WO1991008609A2

WO1991008609A2 - An alternator unit and an engine including the same

Info

Publication number: WO1991008609A2
Application number: PCT/GB1990/001887
Authority: WO
Inventors: Iorwerth Thomas
Original assignee: Iorwerth Thomas
Priority date: 1989-12-04
Filing date: 1990-12-04
Publication date: 1991-06-13
Also published as: AU7896291A; WO1991008609A3

Abstract

An alternator unit in an engine (45) in a vehicle (157) comprises two alternator assemblies (2, 4) each alternator assembly (2, 4) including a rotor winding (18, 20) and a plurality of stator windings (37, 38, 39, 40, 41). The alternator assemblies (2, 4) are mounted adjacently with their rotor windings (18, 20) arranged to rotate about a common axis. Each rotor winding (18, 20) is wound in an opposite sense to the other to intensify the electromagnetic field in the region of the stator windings (37, 38, 39, 40, 41) and thus increase current output. The output from one stator winding (39, 41) in each alternator assembly (2, 4) is connected to the input for the rotor windings (18, 20) so that the alternator can be self-exciting. The output from those same stator windings (39, 41) is also connected to a battery (53) of the vehicle to re-charge the battery (53). The other stator windings (37, 38, 40) of each alternator assembly (2, 4) are connected to an electrolysis unit (46) for producing hydrogen and oxygen to be supplied to the engine intake.

Description

AN ALTERNATOR DNIT AND AN ENGINE INCLUDING THE SAME

The invention relates to an alternator unit and to an engine including the same.

In a conventional alternator in an engine of a vehicle, such as a car, the rotor winding of the alternator is continuously supplied with electrical current from a battery carried by the vehicle.

According to one aspect of the invention there is provided an alternator unit comprising at least one rotor winding and at least one stator winding, at least part of the output from the or at least one stator winding being connected to the input for the or at least one rotor winding.

In this way, the alternator unit can be self-exciting either in part or entirely.

Preferably, the output from the or at least one stator winding is connected to the output for the or at least one rotor winding directly, passing only through a rectifier. The alternator unit may include a battery and the battery may be connected through switch means to the input to the or at least one rotor winding. Thus, the battery may be used to excite the or at least one rotor winding, for example, initially, and the switch means can be used to disconnect the battery.

The switch means is preferably arranged to disconnect the battery when the rotor rotational speed is above a pre-determined limit. Thus, for example, the battery may be used to supply current to the or at least one rotor winding until the output from the or at least one stator winding is sufficient for the alternator unit to be self-exciting. A sensor may provide a signal relating to rotor speed to the switch means.

Preferably relay means is provided, and, where a battery is provided the relay means is arranged to connect and disconnect the battery to an electrolysis unit. The power of the battery can thus be used in electrolytic process. The relay means is preferably arranged to connect the battery to the electrolysis unit when the rotor rotational speed is above a pre¬ determined limit which may suitably be 7500 rpm. In the case where the battery is also connected via the switch means to the input to the or at least one rotor winding, once the battery has been disconnected from the or at least one rotor winding, it can be connected to the electrolysis unit so that its power is still used.

Conveniently, a sensor may provide a signal relating to rotor speed to the relay means.

Preferably, at least part of the output from the or at least one stator winding is arranged to be connected through a rectifier to the battery thereby to charge the battery. The connection to the rectifier may be through a voltage regulator where appropriate.

In the applicant's prior International patent application published under number WO 87/00703 an alternator unit for a vehicle is disclosed in which a high current alternator is mounted co-axially with a normal alternator, the output of the normal alternator being arranged inter alia to charge the vehicle battery.

According to another aspect of the invention, there is provided an alternator unit comprising two alternator assemblies, each alternator assembly comprising a rotor winding and a plurality of stator windings, the stator windings of each alternator assembly including at least one stator winding the output from which is connected to a battery and at least one stator winding the output from which is connected to a different device.

In this way, a more efficient and compact arrangement is achieved.

The alternator assemblies are preferably mounted adjacently with their rotor windings arranged to rotate about a common axis.

Preferably there are more turns on the or each stator winding the output from which is connected to the battery in one alternator assembly than in the other alternator assembly.

Conveniently, the stator windings the outputs from which are connected to the battery are in thinner diameter wire than the other stator windings.

In one alternator assembly, preferably, there is a plurality of stator windings, the outputs from which are connected to the different device and adjacent of those stator windings are wound in an opposite sense. Current output from the stator windings is thus increased, as discussed in International patent application no. WO 87/00703. Preferably, in the said one alternator assembly, the or each stator winding the output from which is connected to the battery is wound in an opposite sense to the stator winding adjacent to it.

Preferably, in one alternator assembly there is a plurality of stator windings connected to the different device and those stator windings are all wound in the same sense. In the said alternator assembly, the or each stator winding, the output from which is connected to the battery is preferably wound in the same sense to the stator windings which are connected to the different device.

It is particularly preferred that an alternator unit should include alternator assemblies as described in both the preceding paragraphs.

The different device may be any suitable device and may be an electrolysis unit.

The electrolysis unit mentioned in relation to either of the aspects of the invention described thus far may be arranged to produce hydrogen and oxygen gases from an aqueous solution. The electrolyte in the electrolysis unit may include an agent to inhibit polarisation of the electrodes and that agent may be sulphuric acid. The electrolyte may include an agent to inhibit frothing of the electrolyte and that agent may be manganese oxide. The electrolyte may comprise an aqueous solution of sodium hydroxide. Preferably, the composition of the electrolyte is in water, 30% sodium hydroxide, 10% manganese oxide and 1% sulphuric acid.

According to a further aspect of the invention, there is provided an alternator unit comprising two alternator assemblies, each alternator assembly comprising a rotor winding and a stator winding, the alternator assemblies being mounted adjacently with their rotor windings arranged to rotate about a common axis, each rotor winding being wound in an opposite sense to the other. It has been found that by adopting this novel arrangement, the electromagnetic fields from the alternator assemblies are opposed which has the effect of intensifying the field of the stator windings thus increasing the output of the unit.

A further stator winding may be provided between the stator windings of the alternator assemblies. The further stator winding will pick up electromagnetic field not intercepted by the stator windings of the alternator assemblies.

According to another aspect of the invention there is provided an engine including an alternator assembly according to any previous aspect of the invention and including any or none of the sub-features mentioned in relation thereto.

Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is an axial cross-section through the first embodiment;

Fig. 2 is a plan view of part of the rotors of the first embodiment;

Fig. 3 is an end elevation of a rotor of the first embodiment;

Fig. 4 is a view of part of a stator winding of the first embodiment showing the double-layer winding;

Fig. 5 is a diagrammatic view of a supply system for powering an engine of a motor vehicle by gas derived from water;

Fig. 6 is an axial cross-section through the first embodiment with the rectifiers 24 in an alternative position; Fig. 7 is an axial elevation in cross section part of an alternator assembly of a second embodiment;

Fig. 8 is a schematic view of the electrolysis unit and the alternator assembly of the second embodiment;

Fig. 9 is a schematic elevation of the electrolysis unit;

Fig. 10 is a schematic view of the battery circuit of the vehicle alternator in the second embodiment;

Fig. 11 is a side elevation of an alternative stator;

Fig. 12 is a front elevation of the stator of Fig. 12;

Fig. 13 is a cross-sectional view of two stator windings;

Fig. 14 is a side elevation of another alternative stator; and

Fig. 15 is an elevation of a vehicle.

In Fig. 1, first and second alternator assemblies 2, 4 are positioned back to back in casing 3, the alternators sharing a common drive shaft 6. Shaft 6 is driven by the engine 45 by way of pulley wheel 8, and is journalled for rotation in bearings 10, mounted in the end of the alternator casing. A slip ring 14, is positioned around drive shaft 6 to supply exciter current to first and second rotor windings 18, 20 of the first and second alternators 2, 4.

Drive shaft 6 has a diameter of 20.00mm and carries a bobbin 26 having a radial thickness of 1.6mm. the inner layer of each rotor windings 18, 20 of the alternators 2, 4 thus being positioned close to the rotor axis, so as to allow a larger number of rotor turns to be provided than when using a conventional bobbin of radial thickness 25mm or above.

Conveniently 420 turns of 17 swg copper wire are provided.

As seen in Fig. 2, the rotor windings 18, 20 are enclosed by pole pieces 28, 29 of claw form set to intercalate the claws having flattened peaks 32 since this has been found to increase the available field at the periphery of the rotor.

The rotor windings 18, 20 are wound oppositely to one another and the pole pieces 28, 29 are aligned to provide maximum opposition between the electromagnetic fields of the rotor windings 18, 20 so that the field in the region of the stator windings 35, 36 is intensified increasing current output.

First and second stators 35, 36 are supported on brackets 159 on the inner surface of the casing 3.

Each rotor winding 18, 20 is associated with a stator 36, having three sets of windings 37, 38, 39; 40, 4 \ (Fig. 4) wound on former 34 axially slotted to receive the windings, The former 34 shown in Fig. 4 has inwardly facing axial slots but a former 151 such as shown in Figs. 1 and 12 could be used which has outwardly facing slots in which the windings 37, 38, 39; 40, 41 are received. It is also possible not to use a former core at all, but to provide the stator windings 37, 38, 39; 40, 41, wound in the appropriate manner, within a former hoop 152 as shown in Fig. 14. The windings 37, 38, 39; 40, 41 may be retained frictionally or in any other suitable manner and in the embodiment shown are retained by three equi-spaced fingers 153 extending from the former hoop 152 around the windings 37, 38, 39; 40, 41.

Each set of windings comprises three windings wound to provide three-phase output and delta connected. In the windings 37, 38, 39 of the first stator 35, two of the sets of windings 37, 39 are wound in one sense and the other set of windings 38, is wound in the other sense as shown in Fig. 4. Adjacent sets of windings are thus wound oppositely. The outer set of windings 39 is of smaller diameter wire than the two inner sets of windings 37, 38 (Fig. 14).

In the windings 40, 41 of the second stator 36, all three sets of windings 40, 41 are wound in the same sense. The outer set of windings 41 is of smaller diameter wire than the two inner sets of windings 40.

There are half as many turns again of the smaller diameter wire winding 39 on the first stator 35 than there are turns of the smaller diameter wire winding 41 on the second stator 36.

In the first stator 35, where the windings 37, 38, 39 are provided on a former 34, the former is preferably made from a non-magnetic material such as polyethylene or nylon. However, it may be made from the conventional soft iron laminations and a former 34 for the second stator 36 is preferably of that type.

The windings 37, 38, 39; 40, 41 are connected to rectifier units 24 from which the rectified (D.C. ) output can be taken, as to an electrolysis unit hereinafter illustrated in Figs. 5, 8 and 9. The rectifier units 24 for the alternators 2, 4 are mounted externally of the housing 3, so that they are in the vehicle air stream and so can be cooled. As seen in Fig. 1, I provide a large diameter fan 12 to increase the flow of air over rectifier units 24, and ducting (not shown) can also be provided to direct additional air over the rectifier units, from fan 12 or from the ambient air whilst the vehicle is in motion, or both.

Fig. 6 shows an alternative position of mounting for the rectifiers 24 on the end of the housing 3 adjacent the fan 12. The fan 12 can then be of smaller diameter.

The outputs from the windings 37, 38, 40 are connected to the electrodes 111, 112, 113, 114 of an electrolysis unit 46, while the outputs from the windings 39, 41 are connected to a battery 53.

A current of 400+ Amps at 2i volts will produce large volumes of hydrogen and oxygen by electrolysis of water which can be fed as in Fig. 5 to the manifold 42 of an internal combustion engine 45 of a vehicle 157 (Fig. 15) and thereby reduce the amount of other fuel required. Since the output through the stator windings 37, 38, 40 of the alternators 2, 4 permits sufficient gas to be produced to meet the instantaneous demand, it is not necessary to store any gas, or to transport it on the vehicle 147 with the attendant risk of explosion.

The larger diameter wore windings 37, 38, 40 may be of 3.16mm diameter wire and using for each phase a 5 metre length, so requiring about 15 metres.

Fig. 7 shows a second embodiment which is similar to the first but a third alternator 5 is provided co¬ axially with the first and second alternators 2, 4. The first and second alternators 2, 4 are identical to the first embodiment but the stators 35, 36 do not include windings 39, 41 connected to the battery 53. Instead, those windings 39, 41 are provided on the stator 70 of the third alternator 5 which is of conventional design. The pole pieces 28, 29 enclosing the rotor windings 18, 20, 71 of the three alternators 2, 4, 5 are of conventional form and do not comprise separate fingers extending outwardly from a central hub. As mentioned previously, the rotor windings 18, 20 of the first and second alternators 2, 4 are each wound oppositely and the pole pieces 28, 29 are aligned. The rotor winding 71 of the third alternator is wound oppositely to the rotor winding 18 of the first alternator which it is adjacent. The effect of this is to provide maximum opposition between the electro-magnetic fields of the rotor windings 18, 20, 71 so that the field in the region of the stator windings 35, 36, 70 is intensified increasing the current output. The lines of field are shown as dotted lines 99 in the drawing. An additional stator 150 is provided between the first and second stators 35, 36 in the region of intensified field.

The outputs from the first and second alternators 2, 4 can be used for any purpose for which they are suitable and if rectified can be supplied to separate pairs of electrodes in an electrolysis unit 46, for example, as in the first embodiment. An example of such as electrolysis unit is shown in Figs. 8 and 9.

The electrolysis unit tank 110 contains four sets of electrodes indicated generally at 111, 112, 113 and 114. Each set of electrodes 111, 112, 113, 114 comprises a bank of anode electrodes 111a, 112a, 113a, 114a and a bank of cathode electrodes 111b, 112b, 113b, 114b. The electrode sets are connected to the rectifier units 24.

The sets of electrodes 111, 112, 113, 114 are immersed in an electrolyte in the tank 110 which may be an aqueous solution comprising 30% sodium hydroxide, 10% manganese oxide and 1% sulphuric acid. The proportions can vary as desired.

The tank is provided with a lid 118 which includes an inlet 119 and an outlet 120. Solution is fed to the inlet from a reserve tank 122 to maintain a constant level 121 of solution in the tank during electrolysis. Gas produced by electrolysis, that is hydrogen and oxygen, leaves the outlet 120 and passes through a conduit 123 having an outlet end positioned beneath the surface of water in a water valve 124. A pipe 125 has an inlet end located above the surface of the water in a valve 124 and has an outlet end terminating at a manifold 42 of the engine.

Once the engine is running, the alternator produces current which is rectified and then fed at potentials of, e.g. 3 to 4 volts, to the respective electrode sets 111, 112, 113 and 114. If desired the potentials may be different for each set of electrodes. The electrodes may be of stainless steel each set may comprise seven pairs of plates and each plate may measure 2? ins. x 4 ins. (6.3cm x 10.2cm). The spacing between adjacent electrode plates of each set may be around 4.76mm (3/16"). The use of an electrolysis unit as described is particularly advantageous because it enables sufficient gas to be produced to avoid the use of an intermediate storage reservoir between the electrolysis unit and the carburetter. The use of a single electrolyte tank common to all the electrodes makes available more ions for the electrolysis unit as a whole than would be the case if the electrodes were immersed in respective individual containers of electrolyte. The use of the water valve prevents any risk of explosion travelling through the pipe 123 from the engine.

The tank may be made of material such as plastics and can be as small as 152mm (6") wide, 127mm (5") deep and 203mm (8") long.

The electrolysis unit produces gas only while the engine drives the alternator which is another advantage over the gas-storage system where large quantities of gas may still be stored after the engine has been switched off.

The hydrogen and oxygen produced by the unit and fed to the engine produces a reduction in pollutant by¬ products of combustion. A control unit 154 controls a petrol choke 155 in the line from the petrol tank 156 of the vehicle 157 to the engine inlet and also controls an air choke 158 in the manifold 42 air inlet opening. The control unit 154 acts to operate the petrol choke in combination with the air choke so that supplies of air and petrol are reduced in proportion in accordance with engine speed and hence in accordance with the rate of production of hydrogen and oxygen. Pollutant by¬ products are thus further reduced as the amount of petrol used in each engine stroke is reduced as well as being more efficiently combusted.

Preferably the pipe 125 includes a valve 14 which controls the pressure of gas fed to the carburetter. In that way the pressure of the gas fed to the carburetter can be maintained e.g. at around 48.2 k Pa (7 lbs/sq. inch).

The level of electrolyte in tank 10 may be sensed by a sensor 132 a signal from which results in transfer of solution from reserve tank 122 to tank 110.

The output of the vehicle alternator may be used to charge the battery. Fig. 10 shows a partially schematic view of the circuit diagram for the system and for clarity shows only one set of stator windings 39 connected to the battery 53 and only one set of stator windings 37, connected to the electrolysis unit 46. The output from the stator windings 39 is rectified through diodes 24 and is then connected to the rotor windings 18, 20 of the alternators 2, 4 in parallel connection. The output is also connected after the diodes 24 to a voltage regulator 52, which may be a 60 Amp charging regulator, which drops the voltage to the battery voltage to charge the battery 53. Thus the output may be converted e.g. from 24V d.c. at 1A to 12V d.c. at 2A. A switch (not shown) is used to cut the battery 53 out of the circuit.

The battery 53 is also connected across electrodes of the electrolysis unit 46. A control box 75 is also provided in this circuit. The control box 75 is also connected to a sensor 76 which is connected to one of the set of stator windings 39. The sensor 76 provides a signal which is dependent upon the speed of rotation of the rotor windings 18, 20. The control box 75 includes a switch 77 which may be used to manually disconnect the battery 53 from the electrolysis unit 46. The control box 75 also includes a warning light 78, which illuminates when battery power has been disconnected from the electrolysis unit 46. Intially the battery 53 is connected to the rotor windings 18, 20. When the engine is started and the rotor windings 18, 20 are rotated, the current output from the stator windings 39, 41 will rise until it is sufficient for the alternator unit to be self- exciting. That may happen at about 1200 rpm engine speed which is about 3000 rpm rotor speed. The sensor 76 is continuously providing a signal to the control box 75 to indicate the rotor speed and once the signal indicates that the pre-determined rotor speed of self- excitation has been reached, the battery 53 is disconnected from the rotor windings 18, 20 by the control box 75. The battery 53 may now be charged by the stator windings 39, 41 through the voltage regulator 52. Once the engine speed rises to a further, higher, pre-determined level, the control box 75 connects the battery 53 to the electrolysis unit 46. The higher pre-determined level may be about 3000 rpm engine speed which is about 7500 rpm rotor speed. The electrolysis unit 46 is then connected to both the stator windings 37, 38, 40 and the battery 53 to maximise gas output.

When engine speed is reduced to stop the engine, the control box 75 disconnects the battery 53 from the electrolysis unit 46 at the higher pre-determined level as sensed by the sensor and reconnects it to the rotor windings 18, 20 at the lower pre-determined level. The control box 75 then disconnects the battery 53 from the rotor windings 18, 20 when the engine speed drops below a third pre-determined level which may be about 250 rpm engine speed which is about 600 rpm rotor speed.

The control box 75 will also disconnect the battery 53 from the rotor windings 18, 20 and the electrolysis unit 46 if the battery charge drops below a threshold which may be 10 volts.

The alternator assemblies of the first or second embodiments are clearly of general application and, for example, may be used in an oil power station to increase efficiency and decrease pollutants

Claims

1. An alternator unit comprising at least one rotor winding and at least one stator winding, at least part of the output from the or at least one stator winding being connected to the input for the or at least one rotor winding.

2. An alternator unit as claimed in claim 1, wherein the output from the or at least one stator winding is connected to the input for the or at least one rotor winding directly, passing only through a rectifier.

3. An alternator unit as claimed in claim 1 or claim 2, wherein the unit includes a battery.

4. An alternator unit as claimed in claim 3, wherein the battery is connected through switch means to the input to the or at least one rotor winding.

5. An alternator unit as claimed in claim 4, wherein the switch means is arranged to disconnect the battery when the rotor rotational speed is above a pre¬ determined limit.

6. An alternator unit as claimed in claim 5, wherein the said pre-determined limit is about 3000 rpm.

7. An alternator unit as claimed in claim 5 or claim 6, wherein a sensor provides a signal relating to rotor speed to the switch means.

8. An alternator assembly as claimed in any of claims 3 to 7, wherein relay means is provided and is arranged to connect and disconnect the battery to an electrolysis unit.

9. An alternator assembly as claimed in claim 8, wherein the relay means is arranged to connect the battery to the electrolysis unit when the rotor rotational speed is above a pre-determined limit.

10. An alternator unit as claimed in claim 9 wherein the pre-determined limit is about 7500 rpm.

11. An alternator unit as claimed in claim 9 or claim 10, wherein a sensor provides a signal relating to rotor speed to the switch means.

12. An alternator unit as claimed in any of claims 4 to 11 , wherein at least part of the output from the or at least one stator winding is arranged to be connected through a rectifier to the battery thereby to charge the battery.

13. An alternator unit as claimed in claim 12, wherein at least part of the output from the or at least one stator is arranged to be connected to the battery through a voltage regulator.

14. An alternator unit as claimed in claim 12 or claim 13, wherein the alternator unit comprises two alternator assemblies, each alternator assembly comprising a rotor winding and a plurality of stator windings at least part of the output from at least one stator winding of each alternator assembly being connected to the battery and at least part of the output from at least one stator winding of each alternator assembly being connected to a different device.

15. An alternator unit comprising two alternator assemblies, each alternator assembly comprising a rotor winding and a plurality of stator windings, the stator windings of each alternator assembly including at least one stator winding the output from which is connected to a battery and at least one stator winding the output from which is connected to a different device.

16. An alternator unit as claimed in claim 14 or claim

15, wherein the alternator assemblies are mounted adjacently with their rotor windings arranged to rotate about a common axis.

17. An alternator unit as claimed in claim 14, 15 or

16, wherein there are more turns on the or each stator winding the output from which is connected to the battery in one alternator assembly than in the other alternator assembly.

18. An alternator unit as claimed in claim any of claims 14 to 17, wherein the stator windings the outputs from which are connected to the battery are in thinner diameter wire than the other stator windings.

19. An alternator unit as claimed in any of claims 14 to 18, wherein in one alternator assembly there is a plurality of stator windings the outputs from which are connected to the different device and adjacent of those stator windings are wound in an opposite sense.

20. An alternator unit as claimed in claim 19, wherein, in the said one alternator assembly, the or each stator winding the output from which is connected to the battery is wound in an opposite sense to the stator winding adjacent to it.

21. An alternator unit as claimed in any of claims 14 to 20, wherein in one alternator assembly there is a plurality of stator windings connected to the different device and those stator windings are all wound in the same sense.

22. An alternator assembly as claimed in claim 21, wherein in the said alternator assembly, the or each stator winding the output from which is connected to the battery is wound in the same sense to the stator windings which are connected to the different device.

23. An alternator unit as claimed in any of claims 14 to 22, wherein the different device is an electrolysis unit.

24. An alternator unit as claimed in claim 23 or as claimed in claim 8 or any claim dependent upon claim 8, wherein the electrolysis unit is arranged to produce hydrogen and oxygen gases from an aqueous solution.

25. An alternator unit as claimed in claim 24, wherein the electrolyte in the electrolysis unit includes an agent to inhibit polarisation of the electrodes.

26. An alternator unit as claimed in claim 25, wherein the agent is sulphuric acid.

27. An alternator unit as claimed in any of claims 24, 25 and 26, wherein the electrolyte in the electrolysis unit includes an agent to inhibit frothing of the electrolyte.

28. An alternator unit as claimed in claim 27, wherein the agent is manganese oxide.

29. An alternator unit as claimed in any of claims 24 to 28, wherein the electrolyte comprises an aqueous solution of sodium hydroxide.

30. An alternator unit as claimed in any of claims 24 to 29, wherein the composition of the electrolyte is in water, 30% sodium hydroxide, 10% manganese oxide and 1% sulphuric acid.

31. An alternator unit comprising two alternator assemblies, each alternator assembly comprising a rotor winding and a stator winding, the alternator assemblies being mounted adjacently with their rotor windings arranged to rotate about a common axis, each rotor winding being wound in an opposite sense to the other.

32. An alternator unit as claimed in claim 31, wherein a further stator winding is provided between the stator windings of the alternator assemblies.

33. An engine including an alternator unit as claimed in any preceding claim.

34. An engine as claimed in claim 33, wherein the alternator unit is as claimed in any of claims 24 to 30, wherein means is provided for conducting the hydrogen and oxygen gases to the engine intake.

35. An engine as claimed in claim 34, wherein the hydrogen and oxygen gases are conducted to the engine inlet manifold.

36. An engine as claimed in claim 34 or claim 35, wherein fuel choke means is provided for restricting the supply of fuel to the engine.

37. An engine as claimed in claim 36, wherein means is provided for operating the fuel choke means automatically.

38. An engine as claimed in claim 37, wherein the said means operates the fuel choke means in accordance with the rate of production of hydrogen and oxygen gases by the electrolysis unit.

39. An engine as claimed in claim 37, wherein the said means operates the fuel choke means in accordance with engine speed.

40. An engine as claimed in any of claims 36 to 39, wherein the fuel is petrol.

41. An engine as claimed in any of claims 34 to 40, wherein air choke means is provided for restricting the supply of air to the engine.

42. An engine as claimed in claim 41 when dependent on any of claims 36 to 40, wherein control means is provided for operating the air choke means in combination with the fuel choke means so that the supplies of air and fuel are reduced in proportion.

43. A vehicle including an engine as claimed in any of claims 33 to 42.