 mounted on a support structure 32. The housing is of generally flat configuration to house the generator which has a width (w) to height (h) dimension of in the order of greater than 4 to 1.

The generator 22 is of generally flat configuration to ensure that an air gap 34 (shown in figure 3) between the rotor 36 and stator 38 )

is at a maximum distance from shaft 20. By ensuring that the airgap 34 is radially far away from the shaft 20, it is ensured that, in use, the speed of the magnets past the winding is as big as possible, which is beneficial for the induction and generation process.

ι As shown in figures 3 and 4 the rotor 36 comprises a circular disk 40 on the periphery of which there is provided magnetic poles in the form of forty-eight alternating south and north permanent magnetic poles 42.

As shown in figures 5 and 6, the stator 38 comprises a plurality of superimposed stamped plates 44.1 to 44.n. In the plates and thus in the laminated stator there are defined slots 46.1 to 46.n for

AP/P/ 96/0081 3

-8AP . ο ο β>»>

receiving the three phase winding of the generator. The winding is best shown in figure 6. The winding for each phase comprises a plurality of interconnected loops 48.11, 48.12 etc for the first phase, for example. Each loop comprises a plurality of conductors 5 50. Loop 48.1 forms part of the first phase winding and is mounted in slots 46.1 and 46.4 where it is connected to another similar loop 48.12 also forming part of the first phase winding and which other loop is mounted in slots 46.4 and 46.7 etc. The loop 48.21 mounted in slot 46.2 forms part of the second phase winding ° and extends between slots 46.2 and 46.5. Similarly the loop 48.31 in slot 46.3 forms part of the third phase.

, As shown in figure 7, the outputs of the three phases are connected to rectifier bridge 24. Regulator 25 protects the battery ! to ensure that it is not overcharged. i

Referring again to figure 1, in use, an ox may be used to be connected to lever 12 and to walk in a circle around shaft 16. It is believed that at a rotational speed of 2rpm, such an animal is capable of delivering 350 Watt power for a sustained period of. 4 hours.

£ 1 8 0 0 / 9 6 /d/dV

-9It is believed that a 70% efficiency rate for assembly 1 8, 70% efficiency rate for generator 22 and 80% for battery 26 (that is delivering 75 Ah when discharged at 10A) are technically feasible.

One 40W TV set plus four 8W fluorescent tubes consume 72W, 5 drawing 6A from the 12V battery. Such a load combination 28 would then use only 36 Ah from the available battery energy over a period of 6 hours. This figure is much less than the 75 Ah which can be supplied by the 90 Ah battery when fully charged.

The ox delivering 350 Watt for four hours and taking into account 10 the aforementioned efficiency rates, generates more energy than

CL needed to drive the aforementioned load combination 28 for 6 <C j^'· hours. If two oxen are used, one for each of two successive four hour shifts, enough power may be generated by one apparatus 10 ©

to drive loads in more than one house 31.

It is believed that the apparatus would be socially and/or culturally acceptable to rural communities. It is also believed that the apparatus can be provided and installed at a cost lower than the currently known systems, for example photovoltaic systems. The

-10ΑΡ.ΟΟβίβ maintenance of the apparatus is relatively easy and cheap, since it primarily involves lubrication of assembly 18 and maintenance of battery 26.

The apparatus according to the invention thus makes television and light available to remote and poor communities. It therefore assists in addressing some of the most pressing needs of these communities, namely education and communication.

Since draught animals are well spread and readily available in rural communities, the apparatus and method according to the invention

- is suited to alleviate the aforementioned needs in these communities.

AP/P/ 9 6 / 0 0 8 1 3

It will be appreciated that there are many variations in detail on the apparatus and method according to the invention without departing from the scope and spirit of the appended claims.

Claims (13)

1. An electrical power generating apparatus, the apparatus comprising an electrical generator; means for, in use, connecting, the generator to a draught animal to drive the generator; and DC

5 power storage means connected to an electrical output of the generator and which storage means is connectable to an electrical load characterised in that the electrical generator provides an AC voltage at its output.

2. An apparatus as claimed in claim 1 wherein voltage rectifier

10 means is connected to the output of the generator and voltage regulator means is connected between the rectifier and the power storage means.

3. An apparatus as claimed in any one of the preceding claims wherein the means for connecting the draught animal to the

15 generator comprises a lever connected to a shaft, the shaft being connected by rotational speed increasing means to an input shaft; of the generator.

-13ΑΡ.00β96

4. An apparatus as claimed in claim 3 wherein the lever is marked along its length to indicate suitable regions along its length to connect different kinds of draught animals.

5. An apparatus as claimed in claim 3 or claim 4 wherein the

5 rotational speed increasing means comprises a gear and chain assembly.

6. An apparatus as claimed in any one of claims 3 to 5 wherein the rotational speed increasing means has a speed increasing ratio of in the order of 1:50 or higher.

10

7. An apparatus as claimed in any one of claims 3 to 6 wherein a slip friction clutch is provided between the lever and the input shaft of the generator.

8. An apparatus as claimed in any one of claims 1 to 7 wherein the generator comprises a permanent magnet, three phase generator,

15

9. An apparatus as claimed in any one of ciaims 1 to 8 wherein the generator comprises a circular disc shaped rotor carrying permanent

-14AP . 0 0 6 9 6 magnets along a periphery thereof and wherein windings of thi·· generator are provided in a stator on the other side of a circular airgap as the rotor.

10. An apparatus as claimed in claim 9 wherein the spacing between the airgap and the input shaft is bigger than an axial length of the generator.

11. Electrical power generating system comprising an electrical generator; a draught animal connected to the generator to drive the generator; DC power storage means connected to an electrical output of the generator to be charged thereby; and an electrical load which is connectable to the battery, characterized in that the electrical generator is an AC voltage generator.

12. A method of generating electricity comprising the step ol utilising a draught animal to drive an electrical power generator to provide an AC output voltage.

-15AP . Ο Ο 6 9 6

13. A method as claimed in claim 12 comprising the step of charging with the generator DC power storage means which is connectable to an electrical load.