GB2572167A

GB2572167A - A surface conditioning device

Info

Publication number: GB2572167A
Application number: GB1804469.3A
Authority: GB
Inventors: Francis Ralph Swan Julian; Spencer Jaynes Candy Matthew; Radoiu Marilena; David Richardson Gareth
Original assignee: Imagination Factory Ltd
Current assignee: Imagination Factory Ltd
Priority date: 2018-03-21
Filing date: 2018-03-21
Publication date: 2019-09-25
Anticipated expiration: 2038-03-21
Also published as: GB201804469D0; GB2572167B

Abstract

The device 1 for removing matter such as compacted leaves and dew from railway tracks or wheels, has a microwave generator 3 connected to a power supply 4 and waveguide 11 which delivers microwaves to a microwave cavity 5 located within plasma delivery head 13 also containing a dielectric delivery tube 6 passing through the cavity, the device including a first gas delivery means in fluid communication with the delivery tube and suitable for generating a vortex in the delivery tube, and an ignition means for igniting the gas in the delivery tube. The microwave energy in the cavity energises the ignited first gas to maintain a plasma. The device may be mounted between the wheels of a train to deliver plasma, driven by the vortex, out of the delivery tube and onto a track to clear matter therefrom. Also claimed is a rail vehicle including the device. There may be a second gas used for the ignition stage. The delivery tube may include a nozzle to deliver the plasma.

Description

A Surface Conditioning Device

This invention pertains generally to the field of surface conditioning, and in particular surface conditioning devices for use on railway track rails and train wheels to help maintain the optimum condition of rail to wheel interface.

The surface condition of railway tracks presents a real challenge to rail network operators who must ensure that they are well maintained and kept in optimum condition for the passage of rail vehicles. The railway track rails, typically made from steel, are subjected to considerable forces from passing vehicles that can cause surface and structural wear, whilst also being exposed to adverse and frequently changeable weather conditions, along with other environmental hazards throughout the year. The rail to wheel interface, typically steel against steel, provides an energy efficient combination, yet this interface can prove to be highly sensitive to contamination. Precipitation, dew, leaf fall, localised temperature changes, extreme weather conditions, vegetation and other detritus, are just some of the events that can affect the surface condition of the rail track, and therefore the passage of the rail vehicle passing thereon. The majority of these contaminants have significant water content, which affects adhesion of the wheel on the rail surface.

The smooth, safe and efficient running of a rail vehicle relies upon the friction between the steel rails and the steel wheels. Fundamental to predictable and optimised braking of a rail vehicle using conventional brakes, is creating a reliable rail to wheel interface that has sufficient friction for the desired rate of deceleration. Friction can be reduced when the rails become slippery or greasy, often because of rain, dew, fluids such as oil or even decomposing leaves that fall onto the line and can become compacted. This can result in a chemical reaction occurring between the water soluble leaf component and steel rail coating. This coating is semipermanent and therefore it may take time to be sufficiently worn away by the passage of trains. Such variance and unpredictability to surface conditions of the rail tracks in terms of moisture and detritus can present a real challenge to network operators. They must predict the likelihood of low friction conditions being experienced by a passing vehicle, causing the vehicle to slip, before this happens, and take steps to minimise the impact. They must carry out ongoing monitoring of track conditions to flag up areas of concern and again take steps to rectify these. They must ensure that trains are adequately spaced along the line to ensure that required stopping distances are taken into account in light of changeable surface conditions. With such conditions subject to change at any moment, particularly environmental conditions due to changeable weather, it is very common for issues to occur. Rail network operators are quick to delay or cancel trains, rather than risk passenger safety. Timetables are often altered for different seasons, such as in the UK regular Autumnal timetabling takes please to anticipate these delays during the leaf fall season. This comes at considerable cost to the rail industry. It was estimated that leaves on the line costs around £60million each year in the UK alone.

A loss of friction at the rail to wheel interface effects traction when the train first sets off and starts moving, which in the case of freight trains, affects hauling capability. The wheels can be caused to spin, and in some instances the train is unable to move. These low friction conditions results in poor adhesion between the wheel to rail interface, also causing issues when braking and coming to a stop. Substantial loss of friction results in reduced braking forces, meaning that stopping distances are considerably longer and this must be accounted for when dispatching trains within the rail network. In extreme cases the wheels may even lock, causing the train to go into a slide. This can cause considerable damage to the wheel and rail track. Station platforms may also be overshot where a driver has not allowed a sufficient distance to bring the train to a standstill.

Snow and ice, when deposited on rail tracks, can cause such low adhesion conditions to occur, making rail vehicles prone to slide or slip during braking, whilst also causing the train to encounter difficulties pulling away. But less obvious conditions such as light rain following a spell of dry weather, or morning dew on the rails, can also cause challenging rail conditions for the rail networks to account for. The effect on the surface condition of the rail tracks may only be short term, but the unpredictable nature of such effects may be sufficient for a significant incident to occur to a passing rail vehicle. Tests have shown that there is a strong correlation between low adhesion incidents and the occurrence of the dew point, where water vapour from the air condenses onto the railhead forming a fluid film. This fluid film leads to a loss of traction at the wheel to rail interface.

Other contributing factors are thought to include the move from brake shoes to disc brakes, which means that some surface cleaning and conditioning of the rails no longer occurs by abrasion. It is also thought that rail network operators no longer have to carry out sufficient lineside maintenance that would have been essential during the steam locomotive era, to prevent vegetation from catching fire. The extra growth from vegetation increases the supply of leaves and the increase of leaf fall onto the line, thereby exacerbating the problem. It may also effect the dew point and localised climate in some areas. In extreme cases, the build-up of leaf matter can electrically insulate the wheels from the rails, resulting in signal failure. This can cause an event such as Wrong Side Track Circuit Failure, or WSTCF, when leaf matter electrically insulates the wheels from the rails resulting in signal failure. Other events such as Signal Passed at Danger, or SPAD, can also occur when a train slides past a signal because it could not stop.

Rail vehicles are typically fitted with wheel slide protection, in an attempt to counter slippery rail conditions. When wheels become locked, flat spots can be ground into the steel rims, especially if the wheel is still sliding when entering a non-slippery portion of rail track. This can cause wheel flats, where the wheel shape has been altered from its original profile, leading to severe vibrations and the need for reprofiling of the wheels, or even wheel replacement, at considerable expense.

Numerous different ways of surface conditioning the rail tracks to deal with such changeable circumstances have been tried, and many are in operation. These range from applying a jet to blast away any deposits or detritus, such as with waterjets alongside a mechanical scrubbing apparatus of some form. Laser blasting the rails has also been tried and tested. Or coating the rail tracks and/or wheels with a high friction material, such as by depositing sand as a paste or otherwise, or the application of adhesion modifying chemicals, onto the rail. The sand assists adhesion during braking and acceleration. However, using sand may increase the risk of unwanted insulation, and therefore may also contain metal particles. For an example, an adhesion modifier such as Sandite™, a combination of sand, aluminium particles and adhesive. Blasting or coating the rails with sand and substances such as Sandite™ is not thought to offer an economically sound solution, nor is it thought to be environmentally friendly to release these substances into the environment. To attempt to combat the issues experienced by moisture and the formation of dew on the rail tracks, and thereby improve both traction and impedance properties, the rails have typically been treated with hydrophobic products. To apply these coating or treatments to the rail tracks typically requires special trains or rail vehicles, and may also involve manual or application by hand. In the UK these vehicles typically include Rail Head Treatment Trains or RHTTs, or Multi-Purpose Vehicles or MPVs. Again, a challenge for the rail network operators to factor into the overall operation of the network, ensuring the passage of such rail vehicles, or the application of such coating and substances at times when the track is not in use.

At specific sites, or portion of rail track, where significant low adhesion regularly occurs, such as on the approach to a station, traction gel applicators may have been installed. These apply liquid to the railhead as a rail vehicle passes therethrough.

These processes are only effective for a short period of time. Jet blasting the rail track is ineffective as soon as the next leaf falls, or is positioned onto the rails due to the aerodynamic turbulence of a passing train, or other detritus lands along the line. Sand and other treatment products deposited directly onto the rail track or railhead may prove more durable, but these substances can be easily washed away by rainfall.

The prior art shows a number of devices which attempt to address these needs in various ways.

US 3 685 454 (British Railways Board) discloses a means of cleaning rails to improve wheel to rail adhesion, using a plasma torch or plurality of plasma torches supported on a vehicle. The apparatus comprises an electromagnetic detector mounted on the carrier for detecting and transmitting an error signal when a torch head is no longer acting upon the rail track at a suitable distance from said track. This document introduces the use of plasma torches to condition the track surface, but is more concerned with positioning of the torch head in relation to the track, than a combination of efficient and effective plasma generation alongside application to the rail track to railhead interface. The means of plasma generation disclosed is that of any conventional plasma torch, generating plasma through a DC thermal arc, which raise issues of efficiency and effectiveness for all surface conditions.

DE 4 323 700 (Herman Hans) discloses a device for changing the friction between a wheel and rail interface, comprising one or more nozzles that are arranged in front of at least one wheel. Fluid, such as compressed air, pressurized water or water vapour, that may be heated, is blown onto the rails. The device proposes the use of microwaves or laser beams to heat said fluid and improve the effectiveness, although the arrangement of microwaves and/or laser in relation to the device is not given.

Whi 1 st the prior art appears to address the issue of removing some of the detritus, moisture or other matter from a rail track and/or wheel, thus improving the adhesion between the two surfaces, it does not propose a solution that conditions the surface of the rail track and or surface of the wheel on a continuous or intermittent basis, during travel of a passing rail vehicle, thereby requiring minimal intervention by a rail network provider. Whilst the prior art also attempts to address the issue of improving friction and therefore adhesion of the rail track surface, by cleaning the surface through sand blasting, jet blasting or the addition of chemical substances, it does not provide a means of conditioning said track surface, and sensing and responding to a change of conditions of the track surface on an instantaneous basis. The wheel to rail interface, and the adhesion of one surface to the other, is not optimised by these proposed solutions to the point where normal levels of braking of the rail vehicle can be applied throughout the network and during ever-changing conditions.

Preferred embodiments of the present invention aim to provide a surface conditioning device for conditioning the surface of rail track rails and/or rail vehicle wheels, on a continuous or intermittent basis, during the passage of a rail vehicle along the track, the surface conditioning device providing means to target water and other contaminants by delivering energy to the rail to wheel interface, to effectively remove moisture, debris and other detritus from said interface, thus improving friction and therefore adhesion therebetween. Preferred embodiments also aim to provide a conditioned rail track and wheel interface, in an energy efficient manner, with no detriment to the track and/or rail. Further embodiments of the present invention aim to provide a surface conditioning device for a rail to wheel interface, that supplies and optimises treatment conditions of the rail track surface in direct response to a change in conditions. By optimising adhesion at the rail to wheel interface, allows for consistent braking of a rail vehicle, reducing the likelihood of wheel and/or rail damage such as wheel flats.

According to one aspect of the present invention, there is provided a surface conditioning device for railway track rails and/or rail vehicle wheels, the surface conditioning device comprising: a microwave generator for generating microwave energy; a power supply operatively connected to the microwave generator for providing power thereto; a plasma delivery head comprising a microwave cavity and a dielectric delivery tube passing therethrough; a waveguide assembly operatively connected from the microwave generator to the microwave cavity for delivering microwave energy thereto; a first gas delivery means operatively connected to a first gas supply and in fluid communication with the dielectric delivery tube, for generating a vortex from a first gas and passing the first gas through said dielectric delivery tube; and, at least one ignition means operatively connected to the dielectric delivery tube, for generating a spark and igniting a portion of the first gas upon passing into the dielectric delivery tube, and for converting said portion of first gas into plasma, whereby the dielectric delivery tube is configured to deliver the plasma onto the rail track rail and/or rail vehicle wheel, and such that, in use, the microwave energy within the microwave cavity energises the plasma and the first gas within the dielectric delivery tube, ionizing the first gas to form plasma, and the first gas vortex drives the plasma out of the dielectric delivery tube and onto the rail track rail and/or rail vehicle wheel.

Preferably, the surface conditioning device may comprise a second gas delivery means operatively connected to a second gas supply and in fluid communication with the dielectric delivery tube for passing a second gas through said dielectric delivery tube, and the at least one ignition means is operatively connected to said second gas delivery means, for igniting a portion of the second gas and converting said second gas into plasma.

The at least one ignition means comprises an ignition rod supported by a linear actuator, whereby the linear actuator is configured to move the ignition rod into and out of the dielectric delivery tube.

Preferably, the microwave cavity is substantially cylindrical and the dielectric delivery tube is configured to pass along the axis of said cylinder.

The dielectric delivery tube may incorporate a nozzle at one end, juxtaposed in coaxial alignment with said dielectric delivery tube, for delivering the plasma onto the rail track rail and/or rail vehicle wheel.

Preferably, the waveguide assembly comprises at least one tuning means for tuning said microwave energy.

The tuning means may comprise one or more of the following: a waveguide filter, resonator, cavity, iris, post.

Preferably, the microwave cavity is single mode.

Preferably, the microwave cavity comprises a metal block.

The plasma delivery head may incorporate cooling means.

Preferably, the cooling means comprises a water cooling jacket.

Alternatively, the cooling means comprises an oil cooling jacket.

In a further embodiment the cooling means may comprise a phase change system.

Preferably, the surface conditioning device is operatively connected to at least one sensor, whereby said sensor comprises one or more of the following: accelerometer, thermometer, frictional sensor, moisture sensor, visual track condition sensor, slippage sensor, speed sensor.

The at least one sensor may comprise an accelerometer such that, in use, the accelerometer detects braking of a rail vehicle, and generates plasma for treating the portion of rail track rail and/or wheel during a braking cycle.

Preferably, the first gas is nitrogen, and the second gas is argon.

The microwave generator may comprise a magnetron.

The surface conditioning device may incorporate at least one mounting means for mounting the surface conditioning device to a rail vehicle.

The mounting means may be configured to mount the plasma delivery head such that the plasma is delivered from a distance of between 25mm to 75mm to a rail surface and/or rail vehicle wheel surface.

The mounting means may be configured to mount the plasma delivery head between a pair of wheels of the rail vehicle.

The surface conditioning device may comprise a plurality of plasma delivery heads operatively connected through a corresponding number of waveguide assemblies to the microwave generator.

The portion of rail track rail and/or rail vehicle to be conditioned at any one time may be between 5mm and 72mm.

The power supply may comprise a regenerative braking system.

A rail vehicle may incorporate the aforementioned surface conditioning device.

For a better understanding of the invention and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:

Figure 1 shows one embodiment of a surface conditioning device when mounted to a rail vehicle, showing a pair of plasma delivery heads between wheels of said rail vehicle;

Figure 2 shows a further embodiment of surface conditioning device when mounted to a manual track treatment vehicle, showing the remote location of power supply and microwave generator operatively connected to the plasma delivery head;

Figure 3 shows a further embodiment of surface conditioning device when configured as a rail vehicle specific for rail track treatment, showing possible locations for mounting plasma delivery heads;

Figure 4 shows a further embodiment of surface conditioning device when mounted to a freight train, showing possible locations for mounting plasma delivery heads to rail vehicles for carrying freight;

Figure 5 shows one embodiment of flow diagram of the surface conditioning device, showing one possible configuration of power supply, microwave generator, waveguide and plasma delivery head for generating and delivering plasma through a dielectric delivery tube;

Figure 6 shows the plasma delivery head of Figure 5, showing the internal arrangement of elements that make up the plasma delivery head and showing diagrammatically the passage of microwaves through the surface conditioning device;

Figures 7A to 7F show a series of schematics to show the sequence of events that generate and deliver plasma from the plasma delivery head for conditioning a surface;

Figure 8 shows one embodiment of cooling means for cooling the plasma delivery head;

Figure 9 shows the cooling means of Figure 8 in detail, showing cooling fluid entering into a cooling jacket that surrounds the plasma delivery head;

Figure 10 shows a further embodiment of cooling means comprising a cooling fluid tube that wraps around the plasma delivery head, showing a pair of said cooling fluid tubes spaced along the plasma delivery head;

Figure 11 shows one embodiment of mounting means for mounting the surface conditioning device to a rail vehicle;

Figure 12 shows one possible arrangement of sensing means showing a plurality of different sensors mounted to the rail vehicle; and,

Figures 13A and 13B show a further embodiment of ignition means comprising a mechanical ignition system.

In the figures like references denote like or corresponding parts.

Figure 1 shows one embodiment of surface conditioning device 1 when mounted between the wheels 7 of atypical rail vehicle 8. The wheels 7 run along the railway track rail 2 or rail head, and the surface conditioning device 1 is mounted such that it conditions the surface of the railway track rail 2 as the rail vehicle 8 passes along. The surface conditioning device 1 comprises at least one power supply 4, at least one microwave generator 3 and at least one plasma delivery head 13. Shown in Figure 1 is a pair of plasma delivery heads 13 mounted adjacent to one another, that are operatively connected to one micro wave generator 3, which is provided with power from one power supply 4. The surface conditioning device 1 may comprise a modular arrangement with multiple plasma delivery heads 13 being supplied by one microwave generator 3 and one power supply 4. In such a modular arrangement the plasma delivery heads 13 may be mounted at various locations throughout the rail vehicle 8 to enable the surface conditioning device 1 to condition a surface of the railway track rails 2 and/or to condition a surface of the wheels 7 of the rail vehicle 8 at any one time, intermittently or on an ongoing basis. Each plasma delivery head 13 may be controlled independently or all of the plasma delivery heads 13 may be controlled to operate at the same time, through a control means 9. The control means 9 may be within the cabin of the rail vehicle 8, or mounted at a suitable location within the rail vehicle 8 such that a display 10 of the control means 9 can be read and responded to be a rail vehicle operator.

Each plasma delivery head 13 is operatively connected to the microwave generator 3 through a waveguide 11. The waveguide 11 provides an electromagnetic feed line for microwaves emitted from the microwave generator 3. The waveguide 11 guides the microwaves with minimal loss of energy from the microwave generator 3 to a microwave cavity 5 within the plasma delivery head 13.

The plasma delivery head 13 incorporates a dielectric delivery tube 6 that is arranged within the micro wave cavity 5 of the plasma delivery head 13, and as shown in Figure 1, one end of the dielectric delivery tube 6 is mounted to the rail vehicle 8 such that the end is at a suitable distance from the surface of the railway track rail 2 for conditioning the surface. Mounting the plasma delivery heads 13 between wheels 7 of the rail vehicle 8 ensures that the plasma delivery heads 13 are shielded from the harsher conditions experienced infront of the leading wheel 7 of the rail vehicle 8.

Figure 2 shows the surface conditioning device 1 forming part of a specialist rail vehicle 8 or manual track treatment vehicle. This rail vehicle 8 has the sole purpose of travelling along railway track rails 2 and providing means to condition said railway track rails 2. Unlike in Figure 1 where the rail vehicle 8 may be an engine or carriage of any rail vehicle 8 for transporting passengers or cargo, and the surface conditioning means 1 would therefore be carried out during the usual passage of such a rail vehicle 8 along the railway track rails 2. This track treatment vehicle is provided with carriages that carry the components of the surface conditioning device 1. In the configuration shown, the rear carriage carries the power supply 4, and is operatively connected to the adjacent carriage to supply power to the microwave generator 3. The microwave generator 3 generates microwaves and delivers this microwave energy along the waveguide 11 to the plasma delivery head 13. The plasma delivery head 13 is mounted to the carriage of the rail vehicle 8 such that the dielectric delivery tube 6 that passes through the microwave cavity 5 has one end in close communication with the surface of the railway track rail 2 that is to be conditioned.

Figure 3 shows a further embodiment of rail vehicle 8 or track treatment vehicle with a pair of plasma delivery heads 13 mounted at intervals along the undercarriage of the rail vehicle 8. This track treatment vehicle conditions the railway track rails 2 when there are no freight or passenger trains needing to use the line. Figure 4 shows the surface conditioning device 1 when installed within a typical rail vehicle 8, that provides the advantage of conditioning the railway track rails 2 during the usual passage of said rail vehicle 8 along the line. Shown in this modular arrangement are two plasma delivery heads 13 mounted to the undercarriage of the rail vehicle 8, and likely a further pair of plasma delivery heads 13 in a similar location on the other side of the rail vehicle 8. This modular arrangement allows for a number of plasma delivery heads 13 to be conditioning the railway track rails at various locations at any one time, to ensure thorough coverage and conditioning of the surfaces of the railway track rails 2.

For each of Figures 1 to 4, the plasma delivery heads may additionally or alternatively be mounted to condition the surfaces of the wheels 7 of the rail vehicles 8, not shown. In these embodiments the dielectric delivery tube 6 would be mounted such that the end of the dielectric delivery tube 6 is directed towards, yet at a suitable distance from, the surface of each wheel 7 of the rail vehicle 8 that requires conditioning. The power supply 4 may be located at a fair distance away from the microwave generator 3 within any of these rail vehicles 8 whilst still being operatively connected to provide power to the microwave generator 3, allowing what may be a bulky and heavy element of the surface conditioning system to be located in a more suitable position within the rail vehicle 8. The sensitive elements that make up the surface conditioning device 1 may be provided with a buffer or vibration damping element, not shown, to prevent those elements from being exposed to vibrations and shocks during operation.

Figure 5 shows one embodiment of surface conditioning device 1 showing the power supply 4 operatively connected to the microwave generator 3 for providing power to the microwave generator 3. The power supply 4 may comprise a rechargeable battery, or may use regenerative power. The microwave generator 3 may comprise at least one magnetron. The magnetron may operate at ISM (Industrial, Scientific and Medical) frequencies for example 433MHz, 896MHz, 915MHz, 2.45GHz, 5.8GHz. Where the power supply 4 comprises a solidstate magnetron, this may be configured to have its energy split which would allow it to supply multiple plasma delivery heads 13. However, where the power supply 4 is a filament magnetron, it has to be matched to only one waveguide 11 and therefore only one plasma delivery head 13. The surface conditioning device 1 may be manually controlled by an operator, or one or more sensors, not shown, may be in communication with the control means to operate the surface conditioning device 1 in response to one or more conditions. For an example, the surface conditioning device 1 may be configured to condition the surface of the railway track rail 2 and/or wheel 7 when the rail vehicle 8 begins braking. In a further example, the surface conditioning device 1 may respond to environmental conditions, such as the detection of moisture in the vicinity of the railway track rail 2, or in response to a drop in temperature of the environment surrounding the railway track rail 2. This allows surface conditioning to occur in direct response to a specific condition being detected, by the rail vehicle 8 that has detected the condition. It also allows rail vehicles 8 that pass along the railway track rails 2 to condition these railway track rails 2 as they travel.

The surface conditioning device 1 comprises a waveguide 11 which incorporates tuning means 12 as part of the waveguide assembly. The waveguide 11 confines the microwaves to propagate in one dimension, so that the microwaves lose minimal power whilst propagating. This is due to walls of the waveguide 11 ensuring total internal reflection of the microwaves. The waveguide assembly incorporates tuning means 12, for tuning the microwaves and for waveguide impedance matching, thus insuring the optimum power transfer between microwave generator 3 and microwave cavity 5 and the minimum level of reflected power from the microwave cavity of the microwaves. The waveguide impedance is matched to the source impedance or the load impedance through the tuning means 12. Impedance matching can be achieved through gradual changes in the dimensions of the waveguide 11, use of additional elements within the waveguide 11 such as an iris, post or screw, or use of resonators, cavities or filters. Waveguide horns or funnel shaped antennas may also make up the tuning means 12, where the dimensions of the waveguide gradually expand along certain planes such as the E plane or the H plane.

The surface conditioning device 1 may incorporate an isolator 28 for ensuring that the microwave generator 3 is shielded from any reflected microwaves passing through the waveguide 11. The waveguide 11 carries microwaves and therefore microwave energy from the microwave generator 3 to the microwave cavity 5 within the plasma delivery head 13. The waveguide 11 is connected to the microwave cavity 5 through the microwave inlet 19 or window. Microwaves pass through the microwave cavity, and some pass through the microwave outlet 22. The microwave outlet 22 is provided with an end tuner or reflector 18 to reflect the microwaves back through into the microwave cavity 5. The microwave cavity 5 comprises a single mode microwave cavity incorporating a single-mode, or selective multimode, cylindrical cavity to match and focus the microwave energy onto the dielectric delivery tube 6. The single mode, cylindrical microwave cavity 5 is configured for microwave processing of a continuously flowing fluid. The dielectric delivery tube 6 is configured to run along the axis of the cylindrical microwave cavity 5, and the continuously flowing fluid flows along the dielectric delivery tube 6. In one embodiment the microwave cavity 5 comprises a metal block, and forms a resonator that comprises a closed metal structure for confining the microwaves. The microwaves bounce off the walls of the microwave cavity 5 and cannot escape. The microwave cavity 5 is either hollow, or filled with dielectric material.

The dielectric delivery tube 6 comprises a hollow, elongate tube of dielectric material, with a first end in fluid communication with a first gas supply 17 and a second gas supply 30, and a second end that passes out of the microwave cavity 5, where it is configured to supply plasma to a surface. The dielectric delivery tube 6 may be made from a ceramic material, or similar electrically insulating material. The dielectric delivery tube 6 may incorporate a nozzle 14 at the second end, formed as one piece with the tube, or the nozzle 14 may be a separate element affixed to the plasma delivery end of the dielectric delivery tube 6. The dielectric delivery tube 6 may be shaped at one end to form an effective nozzle 14, through it’s geometry such a venture, divergent, convergent or assymetrical. The nozzle 14 helps to focus the plasma onto the portion of railway track rail 2 or wheel 7 that is to be treated. This portion of surface of railway track rail 2 or wheel is likely to be within the range of 5mm to 20mm that is to be conditioned at any one time. Mounting the end bore of the nozzle 14 at a distance of between 25mm and 75mm to the surface to be conditioned provides sufficient coverage to this portion of rail track rail surface. The nozzle 14 may comprise metal, which would therefore reduce EMC emissions. The nozzle 14 and/or dielectric delivery tube 6 and/or plasma delivery head 13 may incorporate some form of shielding, not shown, for shielding the surroundings from any emitted ultraviolet light, and the shielding may also create an aerodynamic effect to assist delivery of the plasma 21 onto the railway track rail 2.

Figure 6 shows a flow diagram showing the passage of microwaves 24 from the microwave generator 3 along the waveguide 11 and into the microwave cavity 5 where they pass through into the end tuner or reflector 18, to be reflected back through the microwave cavity 5, and back through the waveguide 11 to the tuning means 12 that makes up the waveguide assembly. This arrangement of reflected microwaves 40 ensures that the treatment conditions are optimised, by making the surface conditioning device 1 adaptable and thus delivering more efficient plasma.

Figures 7A to 7F show the sequence of events that occur to generate plasma within the surface conditioning device 1 for delivery to the railway track rail 2 or wheel 7. The plasma delivery head is fluidly connected to a first gas delivery means 16 that comprises a first gas supply for supplying a first gas 23 to the dielectric delivery tube 6 within the microwave cavity 5. The plasma delivery head is also fluidly connected to a second gas delivery means 29 that comprises a second gas supply 30 for supplying a second gas 31 to the dielectric delivery tube 6 within the microwave cavity 5. Figure 7A shows the passage of microwaves 24 passing through the microwave cavity 5 of the plasma delivery head 13, and the first gas and second gas being supplied to the dielectric delivery tube 6 from the first gas supply 17 and the second gas supply 30 respectively. The second gas 31 may be argon. The second gas 31 may be supplied through a single inlet, linear supply. The first gas 23 may be nitrogen, and may also incorporate reactive gases or agents such as oxygen or water. The first gas may be supplied through one inlet, two inlets or four inlets such that a first gas vortex 20 is generated. The axis line of the first gas vortex 20 is substantially the same as the central axis of the dielectric delivery tube

6. The microwaves 24 are configured through the tuning means 12 of the waveguide assembly to be a standing wave.

Figure 7B shows one embodiment of ignition means 15 that is configured to ignite the second gas 31 by generating a spark that ignites a portion of the second gas 31. A single spark from the ignition means 15 excites and ignites the second gas 31, and by adding such heat energy the second gas 31 loses some of its electrons, becoming ionised and converted into plasma 21. This plasma 21 passes along the dielectric delivery tube 6 to be exposed to the microwaves 24. Figure 7C shows the generated plasma 21 being carried by the rest of the second gas 31, passing into the microwave field through the dielectric delivery tube 6. As shown in Figure 7D, once the plasma 21 has reached the dielectric delivery tube 6, and is being acted upon by the microwaves 24, the second gas supply can be switched off. The plasma 21 gains energy from the microwaves 24, and as shown in Figure 7E, more plasma 21 is generated from the first gas 23 by the generated plasma 21 and the microwaves 24 exciting and ionising the first gas 23 at atmospheric pressure. The first gas vortex 20 continues to become excited by the microwaves 24, and the first gas vortex 20 drives the plasma 21 through the dielectric delivery tube 6 and out of the end bore of said dielectric delivery tube 6 onto the surface to be conditioned. The dielectric delivery tube 6 helps to contain and concentrate the plasma 21.

The ignition means 15 may therefore only be activated for a few seconds, sufficient to generate a spark and ignite the second gas 31. It is the microwaves 24 and the microwave field created by these microwaves 24 that sustains the excited first gas 23 and the excited second gas 31 to form the plasma 21. The first gas 23 and the second gas 31 can be any monoatomic or diatomic gas or gas mixture. For an example the gas mixture may comprise water molecules added to the gas.

The surface conditioning device 1, as shown in Figure 8, may incorporate cooling means 26, to ensure that the microwave cavity 5 and therefore the plasma delivery head 13 is not allowed to exceed a predetermined temperature level that could cause risk to the surroundings. This cooling means 26 is configured to help cope with the high heat loads that the plasma delivery head 13 experiences. The cooling means 26 may comprise a water cooling jacket, compressed air, oil cooling jacket, or a sleeve of phase change material. Figure 9 shows one embodiment of cooling means 26 comprising a cooling jacket 33, whereby the cooling jacket 33 is supplied with cooling fluid 32. The cooling fluid 32 may comprise water, oil or similar fluid for drawing heat energy from the dielectric delivery tube 6. Figure 10 shows a further embodiment of cooling means 26 showing a cooling fluid tube 34 that is supplied with cooling fluid 32 through a cooling fluid inlet 41, where the cooling fluid 32 extracts heat energy from the surface of the dielectric delivery tube 6, and exits through the cooling fluid outlet 42. Figure fO shows two cooling fluid tubes 34 spaced along the dielectric delivery tube 6.

The surface conditioning device 1 may incorporate at least one mounting means 27 for mounting the component parts that make up the surface conditioning device 1 to the rail vehicle 8. This mounting means 27 may be permanent or releasable. Permanent means might include welding, or securing through a plurality of bolts or rivets to the rail vehicle 8. Figure 11 shows one embodiment of mounting means 27, and the location of the various elements that make up the surface conditioning device 1, and how these elements may be configured within a rail vehicle 8.

The surface conditioning device 1 may incorporate at least one sensor 25 for sensing a condition and activating the surface conditioning device 1 in response to a change or a predetermined value for that condition. Figure 12 shows one possible configuration of sensing means 25 and where these various sensors may be installed within the rail vehicle 8. The sensor 25 may comprise thermal sensors, mechanical sensors and/or motion sensors, or any combination of these. Thermal sensors detect a change in temperature within a surrounding environment, which may affect the condition of railway track rails 2 and require surface conditioning to be activated to ensure that the surface of the railway track rails 2 remains unaffected by the change. Thermal sensors may comprise thermometers or thermostats. The sensor 25 may comprise a motion sensor or speed sensor 39, such as an accelerometer or speedometer, for detecting retardation or braking of a rail vehicle 8, and activating the surface conditioning device 1 during braking of the rail vehicle 8. The sensor may comprise a frictional sensor 35, visual track condition sensor 37, slippage sensor 38. This should help to prevent slip between the railway track rail 2 and wheel 7 interface. The sensor 25 may also comprise a moisture sensor 36 for detecting dew within the immediate environment surrounding a railway track rail 2.

Figures 13A and 13B shows a further embodiment of ignition means 15, showing a linear actuator 44 that may be mechanically operated, electromechanically operated or pneumatically operated to drive the ignition means 15 into and out of the first gas 20 to be ignited. The linear actuator 44 is configured to drive an ignition rod 43 into the passage of the first gas 20. The ignition rod 43 ignites the first gas 20 with a spark, due to the creation of a short circuit, thus generating the plasma 21. The ignition rod 43 is then removed by the linear actuator 44 when a portion of plasma 21 has been generated. The linear actuator 44 may be configured to drive the ignition rod 43 into the path of the first gas 20 for a short period of time, such as a fraction of a second. The ignition rod 43 may be made from tungsten and may therefore comprise a tungsten wire, or indeed an alternative metallic material such as mild steel, high carbon steel, copper, carbon electrode or cast iron.

The advantage of using microwave energy for obtaining a plasma 21 is that higher degrees of ionization and dissociation can be obtained, compared to other types of electrical excitation. This higher ionization and dissociation reduces the activation energy and enhances the kinetics to initiate chemical reactions. Depending on the additives (for an example molecular oxygen, water, carbon dioxide) mixed with the plasmagen gas, such as helium, nitrogen, argon, in addition to ions, free electrons, neutral gas species, and dissociated gas, a microwave plasma will also form precursor molecules or reactive species (atomic oxygen, hydroxyl radicals etc.) which will combust remove the organic deposits formed on the metal surface.

Claims

1. A surface conditioning device for railway track rails and/or rail vehicle wheels, the surface conditioning device comprising:

a microwave generator for generating microwave energy;

a power supply operatively connected to the microwave generator for providing power thereto; a plasma delivery head comprising a microwave cavity and a dielectric delivery tube passing therethrough;

a waveguide assembly operatively connected from the microwave generator to the microwave cavity for delivering microwave energy thereto;

a first gas delivery means operatively connected to a first gas supply and in fluid communication with the dielectric delivery tube, for generating a vortex from a first gas and passing the first gas through said dielectric delivery tube; and, at least one ignition means operatively connected to the dielectric delivery tube, for generating a spark and igniting a portion of the first gas upon passing into the dielectric delivery tube, and for converting said portion of first gas into plasma, whereby the dielectric delivery tube is configured to deliver the plasma onto the rail track rail and/or rail vehicle wheel, and such that, in use, the microwave energy within the microwave cavity energises the plasma and the first gas within the dielectric delivery tube, ionizing the first gas to form plasma, and the first gas vortex drives the plasma out of the dielectric delivery tube and onto the rail track rail and/or rail vehicle wheel.

2. A surface conditioning device according to claim 1, wherein the surface conditioning device comprises a second gas delivery means operatively connected to a second gas supply and in fluid communication with the dielectric delivery tube for passing a second gas through said dielectric delivery tube, and the at least one ignition means is operatively connected to said second gas delivery means, for igniting a portion of the second gas and converting said second gas into plasma.

3. A surface conditioning device according to claim 1 or claim 2, wherein the at least one ignition means comprises an ignition rod supported by a linear actuator, whereby the linear actuator is configured to move the ignition rod into and out of the dielectric delivery tube.

4. A surface conditioning device according to any one of the preceding claims, wherein the microwave cavity is substantially cylindrical and the dielectric delivery tube is configured to pass along the axis of said cylinder.

5. A surface conditioning device according to any one of the preceding claims, wherein the dielectric delivery tube incorporates a nozzle at one end, juxtaposed in coaxial alignment with said dielectric delivery tube, for delivering the plasma onto the rail track rail and/or rail vehicle wheel.

6. A surface conditioning device according to any one of the preceding claims, wherein the waveguide assembly comprises at least one tuning means for tuning said microwave energy.

7. A surface conditioning device according to claim 6, wherein the tuning means comprises one or more of the following: a waveguide filter, resonator, cavity, iris, post.

8. A surface conditioning device according to any one of the preceding claims, wherein the microwave cavity is single mode.

9. A surface conditioning device according to any one of the preceding claims, wherein the microwave cavity comprises a metal block.

10. A surface conditioning device according to any one of the preceding claims, wherein the plasma delivery head incorporates cooling means.

11. A surface conditioning device according to claim 10, wherein the cooling means comprises a water cooling jacket.

12. A surface conditioning device according to claim 10, wherein the cooling means comprises an oil cooling jacket.

13. A surface conditioning device according to claim 10, wherein the cooling means comprises a phase change system.

14. A surface conditioning device according to any one of the preceding claims, wherein the surface conditioning device is operatively connected to at least one sensor, whereby said sensor comprises one or more of the following: accelerometer, thermometer, frictional sensor, moisture sensor, visual track condition sensor, slippage sensor, speed sensor.

15. A surface conditioning device according to claim 14, wherein the at least one sensor comprises an accelerometer such that, in use, the accelerometer detects braking of a rail vehicle, and generates plasma for treating the portion of rail track rail and/or wheel during a braking cycle.

16. A surface conditioning device according to any one of the preceding claims, wherein the first gas is nitrogen.

17. A surface conditioning device according to any one of claims 2 to 16, wherein the second gas is argon.

18. A surface conditioning device according to any one of the preceding claims, wherein the microwave generator comprises a magnetron.

19. A surface conditioning device according to any one of the preceding claims, wherein the surface conditioning device incorporates at least one mounting means for mounting the surface conditioning device to a rail vehicle.

20. A surface conditioning device according to claim 19, wherein the mounting means is configured to mount the plasma delivery head such that the plasma is delivered from a distance of between 25mm to 75mm to a rail surface and/or rail vehicle wheel surface.

21. A surface conditioning device according to claims 19 or 20, wherein the mounting means is configured to mount the plasma delivery head between a pair of wheels of the rail vehicle.

22. A surface conditioning device according to any one of the preceding claims, whereby the surface conditioning device comprises a plurality of plasma delivery heads operatively connected through a corresponding number of waveguide assemblies to the microwave generator.

23. A surface conditioning device according to any one of the preceding claims, whereby the portion of rail track rail and/or rail vehicle to be conditioned at any one time is between 5mm and 72mm.

24. A surface conditioning device according to any one of the preceding claims, wherein the power supply comprises a regenerative braking system.

25. A rail vehicle incorporating the surface conditioning device of any one of the preceding claims.