Title of Invention

DYNAMIC BRAKING RESISTOR

Abstract

The present provides a dynamic braking resistor comprising a plurality of resistor element stacked in parallel path in a housing, each of said resistor elements comprising of at least one resistor strip, and each said resistor elements being located with interstitial spaces there between to ensure easy flow of atmospheric air for cooling, each said resistor element is weldably connected to the adjoining resistor element, a collared insulator being located in an elliptical hole provided on the welded resistor element at the upper and lower portion thereof each said insulator being supported on a corresponding insulation coated metal rod.

Full Text

FORM 2 THE PATENTS ACT, 1970 COMPLETE SPECIFICATION [See Section 10] "DYNAMIC BRAKING RESISTOR" SATISH NATH SHARMA and CHANDER PRAKASH SHARMA, both Indian citizens, of 10 E, Industrial Estate, Govindpura, Bhopal 462 023, Madhya Pradesh, India The following specification particularly describes the nature of the invention and the manner in which it is to be performed. 23-7-2004 GRANTED 1 8 OCT 2000 DYNAMIC BRAKING RESISTOR Field of the invention The present invention relates to a novel dynamic braking resistor. More particularly, the present invention relates to a novel dynamic braking resistor for locomotives. Background of the invention An important unit of a locomotive system is the braking arrangement provided thereon. Safety in locomotive travel has become an important area of focus due to the large number of railroad related accidents all over the world. In India, the problem is compounded by the fact that the railway system is one of the largest in the world and is responsible for hauling more freight and passengers annually than any other railway system. Another feature affecting the safety of rail travel in India is that in most areas, the rail tracks are unprotected enabling easy access to human and animal population across the tracks. Due to this, it is essential that railroad locomotives be provided with an efficient braking system that is long-lasting and economical. Prior art braking systems in locomotives in use in India comprise of mechanical braking arrangements and include conventional features such as brake shoes and brake blocks. Modern day locomotives are primarily electric locomotives that generally are fed direct electrical power from overhead cables lining the entire route of the train. An alternative method of supply of electric power in locomotives is self-generated power by burning carbonaceous fuels in the locomotive cab to generate the power required throughout the train. In both the above cases, the motive power is electricity. The electricity generated powers electric motors generally referred to as traction motors, which in turn provide motive power to the wheels of the cab through a simple gear arrangement. In prior art systems, the application of brakes in the locomotive cab results in the stopping of the supply of electricity to the armature of the traction motor. However, the stator, which is the non-mobile part of the traction motor continues to be fed with electricity. The moving rotor in the motor generates electricity as a principle and the electric flux in the stator acts upon the rotating armature to produce a braking effect. However, during the time taken for the braking effect to act, the rotating armature continues to generate electricity, which is converted into heat by feeding it to resistors. The high levels of heat energy generated require to be dissipated quickly so as to avoid overheating of the braking system. In view of the above, prior art braking systems are provided with an independent cooling system to ensure quick dissipation of heat. However, the cooling system of such prior art systems is subject to failure. Also, prior art systems result in high wear and tear of the braking components requiring servicing and/or replacement of the components almost every six months. US Patent 6,036,284 discloses a modular locomotive brake control unit with electropneumatic modules, each including removable pneumatic elements as a unit in a manifold. However, the focus of the disclosure in the above-referred US Patent is on braking control and there is no disclosure or reference to prevention of wear and tear or dissipation of the heat energy generated during braking operations. US Patent 6,035,250 discloses a locomotive brake control unit with dynamic brake interlock. The invention of the above-referred US Patent is generally for computer controlled railroad braking equipment and not for manually operated braking systems. US Patent 5, 813,730 discloses a retrofit air distribution apparatus for a locomotive braking system which is configured to act as an interface with an electronic braking control device. The disclosure does not provide any information for control of a manual braking operation. US Patent 4, 352,049 discloses a brake control apparatus and method for transit vehicles generally with a brake effort request P signal indicating the desired brake effort and with the receptivity of the power supply line determining how much electric braking energy is regenerated to the power supply line and how much is dissipated in the dynamic braking resistors. Prior art systems suffer from the disadvantages of not providing a failsafe system for dissipation of heat energy generated during braking operations and therefore result in wear and tear of the braking systems. The prior art systems also require constant monitoring to ensure that the resistors and the cooling systems are functioning effectively. On an average, prior art systems require replacement and/or servicing every six months and are therefore also more expensive. Mechanical braking systems of the prior art are not only subject to fast wear and tear but are also not completely fail safe and can result in wheel skidding and consequent derailment when the brakes are applied in an emergency. Our copending Indian patent application number 512/MUM/2000 relates to a novel dynamic braking resistor which substantially overcomes the disadvantages associated with braking systems available in the prior art. The present invention is an improvement over the dynamic braking resistor of our copending patent application No. 512/MUM/2000. It is therefore imperative to devise a system for braking of locomotives that is inexpensive, failsafe, requires less maintenance in terms of reduced wear and tear of component parts and generates greater confidence in the locomotive driver and is also efficient. Objects of the invention It is therefore an object of the invention to provide a dynamic braking resistor with improved efficiency that is also cost effective. It is another object of the invention to provide a failsafe dynamic braking resistor that ensures quick dissipation of heat energy generated during braking operations. It is a further object of the invention to provide a dynamic braking resistor that eliminates the need for an expensive and cumbersome cooling system used in the prior art. It is another object of the invention to provide a dynamic braking resistor that has a self-floating design for the elements of the resistor and thereby minimises the wear and tear of the resistor elements. Summary of the invention Accordingly the present invention provides a dynamic braking resistor comprising a plurality of resistor elements (001) stacked in parallel path in a housing, each of said resistor elements comprising of at least one resistor strip, (007) and each said resistor elements (001) being located with interstitial spaces there between to ensure easy flow of atmospheric air for cooling, characterised in that each said resistor element is weldably connected to the adjoining resistor element, a collared insulator (002, 004, 005, 006) being located in an elliptical hole provided on the welded resistor element at the upper and lower portion thereof, each said insulator being supported on a corresponding insulation coated metal rod (011). In one embodiment of the invention, the resistor strip (007) is provided with corrugations (003). In a further embodiment of the invention, the housing comprises a frame, wherein the said plurality of resistor elements are stacked in a parallel path. In a further embodiment of the invention, the dynamic braking resistor is connected to the traction motor of the locomotive by means of a bus bar. In another embodiment of the invention, the spacing between the resistor elements is between 15 to 20 mm. The invention also relates to a strip useful for the making of a resistor element, said strip comprising of an elongated piece of material being provided with evenly spaced corrugations. In another embodiment of the invention, the resistor element comprises of at least four resistor strips with even spacing therebetween. Brief description of the accompanying drawings Figure 1 is a side representation of the roof mounted dynamic braking resistor of the invention Figure 2 is a top representation of the roof mounted dynamic braking resistor of the invention. Figure 3 is a representation of the element assembly in accordance with the invention. Figure 4 is a representation of the element tray assembly according to one aspect of the invention. Figure 5 is a representation of the complete tray of the element tray assembly in accordance with one aspect of the invention. Detailed description of the invention The dynamic braking resistor of the invention eliminates the presence of cooling systems such as blowers or blower motors present in the prior art. As a result, the failure factor in dynamic braking is minimised since the apparatus of the invention relies on atmospheric dissipation of heat and not on an artificial cooling system. One feature of the present invention is that a spring loading for the resistor is eliminated. The element is not woven over the insulators. In the present invention, each element is cut in vertical height and welded to another vertical element. An elliptical punch is made on the welded area of the two resistors at the upper and lower portions thereof. A collared insulator (004, 005, 006) is inserted in the elliptical hole of the resistor (007), which is in turn supported on a steel rod coated in mica. The mica coated steel support rod acts as the primary insulation. The provision of an elliptical hole on the upper and lower portion of the resistor with collared insulator provided therein allows the expansion and contraction of the resistors without creating any stress and strain on the insulators (004, 005). The self-floating mechanism described above results in at least two positive advantages - a complicated spring arrangement for support is eliminated and the warpage and stress and strain factor on the insualtors is substantially reduced resulting in a longer life and reduction in maintenance costs. The gap between each element in an element tray assembly is preferably in the range of 15 - 20 mm uniformly throughout the tray assembly. The gap between the outermost elements of one tray and the abutting outermost elements of an adjacent tray are in the range of 40 to 55 mm. The gap between the elements reduces the chances of shorting of the resistor element with an adjoining element and also speeds up the cooling process. The dynamic braking resistor can comprise of any number of resistor elements stacked preferably in parallel so as to ensure that maximum benefit of the air currents in atmosphere are availed. Each resistor element comprises preferably at least one resistor strip made of Nickel chrome 60.15. The optimum size of the strip is 43.0 to 56 mm and length is about 18.11 meters. and length is about 18.11 meters. The total preferred volume of the resistance element for Indian conditions for the complete unit is 0.26488 Cu. meters. The preferred resistance of the resistor is 0.460 Ohms. The resistor strip is preferably corrugated to ensure complete circulation of air and least resistance to heat dissipation. The enlarged surface area thus available on the corrugated strip enables greater dissipation of heat generated during braking operation in a more timely manner and thus ensures that the equipment wear and tear and stress due to heat are minimised substantially. The length of the corrugated strip is normally about 0.67 meters as compared to prior art strip length of one meter. The entire resistor is housed in a corrosion and weather proof housing comprising preferably a steel frame so as to ensure that rain, moisture or coastal salty air does not affect the frame itself. The hole pitch of the frame where the insulator is mounted is done so as to ensure that the gap between the element strips as mounted is at least 10 to 15 mm. - We Claim 1. A dynamic braking resistor comprising a plurality of resistor elements (001) stacked in parallel path in a housing, each of said resistor elements (001) comprising of at least one resistor strip (007) and each said resistor element being located with interstitial spaces there between to ensure easy flow of atmospheric air for cooling, characterised in that each said resistor element is weldably connected to the connected to the adjoining resistor element, a collared insulator (002, 004, 005, 006) being located in an elliptical hole provided on the welded resistor element at the upper and lower portion thereof, each said insulator being supported on a corresponding insulation coated metal rod (011). 2. A dynamic braking resistor as claimed in claim 1 wherein the resistor strip (007) comprises of corrugations. 3. A dynamic braking resistor as claimed in claim 1 wherein the housing comprises a frame, wherein the said plurality of resistor elements are stacked in a parallel path. 4. A dynamic braking resistor as claimed in claim 1 wherein the dynamic braking resistor is connected to the traction motor of the locomotive by means of a bus bar. 5. A dynamic braking resistor as claimed in claim 1 wherein the spacing between the resistor elements in one element tray assembly is between 15 to 20 mm. 6. A dynamic braking resistor as claimed in claim 1 wherein the spacing between the outermost resistor elements in one element tray assembly and the corresponding abutting outermost elements of the adjacent tray assembly is between 40 to 45 mm. 7. A dynamic braking resistor as claimed in claim 1 the resistor element comprises of at least four resistor strips with even spacing therebetween. 8. A dynamic braking resistor as claimed in claim 1 wherein said strip comprising of an elongated piece of material being provided with evenly spaced corrugations. 9. A dynamic braking resistor substantially as described hereinbefore and with reference to the accompanying drawings. Dated this the 17* day of October 2000 G. 1NATARAJ Of SUBRAMANIAM, NATARAJ & ASSOCIATES Attorneys for the Applicants

Documents:

933-mum-2000-canceled pages(23-07-2004).pdf

933-mum-2000-claims(granted)-(23-07-2004).doc

933-mum-2000-claims(granted)-(23-07-2004).pdf

933-mum-2000-correspondence(23-07-2004).pdf

933-mum-2000-correspondence(ipo)-(02-12-2005).pdf

933-mum-2000-drawing(23-07-2004).pdf

933-mum-2000-form 1(18-10-2000).pdf

933-mum-2000-form 19(01-08-2003).pdf

933-mum-2000-form 2(granted)-(23-07-2004).doc

933-mum-2000-form 2(granted)-(23-07-2004).pdf

933-mum-2000-form 3(18-10-2000).pdf

933-mum-2000-other document(29-07-2000).pdf

933-mum-2000-power of authority(18-10-2000).pdf

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