GB2616260A

GB2616260A - Hydrogen-oxygen powered engine system and associated methods

Info

Publication number: GB2616260A
Application number: GB2202782.5A
Authority: GB
Inventors: Earl Berrow Stephen
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-03-01
Filing date: 2022-03-01
Publication date: 2023-09-06
Also published as: GB202202782D0; WO2023166286A1

Abstract

A hydrogen - oxygen powered engine system 10 is detailed. The system comprises an oxygen container 12, a hydrogen container 14 and an internal combustion engine 16 (ICE). The ICE has a combustion cylinder 20 and piston. The cylinder 20 has no external air intake and receives oxygen and hydrogen at a pressure of less than 200 kPa. The internal combustion engine 16 includes at least one spark plug and a starter motor 22 having a crank speed of at least 700 rpm so that the hydrogen is combustible with the oxygen in the cylinder 20. Unreacted hydrogen and oxygen and/or water vapour/droplets may be returned to the cylinder 20 via a return flow path. An ECU 18 (electronic control unit) may also be used to control the flow of gases to the cylinder through the use of valves 30, 32. A method of converting a hydrocarbon powered engine to a hydrogen-oxygen powered engine is also described.

Description

Hydrogen -Oxygen Powered Engine System and Associated Methods The present invention relates to a power system, in particular to a hydrogen -oxygen powered engine system. The invention further relates to a method of converting a hydrocarbon powered engine system to a hydrogen and oxygen powered engine system, 5 which may have mobile or static applications.

Internal combustion engines are used in most road vehicles, such as cars, vans, and trucks or busses. Such engines are also used to power marine vessels, aircraft and static power generators. Liquid hydrocarbons, such as petrol (also termed gasoline), diesel, or liquefied petroleum gas (LPG), are combusted in the internal combustion engine to turn a crankshaft so as to power the vehicle.

However, combustion of hydrocarbons exhausts carbon dioxide, contributing to global warming, as well as other emissions, such as nitrous oxides (N0x), sulphur oxides (S0x), carbon monoxide (CO) and particle matter which contribute to poisonous air pollution.

Hydrogen can be used in internal combustion engines, and this does not omit carbon dioxide. However, when hydrogen is combusted in air it produces high levels of nitrous oxides, and so contributes to air pollution.

Electric cars can be used which do not produce exhaust gases. However, electric cars are expensive, are inconvenient to charge, and drivers have concern over the range 20 thereof Furthermore, replacing all conventional hydrocarbon vehicles with electric vehicles would take a long time, and would result in great material waste.

Therefore, it would be desirable to provide a power system which is inexpensive, does not exhaust pollutants, and which can be retrofitted to existing road vehicles in a timely fashion.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the present invention, there is provided a road-vehicle power system comprising: an oxygen container including oxygen; a hydrogen container including hydrogen; an internal combustion engine having at least one combustion cylinder and piston, the cylinder having no external air intake and being fluidly communicated with the oxygen container and the hydrogen container so as to receive oxygen and hydrogen at a pressure of less than 200 kPa, the internal combustion engine including at least one spark plug and a starter motor having a crank speed of at least 700 rpm so that the hydrogen is combustible with the oxygen in the cylinder without front-fire or back fire.

By providing on-board containers of oxygen and hydrogen, and having no external air intake, hydrogen can be used in an internal combustion engine without the generation of polluting gases which result from combustion of hydrogen in air. For example, the power system would not generate nitrous oxides due to no nitrogen being present in the cylinder. The engine system is thus non-polluting. Typical starter motors have a crank speed of 300 to 400 rpm. If the oxygen and hydrogen containers were used with an engine which did not have direct injection and had a typical starter motor, then this would cause front fire and/or back-fire. This is since the molecular hydrogen is small and fast enough that it will detonate around and past the intake -exit valve of the slow-moving engine and escape into an intake-exhaust conduit. Detonation of hydrogen within the intake -exhaust conduit and a large noise would result. Using a starter motor with a crank speed of at least 700 rpm prevents or limits such front fire or back-fire.

Preferably, the oxygen and hydrogen may be provided at a pressure of less than 150 kPa.

Beneficially, the internal combustion engine may comprise an intake conduit between 20 the oxygen and hydrogen container and the cylinder, the internal combustion engine configured so that hydrogen and oxygen is drawn into the cylinder from the intake conduit.

Advantageously, the internal combustion engine may be configured so that the oxygen and hydrogen is received directly from the oxygen container and hydrogen container.

In a preferable embodiment, the oxygen and hydrogen containers may contain only oxygen and hydrogen respectively. In particular, the oxygen and hydrogen containers do not contain nitrogen. This prevents the generation of polluting gases, since the byproduct of the oxygen and hydrogen reaction is only water.

Optionally, the starter motor may have a crank speed of less than 900 rpm.

Preferably, the power system further comprises a return flow-path for returning unreacted hydrogen and oxygen and/or water droplets or vapour to the cylinder. The recycling of the hydrogen in this way ensures that all or nearly all of the fuel is burned, compared to around 50% to 55% of hydrocarbon fuel in conventional internal combustion engines. This improves the efficiency of the engine. Additionally, returning water mist droplets can absorb the latent heat in the combustion process in the cylinder, producing steam and adding to the expansion thrust, which increases energy efficiency.

Advantageously, there may be a phase separator in the return flow-path for separating unreacted hydrogen from oxygen, the return flow-path including a hydrogen branch for returning hydrogen separated by the phase separator to the cylinder, and an oxygen branch for returning oxygen separated by the phase separator to the cylinder.

Beneficially, the hydrogen branch and/or oxygen branch may include a regulation valve. 10 This can allow for control of the amount of returning hydrogen, oxygen and/or water vapour to the cylinder.

In a preferable embodiment, the system may further comprise a -condenser or heatexchanger-condenser, for condensing water. This removes at least some of the water vapour from the cycle, to reduce the amount of water received in the cylinder.

Optionally, there may be a first condenser downstream of the combustion cylinder and upstream of the phase separator, and a second condenser on the oxygen branch of the return flow-path. This can increase the amount of water vapour and heat which are removed from the cycle.

Additionally, the system may further comprise a water outlet for discharging condensed 20 water. This allows discharge of condensed water. Unreacted oxygen may also be outputted from the water outlet. Retention of at least some water in the cycle is preferred for exhaust valve lubrication, cooling, and volume expansion purposes.

Preferably, the water outlet may be on the return conduit.

Advantageously, the system may further comprise a filling valve at or adjacent to the 25 oxygen container and hydrogen container. This allows for the filling of oxygen and hydrogen.

Beneficially, the system may further comprise at least one regulation valve between the oxygen and hydrogen containers and the cylinder. This can allow for the amount of oxygen and hydrogen provided to the cylinder to be controlled.

Additionally, the system may further comprise an electronic control unit (ECU) configured to actuate the or each valve between the oxygen and hydrogen containers and the cylinder to provide a determined amount of oxygen and hydrogen to the cylinder. As such, the power output of the engine can be controlled According to a second aspect of the invention, there is provided a vehicle comprising the vehicle power system as claimed in any one of the preceding claims. In particular, the 5 vehicle may be a road vehicle. However, it will be appreciated that water-based and air vehicles may be considered, along with static applications.

According to a third aspect of the invention, there is provided a method of converting a hydrocarbon powered engine system to a hydrogen and oxygen powered engine system, the method comprising the steps of: a) providing a hydrocarbon powered engine system having a hydrocarbon fuel tank and an internal combustion engine including at least one combustion cylinder, a piston, at least one spark plug or compression ignition means, a starter motor having a crank speed of less than 700 rpm, and in particular less than 400 rpm, and an external air intake; b) providing an oxygen container including oxygen, a hydrogen container including hydrogen, and a modified starter motor having a crank speed of more than 700 rpm; c) closing the external air intake; d) installing the oxygen container and hydrogen container and communicating the oxygen container and hydrogen container with the cylinder so as to receive oxygen and hydrogen at a pressure of less than 200 kPa; and e) installing the modified starter motor.

The hydrogen and oxygen containers, and the modified starter motor may be considered 20 to be a conversion system or kit.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a first embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 2 shows a second embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 3 shows a third embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 4 shows a fourth embodiment of a hydrogen -oxygen powered engine 30 system in accordance with a first aspect of the present invention; Figure 5 shows a fifth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 6 shows a sixth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 7 shows a seventh embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 8 shows an eighth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 9 shows a ninth embodiment of a hydrogen -oxygen powered engine 10 system in accordance with a first aspect of the present invention; Figure 10 shows a tenth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 11 shows an eleventh embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; Figure 12 shows a twelfth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention; and Figure 13 shows a thirteenth embodiment of a hydrogen -oxygen powered engine system in accordance with a first aspect of the present invention.

Referring firstly to Figure 1 there is shown a first embodiment of a hydrogen -oxygen 20 powered engine system 10 which comprises an oxygen container 12, a hydrogen container 14, an internal combustion engine 16, and an electronic control unit (ECU) 18 for controlling the function of the engine 16.

The oxygen container 12 contains oxygen, which is diatomic and preferably is in gaseous form, although the oxygen may feasibly be stored as a liquid in some instances. The oxygen container 12 preferably contains only oxygen, and in particular does not contain any nitrogen. The oxygen is preferably stored at a high pressure, which may for example be 200 bar to 900 bar (20 MPa to 90 MPa) although higher or lower pressures may be considered, and so the container 12 may be considered to be a high-pressure storage vessel, chamber or cylinder 20.

Similarly, the hydrogen container 14 contains hydrogen, which is diatomic and preferably is in gaseous form. The hydrogen container 14 contains only hydrogen, and in particular does not contain nitrogen. The hydrogen is preferably stored at a high pressure, which may for example be 200 bar to 900 bar (20 MPa to 90 MPa) although higher or lower pressures may be considered, and so the container 14 may be considered to be a high-pressure storage vessel or cylinder 20.

The internal combustion engine 16 has at least one combustion cylinder 20 and piston. It will be appreciated that the engine 16 may, for example, four, six, eight or more than eight cylinders and pistons. The cylinder 20 and piston are arranged as per a conventional combustion engine. The internal combustion engine 16 in Figure 1 is a four-stroke engine.

The cylinder 20 has no external air intake, and is fluidly communicated with the oxygen container 12 and the hydrogen container 14 so as to receive oxygen and hydrogen therefrom. The oxygen and hydrogen are provided to the cylinder 20 without direct injection since the inlet of the cylinder 20 is open to the intake conduit, although an intake valve may be present, and receives hydrogen and oxygen therefrom. As such, the oxygen and hydrogen are provided under a relatively low pressure, at a pressure of less than 200 kPa, and more preferably at a pressure of less than 150 kPa, and are drawn into the cylinder 20, rather than being injected under high pressure.

The internal combustion engine 16 includes at least one spark plug in or at each cylinder 20, and a starter motor 22 having a crank speed of at least 700 revolutions per minute (rpm) so that the hydrogen is combustible with the oxygen in the cylinder 20 without front-fire or backfire. Preferably the crank speed of the starter motor 22 is less than 900 rpm. Although a spark plug is described, it will be appreciated that compression ignition means may also be considered.

In the first embodiment, the oxygen and hydrogen containers 12, 14 are fluidly communicated with the cylinder 20 via separate oxygen and hydrogen fuel conduits 24, 26, which join to an intake conduit 28 or manifold. There is a first valve 30 between the oxygen container 12 and the oxygen fuel conduit 24, and between the hydrogen container 14 and the hydrogen fuel conduit 26. The first valves 30 are preferably electrically controlled, and may be solenoid safety on/off valves. The first valves 30 are preferably pressure regulated, for example to provide hydrogen and oxygen therethrough at a pressure of 4 bar (400 kPa) or 2 bar (200 kPa). The first valves 30 may also be filling valves for filling the oxygen and hydrogen containers 12, 14.

There is a second valve 32 between the oxygen and hydrogen fuel conduits 24, 26 and the intake conduit 28. Each second valve 32 is preferably a feed valve, and may be solenoid operated or motor operated, for example. Actuation of the second valves 32 may control the acceleration and deceleration of the engine 16, and these may be operated or actuated by the ECU 18.

The intake conduit 28 is fluidly connected to the or each cylinder 20. The intake conduit 28 may have a venturi tube.

A return and water outlet flow-path extends from the cylinder 20 and back to the intake conduit 28. The return and water outlet flow-path may be termed the return conduit. An exhaust valve is preferably between the cylinder 20 and the return conduit.

Downstream of the cylinder 20 and along the return and water outlet flow-path is a first condenser 34 for condensing water vapour from the cylinder 20. The first condenser 34 15 is fluidly communicated with the or each cylinder 20 via a first portion 36 of return conduit.

The first condenser 34 preferably comprises a plurality of baffles, and/or a serpentine, circuitous or tortuous flow path. This arrangement maximises the heat exchange surface area of the condenser and may reduce the speed of the water vapour, promoting condensation and disentailment of moisture. It will be appreciated that in some instances the condenser may be chilled or cooled, so as to promote condensation.

Downstream of the first condenser 34 are second and third portions of return conduit 38, 40.

Downstream of the second and third portions 38, 40, the return conduit preferably branches into a hydrogen branch 42 for returning hydrogen to the cylinder 20, and an oxygen branch 44 for returning oxygen to the cylinder 20. A phase separator 46 is used in the return conduit at the branching of the oxygen and hydrogen branch 42. The phase separator 46 is configured to separate hydrogen into the hydrogen branch 42, and oxygen into the oxygen branch 44. Water droplets and/or uncondensed water vapour may pass into either branch, although the majority of the water may pass into the oxygen branch 44.

The hydrogen branch 42 fluidly communicates with or connects to the intake conduit 28. There is preferably a suction regulation valve 48 and/or a non-return valve in the hydrogen branch 42, which may be a venturi suction regulation valve 48. The suction regulation valve 48 may be a choke valve and/or motorised valve and ensures that unburnt hydrogen goes back to cylinder 20. Additionally or alternatively, the suction regulation valve 48 may regulate the water droplets or vapour. This may control the flow of hydrogen and/or water into the intake conduit 28.

The suction regulation valve 48 may be set to provide a predetermined flow of hydrogen into the intake conduit 28, the predetermined flow based on the volume of the engine 16 and the maximum speed of the engine 16. Alternatively, the flow of hydrogen permitted by the suction regulation valve 48 may be variable and may be actuated by the ECU 18. As such, the suction regulation valve 48 may be communicatively connected to the ECU 18. The ECU may adjust the hydrogen feed valve 30 based on the amount of hydrogen provided by the suction regulation valve 48.

At least one oxygen mass flow sensors may be included and also communicatively connected to the ECU 18. The oxygen mass flow sensor may measure the flow of oxygen through the oxygen fuel conduit 24. The ECU 18 may therefore set the flow of hydrogen permitted by the suction regulation valve 48 and/or hydrogen feed valve 30 dependent on readings from the oxygen mass flow sensor.

The oxygen branch 44 includes a second condenser 50 for condensing water vapour and cooling oxygen. The oxygen branch 44 also includes a water outlet 52, which may be infrared controlled. This is since there may be a container for holding a reservoir of water at the water outlet 52. When the infrared sensor determines that the container is full, the reservoir may be emitted via the water outlet and/or may be pumped to an outside portion of the engine to be evaporated. The water outlet 52 may include a water-outlet valve 54, which may be a pressure regulation safety valve and/or a non-return valve.

Between the second condenser 50 and the intake conduit 28 there is preferably a flow regulation valve 56 or venturi valve.

In use, the starter motor 22 moves the or each piston and fires the or each spark plug. 30 The second valve 32 is opened, for example via instruction from the ECU 18, which allows for hydrogen and oxygen to be provided or drawn into the intake conduit 28 from the hydrogen and oxygen containers 12 and then into the cylinder 20. The hydrogen and oxygen may be provided or presented into the intake conduit 28 and then into the cylinder 20 via positive and/or vacuum pressure. Unreacted hydrogen and/or oxygen, and water vapour or droplets, also are provided or drawn into the intake conduit 28 from the oxygen and hydrogen branches 40, 42 and via the relevant valves 48, 56, which may also be controlled by the ECU 18.

Hydrogen and oxygen are mixed at a stoichiometric amount or ratio of around 2:1 to 17.4:1 in the intake conduit 28 and/or the or each cylinder 20.

Hydrogen and oxygen gas pressures can be regulated to obtain the same pressures as a turbo charger, which is about 6 psi (around 40 kPa) above standard atmospheric pressure and/or a super charger 9 psi (around 62 kPa) above standard atmospheric pressure. It is possible to go up to and over 30 psi (around 200 kPa) above atmospheric pressure. This may be achieved by setting the first valves 30 to permit higher pressures of oxygen and hydrogen to be released from the hydrogen and oxygen containers 12, 14.

The hydrogen is reacted with the oxygen in the or each cylinder 20 by way of the firing of the or each spark plug. The hydrogen and oxygen may react in primary and secondary detonation events. This may move the piston in the or each cylinder 20 in a conventional internal-combustion-engine manner and the movement of the pistons drives a crankshaft to provide rotary motion.

A detonation occurs when the flame velocity reaches supersonic speeds above 600 m/s and generally in the 2000 to 2500 m/s range. Peak overpressures can be 20 to 100 times the initial pressure, with typical values of greater than 20 bar (2000 kPa) The primary detonation event is an implosion, and so generates a vacuum. This is due to the rapid reduction in pressure as the hydrogen and oxygen form water. This draws 25 the piston upwards.

The secondary detonation event is rapid expansion as the heat from the bonding of the atoms to form water and/or steam causes expansion of the gases in the cylinder 20. This includes steam, which has an expansion ratio compared to water of around 1200:1, and ambient unused oxygen. The expansion of the steam provides greater efficiency. The piston is thus forced downwards in the cylinder 20.

Unreacted hydrogen and oxygen, along with the produced water vapour, travel out of the cylinder 20 via the exhaust valve and along the first portion 36 of the return conduit and into the first condenser 34. The steam vapour helps to lubricate the exhaust valve and maintain a lower temperature which is important since hydrogen burns at a higher temperature than typical hydrocarbons such as petrol, diesel, liquefied petroleum gas, butane or propane. A muffler may also be provided here which may slow piston shock waves or fluid flow and start the heat loss to cause condensation of steam. The temperature drop created here is expected to cause condensation of steam to dew point or mist.

In the first condenser 34, at least some of the water vapour condenses. The condensed water may flow as a liquid along the return conduit to the water outlet 52, and therefore the return conduit may have a slope to the water outlet 52 to facilitate this.

The unreacted hydrogen and oxygen, and remaining water vapour then travels along the second and third return conduit portions 38, 40. Along these sections 38, 40, the hydrogen and oxygen phase separate and reach the phase separator 46 where hydrogen is directed into the hydrogen branch 42, and oxygen is directed into the oxygen branch 44. Water vapour is preferably also directed into the hydrogen branch and/or the oxygen branch 44, where it condenses in the second condenser 50 and flows to the water outlet 52 to be emitted via the valve.

The unreacted hydrogen and oxygen, and water vapour or droplets, can be provided from the hydrogen and oxygen branches 44 via the respective valves 48, 56 into the intake conduit 28. The valves 48, 56 may be operated by the ECU 18 in response to acceleration demands and/or the flow of gases in the intake conduit 28.

The described hydrogen -oxygen powered engine system 10 may be provided for new vehicles, and in particular road vehicles. Alternatively, and with greater relevance for the present time, the power system 10 may be retrofitted to pre-existing road vehicles with conventional internal combustion engines. This may be achieved via providing a hydrocarbon powered vehicle having a hydrocarbon fuel tank and an internal combustion engine including at least one combustion cylinder 20, a piston, at least one spark plug, and a starter motor having a crank speed of less than 700 rpm, and in particular less than 400 rpm. The engine would also have an external air intake to the cylinder 20, to allow combustion of the hydrocarbon fuel in air.

An oxygen container 12, including oxygen, and a hydrogen container 14, including hydrogen, would be fitted to replace the function of the hydrocarbon fuel tank, although the hydrocarbon fuel tank may be left in place if so desired. A modified starter motor 22 having a crank speed of more than 700 rpm would be fitted to replace the starter motor 22 having a crank speed of less than 400 rpm. The external air intake to the cylinder 20 would need to be closed to prevent nitrogen from the air reacting with oxygen in the cylinder 20.

The oxygen container 12 and hydrogen container 14 would be communicated with the cylinder 20 so that hydrogen and oxygen are provided thereto. A return conduit would 10 then be installed, including the condensers and water outlet 52.

Although described as being for vehicles, the engine system 10 may also have static applications.

Referring now to Figure 2, there is shown a second embodiment of a hydrogen -oxygen powered engine system 10. The second embodiment is similar or identical as the first embodiment, except the engine 16 is a two-stroke engine. As such, the intake conduit 28 connects to the or each cylinder 20 in a different position, and the return conduit is configured correspondingly.

Referring now to Figure 3, there is shown a third embodiment of a hydrogen -oxygen powered engine system 10. The third embodiment is similar or identical as the first embodiment, except there is no retum conduit. Instead, the water vapour passes through an exhaust conduit, into a condenser and out of the water inlet. Additionally, the hydrogen and oxygen are provided directly to the or each cylinder 20, rather than via an intake conduit 28.

The hydrogen and oxygen are provided into the cylinder 20 at a stoichiometric amount 25 or ratio of 2:1. A sensor can be fitted on the inlet port to allow the valves to measure the exact amount of hydrogen and oxygen to be presented to the cylinder 20. Such a modification may also be used in the other embodiments.

When retrofitting the third embodiment to an engine 16, an inlet valve may be removed, or fixed in an open condition, or allowed to open and close. This may also apply to the 30 other embodiments.

A spark plug 58 is shown in this embodiment, although it will appreciated that it may be present in the other embodiments.

Referring now to Figure 4, there is shown a fourth embodiment of a hydrogen -oxygen powered engine system 10. The fourth embodiment is similar or identical to the first embodiment, except that hydrogen is directly provided to the or each cylinder 20. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 5, there is shown a fifth embodiment of a hydrogen -oxygen powered engine system 10. The fifth embodiment is similar or identical to the first embodiment, except that hydrogen and oxygen is directly provided to the or each cylinder 20. Although the hydrogen and oxygen are shown to be provided via separate fuel conduits, it will be appreciated that a single fuel conduit may be considered. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 6, there is shown a sixth embodiment of a hydrogen -oxygen powered engine system 10. The sixth embodiment is similar or identical to the fifth embodiment, except that recycled hydrogen and/or oxygen are provided via the hydrogen and oxygen branches 42 44 of the return conduit separately and directly into the cylinder 20. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 7, there is shown a seventh embodiment of a hydrogen -oxygen powered engine system 10. The seventh embodiment is similar or identical to the sixth embodiment, except that the hydrogen and oxygen fuel conduits 26, 24 merge into a single fuel conduit before the cylinder 20. The hydrogen branch 42 of the return conduit also merges into the single fuel conduit. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 8, there is shown an eighth embodiment of a hydrogen -oxygen powered engine system 10. The eighth embodiment is similar or identical to the first embodiment, except that there is no oxygen branch of the return conduit as such, and no second condenser. Instead, hydrogen is phase separated by the phase separator 46 and returned to the intake conduit 28 via the suction regulation valve 48. The oxygen and water is exhausted via the outlet.

Referring now to Figure 9, there is shown a ninth embodiment of a hydrogen -oxygen powered engine system 10. The ninth embodiment is similar or identical to the eighth embodiment, except that it is a two-stroke engine 16, rather than a four-stroke engine 16.

Referring now to Figure 10, there is shown a tenth embodiment of a hydrogen -oxygen powered engine system 10. The tenth embodiment is similar or identical to the eighth embodiment, except that hydrogen is directly provided to the or each cylinder 20. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 11, there is shown an eleventh embodiment of a hydrogen -oxygen powered engine system 10. The eleventh embodiment is similar or identical to the eighth embodiment, except that hydrogen and oxygen is directly provided to the or each cylinder 20. Although the hydrogen and oxygen are shown to be provided via separate fuel conduits, it will be appreciated that a single fuel conduit may be considered.

This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 12, there is shown a twelfth embodiment of a hydrogen -oxygen powered engine system 10. The twelfth embodiment is similar or identical to the eleventh embodiment, except that recycled hydrogen is provided via the return conduit directly into the cylinder 20. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Referring now to Figure 13, there is shown a thirteenth embodiment of a hydrogen -oxygen powered engine system 10. The thirteenth embodiment is similar or identical to the twelfth embodiment, except that the hydrogen and oxygen fuel conduits 22, 24 merge into a single fuel conduit before the cylinder 20. The hydrogen branch 42 of the return conduit also merges into the single fuel conduit. This engine may have low pressure gas presentation into the cylinder on the suction stroke but not via the inlet valve.

Although the starter motor is described as having a crank speed of at least 700 rpm, it will be appreciated that lower crank speeds may be considered, such as those of at least 30 500 rpm or at least 600 rpm.

Although the oxygen and hydrogen are described as being provided at a pressure of less than 200 kPa, it will be appreciated that higher pressures may be considered, such as pressures of up to 400 kPa.

Although road vehicle applications are described, it will be appreciated that the disclosed 5 principles of using onboard oxygen and hydrogen containers provided to a combustion chamber at a low pressure and with a high revolution starter motor may also be used with gas turbine, jet engines and rotary engines.

It is therefore possible to provide a hydrogen -oxygen powered engine system which is adaptable or retrofittable to internal combustion engines of conventional hydrocarbon powered vehicles. Onboard hydrogen and oxygen containers with no air intake allows for the use of a hydrogen combustion engine which does not produce pollutants, such as nitrous oxides, carbon monoxide, and/or sulphur oxides. The hydrogen and oxygen can be provided at a low pressure and yet can still be detonated via the spark plugs without front fire or backfire due fluid dynamics provided by the use of a high revolution starter motor.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 2. 6A hydrogen -oxygen powered engine system comprising: an oxygen container including oxygen; a hydrogen container including hydrogen; an internal combustion engine having at least one combustion cylinder and piston, the cylinder having no external air intake and being fluidly communicated with the oxygen container and the hydrogen container so as to receive oxygen and hydrogen at a pressure of less than 200 kPa, the internal combustion engine including at least one spark plug and a starter motor having a crank speed of at least 700 rpm so that the hydrogen is combustible with the oxygen in the cylinder without front-fire or back-fire.
A hydrogen -oxygen powered engine system as claimed in claim 1, wherein the oxygen and hydrogen are provided at a pressure of less than 150 kPa.
A hydrogen -oxygen powered engine system as claimed in claim 1 or claim 2, wherein internal combustion engine comprises an intake conduit between the oxygen and hydrogen container and the cylinder, the internal combustion engine configured so that hydrogen and oxygen is drawn into the cylinder from the intake conduit.
A hydrogen -oxygen powered engine system as claimed in claim 1 or claim 2, wherein the internal combustion engine is configured so that the oxygen and hydrogen is received directly from the oxygen container and hydrogen container.
A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, wherein the oxygen and hydrogen containers contain only oxygen and hydrogen respectively.
A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, wherein the starter motor has a crank speed of less than 900 rpm.
A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, further comprising a return flow-path for returning unreacted hydrogen and oxygen and/or water droplets or vapour to the cylinder.
8 A hydrogen -oxygen powered engine system as claimed in claim 7, wherein there is a phase separator in the return flow-path for separating unreacted hydrogen from oxygen, the return flow-path including a hydrogen branch for returning hydrogen separated by the phase separator to the cylinder, and an oxygen branch for returning oxygen separated by the phase separator to the cylinder.
9. A hydrogen -oxygen powered engine system as claimed in claim 8, wherein the hydrogen branch and/or oxygen branch includes a regulation valve.
10. A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, further comprising a condenser for condensing water.
11.A hydrogen -oxygen powered engine system as claimed in claim 10 when dependent on claim 8, wherein there is a first condenser downstream of the combustion cylinder and upstream of the phase separator, and a second condenser on the oxygen branch of the return flow-path.
12. A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, further comprising a water outlet for discharging condensed water.
13. A hydrogen -oxygen powered engine system as claimed in claim 12, wherein the water outlet is on the retum conduit.
14. A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, further comprising a filling valve at or adjacent to the oxygen container and hydrogen container.
15. A hydrogen -oxygen powered engine system as claimed in any one of the preceding claims, further comprising at least one regulation valve between the oxygen and hydrogen containers and the cylinder.
16. A hydrogen -oxygen powered engine system as claimed in claim 15, further comprising an electronic control unit (ECU) configured to actuate the or each valve between the oxygen and hydrogen containers and the cylinder to provide a determined amount of oxygen and hydrogen to the cylinder.
17. A vehicle comprising the hydrogen -oxygen powered engine system as claimed in any one of the preceding claims.
18. A road vehicle comprising the hydrogen -oxygen powered engine system as claimed in any one of claims 1 to 16.
19 A method of converting a hydrocarbon powered engine system to a hydrogen -oxygen powered engine system, the method comprising the steps of: a) providing a hydrocarbon powered engine system having a hydrocarbon fuel tank and an internal combustion engine including at least one combustion cylinder, a piston, at least one spark plug or compression ignition means, a starter motor having a crank speed of less than 700 rpm, and an external air intake; b) providing an oxygen container including oxygen, a hydrogen container including hydrogen, and a modified starter motor having a crank speed of more than 700 rpm; c) closing the external air intake; d) installing the oxygen container and hydrogen container vehicle and communicating the oxygen container and hydrogen container with the cylinder so as to receive oxygen and hydrogen at a pressure of less than 200 kPa; and e) installing the modified starter motor.