WO2014199392A1

WO2014199392A1 - "safe and eco friendly train traction system with air cushion for lift and with horizontally mounted all wheel driven traction for mobility with no rails"

Info

Publication number: WO2014199392A1
Application number: PCT/IN2014/000100
Authority: WO
Inventors: Giridharan K.
Original assignee: K Giridharan
Priority date: 2013-06-10
Filing date: 2014-02-18
Publication date: 2014-12-18

Abstract

The present invention offers a path to widespread use of safe and eco friendly train traction wherein chance of derailment is completely eliminated and wherein even in the event of failure of few traction wheel stations during run, the train remains mobile with absolute safety even at high speeds. The present invention describes a novel and safe method of train traction wherein the lift from the ground is achieved by air cushion similar to hovercraft model. Horizontally mounted all wheels driven traction motor drive powered by overhead electrification is used for mobility to maintain high power to weight ratio and faster acceleration. In the present invention, no rail but just a flat surface on the vertical side walls of the simple traction bed is used. This eliminates the enormous cost of laying the complex and expensive railway tracks. Other advantages include the lack of exhaust fumes and carbon emissions at point of use especially in countries where electricity comes primarily from non- fossil sources, less noise, lower maintenance requirements of the traction units. In case, where the availability or laying the overhead electrification is an issue, especially where tunnels and bridges and other obstructions have to be altered for clearance, the present invention has the potential to adopt alternate power sources such as petrol or diesel or gas turbine or jet engines or hybrid power sources for traction. But ecological issues may have to be compromised in such cases. The present invention has a potentially wide scope to revolutionize urban and suburban railway traction (both passengers and goods) and long distance traction.

Description

Description:

Background:

Conventional trains use complex and expensive rail beds needed to support the entire weight on two thin rails. At high speeds, trains suffer from a form of instability known as "hunting oscillation" that forces the flanges on the sides of the wheels to hit the sides of the rails, as if they were rounding a tight bend. If the frequency of these hits increased to the point, where they became a major form of drag, rolling resistance is dramatically increased and potentially causing a derailment. That meant that for travel above some critical speed, a hovercraft could be more efficient than a wheeled vehicle of the same weight. In practice it has been found that air-cushion vehicles can be overloaded by as much as 100 percent of the design payload and still operate. [1]

One of the earliest hovertrain concepts predates hovercraft by decades; in the early 1930s Andrew Kucher, an engineer at Ford, came up with the idea of using compressed air to provide lift as a form of lubrication. This led to

the Levapad concept, where compressed air was blown out of small metal disks, shaped much like a poppet valve. The Levapad required extremely flat surfaces to work on, either metal plates, or as originally intended, the very smooth concrete of a factory floor. Kucher eventually became VP in charge of the Ford Scientific Laboratory, continuing development of the Levapad concept throughout. It does not appear any effort was put into vehicle use until the 1950s, when several efforts used Levapad-like arrangements running on conventional rails as a way to avoid the hunting problems and provide high-speed service. An article in Modern Mechanix, October 1958 publication is one of the first popular introductions of the Levapad concept. The article focuses on cars, based on Ford's prototype "Glideair" vehicle, but quotes Kucher noting "We look upon Glideair as a new form of high-speed land transportation, probably in the field of rail surface travel, for fast trips of distances of up to about 1 ,000 miles".[2] A 1960 Popular Mechanics article notes a number of different groups proposing a hovertrain concept.

What was lacking from all of them was a suitable way to move the vehicles forward - since the whole idea of the hovertrain concept was to eliminate any physical contact with the running surface, especially wheels, some sort of contact-less thrust would have to be provided. There were various proposals using air ducted from the lift fans, propeller, or even jet engines, [2] but none of these could approach the efficiency of an electric motor powering a wheel.

Once air-cushion suspension was proved practical in Hovercraft, the . system was quickly applied to other forms of transport, and it soon became clear that a tracked vehicle, similar to a train or monorail, would benefit considerably from the lack of friction inherent in an air-cushion system. A French company was the first in the world to produce a practical device, and a later version of its machine was considered for a high-speed link between Orleans and Paris by the mid-1970s. The system used air-cushion pads above and at the side of a single concrete track to support the "aerotrain," while propulsion was via a large ducted fan mounted at the rear.

In Britain, tracked air-cushion vehicle development was also under way, with construction of a "Hovertrain," propelled by a relatively silent linear induction motor that has no moving parts and picks up current as it moves along the track.

Research also is proceeding in other countries. Air-cushion trains have speed potentials of up to 300 miles (480 kilometers) per hour; track costs are relatively low because of the simple concrete structure involved, which can be elevated on pylons, laid on the surface, or sunk in tunnels. Engineers in Britain, the United States, France, and Germany see this kind of high-speed surface transport as a means of connecting large urban centers with each other and with international airports.

DETAILED DESCRIPTION

As required, a detailed illustrative embodiment of the present invention is disclosed herein. The present invention offers a path to widespread use of safe and eco friendly train traction wherein chance of derailment is completely eliminated and wherein even in the event of failure of few traction wheel stations during run, the train remains mobile with absolute safety even at high speeds. The present invention has a potentially wide scope to revolutionize urban and suburban railway traction (both passengers and goods) and long distance traction.

In the present invention, a safe method of train traction as illustrated in Figure 1 , is described using a novel combination of lift by air cushion and mobility by horizontally mounted all wheel traction motor drive powered by overhead electrification is used to maintain high power to weight ratio and faster

acceleration. In the present invention, no rail but just a flat surface on the vertical side walls of the simple traction bed is used. This eliminates the enormous cost of laying the complex and expensive railway tracks. Lack of exhaust fumes and carbon emissions, less noise, and lower maintenance requirements of the traction units are the inherent advantages of the present invention.

In case, where the availability or laying the overhead electrification is an issue, especially where tunnels and bridges and other obstructions have to be altered for clearance, the present invention has the potential to adopt alternate power sources such as petrol or diesel or gas turbine or jet engines or hybrid power sources for traction. But ecological issues may have to be compromised in such cases. Lift by Air-cushion similar to hovercraft model:

In the present invention, as illustrated in Figure 1 , a centrifugal fan driven by an electric motor directly or through a gear box, creates air cushion underside of the vehicle which lifts the vehicle off the ground to eliminate ground friction. A centrifugal fan is preferred here because the volume of air needed is very large and a conventional propeller is designed to be most efficient in open air like on an aircraft. Also the fan needs to force air into the chamber below the vehicle to maintain a specific pressure. Propellers again are not efficient in applications when an air backpressure will be applied to the propeller blades as they rotate.

When the assembly is rotated at high-speed, air is sucked through the air duct, as shown in Figure 1 , into the center of the fan and the slats force it out at the edges with high pressure. The advantages of the centrifugal fan are two fold. Centrifugal fan operates efficiently in an environment when backpressure is high and it will move larger volumes of air for a given rotation speed than a

conventional propeller with the same speed and power input.

Due to lift and suspension of vehicle using air cushion, small imperfections in the ground surface would have no effect on the ride quality, so the complexity of the suspension system could be reduced. Additionally, since the load is spread out over the surface of the lifting pads, here the entire underside of the vehicle, the pressure on the running surface is greatly reduced - about 1/10000 th the pressure of a train wheel, about 1/20 th of the pressure of a tire on a road.[3] These two properties meant that the running surface could be considerably simpler than the surface needed to support the same vehicle on wheels. This vehicle could be supported on surfaces similar to existing light-duty roadways, instead of the much more complex and expensive rail beds needed for conventional trains. This could dramatically reduce infrastructure capital costs of building new lines and offer a path to widespread use of safe high-speed trains.

As shown in Figure 1 and Figure 2, the skirts in the shape of a semicircle, is fastened around the perimeter of the vehicle. The inflated skirt forms a semicircular cross section. Materials used in the skirts have varied from the original rubberized fabric, through pure rubber and nylon, to a lamination of nylon and a proprietary plastic known as neoprene.[1] Bondings between the different layers have to be especially strong; otherwise the fabric delaminates under the severe conditions of wear and loses its tear resistance.

Mobility of the vehicle:

From the survey of prior disclosures, it was observed that the hover traction methods were lacking from a suitable way to move the vehicles forward - since the whole idea of the hover traction concept was to eliminate any physical contact with the running surface, especially wheels, some sort of thrust would have to be provided for mobility. There were various proposals using air ducted from the lift fans, propeller, or even jet engines,[2] but none of these could approach the efficiency of an electric motor powering a wheel. The maglev technology used for railway traction is still under proving trials in different countries. In the present invention, as illustrated in Figure 1 and Figure 2, mobility of the vehicle is achieved by horizontally mounted all wheel traction motor drive powered by overhead electrification. This helps to maintain high power to weight ratio and faster acceleration. The horizontally mounted traction wheels roll over no rails but just a flat surface on the vertical side walls of the simple traction bed. This eliminates the enormous cost of laying the complex and expensive railway tracks. The present invention completely eliminates the chance of derailment and provides excellent stability even during high speed run. Even if few traction wheel stations fail during run, the train remains mobile providing absolute safety even at high speeds.

In case, where the availability or laying the overhead electrification is an issue, especially where tunnels and bridges and other obstructions have to be altered for clearance, the present invention has the potential to adopt alternate power sources such as petrol or diesel or gas turbine or jet engines or hybrid power sources for traction. But ecological issues may have to be compromised in such cases.

The minimum number of horizontal traction wheels required for providing the thrust for mobility in this present invention is one on each side. But this single wheel arrangement on each side needs a bigger sized heavy traction motor with high power rating. The multiple numbers of all wheel traction drives on each side of the vehicle provides certain advantages. One advantage is that the size, weight and power rating of traction motor at each wheel station are at comfortable limits. The weight of traction system is spread evenly throughout the vehicle which helps in better vehicle stability. Even if few traction wheel stations fail during run, the train remains mobile providing absolute safety even at high speeds. In the present invention, the traction wheel can be a simple cylindrical wheel with rubberized flat rim surface. Even an inflated or solid rubber tire (tyre) used in road vehicles also can be used. Such wheels are simple in design, low in weight and less in cost.

As shown in Figure 1 and Figure 2, since the weight of the vehicle is already supported by the air cushion, the horizontally mounted all wheel traction motor drive will need to provide only the thrust required for mobility of the vehicle. As illustrated in Figure 1 , the arrangement of horizontally mounted all wheel traction motor drive with each wheel station consisting of a traction motor powered by overhead electrification, a simple optional gear box, a horizontally mounted wheel, a linear actuator cum damper and a friction brake system. In addition to the friction braking, regenerative braking is also used in the present method for better energy management during braking and reduced frictional wear of the friction brakes. Each of the above mobility elements of the present invention is described as follows.

Traction Motors:

The present invention demonstrates a capability to use a wide

classification of traction motors. This includes the traditional series wound DC motors, AC induction asynchronous traction motors, synchronous AC motors, wheel hub motors and Permanent Magnet Brushless Motors. Each classification of these motors is discussed in the following paragraphs. Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion (traction). Traction motors are used in electrically powered rail vehicles such as electric multiple units and electric locomotives, other electric vehicles such as electric milk floats, elevators, conveyors, and trolleybuses, as well as vehicles with electrical transmission systems such as diesel-electric, electric hybrid vehicles and battery electric vehicles.

Traditionally, these were series-wound brushed DC motors, usually running on approximately 600 volts. The availability of high-powered

semiconductors (such as thyristors and the IGBT) has now made practical the use of much simpler, higher-reliability AC induction motors known as

asynchronous traction motors. Synchronous AC motors are also occasionally used, as in the French TGV. Before the mid-20th century, a single large motor was often used to drive multiple driving wheels through connecting rods that were very similar to those used on steam locomotives. Examples are the

Pennsylvania Railroad DDI, FF1 and L5 and the various Swiss Crocodiles. It is now standard practice to provide one traction motor driving each axle through a gear drive. In the case of French TGV power cars, a motor mounted to the power car's frame drives each axle; a "tripod" drive allows a small amount of flexibility in the drive train allowing the trucks bogies to pivot.

The DC motor was the mainstay of electric traction drives on both electric and diesel-electric locomotives, street-cars/trams and diesel electric drilling rigs for many years. It consists of two parts, a rotating armature and fixed field windings surrounding the rotating armature mounted around a shaft. The fixed field windings consist of tightly wound coils of wire fitted inside the motor case. The armature is another set of coils wound round a central shaft and is connected to the field windings through "brushes" which are spring-loaded contacts pressing against an extension of the armature called the commutator. The commutator collects all the terminations of the armature coils and distributes them in a circular pattern to allow the correct sequence of current flow. When the armature and the field windings are connected in series, the whole motor is referred to as "series-wound". A series-wound DC motor has a low resistance field and armature circuit. Because of this, when voltage is applied to it, the current is high due to Ohm's law. The advantage of high current is that the magnetic fields inside the motor are strong, producing high torque (turning force), so it is ideal for starting a train. The disadvantage is that the current flowing into the motor has to be limited, otherwise the supply could be overloaded or the motor and its cabling could be damaged. At best, the torque would exceed the adhesion and the driving wheels would slip. Traditionally, resistors were used to limit the initial current.

As the DC motor starts to turn, the interaction of the magnetic fields inside causes it to generate a voltage internally. This back EMF (electromagnetic force) opposes the applied voltage and the current that flows is governed by the difference between the two. As the motor speeds up, the internally generated voltage rises, the resultant EMF falls, less current passes through the motor and the torque drops. The motor naturally stops accelerating when the drag of the train matches the torque produced by the motors. To continue accelerating the train, series resistors are switched out step by step, each step increasing the effective voltage and thus the current and torque for a little bit longer until the motor catches up. This can be heard and felt in older DC trains as a series of clunks under the floor, each accompanied by a jerk of acceleration as the torque suddenly increases in response to the new surge of current. When no resistors are left in the circuit, full line voltage is applied directly to the motor. The train's speed remains constant at the point where the torque of the motor, governed by the effective voltage, equals the drag - sometimes referred to as balancing speed. If the train starts to climb an incline, the speed reduces because drag is greater than torque and the reduction in speed causes the back-EMF to fall and thus the effective voltage to rise - until the current through the motor produces enough torque to match the new drag.

If the train starts to descend a grade, the speed increases because the (reduced) drag is less than the torque. With increased speed, the internally generated back-EMF voltage rises, reducing the torque until the torque again balances the drag. On a sufficiently steep grade, the internally generated back EMF voltage may rise higher than the full line voltage. On such steep grades, the motor acts as a regenerative brake— the motor generates electric power, returns that power to the electric lines, and acts as a brake to prevent run-away acceleration down the grade. (On such a steep grade, adding resistors— or disconnecting the motor from the line entirely— would make the train go faster).

On an electric train, the train driver originally had to control the cutting out of resistance manually, but by 1914, automatic acceleration was being used. This was achieved by an accelerating relay (often called a "notching relay") in the motor circuit which monitored the fall of current as each step of resistance was cut out. All the driver had to do was select low, medium or full speed (called "shunt", "series" and "parallel" from the way the motors were connected in the resistance circuit) and the automatic equipment would do the rest. The wheel hub motor (also called wheel motor, wheel hub drive, hub motor or in-wheel motor) is an electric motor that is incorporated into the hub of a wheel and drives it directly. There are two basic categories of hub motors: direct drive and geared. Hub motor electromagnetic fields are supplied to the stationary windings of the motor. The outer part of the motor follows, or tries to follow, those fields, turning the attached wheel. In a brushed motor, energy is transferred by brushes contacting the rotating shaft of the motor. Energy is transferred in a brushless motor electronically, eliminating physical contact between stationary and moving parts. Although brushless motor technology is more expensive, most are more efficient and longer-lasting than brushed motor systems. Wheel hub motors have their greatest torque at startup, making them ideal for vehicles as they need the most torque at startup too. Their greatest torque occurs as the rotor first begins to turn, which is why wheel hub motors do not require an external gear box. Wheel hub motors are increasingly common on electric bikes and electric scooters in some parts of the world, especially Asia. [4]

The use of induction motors (asynchronous motors) in urban transport instead of d.c. motors allows both the mono-motor driving on the axle and the driving of each wheel in order to meet the new requirements of the traction system, especially the low floor vehicle. The main advantage of the direct driving is to avoid the mechanical gearbox. The last one becomes soon worn due to the hard working conditions. The state-of-the-art light traction system of street cars (tramways, trolley lines, subway trains) consists of GTO or IGBT power inverter, feeding a.c. electric motors (cage induction, permanent magnet brushless or switched reluctance motors). An important feature of any traction motor is the rather long range of constant power. The both constant torque and constant power conditions on a wide speed range can be achieved through electronic control. Traction motors should meet a set of requirements: high instant power, high power density, high torque at low speed, fast torque response, high efficiency over wide speed and torque ranges, high reliability and robustness, low cost. On the other hand, the direct drive system (i.e. drive of axle or wheel without use of any gears) offers many benefits that must be considered: no gear energy losses; no gear maintenance; no gear noise; oil-free drive system;

reduced noise of the traction motor by rather low motor speed and by inverter feeding.

Nowadays, majority of the researchers consider that the Permanent Magnet Brushless Motors are more efficient, more compact, have better steady- state and dynamic performances at low speed and are excellent motors for direct drive traction applications. However, by special design, the induction motor proved to be a good economical solution, meeting the demands of power and speed for street car application. In the paper the authors states that the totally enclosed a.c. induction motor is the best choice for most variable-speed applications and for some applications the direct-drive a.c. induction motor is the better choice. The aim of the paper is to prove that the induction motor can develop enough torque to perform the required speed and acceleration for a tramway. It was decided to build a prototype in order to verify the theoretical data by measurement. The paper presents this work and some results concerning the motor-prototype tests by sinusoidal voltage supply, using a data acquisition and processing system.

The direct drive traction motor which eliminates gears and hence noise and transmission losses was performed and tested in the laboratory using the data acquisition and processing system. In the field, the measurement results show that this motor prototype can develop enough torque to perform the required acceleration of the tramway. The proposed traction system including the induction motor and the power inverter with variable both voltage and frequency can be a realistic direct drive solution for modern tramways or streetcars.

Overhead railway electrification:

The present invention demonstrates the versatility of using wide power classification of overhead railway electrification as the power source. The following paragraphs discuss on the advantages, disadvantages of wide power classification of overhead railway electrification.

The main advantage of overhead electrification is a higher power-to- weight ratio than forms of traction such as diesel or steam that generate power on board. Electricity enables faster acceleration and higher tractive effort on steep grades. On locomotives equipped with regenerative brakes, descending grades require very little use of air brakes as the locomotive's traction motors become generators sending current back into the supply system and/or on-board resistors, which convert the excess energy to heat. Other advantages include the lack of exhaust fumes at point of use, less noise and lower maintenance requirements of the traction units. Given sufficient traffic density, electric trains produce less carbon emissions than diesel trains, especially in countries where electricity comes primarily from non-fossil sources.

A railway electrification system supplies electrical energy to railway locomotives and multiple units so that they can operate without having an onboard prime mover. There are several different electrification systems in use throughout the world. Railway electrification has many advantages but requires heavy capital expenditure for installation. In India 1500 V DC and 25 kV AC, 50 Hz, is used for main line trains. The 1500 V DC overhead system (negative earth, positive catenary) is used around Mumbai. The Mumbai region is the last bastion of 1500 V DC electrified lines on Indian Railways. There are plans to change this to 25 kV AC by 2010. The 25 kV AC system with overhead lines is used throughout the rest of the country. The dual-voltage WGAM series locomotives haul intercity trains out of Mumbai DC suburban region. The new AC/DC EMU rakes used in Mumbai are also designed to operate with both DC and AC traction as the Mumbai area switches over to the 25 kV AC system. The Kolkata

Metro uses 750 V DC traction with a third rail for delivering the electricity to the EMUs. The Kolkata trams use 550 V DC with overhead lines with underground conductors. The catenary is at a negative potential. The Delhi Metro uses 25 kV AC overhead lines on the ground-level and elevated routes, and uses a rather unusual "rigid catenary", or overhead power rail, in the underground tunnel sections

Electric-traction systems can be broadly divided into those

using alternating current and those using direct current. With direct current, the most popular line voltages for overhead wire supply systems have been ,500 and 3,000. Third-rail systems are predominantly in the 600-750 volt range. The disadvantages of direct current are that expensive substations are required at frequent intervals and the overhead wire or third rail must be relatively large and heavy. The low-voltage, series-wound, direct-current motor is well suited to railroad traction, being simple to construct and easy to control. Until the late 20th century it was universally employed in electric and diesel-electric traction units. The potential advantages of using alternating instead of direct current prompted early experiments and applications of this system. With alternating current, especially with relatively high overhead-wire voltages (10,000 volts or above), fewer substations are required, and the lighter overhead current supply wire that can be used correspondingly reduces the weight of structures needed to support it, to the further benefit of capital costs of electrification. In the early decades of high-voltage alternating current electrification, available alternating- current motors were not suitable for operation with alternating current of the standard commercial or industrial frequencies (50 hertz [cycles per second] in Europe; 60 hertz in the United States and parts of Japan). It was necessary to use a lower frequency (16 hertz is common in Europe; 25 hertz in the United States); this in turn required either special railroad power plants to generate alternating current at the required frequency or frequency-conversion equipment to change the available commercial frequency into the railroad frequency.

The main disadvantage is the capital cost of the electrification equipment, most significantly for long distance lines which do not generate heavy traffic. Suburban railways with closely-spaced stations and high traffic density are the most likely to be electrified, and main lines carrying heavy and frequent traffic are also electrified in many countries.

1.5 kV DC is used in the Netherlands, Japan, Ireland, Australia (parts), India, France, New Zealand and the United States. In Slovakia, there are two narrow- gauge lines in the High Tatras . In Portugal, it is used in the Cascais Line, and in Denmark on the suburban S-train system.

The main advantages of overhead electrification include: lower running cost of locomotives and multiple units, lower maintenance cost of locomotives and multiple units, higher power-to-weight ratio, resulting in fewer locomotives, faster acceleration, higher practical limit of power, higher limit of speed, less noise pollution, reduced power loss at higher altitudes, lack of dependence on crude oil as fuel.

There is a significant amount of published material that concludes that electric trains are more energy efficient than diesel-powered trains, and with proper energy production can have a smaller carbon dioxide footprint. Some of the reasons for this are as follows: electric trains may be powered from a number of different sources of energy as opposed to diesel trains that are reliant on oil. Under certain conditions trains can return power to the network, further increasing efficiency. Electric trains do not have to carry around the weight of their fuel unlike diesel traction.

In order for trains to return power to the network, both the rolling stock and the network must be prepared to do so. Presently the energy returned by vehicles is not sent back to the public network, but made available for other vehicles within the network. Regenerative braking is therefore often implemented in tram networks, where the density of vehicles per powered section is high, but is more difficult with trains, especially where the voltage is relatively low, hence the sections are small. According to widely accepted global energy reserve statistics the reserves of liquid fuel are much less than gas and coal (at 42, 167 and 416 years respectively). And most countries with large rail networks do not have significant oil reserves, and those that do, like the United States and Britain, have exhausted much of their reserves and have had declining oil output for decades. Therefore there is also a strong economic incentive to substitute oil for other fuels. The main disadvantages of overhead electrification include: upgrading brings significant cost, especially where tunnels and bridges and other obstructions have to be altered for clearance, alterations or upgrades will be needed on the railway signaling to take advantage of the new traffic characteristics.

In case, where the availability or laying the overhead electrification is an issue, the present invention has the potential to adopt alternate power sources such as petrol or diesel or gas turbine or jet engines or hybrid power sources for traction. But ecological issues may have to be compromised in such cases.

Horizontally mounted all wheel driven traction wheels:

As illustrated in Figure 1 and Figure 2, in the present invention, since the conventional tracks laid on rail beds are eliminated using the lift by air- cushion, the traction mobility is provided using horizontally mounted traction wheels. These traction wheels roll over no rail but just a flat surface on the vertical side walls of the simple traction bed. This eliminates the enormous cost of laying the complex and expensive railway tracks. In the present invention, the traction wheel can be a simple cylindrical wheel with rubberized flat rim surface. Even an inflated or solid rubber tire (tyre) used in road vehicles also can be used. Such wheels are simple in design, low in weight and less in cost.

The wheels roll over the flat surface on the sides of the vertical walls of simple traction bed for train traction. The horizontally mounted traction wheels receive power from the traction motor either through a gear box or directly, based on the type of the traction motor employed. As shown in Figure , the horizontally mounted traction wheel is pushed against the flat surface on the sides of the vertical walls of traction bed by a linear actuator cum damper mechanism. Only when the air cushion at the underside of the train is inflated and the train is lifted off the ground, the linear actuator cum damper pushes the traction wheels against the flat surface for mobility. When the vehicle is not mobile, then, the linear actuator cum damper pulls back the traction wheel and there will be a gap between the flat surface and the traction wheel as illustrated in Figure 1 and Figure 2.

The minimum number of horizontal traction wheels required for providing the thrust for mobility in this present invention is one on each side. But this single wheel on each side arrangement needs a bigger sized heavy traction motor with high power rating. The multiple numbers of all wheel traction drives on each side of the vehicle provides certain advantages. One advantage is that the size, weight and power rating of traction motor at each wheel station are at comfortable limits. The weight of traction system is spread evenly throughout the vehicle which helps in better vehicle stability. Even if few traction wheel stations fail during run, the train remains mobile providing absolute safety even at high speeds.

Gear box- As shown in Figure 1 , the present invention, demonstrates the flexibility to adopt an optional gear box suitable to the type of traction motor employed. The optional gear box connects the traction motor to the respective traction wheel. The horizontally mounted traction wheels receive power from the traction motor either through a gear box or directly, based on the type of the traction motor employed. If the power and torque rating of the selected traction motor makes it suitable for a direct drive, then, there will not be a need for a gear box. The present invention has the flexibility to adopt gear boxes assembled with either conventional gears or planetary gears.

Linear actuator cum damper:

As illustrated in Figure 1 , in the present invention, a linear actuator cum damper is provided in each traction wheel station for pushing or pulling the horizontally mounted traction wheel against or away from the flat surface on the sides of the vertical walls of traction bed. Only when the air cushion is inflated and the train is lifted off the ground, the linear actuator cum damper will push the traction wheel against the flat surface for mobility. When the vehicle is not mobile, then, the linear actuator cum damper pulls back the traction wheel and there will be a gap between the flat surface and the traction wheel as illustrated in Figure 1 and Figure 2. In the present invention, flexibility is provided in such a way that the pneumatically or hydraulically or spring operated linear actuator cum damper mechanism can be employed to push and pull the traction wheel against or away from the flat surface on the sides of the vertical walls of traction bed.

Brake system:

In the present invention, dual brake system is used. They are

regenerative braking and friction brakes (Figure 1 & Figure 2). The following paragraphs describe the brake system in detail. A regenerative brake is an energy recovery mechanism which slows a vehicle or object down by converting its kinetic energy into another form, which can be either used immediately or stored until needed. This contrasts with conventional braking systems, where the excess kinetic energy is converted to heat by friction in the brake linings and therefore wasted.

The most common form of regenerative brake involves using an electric motor as an electric generator. In electric railways the generated electricity is fed back into the supply system, whereas in battery electric and hybrid

electric vehicles, the energy is stored chemically in a battery, electrically in a bank of capacitors, or mechanically in a rotating flywheel. Hydraulic

hybrid vehicles use hydraulic motors and store energy in form of compressed air.

Traditional friction-based braking is used in conjunction with regenerative braking for the following reasons: The regenerative braking effect drops off at lower speeds; therefore the friction brake is still required in order to bring the vehicle to a complete halt. Physical locking of the wheel is also required to prevent vehicles from rolling down hills. The friction brake is a necessary back-up in the event of failure of the regenerative brake. Most road vehicles with regenerative braking only have power on some wheels (as in a two-wheel drive car) and regenerative braking power only applies to such wheels because they are the only wheels linked to the drive motor, so in order to provide controlled braking under difficult conditions (such as in wet roads) friction based braking is necessary on the other wheels. The amount of electrical energy capable of dissipation is limited by either the capacity of the supply system to absorb this energy or on the state of charge of the battery or capacitors.

Regenerative braking can only occur if no other electrical component on the same supply system is drawing power and only if the battery or capacitors are not fully charged. For this reason, it is normal to also incorporate dynamic braking to absorb the excess energy. Under emergency braking it is desirable that the braking force exerted be the maximum allowed by the friction between the wheels and the surface without slipping, over the entire speed range from the vehicle's maximum speed down to zero. The maximum force available for acceleration is typically much less than this except in the case of extreme high- performance vehicles. Therefore, the power required to be dissipated by the braking system under emergency braking conditions may be many times the maximum power which is delivered under acceleration. Traction motors sized to handle the drive power may not be able to cope with the extra load and the battery may not be able to accept charge at a sufficiently high rate. Friction braking is required to dissipate the surplus energy in order to allow an acceptable emergency braking performance.

During braking, the traction motor connections are altered to turn them into electrical generators. The motor fields are connected across the main traction generator (MG) and the motor armatures are connected across the load. The MG now excites the motor fields. The rolling locomotive or multiple unit wheels turn the motor armatures, and the motors act as generators, either sending the generated current through onboard resistors (dynamic braking) or back into the supply (regenerative braking). Compared to electro-pneumatic friction brakes, braking with the traction motors can be regulated faster improving the performance of wheel slide protection. For a given direction of travel, current flow through the motor armatures during braking will be opposite to that during motoring. Therefore, the motor exerts torque in a direction that is opposite from the rolling direction. Braking effort is proportional to the product of the magnetic strength of the field windings, multiplied by that of the armature windings.

The present invention, as shown in Figure 1 and 2, demonstrates the capability of working with vacuum controlled or compressed air controlled or hydraulically controlled friction brake system. The present invention also demonstrates the capability of working with disc or drum or shoe brake systems.

Simple traction bed with just a flat surface on the sides of vertical walls through which the train maneuvers:

The present invention, as shown in Figures 1 and Figure 2, uses no rail but just a flat surface on the vertical side walls of the simple traction bed through which the train maneuvers. This eliminates the enormous cost of laying the complex and expensive railway tracks. In the present invention, no rail but a combination of simple cylindrical wheel rolling over a flat surface is used for traction. But for the traction of heavy loads, the rack and pinion design can be used.

Due to lift and suspension of vehicle using air cushion, small imperfections in the ground surface would have no effect on the ride quality, so the complexity of the suspension system could be reduced. Additionally, since the load is spread out over the surface of the lifting pads, here the entire underside of the vehicle, the pressure on the running surface is greatly reduced - about 1/10000 th the pressure of a train wheel, about 1/20 th of the pressure of a tire on a road.[2]

These two properties meant that the running surface could be

considerably simpler than the surface needed to support the same vehicle on wheels. This vehicle could be supported on surfaces similar to existing light-duty roadways, instead of the much more complex and expensive rail beds needed for conventional trains. This could dramatically reduce infrastructure capital costs of building new lines and offer a path to widespread use of safe high-speed trains.

Complete Specification:

The complete specification of the present invention is explained using Figure 1 and Figure 2. Figure 1 is the view of frontal elevation with the following details: centrifugal fan and drive motor for producing the air cushion underside of the vehicle, horizontally mounted all wheel driven traction system, linear actuator cum damper, no rail but just a flat surface running through the sides of the vertical walls of the simple traction bed through which the train maneuvers and overhead electrification.

Figure 2 is the top view with the details of the following: the top view of the horizontally mounted all wheel driven traction system, top view of the air ducts for creating air cushion underside of the vehicle. No rail but just a flat surface running through the traction bed and passengers' seating. The present invention offers a path to widespread use of safe and eco friendly train traction wherein chance of derailment is completely eliminated and wherein even in the event of failure of few traction wheel stations during run, the train remains mobile with absolute safety even at high speeds. The present invention has a potentially wide scope to revolutionize urban and suburban railway traction (both passengers and goods) and long distance traction.

In the present invention, a novel and safe method of train traction as illustrated in Figure 1 , is described wherein the lift from the ground is achieved by air cushion similar to hovercraft model. Horizontally mounted all wheels driven traction motor drive powered by overhead electrification is used for mobility to maintain high power to weight ratio and faster acceleration. In the present invention, no rail but just a flat surface on the vertical side walls of the simple traction bed is used. This eliminates the enormous cost of laying the complex and expensive railway tracks. Other advantages include the lack of exhaust fumes and carbon emissions at point of use especially in countries where electricity comes primarily f rom non-fossil sources, less noise, lower

maintenance requirements of the traction units.

In the present invention, as illustrated in Figure 1 , a centrifugal fan driven by an electric motor directly or through a gear box creates air cushion underside of the train which lifts the train off the ground to eliminate ground friction. As shown in Figure 1 and Figure 2, the skirts in the shape of a semicircle, is fastened around the perimeter of the vehicle. The inflated skirt forms a semicircular cross section. Materials used in the skirts have varied from the original rubberized fabric, through pure rubber and nylon, to a lamination of nylon and a proprietary plastic known as neoprene.[1] Bondings between the different layers have to be especially strong; otherwise the fabric delaminates under the severe conditions of wear and loses its tear resistance.

In the present invention, as illustrated in Figure 1 and Figure 2, mobility of the vehicle is achieved by horizontally mounted all wheel traction motor drive powered by overhead electrification. This helps to maintain high power to weight ratio and faster acceleration. The horizontally mounted traction wheels roll over no rails but just a flat surface on the vertical side walls of the simple traction bed. This eliminates the enormous cost of laying the complex and expensive railway tracks. The present invention completely eliminates the chance of derailment and provides excellent stability even during high speed run. Even if few traction wheel stations fail during run, the train remains mobile providing absolute safety even at high speeds.

The minimum number of horizontal traction wheels required for providing the thrust for mobility in this present invention is one on each side. But this single wheel arrangement on each side needs a bigger sized heavy traction motor with high power rating. The multiple numbers of all wheel traction drives on each side of the vehicle provides certain advantages. One advantage is that the size, weight and power rating of traction motor at each wheel station are at comfortable limits. The weight of traction system is spread evenly throughout the vehicle which helps in better vehicle stability. Even if few traction wheel stations fail during run, the train remains mobile providing absolute safety even at high speeds.

The present invention demonstrates a capability to use a wide

classification of traction motors. This includes the traditional series wound DC motors, AC induction asynchronous traction motors, synchronous AC motors, wheel hub motors and Permanent Magnet Brushless Motors.

The present invention demonstrates the versatility of using wide power classification of overhead railway electrification as the power source.

As illustrated in Figure 1 and Figure 2, in the present invention, since the conventional tracks laid on rail beds are eliminated using the lift by air-cushion, the traction mobility is provided using horizontally mounted traction wheels.

These traction wheels roll over no rail but just a flat surface on the vertical side walls of the simple traction bed. This eliminates the enormous cost of laying the complex and expensive railway tracks. In the present invention, the traction wheel can be a simple cylindrical wheel with rubberized flat rim surface. Even an inflated or solid rubber tire (tyre) used in road vehicles also can be used. Such wheels are simple in design, low in weight and less in cost. The wheels roll over the flat surface on the sides of the vertical walls of simple traction bed for train traction. The horizontally mounted traction wheels receive power from the traction motor either through a gear box or directly, based on the type of the traction motor employed. As shown in Figure 1 , the horizontally mounted traction_. wheel is pushed against the flat surface on the sides of the vertical walls of traction bed by a linear actuator cum damper mechanism. Only when the air cushion is inflated and the vehicle is lifted off the ground, the linear actuator cum damper pushes the traction wheels against the flat surface for mobility. When the vehicle is not mobile, then, the linear actuator cum damper pulls back the traction wheel and there will be a gap between the flat surface and the traction wheel as shown in Figure 1 and Figure 2.

As shown in Figure 1 , the present invention, demonstrates the flexibility to adopt an optional gear box suitable to the type of traction motor employed. The optional gear box connects the traction motor to the respective traction wheel. The horizontally mounted traction wheels receive power from the traction motor either through a gear box or directly, based on the type of the traction motor employed. If the power and torque rating of the selected traction motor makes it suitable for a direct drive, then, there will not be a need for a gear box. The present invention has the flexibility to adopt gear boxes assembled with either conventional gears or planetary gears.

As illustrated in Figure 1 , in the present invention, a linear actuator cum damper is provided in each traction wheel station for pushing or pulling the horizontally mounted traction wheel against or away from the flat surface on the sides of the simple traction bed. Only when the air cushion is inflated and the train is lifted off the ground, the linear actuator cum damper will push the traction wheels against the flat surface for mobility. When the train is not mobile, then, the linear actuator cum damper pulls back the traction wheel and there will be a gap between the flat surface and the traction wheel. In the present invention, flexibility is provided in such a way that the pneumatically or hydraulically or spring operated linear actuator cum damper mechanism can be employed to push and pull the traction wheel against or away from the flat surface.

In the present invention, dual brake system is used. They are

regenerative braking and friction brakes (Figure 1 & Figure 2).

References:

1. United States Patent 6,464,459 illingworth Oct 15 2002

2. "Cars That Fly", Modern Mechanix, October 1958, pp. 92-95

3. John Volpe, "Streamliners Without Wheels", Popular Science, December 1969, p. 54

4. "History of Hybrid Vehicles". HybridCars.com. 2006-03-27. Retrieved 2010- 03-21.

Drawing Summary:

Figure 2 is the top view with the details of the following: the top view of the horizontally mounted all wheel driven traction system, top view of the air ducts for creating air cushion underside of the vehicle. No rail but just a flat surface running through the traction bed and passengers' seating.

Claims

Claims: I claim

1. A safe and eco friendly train traction system; safe means wherein chance of derailment is completely eliminated, wherein even in the event of failure of few traction wheel stations during run, the train remains mobile with absolute safety even at high speeds and wherein no rail but just a flat surface on the vertical side walls of the simple traction bed is used for traction; eco friendly means wherein exhaust fumes and carbon emissions at point of use are eliminated, wherein less noise and lower maintenance requirements of the traction units are ensured and which has a potentially wide scope to revolutionize urban and suburban railway traction (both passengers and goods) and long distance traction; such a system comprising;

a centrifugal fan driven by a power source directly or through a gear box for creating air cushion underside of the vehicle as found in hovercrafts for lift;

the horizontally mounted all wheel driven traction motor drive powered by overhead electrification for mobility;

a skirt for holding the air cushion fastened around the underside perimeter of the vehicle;

a combination of simple cylindrical wheel rolling over a flat surface for traction; an optional gear box/ transmission suitable to the type of traction power source employed;

a linear actuator cum damper provided in each traction wheel station for pushing or pulling the horizontally mounted traction wheel against or away from the flat surface on the side of the traction bed;

a dual brake system consisting of regenerative braking and friction brakes;

a traction bed with no rail but just a flat surface on the sides of the vertical walls through which the train maneuvers.

2. The safe and eco friendly train traction system of claim 1 wherein the air cushion underside of the vehicle is created by at least one fan driven by a power source.