GB2529402A

GB2529402A - Generator unit

Info

Publication number: GB2529402A
Application number: GB1414591.6A
Authority: GB
Inventors: David Duerden
Original assignee: JET PROPULSION SYSTEMS Ltd
Current assignee: JET PROPULSION SYSTEMS Ltd
Priority date: 2014-08-18
Filing date: 2014-08-18
Publication date: 2016-02-24
Also published as: GB201414591D0

Abstract

A generator unit 10 comprises a compressor 12, a plurality of combustion units 30 each being connected to the compressor so as to receive compressed air there from, each combustion unit 30 including a fuel inlet 36 and an ignition means 38 for igniting a fuel/air mix located within the combustion unit 30. Each combustion unit 30 includes an exhaust 34 whereby combustion products are supplied from the combustion unit 30 to an associated turbine 40, the turbine 40 being operable to drive an electrical generator 28 and also to drive the compressor. It is particularly envisaged that the generator could be used to supply electrical power to an electrical motor associated with one or more wheels of an road vehicle. Also claimed is such a vehicle.

Description

GENERATOR UNIT

This invention relates to an electrical generator unit, and in particular to a gas turbine engine powered electrical generator unit, for example for use in supplying electrical power to an S electrically driven road vehicle.

Electrically driven road vehicles are becoming increasingly common. Some of these make use of rechargeable batteries, capacitors or the like to store electrical power to be used by electrical motors to drive one or more wheels of the vehicle, the batteries, capacitors or the like being arranged to be charged when the vehicle is not in use by connection to, for example, the mains electricity supply network. Alternatively, the batteries, capacitors or the like may be removable and once the charge therein has been used they may be removed and replaced with pre-charged batteries, capacitors or the like.

An alternative form of vehicle is a hybrid vehicle which includes) for example) an internal combustion engine operable to drive an electrical generator, the output of which is used to power electrical motors to drive one or more wheels of the vehicle for movement. In some arrangements, drive from the engine may further be capable of being applied to the wheels of the vehicle. In such an arrangement, where the engine is being used to generate electricity, the engine can be driven at a speed at which it is of good efficiency, rather than at speeds associated with the desired speed of the vehicle, and as a result, fuel savings can be made compared to conventionally powered vehicles.

It is thought that the use of a gas turbine engine would be of benefit in supplying power to a vehicle as it may allow further efficiencies to be made. Vehicles have been manufactured in the past in which the output of a gas turbine engine is supplied, via a suitable gearbox, to the wheels of a vehicle. However, such a vehicle is relatively difficult to control as the responsiveness of the gas turbine engine to changes in demand is relatively poor.

It is an object of the invention to provide an electrical generator unit whereby at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

A further object of the invention is to provide a drive system for a vehicle in which such a generator unit is employed.

According to the present invention there is provided a generator unit comprising a compressor, a plurality of combustion units each being connected to the compressor so as to receive compressed air therefrom, each combustion unit including a fuel inlet and an ignition means for igniting a fuel/air mix located within the combustion unit, and each combustion unit including an exhaust whereby combustion products are supplied from the combustion unit to an associated turbine, the turbine being operable to drive an electrical generator and also to drive the compressor.

It will be appreciated that, in such an arrangement, one or more of the combustion units and associated turbines may be operated independently of another of the combustion units with the result that the output of the generator unit can be varied. By way of example, one or more of the combustion units may be switched off' by terminating the fuel supply thereto and/or switching off the associated ignition means, with the result that the output of the generator unit as a whole is reduced.

Conveniently, each turbine is a multi-stage turbine comprising a first stage turbine unit connected to the exhaust from the combustion unit, and a second stage turbine unit connected to an outlet of the first stage turbine unit. One or more further stage turbine units could be provided if desired. As each turbine unit receives just the exhaust gases from the associated combustion unit, each turbine unit can be relatively small. It is thought that mass produced turbine units already in production for other purposes, for example for use with the internal combustion engines of road vehicles, may be used.

In order to reduce drag or frictional losses within the generator unit, it may be desired to incorporate clutch mechanisms or the like to disconnect the turbine units associated with the combustion units not in use at any given time from the electrical generator. However) arrangements in which no such clutch mechanisms are provided are envisaged, and it is thought that the air flow through the combustion units not in use at any given time will be sufficient to rotate the turbines of the associated turbine units, and so such frictional losses are thought to S be relatively low.

The output of the electrical generator is conveniently used to supply electrical power to one or more electrical motors associated with one or more wheels of a road vehicle. By way of example, the road vehicle may comprise a motor car. However, the invention could alternatively be applied to, for example, heavy goods vehicles or the like.

By way of example, the output of the electrical generator may be supplied to a power controller operable to control the supply of electrical power to the motor and to control the charging of a power store in the form of, for example, a capacitor bank or a rechargeable battery. A control unit may be operable, based upon demand information derived from, for example, accelerator and brake pedals or the like and information relating to the current level of charge stored in the power store, to determine a required output level from the generator unit and to control the operation of the generator unit accordingly. The control unit may also control the operation of the power controller to determine the proportion of the power requirement of the motor that is to be satisfied from the power store and the proportion to be satisfied from the output of the generator unit. Any excess supply from the generator unit can be supplied to the power store, increasing the charge level thereof.

Potentially, for example when the vehicle is to be slowed, a kinetic energy recovery system may be employed to permit additional electrical energy to be generated and stored within the power store for subsequent use.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded diagrammatic representation of a generator unit in accordance with an embodiment of the invention; and Figure 2 is a diagrammatic representation illustrating elements of a drive system for a road S vehicle incorporating the generator unit of Figure 1.

Referring firstly to Figure 1, an electrical generator unit 10 is illustrated. The generator unit 10 comprises a compressor housing 12 in the form of a hollow tapering tubular body 14, an end of which is closed by an end wall 16. The inner surface of the body 14 is provided with a series of fixed vanes 18 which cooperate with moveable vanes 20 provided upon the exterior of a compressor rotor 22 such that, upon rotation of the rotor 22, air is drawn into the compressor housing 12 and is supplied under pressure through outlets 24 formed in the end wall 16. As illustrated, the rotor 22 is mounted upon a drive shaft 26 supported by suitable bearings (not shown) or the like, the drive shaft 26 being connected to an output of an electrical motor/generator 28.

Connected to each outlet 24 is an associated combustion unit 30 (only one of which is shown in Figure 1). The combustion units 30 could be connected directly to the end wall 16 and associated outlets 24. Alternatively, they may be interconnected by suitable ducts or the like.

Each combustion unit 30 comprises a tubular housing 32 connected at one end so as to receive the compressed air leaving the compressor housing 12 through the associated outlet 24, and defining at an opposite end thereof an exhaust outlet 34. The interior of the combustion unit housing 32 defines a combustion chamber to which fuel is supplied via a fuel injection nozzle 36. The fuel is preferably a gaseous fuel, for example it could comprise methane, hydrogen gas or a range of other suitable materials. The combustion unit 30 further comprises an ignition means 38, for example in the form of an electrically operated spark discharge device, whereby the fuel/air mixture located within the combustion chamber is ignited, in use.

The combustion of the pressurised fuel/air mixture within the combustion unit 30 results in the generation of exhaust gases which leave the combustion chamber through the exhaust outlet 34 under high pressure, in use.

S Connected to the exhaust outlet 34so as to receive the pressurised exhaust gases therefrom is a multi-stage turbine arrangement 40 comprising a first stage turbine unit 42 and a second stage turbine unit 44 connected in series. Exhaust gases exiting the combustion chamber thus enter the first stage turbine unit 42, driving a rotor (not shown) thereof for rotation. The rotor is mounted upon a rotor shaft 46 which, in turn, carries a gear 48 positioned so as to mesh with a sun gear 50 mounted upon an extension to the drive shaft 26so that rotation of the rotor of the first stage turbine unit 42 results in rotation of a rotor of the motor/generator 28 resulting in the generation of electricity thereby.

As the first stage turbine unit 42 will not be able to extract all of the energy from the exhaust gases exiting the combustion unit 30, a significant quantity of extractable energy still being present in the flow of exhaust gases exiting the first stage turbine unit 42, these gases are supplied to the second stage turbine unit 42, after having had water under pressure supplied thereto by a water injector 60 to result in the generation of steam, to cause rotation of a rotor shaft 52 and gear 54 associated therewith, assisting in driving the sun gear 50 for rotation and so further enhancing the generation of electricity by the generator unit 10.

The sun gear 50 also meshes with the gears 48,54 associated with the turbine arrangements 40 in turn associated with the other combustion units 30 of the generator unit 10. The sun gear 50 and gears 48, 54 associated with the various turbine arrangements 40 are conveniently located within a common gearbox 56. An oil pump 58 may be provided to supply lubricating/cooling oil to the gearbox 56 and gears contained therein and other moving parts of the generator unit 10, the pump 58 being driven from the sun gear 50.

The compressor is conveniently a cold compressor, and so the compressor housing 12, rotor 22 and vanes 18, 20 may be of, for example, moulded plastics material, or plastics composite material form. The first and second stage turbine units 42, 44 are conveniently scroll type turbine units. As the capacity of the units 42)44 may be relatively small) it is thought that mass produced scroll turbine units intended for other purposes, for example for use with road vehicle internal combustion engines, may be used. Such an arrangement may lead to cost savings.

S Furthermore, the use of a number of small turbines rather than a single large turbine allows packaging of the generator unit within a relative small space.

However, this need not be the case and bespoke components could be used if desired. Of course, in the conventional use of automotive turbines, the turbines are only driven by the energy resulting from the exhaust gas velocity post combustion and extraction of energy by the piston, whereas in the present invention they receive directly the energy from combustion and so form an integral part of the engine'. In addition to the gas velocity there is also an expansion element that results in more power directly impinging on the turbine rotor than when used in traditional automotive applications. is

The use of turbines in the generation of electricity for use in automotive applications is not new.

The current generation of Formula 1 cars include turbines to generate electricity from exhaust gases. However, as mentioned above, such turbines are extracting residual energy after the engine pistons have been driven.

In use, in order to start the generator unit 10 power is supplied to the motor/generator 28 to drive the shaft 24 and rotor 22 for rotation. The rotation of the rotor 22 results in the supply of air under pressure to the combustion units 30. Once the supply of air under pressure to the combustion units 30 has commenced, the supply of power to the motor/generator 28 can be interrupted. The addition of fuel to the air supplied to the combustion units 30, and the ignition of the resulting fuel/air mix results in the generation of high pressure exhaust gases which pass through the turbine arrangements 40 as described hereinbefore, resulting in the rotation of the sun gear 50 which in turn drives the motor/generator 28 for the generation of electricity.

A control unit (see below) controls which, or how many) of the combustion units 30 receive fuel at any given time, and so controls the level of electrical generation occurring at any given time.

By interrupting the flow of fuel to one or more of the combustion units 30 to reduce the overall level of generation whilst leaving the remaining combustion units 30 operating normally, it will S be appreciated that each combustion unit 30 can be operated at or around its most efficient level.

In the present invention, the turbines are used to generate electricity from the operation of a gas turbine engine in a manner that allows a good degree of control over the generation of electricity. The use of a gas turbine engine as the primary driver allows harnessing of the improved efficiencies and potential reduced emissions that these units can obtain particularly when using gaseous fuels, over conventional internal combustion piston engines. The particular advantage of the present invention is that in addition to the switching capability already mentioned, low combustion temperatures and the catalysing effect of the steam in the second stage unit lead to further emissions improvements.

Turning to Figure 2, a drive system for a road vehicle which makes use of the generator unit 10 described hereinbefore is illustrated. The drive system comprises a fuel store 70 arranged to supply fuel via a generator control unit 72 to the generator unit 10 for use as described hereinbefore for the generation of electricity. The generated electricity is supplied to a power controller 74. The generator control unit 72 controls which or how many of the combustion units 30 of the generator unit 10 are to receive the fuel as denoted by dashed line 76 in Figure 2.

The power controller 74 is connected both to the generator unit 10 and to a power store 78. It is envisaged that the power store 78 will comprise a bank of capacitors as such a power store allows rapid charging and discharging, tends to have a relatively long working life, and has a good storage capacity for a given volume. Whilst it is envisaged that the power store 78 will comprise a capacitor bank, itwill be appreciated that the invention is not restricted in this regard and could take other forms. By way of example, it could comprise a rechargeable battery or the like.

Furthermore, the power controller 7415 connected to one or more electrical motors 80 operable to drive one or more wheels 82 of a road vehicle for rotation. Conveniently, the motor output is supplied directly to the wheels. However, arrangements are also possible in which other components are provided therebetween, for example gear boxes, differentials or other devices may be included, depending upon the design of the vehicle with which the drive system is to be used.

A control unit 84 is provided and is arranged to supply control signals 90, 92 to the generator control unit 72 and the power controller 74 depending upon inputs received from brake and accelerator pedals 86a, 86b and upon information 88 indicative of the level of energy stored within the power store 78.

In use, using inputs from the brake and accelerator pedals 86a, 86b and the information 88 relating to the charge level of the power store 78, the control unit 84 determines whether or not the power store 78 will be able to satisfy the needs of the motor 80 at anygiven time. If the power store 78 contains sufficient energy then the control unit 84 may instruct the power controller 74 to supply the motor 80 using energy solely from the power store 78. If, on the other hand, the power store 78 contains insufficient stored energy to satisfy the demand then the control unit 84 instructs the generator control unit 72 accordingly with the result that operation of the generator unit 10 commences to supply electrical power to the power controller 74. The power controller 74, under the control of the control unit 84, then controls the supply of electrical energy to the motor 80 and charging/discharging of the power store 78.

It will be appreciated that the generator control unit 72 may further control the number of combustion units 30 of the generator unit 10 in use at any given time, to thereby control the output of the generator unit 10.

Preferably, the control unit 84 is further capable of controlling the system such that under appropriate conditions, such as when the vehicle is slowing, the motor 80 can operate in a generator mode, the output of which is used to charge the power store 78, thereby enhancing the fuel efficiency of the system.

Appropriate anti-lock braking systems and/or traction control systems may also be employed in S the system if desired.

It will be appreciated that the invention is beneficial in that it allows the generation of electricity using a gas turbine engine in a relatively simply and convenient manner, permitting some control over the rate of generation. The generator unit is relatively low in weight and relatively compact and so is suitable for use in road vehicles. As a number of the component parts of the generator unit may be off-the-shelf components, it will be appreciated that the unit may be relatively low in cost and simple to maintain. A vehicle using the generator unit as part of its drive system may be of good fuel efficiency. Depending upon the choice of fuel used, it may produce little in the way of harmful or undesirable emissions. Furthermore, since each combustion unit can be operated at its most efficient level, overall fuel efficiency can be maximised and the production of undesirable emissions minimised.

Whilst a specific embodiment of the invention is described hereinbefore, it will be appreciated that a wide range of modifications or alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A generator unit comprising a compressor, a plurality of combustion units each being connected to the compressor so as to receive compressed air therefrom, each combustion unit S including a fuel inlet and an ignition means for igniting a fuel/air mix located within the combustion unit, and each combustion unit including an exhaust whereby combustion products are supplied from the combustion unit to an associated turbine, the turbine being operable to drive an electrical generator and also to drive the compressor.
2. A generator unit according to Claim 1, further comprising a control unit operable to control which or the number of combustion units and associated turbines operating at a given time.
3. A generator unit according to Claim 1 or Claim 2, wherein each turbine is a multi-stage turbine arrangement comprising a first stage turbine unit connected to the exhaust from the combustion unit, and a second stage turbine unit connected to an outlet of the first stage turbine unit.
4. A generator unit according to Claim 3, further comprising one or more further stage turbine units.
5. A generator unit according to Claim 3 or Claim 4, wherein each turbine unit is an off-the-shelf component.
6. A generator unit according to any of Claims 3 to 5, further comprising clutch means operable to disconnect the turbine units associated with the combustion units not in use at any given time from the electrical generator.
7. A generator unit according to any of the preceding claims and operable to supply electrical power to an electrical motor associated with one or more wheels of a road vehicle.
8. A generator unit according to Claim 7, wherein the output of the electrical generator is S supplied to a power controller operable to control the supply of electrical power to the motor and to control the charging of a power store.
9. A generator unit according to Claim 8, wherein the power store is in the form of a capacitor bank or a rechargeable battery.
10. A generator unit according to Claim 8 or Claim 9, wherein a control unit is operable, based upon demand information derived from accelerator and brake pedals or the like and information relating to the current level of charge stored in the power store, to determine a required output level from the generator unit and to control the operation of the generator unit accordingly.
11. A generator unit according to Claim 10, wherein the control unit also controls the operation of the power controller to determine the proportion of the power requirement of the motor that is to be satisfied from the power store and the proportion to be satisfied from the output of the generator unit.
12. A road vehicle incorporating a generator unit according to any of the preceding claims.