REACTION TURBINE ENGINE

The present invention relates to engines and relates particularly, but not exclusively, to engines used in combined heat and power generators .

In our earlier patent application, published as WO02/059469, the disclosure in which is incorporated herein by reference, an engine which could typically be used for the generation of electricity, was described. The device has a compression fan that is mounted coaxially within a reaction member. Fuel and air are compressed within the compression fan, exit the compression fan radially and are burnt within the reaction member causing it to rotate.

In the device disclosed in WO02/059469 the reaction member includes a plurality of vanes between which the fuel is burnt. In order for the device to work as efficiently as possible, it is necessary for the reaction member to rotate at high speeds with fuel burning at high temperatures. As a result, the cooling of the reaction member is complex and some of the components of the reaction member, in particular the vanes, have to be constructed from materials capable of withstanding extremely high temperatures and stresses . This makes the construction process complex and requires the use of expensive materials.

Preferred embodiments of the present invention seek to overcome disadvantages of the prior art, including, but not limited to, those set out above.

According to the present invention there is provided an engine comprising:

a housing having at least one inlet and at least one outlet;

a compression fan adapted to rotate in a first sense to cause compression of at least one of at least one oxidising fluid and a mixture of at least one oxidising fluid and at least one fuel; and

a reaction member mounted substantially coaxially with said compression fan and comprising a single combustion zone, wherein the reaction member is adapted to receive the or each compressed oxidising fluid or mixture from said compression fan and the or each mixture or the or each oxidising fluid mixed with at least one fuel is burnt within said combustion zone and gases produced by said burning are directed to cause said reaction member to rotate in a second sense opposite to said first sense.

By using a single combustion zone in an engine of the type defined above, the advantage is provided that all of the surfaces of the reaction member which come into contact with combusted, and therefore very hot, gases have external surfaces to which cooling can be easily applied. Furthermore, a single combustion zone can be created in the form of a hollow disc by partially welding along the edges of two substantially circular sheets of metal. This is significantly easier than the process of forming the reaction member of the prior art . In particular, because the vanes have been removed, the reaction member can be formed from significantly fewer components, which can be easily constructed and components which can be easily cooled. The decrease in the number of components also reduces the weight of the reaction member which in turn reduces its inertia.

The reaction member may further comprise a plurality of nozzles which direct the gases produced by said burning so as to cause said reaction member to rotate.

The reaction member may further comprise a pair of side walls having a substantially saw toothed outer edge in which first sections of said edges are connected together and second sections of said edges form said nozzles.

By forming a reaction member with nozzles which result from the joining together of edges of a pair of saw tooth shaped discs, the advantage is provided that the reaction member can be formed from simply welding two sheets of a suitable material along alternate edges of the saw tooth so as to form roughly triangular nozzle shapes. This results in the same directing of combusted gases out of the reaction member as seen in the prior art forcing them in a direction which is substantially tangential to a radius described by the rotating nozzles. As a result, the simplified device of the present invention is able to produce approximately the same output as the device of the prior art.

In a preferred embodiment the nozzles are formed by attaching nozzle shapers to said second sections of said edges.

By using nozzle shapers to determine the exact dimensions of the output of the nozzles, the advantage is provided that the ideal shape and size of nozzle can be provided to draw the maximum power from the engines.

The engine may further comprise flame control means for controlling the location of the flame formed from combustion of the or each fuel within said reaction member.

In a preferred embodiment said flame control means comprises at least one flame grid.

The device may further comprise mixing means for mixing the or each fuel with the or each oxidising fluid prior to combustion.

In a preferred embodiment the mixing means mixes the or each fuel with the or each oxidising fluid prior to it entering the compression fan.

The engine may further comprise heat exchanging means for extracting heat from the gases formed from the combustion.

By providing a device with an output to a heat exchanger, the advantage is provided that the engine can be used as a combined heat and power generator. As a result, the significant heat produced by the combustion of the fuel can be utilised. A device of the type described above is significantly simpler than other combined heat and power units of the prior art. The simple rotating reaction member can be used to produce significant rotational power whilst the excess heat can be utilised through a heat exchanger and heating system. This rotational power can be converted into electricity by a generator. As a result, this type of device is particularly useful for large buildings or industrial premises which have significant heat and power requirements. By producing electrical power on site, the energy losses due to transmission from a large power station are not encountered. Such a combined heat and power unit can therefore be seen to have significant financial and environmental benefits. Alternatively the rotational power from the output shaft could be used directly to, for example, run water pumps for a heating system attached to the engine or run fan units for a larger boiler.

Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense, with reference to the accompanying drawings in which :-

Figure 1 is a perspective partial cut-away view of an engine of the present invention;

Figure 2 is a perspective partial cut-away view of the engine of Figure 1 viewed from a different angle;

Figure 3 is a sectional front view, along the line A-A, of the engine of Figure 1; and

Figure 4 is a sectional side view, along the line B-B, of the engine of Figure 1.

Referring to Figures 1, 2 and 3, an engine 10 has a housing 12 enclosing a compression device in the form of compression fan 14 and a reaction member 16. The compression fan 14 is caused to rotate about axle 18 by a driving device (not shown) . This driving device might be a turbine driven by exhaust gases from the engine or might alternatively be an electrical motor which could be powered by a portion of the electrical power produced by a generator attached to the engine.

The reaction member 16 is mounted coaxially with compression fan 14 on an output drive axle 22. The output drive axle 22 can be connected to an electrical generator such as a permanent magnet AC brushless generator (not shown) . The reaction member 16 is divided into two radially separated portions by a flame control device or flame grid 24. Between the compression fan 14 and the flame grid 24 is a diffusion zone 26. Radially beyond the flame grid 24 is a single combustion zone 28. The reaction member is formed from two

substantially circular discs 30 and 32 which have a saw tooth shape as a result of the radially peripheral edges 34 and 36. The longer edges 34 are folded towards each other and welded to each other thereby forming substantially triangular nozzles 38 which act as an outlet from combustion zone 28. The precise size and dimensions of the nozzles 38 are determined by nozzle shapers 40 which are welded between edges 36 so as to provide reinforcement for the nozzles 38. The nozzle shapers ensure that the shape of the nozzle is maintained in the event of distortion of the reaction member as a result of thermal fatigue.

The reaction member also includes plates 42 and 44 which are bolted to each other by bolts 46 and thereby hold discs 30 and 32 in compressive connection with flame grid 24. Plate 42 has an opening 48 through which fuel is introduced into the compression fan 14.

In use, a mixture of a fuel, for example propane and an oxidising gas, for example air, are drawn into the compression fan 14 through opening 48. Axle 18 is rotated by the fan driver (not shown) which in turn causes rotation of the compression fan 14. As a result of this rotation, the fuel and air mixture is compressed and forced radially into the reaction member 16. The fuel and air mixture initially enters the diffusion zone 26 of reaction member 16 and as the mixture continues to move radially outwards, the increasing passage width and increasing radial distance causes the mixture to slow down, thereby increasing its pressure. This increase continues until the fuel and air mixture reaches the flame grid 24 and passes through the small apertures therein.

On passing through the flame grid 24, the mixture enters the combustion zone 28 where the fuel is burnt. Initial ignition of the mixture can result from a spark from a piezo-

electric ignitor which causes the flame to flash back and settle immediately adjacent, and radially outward of, the flame grid 24. The burning of the fuel causes a significant increase in the volume of the gas which continues to travel radially outward within the combustion zone 28 of reaction member 16. Upon reaching the outer edge 34 of reaction member 16, the combusted gases are directed towards nozzle 38 from where they exit the reaction member 16. The nozzles 38 are sized so as to apply the maximum reaction force to the reaction member at each nozzle.

Because the hot combustion gases only come into direct contact with the discs 30 and 32 within the combustion zone 28, simple cooling vanes (not shown but of the type shown in WO02/059469) attached to the outside surfaces of discs 30 and 32 are able to direct cooling air, drawn in through apertures 50, over these surfaces maintaining the discs at an acceptable working temperature. This cooling air mixes with the hot combustion gases as the exit nozzles 38 within the housing 12 from where they are directed to a heat exchanger (not shown) . The heat exchanger extracts heat from the combustion gases and uses it- in a heating system whilst the rotational output on output drive axle 22 is utilised for example by driving a generator to produce electricity. It is worth noting that even though the flame grid is located within the volume of the reaction member where combustion takes place and does not have any external surfaces, it should not require separate cooling as the mixture of fuel and air act to cool the grid as they pass through it.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure of the scope of the invention as ^' defined by the appended claims . For

example, it is possible that the fuel and air may not be mixed prior to entering the compression fan and that air is introduced either within the diffusion zone or combustion zone of the reaction member 16. Alternatively, the air could be compressed within a compression fan and fuel introduced within the reaction member. The disc 30 and plate 42 could be formed as a single part of reaction member 16 as could disc 28 and plate 44. These single parts could then be welded together to form the reaction member. As an alternative to the perforated flame grid a single annular aperture or a circumferential line of holes could be provided in a sheet located where the flame grid is shown to act as a flame control means . The purpose of this element of the engine is to hold the flame in a controlled position. It should also be noted that other shapes of nozzle may be equally, or more, suitable than the triangular nozzles shown.