FIELD OF THE INVENTION
[0001] The present disclosure relates to a ventilated disc brake assembly. More particularly, the present disclosure relates to a ventilated disc brake assembly for train vehicle.

BACKGROUND OF INVENTION
[0002] A brake is a device by means of which artificial frictional resistance is applied to the moving train vehicle, to stop the motion. In the process of performing this function, the brake absorbs either or both, kinetic energy and potential energy of the moving vehicle. The energy absorbed by brakes is dissipated in the form of heat, to the surrounding atmosphere to stop the vehicle.
[0003] Axle Mounted Ventilated Disc Brake System, where in Brake Disc is that part of train vehicle brake system, that serves to convert kinetic energy into heat by means of friction. Axle mounted brake discs are disc/ring-shaped castings made from Cast Steel or Gray Cast Iron with round cooling spokes.
[0004] Axle mounted brake discs in the train vehicles fac e generally the problems like;
(a) Thermal cracks on/in both sides of brake disc surfaces due to overheating and poor heat convection through the disc
(b) Uneven wear of the fiction surface of the brake disc due to expansion of material surface resulting into a concaved geometry.
[0005] Designs available from other manufacturers are having round shaped cooling spokes only, which are not enough to cool down the disc efficiently. Spokes are placed very narrow, and cleaning of the disc cannot be done effectively.
[0006] The Gray Cast Iron material used to make conventional disc brake are of FG 250, which is harder (Brinell’s Hardness 190-240), and heat dissipation is slower. It produces more heat while friction pads are applied, and overheating of disc leads to thermal cracks.
[0007] The problem with available products/solutions is - excessive heat generation and lower heat dissipation/cooling when brake pads are applied on the brake disc. Additionally, cleaning of the disc is also a problem since thick scaling of dust and other compounds stick on the inner surface, resulting into no air contact with the metal surface, and thus leads to slow surface cooling.
[0008] JP4298099B2 discloses a ventilated type disk. This disc is arranged in parallel and concentrically with a space between each other, an inner disk part and an outer disk part each having an annular shape, and these two disk parts and are opposed to each other. A plurality of coupling ribs (radiating fins) and that couple the surfaces to be coupled. Between the coupling ribs and adjacent to each other in the circumferential direction, air flow paths extending in the diameter direction are provided. Such a ventilated type disk is fixedly attached to a hub unit for rotatably supporting a wheel on a suspension device by means of a mounting part provided concentrically with the disk parts. When the vehicle is running, the ventilated disc rotates with the wheels, and air flows in the air flow paths from the inner diameter side to the outer diameter side based on centrifugal force.
[0009] US5161652 is directed to a ventilated disk brake rotor made of integrally cast metal or allow that includes a central hub having a cylindrical main part, and a pair of friction plates extending radially from the central hub in parallel with one another. The friction plates are disposed in mutually spaced apart relationship by use of a plurality of radial ribs. Further, the friction plates are directly attached to an outer circumferential surface of the cylindrical main part of the central hub at their base ends. As a result, the generation of cracks and premature wear are prevented through the increased rigidity of the friction plates without an increase in the weight of the disk brake rotor.
[0010] US6260669 discloses a vented disc brake rotor which has an airflow director for funnelling air into the braking plate vents thereby improving the cooling effectiveness of the rotor. The vented disc brake rotor includes first and second braking plates connected together in a mutually parallel, spaced apart relationship. Braking plate fins are disposed between the inwardly facing surfaces of the braking plates forming a plurality of braking plate vents between the braking plates. The rotor includes an airflow director having an annular flange extending generally radially inwards from the radially inner end of one of the braking plates. The flange includes an inner surface forming an angle with respect to the inner surface of the other braking plate such that the distance between these inner surfaces increases as the flange extends radially inwards. A plurality of director fins are disposed between the flange and the inner surface of one of the braking plates. The cross sectional area of the director vent inlets are larger than the cross sectional area of the braking plate vent inlets. The larger director vent inlets and the angled inner flange surface create a funnel which directs more air into the braking plate vents thereby improving the cooling effectiveness of the rotor.
[0011] US7066306 discloses a brake disc rotor which have a central hub co-axial with surrounding rings which form brake bands for engagement with brake pads. The rings are supported in a spaced apart parallel configuration with channels therebetween whereby in use of the rotor cooling air is drawn in through vent openings formed around the inner periphery of the rings and then radially outwardly through the channels as the rotor turns. The vent openings include inlet vent ports on the outboard side of the rotor.
[0012] US20120255820A1 discloses an externally vented brake rotor (EVR) core design, such as exemplified by U.S. Pat. No. 6,536,564, is being used to improve the function and effectiveness of a segmented brake rotor (SBR) through more efficient management of the thermal forces created in the segmented rotor. Specifically, segmented friction plates are attached to the EVR core to form friction surfaces. Air flow through the vents contacts the back side of the friction plates. At least one segmented friction plate may be provided with a tab or protrusion that engages a corresponding receiving recess in the carrier surface of the EVR core, thereby relieving lateral stress forces.
[0013] All the previous designs have straight spokes which are placed very dense (close to each other) inside the friction ring, thereby causing difficulty to clean the inner surface of the friction ring. Without cleaning the inner surface, one cannot expect the proper cooling of the friction ring and cleaning is also critical for the brake disc heat convection.
[0014] Prior arts have solved many of the previous problems known to them, and some of those still exist. In ventilated brake disc, the main problem is excess heat generation in friction surfaces due to friction braking, overheating depending upon the material grade, improper ventilation, uneven braking force due to deformity of the brake disc attributed by excess heat generation/lower dissipation of heat etc. Due to overheating and wear of expanded surface, the friction surface becomes concave, so the contact surface of braking area reduces. Also, surface cracks (thermal cracks) develop in the friction area due to excessive heating. These cracks are sometimes minor, and can be very deep/wide also, causing failure/rejection of the Brake Discs.
[0015] Moreover, designs available in prior arts are having round shaped cooling spokes only, which are not enough to cool down the disc efficiently. Spokes are placed very narrow, and cleaning of the disc cannot be done effectively. The Gray Cast Iron material provided by them are of FG 250, which is harder (Brinell’s Hardness 190-240), and heat dissipation is slower. It produces more heat while friction pads are applied, and overheating of disc leads to thermal cracks. Thus, the problem with available products/solutions is - excessive heat generation and lower heat dissipation/cooling when brake pads are applied on the brake disc. Additionally, cleaning of the disc is also a problem since thick scaling of dust and other compounds stick on the inner surface, resulting into no air contact with the metal surface, and thus leads to slow surface cooling.
[0016] There is a need of a braking system which is more efficient and improving the life of the brake disc by way of quicker heat dissipation, avoiding surface cracks as well as deformity.

OBJECT OF THE INVENTION
[0017] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0018] It is a general or primary object of the present disclosure to provide a ventilated disc brake assembly which provide better heat dissipation in disc for proper working and to withstand high temperature condition arising due to friction.
[0019] It is another object of the present disclosure is to provide a ventilated disc brake assembly which has a plurality of round cooling spokes and axial as well as radial ribs, for better air ventilation to improve the cooling of the friction ring due to braking. Ribs are designed and placed in a manner to provide the strength to the inner surface and provide fast cooling due to the dissipation of heat.
[0020] It is yet another object of the present disclosure is to manufacture a ventilated disc brake assembly by using material Gray Cast Iron Grade FG 200 which will generate minimum 50 deg. C less heat than the existing one. Train will also need lesser distance to stop as compared to the existing brake discs due to better friction.
[0021] It is still another object of the present disclosure is to provide a ventilated disc brake assembly in which spokes and Ribs are placed in such a way, so that it is easier to clean inner surfaces using steel wire brush, which will lead to fast heat convection and there by surface cooling will be faster.

SUMMARY OF THE INVENTION
[0022] This summary is provided to introduce concepts related to a ventilated disc brake assembly for train vehicle. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0023] In an aspect, the present disclosure provides a ventilated disc brake assembly for train vehicle, the disc brake assembly, comprising: a central hub, a pair of friction plates extending radially from the central hub, each friction plate having an inner surface and the friction plates are placed parallel with their inner surface facing each other in mutually spaced apart manner, the inner surface having an assembly of cooling ribs. The assembly of cooling ribs comprises: a plurality of cooling rib units placed radially on the inner surface of the friction plates around the circumference of the hub, each cooling rib unit comprises: at least an axial rib having a proximal end and a rear end. Each axial rib has at least a pair of radial ribs connected at an angle with the rear end of the axial rib, each radial rib has a proximal end towards the hub and a rear end away from the hub, wherein the pair of radial ribs are placed in such a way such that their proximal ends are connected with rear end of the axial rib and rear ends of the radial ribs are spaced apart by forming an angle between them.
[0024] In an embodiment, the present disclosure provides that the axial rib and a pair of radial ribs in each of the cooling rib unit are connected with each other in the shape of ‘Y’.
[0025] In another embodiment, the present disclosure provides that at least one round Cooling Spoke is connected to inner surface of the friction plate and it is passing through Cooling Rib and at least a Round Cooling Spoke is provided to every Cooling Rib.
[0026] In yet another embodiment, the present disclosure provides that the rear end of axial rib and the proximal ends of the pair of radial ribs are connected and has a round cooling spoke at their connection.
[0027] In still another embodiment, the present disclosure provides that the rear end of the radial ribs has a round cooling spoke.
[0028] In further embodiment, the present disclosure provides that the inner surface of the friction plate has a plurality of round cooling spokes.
[0029] In preferred embodiment, the present disclosure provides that the inner surface of the friction plate has a plurality of half round flat cooling spokes.
[0030] In more preferred embodiment, the present disclosure provides that the Friction Ring comprises a plurality of lugs with vents arranged circumferentially around the hub to provide ventilation to the brake disc.
[0031] In another embodiment, the present disclosure provides that each cooling rib unit has a central axis when retraced forming an angle in the range of 15-45o degrees with the adjacent cooling rib unit.
[0032] In yet another embodiment, the present disclosure provides that each cooling rib unit has a central axis when retraced forming an angle of 30o degrees with the adjacent cooling rib unit.
[0033] In still another embodiment, the present disclosure provides that the radial ribs in each cooling rib unit are connected with the axial rib and forming an angle in the range of 100-170o degrees with the axial rib.
[0034] In further embodiment, the present disclosure provides that the radial ribs in each cooling rib unit are connected with the axial rib at its one end and forming an angle of 114.44o degrees with the second axial rib.
[0035] In preferred embodiment, the present disclosure provides that the pair of radial ribs in each cooling rib unit forming an angle in the range of 100-170o between them.
[0036] In more preferred embodiment, the present disclosure provides that the pair of radial ribs in each cooling rib unit forming an angle of 131.12o degrees between them.
[0037] In another embodiment, the present disclosure provides that the hub, is connected with the friction plate by placing a ring between them and connected with a plurality of bolts.
[0038] In yet another embodiment, the present disclosure provides that the hub, the ring and the plurality of bolts are made up of carbon steel.
[0039] In still another embodiment, the present disclosure provides that the friction plate, cooling spokes, ribs are made up of Gray Cast Iron Grade FG 200.
[0040] In further embodiment, the present disclosure provides that radial rib has length equal to one third – one fifth of the length of the axial rib.
[0041] In a preferred embodiment, the present disclosure provides that the length of the radial rib is one ninth – one eleventh of the radius of the brake rotor.
[0042] To further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit the scope of the present subject matter.
[0043] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0044] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0045] FIGS. 1 illustrate a perspective view of friction ring in accordance with an embodiment of the present disclosure;
[0046] FIGS. 2 illustrate inner geometry of friction plate in accordance with an embodiment of the present disclosure;
[0047] FIGS. 2A illustrate a sectional view of inner geometry of friction plate in accordance with an embodiment of the present disclosure;
[0048] FIGS. 2B illustrate a 3D view of inner geometry of friction plate in accordance with an embodiment of the present disclosure;
[0049] FIGS. 3 illustrate a front view of friction plate in accordance with an embodiment of the present disclosure;
[0050] FIGS. 3A illustrate an exploded view of connection of friction plate in accordance with an embodiment of the present disclosure;
[0051] FIGS. 3B illustrate a section cut view to explain the connection of two friction plates in accordance with an embodiment of the present disclosure;
[0052] The figures depict embodiments of the present subject matter for illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF INVENTION
[0053] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0054] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0055] The terminology used herein is to describe particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0056] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0057] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0058] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
[0059] Hereinafter, a description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the present disclosure.
[0060] The present disclosure provides a ventilated disc brake assembly 100, for train vehicle, the friction ring of the disc brake assembly as shown in figure 1. The friction ring comprises a pair of friction plates 200 extending radially from the central hub 100. Each friction plate 200 having an inner surface and the friction plates are placed parallel with their inner surface facing each other in mutually spaced apart manner.
[0061] Figure 2 shows the inner geometry of the friction plate 200 of the ventilated disc brake assembly 100. The inner surface of the friction plate having an assembly of cooling ribs, wherein the assembly of cooling ribs comprises: a plurality of cooling rib units 210 placed radially on the inner surface of the friction plates 200 around the circumference of the hub 300.
[0062] Each cooling rib unit 210 as shown in sectional view of inner geometry of Figure 2A, comprises at least an axial rib 211 having a proximal end 211’ and a rear end 211”. Each axial rib 211 has at least a pair of radial ribs 212 connected at an angle with the rear end 211” of the axial rib 211. Each radial rib 212 has a proximal end 212’ towards the hub 300 and a rear end 212” away from the hub 300, wherein the pair of radial ribs 212 are placed in such a way such that their proximal ends 212’ are connected with rear end 211” of the axial rib 211 and rear ends 212” of the radial ribs 212 are spaced apart by forming an angle between them. Also the dimensions of an exemplary embodiment also indicated therein.
[0063] The inner surface of the friction plate also has (i) Half Round Flat Spokes 220 which are radially placed along with round cooling spokes 230 (ii) ventilation is provided through a plurality of ventilation slots 260 provided with lugs 240, used for mounting of the brake disc on the hub 300 are shown in Figure 2B.
[0064] The shapes and configuration is clearly shown in 3D view of inner geometry of inner surface of friction plate as shown in Figure 2B. The axial rib and a pair of radial ribs in each of the cooling rib unit are connected with each other in the shape of ‘Y’.
[0065] Due the new design of the ventilated disc brake assembly as disclosed in an embodiment of the present disclosure will cool down the brake disc efficiently, while cool air (at ambient temperature) enters from inner diameter of the friction ring and through lugs, it rushes outwards by centrifugal forces. It will happen continuously while the train vehicle is in motion. When brakes are applied, the heat flux is produced by brake pads and heat absorbed by both sides of the brake disc is dissipated and travel to the spokes and ribs provided for the faster cooling. This heat is dissipated to the surrounding atmosphere to stop the vehicle.
[0066] Cool air (at ambient temperature) entering through the slots 260 of the lugs 240 and sides of the lugs, will cool the round cooling spokes 230, there by generating the hot air, which will be deflected outwards by the axial ribs 211 as well as radial ribs 212. These axial 211 and radial ribs 212 will cool the hot air additionally by absorbing the heat from hot air. Air through the lug’s ventilation will also cool the lugs inner walls as well as inner round spokes and ribs provided.
[0067] The main features of brake disc are to stop the vehicle within stipulated time/distance, with wear and tear within limits over a period of time. The previous designs and those in use, have many problems i.e. generation of thermal cracks on disc surface, excessive wear due to braking, use of hard grade material, high temperature rise due to poor ventilation etc.
[0068] To overcome these problems, the present disclosure provides a ventilated disc brake assembly which has round cooling spokes 230, axial ribs 211 and radial ribs 212 for better ventilation and faster cooling, so that the air flow through the vented area increases. Thus, we reduce the problem of overheating of disc.
[0069] The material grade of ventilated disc brakes is also changed for better strength as well as improved heat transfer. Existing harder material (FG 250) leads to more slip between friction pads and friction ring. And it leads to rise in temperature. Selected material (FG 200) will have low hardness which provides good frictional properties to the Brake Disc. And it leads to lesser temperature rise on the surface. New selected material will also generate almost 50 deg. C lower temperature in operation, than the existing brake discs in use. Train vehicle will also need lesser distance to stop, due to better friction as compared to where the existing brake discs are being used.
[0070] Figure 3 illustrate a front view of friction plate in accordance with an embodiment of the present disclosure.
[0071] FIGS. 3A illustrate an exploded view of connection of friction plate in accordance with an embodiment of the present disclosure. Figure shows the mating parts of the brake disc and their sizes/dimensions like hub 300, Ring 250, T-Locater Pin 251, hub locator pin 252, nuts 253, bolts 254, washers 255, spring washer 256 and plug 257. The hub 300, is connected with the friction plate 200 by placing a ring 250 between them and connected with a plurality of bolts 254. The hub 300, the ring 250 and the plurality of bolts 254 are made up of carbon steel. As shown in FIGS. 3A, Face A of the friction plate 200 will rest on the Face D of the hub 300. Face E of the ring 250 will rest on the Face B of the friction plate 200. In the bolt assembly Face J of the bolt head will rest on the Face C of the hub 300 and pass through the hub hole diameter 12.5 mm for each 12 Nos. of holes as per an exemplary embodiment. Face G of the spring washer 256 will rest on the Face F of the Ring 250. Face I of the Nut 253 will rest on the Face H of the spring washer 256 and Nut 253 will be tighten. T-Locator pin 251 will be fixed on the hub 300 and the Ring slot by washer 255 and plug 257. hub locator pin 252 will be placed in hub 300 and the friction plate 200.
[0072] FIGS. 3B illustrate a section cut view to explain the connection of two friction plates in accordance with an embodiment of the present disclosure. As shown in FIGS 3B half round flat cooling spoke 220 connected to the friction plates 200 internally. Round cooling spoke 230 connected to friction plates 200 internally. Lug’s 240 connection to friction plates 200 is shown in the FIGS 3B. Connection of the connecting Bolt also shown in the FIGS 3B
[0073] Ventilated dual friction brake disc consists of strength providing half round flat cooling spokes 220, round cooling spokes 230, as well as axial 211 and radial cooling ribs 212, which allow air to flow across the disc surface and throw out hot air by centrifugal action. The design and geometry of spokes, axial and radial ribs to increase its strength and cooling performance, thereby providing better strength to the friction ring and cooling to the ribs.
[0074] In the ventilated disc brake assembly 100, at least a round Cooling Spoke 230 is provided on each axial rib 211. Also, the rear end of axial rib 211 and the proximal ends of the pair of radial ribs 212 are connected and has a round cooling spoke 230 at their connection. The rear end of the radial ribs 212 has a round cooling spoke 230. Also the inner surface of the friction plate 200 has a plurality of round cooling spokes 230. The inner surface of the friction plate 200 has a plurality of half round flat cooling spokes 230. The Friction plate 200 comprises a plurality of lugs 240 with slots 260 arranged circumferentially around the hub 300 to provide ventilation to the brake disc.
[0075] In an exemplary embodiment of the ventilated disc brake assembly 100, half round flat spokes at two places of different sizes are provided to connect both friction rings, to provide strength, and for cooling of the heat dissipated from the outer friction surface to internal surface. Forty-Eight numbers of round cooling spokes on different locations are provided for strength of the friction rings and cooling though convection of hot air, from the heat dissipated through spokes. Twelve Nos. of thin axial cooling ribs of rectangular design are provided to dissipate heat from friction rings and cooling down through the convection. Twenty-Four thin rectangular radial cooling ribs placed radially to both sides of twelve axial cooling ribs, at certain angle mentioned in the drawing. Axial and radial cooling ribs are provided in a manner, that these are connected to round shaped cooling spokes to support the ribs design.
[0076] Purpose of these ribs is to cool down the dissipated heat through convection and provide strength to the friction rings. Twelve lugs are provided to mount the brake disc to hub. Lugs are designed and connected to both the friction rings internally due to the maximum braking torque on these lugs, lugs are designed to sustain such torque and loads. Lugs are designed in a manner to provide ventilation to the lugs to improve the cool air inlet. And also, to increase the tensile strength of the lugs. Gray Cast Iron Grade FG 200 has the fundamentals properties of minimum the cross-sectional area, more the tensile strength. In this ventilated disc brake, the cross-sectional area of the lugs (by providing slots or vents), other spokes and ribs have been reduced within 10 – 30 Sq,MM. In all these cases, we have taken cross-sectional area below 30 Sq.MM for a greater Tensile strength.
Other specifications are:
Wall Thickness >2.5~10 Sq.MM, Tensile Strength 220 Mpa
Wall Thickness >10~20 Sq.MM, Tensile Strength 195 Mpa
Wall Thickness >20~30 Sq.MM, Tensile Strength 170 Mpa
[0077] In the ventilated disc brake assembly of the present disclosure, each cooling rib unit has a central axis when retraced forming an angle is in the range of 15-45o degrees with the adjacent cooling rib unit. In the exemplary embodiment, each cooling rib unit has a central axis when retraced forming an angle of 30o degrees with the adjacent cooling rib unit. The radial ribs in each cooling rib unit are connected with the axial rib and forming an angle in the range of 100-170o degrees with the axial rib. The radial ribs in each cooling rib unit are connected with the axial rib at its one end and forming an angle of 114.44o degrees with the second axial rib. The pair of radial ribs in each cooling rib unit forming an angle in the range of 100-170o between them. The pair of radial ribs in each cooling rib unit forming an angle of 131.12 o between them.
[0078] In the ventilated disc brake assembly of the present disclosure, the radial rib has length equal to one third – one fifth of the length of the axial rib and the length of the radial rib is one ninth – one eleventh of the radius of the friction plate.
[0079] For manufacturing the ventilated disc brake assembly of the present disclosure, material is changed from Gray Cast Iron Grade FG 250 to FG 200, to improve its heat dissipation and frictional properties. FG 200 has lower hardness (Brinell’s Hardness 170-220) as compared to FG 250 (Brinell’s Hardness 190-240). Grade FG 250 having more material hardness, has slower heat dissipation, and it produces more heat when friction pads are applied, resulting in overheating of disc leading to thermal cracks.
[0080] The specifications of Research Design and Standards Organisation (RDSO) of Indian Railways, as per RDSO document Spec.No. RDSO/2017/CG·02 (Rev.1) is followed to make changes in design of Brake Disc. For its design development, parameters defined in - Standard EN 14535-1 for design, and for testing as per standard EN 14535-3. The brake disc offered will be suitable to work with any UIC/RDSO approved Organic Brake Pads as per UIC 541-3.
[0081] Ventilated brake disc consists of a single casting part having connecting parts common for all type of brake discs as stated in the above para. In other words, it is a single piece casting having two friction rings which by design are connected with various Round and Flat Cooling Spokes to provide the strength and cooling, to the heat dissipated through/from outer surface of the friction ring to the inner side of the friction ring. Ventilated lugs are also connected to both the friction rings internally and provide strength as well as cooling to the friction ring.
[0082] In the inner geometry of the brake disc, half round flat spokes, round cooling spokes as well as axial cooling ribs and radial cooling ribs for better strength, ventilation and faster cooling, so that the air flow through the vented area increases, thus reducing the problem of overheating of disc.
[0083] Alternative material to suit the design is used, which is lower hardness material grade for better strength and heat transfer. The friction plate, cooling spokes, ribs are made up of Gray Cast Iron Grade FG 200. Selected material (FG 200) has low hardness, which provides good frictional properties to the Friction Ring. And it leads to lower temperature rise on the friction rings surface. Lugs are provided to mount the brake disc to hub. Lugs are designed and connected to both the friction rings internally. Due to the maximum braking torque on these lugs, these are designed to sustain such torque and loads. Lugs are designed in such a way so as to provide ventilation to the lugs to improve the cool air inlet. Design of lugs is provided in a manner to maximise the tensile strength thereof. Train vehicle will also need lesser distance to stop as compared to the existing brake discs, due to better friction and lower heat generation.

TECHNICAL ADVANTAGES
[0084] The ventilated disc brake assembly in accordance of the present disclosure will help towards making the braking system more efficient, and improving the life of the brake disc by virtue of quicker heat dissipation, avoiding surface cracks as well as deformity. All these will be addressed, as stipulated below:
[0085] (a) Thermal cracks on the brake disc: To resolve this problem, we need to have an efficient cooling which is achieved with our new design by providing (i) round cooling spokes as well as axial cooling ribs and radial cooling ribs on the inner surface (ii) ventilation to the lugs connection to improve the cool/fresh air (at ambient temperature) inlet. Design of the lugs is in such a manner that it will increase the tensile strength of the lugs (minimum the cross-sectional area more the tensile strength). In our design, we have provided the slots and decreased the cross-sectional area of the lugs.
[0086] (b) Lower heat generation: We have provided improved material (Gray Cast Iron Grade FG 200) of the brake disc, which generates lesser heat than the existing material (Gray Cast Iron Grade FG 250). FG 200 has lower hardness (Brinell’s Hardness 170-220) as compared to FG 250 (Brinell’s Hardness 190-240). Lesser hardness of FG 200 means more friction coefficient and better heat dissipation as compared to FG 250. In operation, FG 200 brake disc will produce lesser heat than FG 250, almost 50 deg. C lower temperature rise.
[0087] Material improvement will solve high heat generation problem. Also, lower heat generation will help in faster heat dissipation, therefore there will be less expansion of material, and faster as well as uniform cooling will protect uneven wear of the brake disc.
[0088] These improvements in design will also require the lesser distance to stop the train vehicle as compared to the existing designs in use.
[0089] Spokes and ribs are placed in a way, so that internal cleaning of the brake disc is easy using the steel wire brush. In general, cleaning of the inner surface is a must, otherwise heat convection will not happen and friction ring will not cool down as fast as required. Inner cleaning of the ribs and surfaces are one of the major issues for the thermal cracks.

Equivalents
[0090] The foregoing description of the preferred embodiment of the invention has been presented for illustration and description. It is not intended to be exhaustive, nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiment may be modified in light of the above teachings.

We Claim:

1. A ventilated disc brake assembly, for train vehicle, the disc brake assembly, comprising:
a central hub,
a pair of friction plates extending radially from the central hub, each friction plate having an inner surface and the friction plates are placed parallel with their inner surface facing each other in mutually spaced apart manner, the inner surface having an assembly of cooling ribs, wherein the assembly of cooling ribs comprises:
a plurality of cooling rib units placed radially on the inner surface of the friction plates around the circumference of the hub, each cooling rib unit comprises:
at least an axial rib having a proximal end and a rear end;
each axial rib has at least a pair of radial ribs connected at an angle with the rear end of the axial rib, each radial rib has a proximal end towards the hub and a rear end away from the hub, wherein the pair of radial ribs are placed in such a way such that their proximal ends are connected with rear end of the axial rib and rear ends of the radial ribs are spaced apart by forming an angle between them.
2. The ventilated disc brake assembly, as claimed in claim 1, wherein the axial rib and a pair of radial ribs in each of the cooling rib unit are connected with each other in the shape of ‘Y’.
3. The ventilated disc brake assembly, as claimed in claim 1, wherein at least a round Cooling Spoke is provided on the axial rib which passed through the axial rib.
4. The ventilated disc brake assembly, as claimed in claim 1, wherein the rear end of axial rib and the proximal ends of the pair of radial ribs are connected and has a round cooling spoke at their connection.
5. The ventilated disc brake assembly, as claimed in claim 1, wherein the rear end of the radial ribs has a round cooling spoke.
6. The ventilated disc brake assembly, as claimed in claim 1, wherein the inner surface of the friction plate has a plurality of round cooling spokes.
7. The ventilated disc brake assembly, as claimed in claim 1, wherein the inner surface of the friction plate has a plurality of half round flat cooling spokes.
8. The ventilated disc brake assembly, as claimed in claim 1, wherein the Friction Ring comprises a plurality of lugs with vents arranged circumferentially around the hub to provide ventilation to the brake disc.
9. The ventilated disc brake assembly, as claimed in claim 1, wherein each cooling rib unit has a central axis when retraced forming an angle in the range of 15-45o degrees with the adjacent cooling rib unit.
10. The ventilated disc brake assembly, as claimed in claim 1, wherein each cooling rib unit has a central axis when retraced forming an angle of 30o degrees with the adjacent cooling rib unit.
11. The ventilated disc brake assembly, as claimed in claim 1, wherein the radial ribs in each cooling rib unit are connected with the axial rib and forming an angle in the range of 100-170o degrees with the axial rib.
12. The ventilated disc brake assembly, as claimed in claim 1, wherein the radial ribs in each cooling rib unit are connected with the axial rib at its one end and forming an angle of 114.44o degrees with the second axial rib.
13. The ventilated disc brake assembly, as claimed in claim 1, wherein the pair of radial ribs in each cooling rib unit forming an angle in the range of 100-170o between them.
14. The ventilated disc brake assembly, as claimed in claim 1, wherein the pair of radial ribs in each cooling rib unit forming an angle of 131.12 o between them.
15. The ventilated disc brake assembly, as claimed in claim 1, wherein the hub, is connected with the friction plate by placing a ring between them and connected with a plurality of bolts.
16. The ventilated disc brake assembly, as claimed in claim 1, wherein the hub, the ring and the plurality of bolts are made up of carbon steel.
17. The ventilated disc brake assembly, as claimed in claim 1, wherein the friction plate, cooling spokes, ribs are made up of Gray Cast Iron Grade FG 200.
18. The ventilated disc brake assembly, as claimed in claim 1, wherein radial rib has length equal to one third – one fifth of the length of the axial rib.
19. The ventilated disc brake assembly as claimed in claim 1, wherein the length of the radial rib is one ninth – one eleventh of the radius of the brake rotor.