Girder fork for electric two-wheeler vehicles

Abstract

The present invention discloses a suspension system for a two-wheeler vehicle, comprising a girder fork 102 structure having at least two legs pivotally connected via a linkage system 203, 303 to a steering head or chassis, at least one shock absorber 104-1, 104-2 mounted on each leg of the girder fork 102, a linkage system including upper and lower links 203, 303 pivotally connected to the girder fork 102 and vehicle chassis; and a plurality of needle roller bearings 202, 302 at pivot joints of the linkage system 203, 303, wherein the linkage system 203, 303 provides vertical wheel compliance while constraining lateral and fore-aft movement through pivot joints

Description

GIRDER FORK FOR ELECTRIC TWO-WHEELER VEHICLESFIELD OF INVENTION

[0001] The present disclosure generally relates to the automobile industry, and specifically relates to optimising the kerb weight and aesthetics of two-wheeler electric vehicles.BACKGROUND

[0002] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.

[0003] Electric vehicles are becoming an increasingly popular segment of the automobile industry across the world, and electric two-wheelers contribute massively to the popularity of electric vehicles due to the many benefits and advantages provided. Some of the benefits accrued by users of electric two-wheeler vehicles include the low running cost, ease of maintenance, storage space, and low noise. In addition to the benefits provided to the users, electric vehicles are also environment-friendly as they do contribute to carbon emission.

[0004] Electric vehicles (EVs) represent a rapidly expanding segment of the global automotive industry, driven by regulatory pressures for emission reduction, advancements in battery technology, and shifting consumer preferences toward sustainable mobility. Within this domain, electric two-wheeler vehicles have emerged as particularly dominant, especially in densely populated urban markets offer compelling advantages over their internal combustion engine (ICE) counterparts, including significantly lower running costs (often 70-80% less due to electricity pricing), simplified maintenance requirements (fewer moving parts and no oil changes), compact storage capabilities and substantially reduced noise levels.

[0005] Due to the increasing popularity of two-wheeler electric vehicles, there is an increasing need of improving the structural quality of two-wheeler electric vehicles.Improvement of the structural quality of such vehicles also involved exploring the possible improvements that can be made to the different types of suspensions used in two-wheeler vehicles. There are different types of suspensions that are used in the field of two-wheeler vehicles, and such different types of suspensions are used for either one or both of front and back suspensions of two-wheeler vehicles. The types of suspensions that can be used for the front suspension of two-wheeler vehicles include telescopic fork, upside down telescopic fork, Saxon-Motodd suspension, Hossack suspension, trailing link front suspension, leading link front suspension, GIRDER suspension, and springer suspension.

[0006] The surge in electric two-wheeler adoption, ranging from urban commuters to delivery services, has intensified demands on vehicle design parameters beyond traditional performance metrics. Structural optimization has become paramount, particularly for chassis and suspension components that form the vehicle’s primary load-bearing framework. Front suspension systems, which directly influence steering precision, ride comfort, braking stability, and crash energy absorption, represent a critical area for innovation. Existing front suspension architectures for two-wheelers encompass a diverse spectrum, including conventional telescopic forks (with sliding stanchions), upside-down telescopic forks (optimized for high- performance applications), parallelogram-based systems, trailing / leading link designs that minimize fork dive under braking, and linkage-type suspensions such as girder forks and springer forks. Each configuration offers trade-offs in terms of unsprung mass, wheel path control, progressive damping characteristics, and packaging constraints.

[0007] In addition to exploring the possible improvements that can be made to the suspensions of two-wheeler vehicles, the increasing popularity of two-wheeler electric vehicles also raises the requirement for reducing the kerb weight of such vehicles. Reduction of kerb weight of vehicles, especially electric two-wheeler vehicles, is an effective way of increasing the range and performance of such vehicles. Further, the reduction of kerb weight of the electric two-wheeler vehicles is required to be achieved without compromising on the structural integrity and performance of the vehicles.

[0008] Hence there is a need for developing improved versions of suspensions that are applicable to electric two-wheeler vehicles, and implementing such improvements in a manner that results in reduced kerb weight without compromising on structural integrity of such twowheeler vehicles.OBJECT OF THE INVENTION

[0009] An object of the invention is to create a girder fork suspension mechanism for twowheeler electric vehicles.

[0010] Another objective of the invention is to reduce the kerb weight of the two-wheeler electric vehicle.

[0011] A further object of the invention is to optimize unsprung mass distribution by minimizing the weight of rotating and articulating components forward of the steering headstock,

[0012] Yet another object of the invention is to provide a lightweight girder fork suspension system constructed primarily from high-strength alloys.

[0013] Still another object of the invention is to enhance torsional rigidity and ride quality through the strategic deployment of bilateral (dual) shock absorber configuration.

[0014] Yet another object of the invention is to maximize electric vehicle range and efficiency by reducing overall kerb weight.

[0015] Another object of the invention is to ensure manufacturability and scalability through the selection of forgeable aluminium alloys with excellent formability.SUMMARY OF THE INVENTION

[0016] The summary is provided to introduce aspects related to a rotor lamination profile optimization for maximum reluctance torque and improved thermal behavior. Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

[0017] An aspect of the present invention relates to a suspension system for a two-wheeler vehicle, comprising a girder fork structure having at least two legs pivotally connected via alinkage system to a steering head or chassis, at least one shock absorber mounted on each leg of the girder fork, a linkage system including upper and lower links pivotally connected to the girder fork and vehicle chassis; and a plurality of needle roller bearings at pivot joints of the linkage system, wherein the linkage system provides vertical wheel compliance while constraining lateral and fore-aft movement through pivot joints.

[0018] In another aspect of the present invention, the girder fork structure is formed from a lightweight metal alloy having density at least less than 3.0 g / cm3.

[0019] In another aspect of the present invention, it comprises dual shock absorbers, one on each leg of the girder fork.

[0020] In another aspect of the present invention, the spring and damper units are mounted between the girder fork legs and lower links, providing a motion.

[0021] In another aspect of the present invention, the pivot bearings include float control washers between girder links and spacers for axial location, positioned behind seals.

[0022] In another aspect of the present invention, the needle roller bearings are replaceable with solid polymer or metal bushings.

[0023] In another aspect of the present invention, single spring and damper unit is used, mounted on one side between girder fork leg and lower link, or between lower link and upper yoke.

[0024] Another aspect of the present invention discloses an electric two-wheeler vehicle comprising the girder fork suspension system wherein the system reduces kerb weight compared to steel-based girder forks while maintaining structural integrity.

[0025] In another aspect of the present invention, the girder fork configuration frees packaging space ahead of the headstock.

[0026] In another aspect of the present invention, an electric two-wheeler vehicle comprises wherein the girder fork reduces unsprung mass; dual shock layout enables forward headlight positioning; and overall kerb weight reduction enhances vehicle range by at least 5%.

[0027] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constitute a part of the description and are used to provide further understanding of the present invention. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029] Fig. 1 illustrates a perspective view of the proposed girder fork suspension for an electric two-wheeler vehicle, in accordance with an embodiment of the present invention.

[0030] Fig. 2 illustrates a cross-sectional view through a lower suspension link representing a bearing arrangement to girder sides, in accordance with an embodiment of the present invention.

[0031] Fig. 3 illustrates a cross-sectional view through a lower suspension link representing a bearing arrangement a lower yoke, in accordance with an embodiment of the present invention.

[0032] In the appended figures, similar components and / or features may have the same numerical reference label. Further, various components of the same type may be distinguished by following the reference label with a letter. If only the first numerical reference label is used in the specification, the description is applicable to any one of the similar components and / or features having the same first numerical reference label irrespective of the suffix.DETAILED DESCRIPTION

[0033] The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this invention is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

[0034] Electric automobiles, especially two-wheeler vehicles have been growing in popularity and demand due to the several benefits and advantages offered by such vehicles. The different types of suspensions used in two-wheeler vehicles are classified based on whether they are used for front or back suspension. The girder fork suspension is one of the oldest types of front suspensions that were utilized in motorcycles. A girder fork 102 is a 3-bar linkage attached to the steering mechanism of a motorcycle in order to provide vertical wheel compliance while controlling its movement in other axes. It uses pivots between these links to provide the movement in contrast with the sliding tubes of conventional telescopic front suspension. The axle path is determined by the geometry of the upper and lower links 203, 303 and was arranged to be similar to that of a conventional tubular fork but potentially it could be varied to offer optimised suspension, braking or handling characteristics

[0035] The increasing popularity of electric two-wheeler vehicles has led to the increasing need of improving upon different types of suspensions which can be used in such vehicles, including the girder fork suspension. The suspensions used in two-wheeler electric vehicles, including the girder fork suspension, constitute a part of the structural member of two-wheeler vehicles. Conventionally, structural members of two-wheeler vehicles are created using materials such as steel and component level materials are created using aluminum, which lead to suboptimal kerb weight of two-wheeler vehicles. The kerb weight of a two-wheeler vehicle plays a significant role in the energy required for the acceleration or propulsion of electric twowheeler vehicles. To ensure optimization of kerb weight of electric two-wheeler vehicles, there is a need to create structural members of such vehicles, including suspensions, with lighter materials.

[0036] Hence, the present invention relates to aluminium girder fork 102 suspension system for electric two-wheeler vehicles. Fig. 1 illustrates a perspective view of the proposed girder fork 102 suspension for an electric two-wheeler vehicle, in accordance with an embodiment of the present invention. The present invention comprises a girder fork 102 made of aluminium. The present invention further comprises two dual shocks 104-1 and 104-2, one on either leg of the girder fork 102. The dual shocks 104-1 and 104-2 installed on both legs of the girder fork 102 ensure that torsional twisting is reduced in the two-wheeler electric vehicles. Girder forks 102 help reduce unsprung mass compared to traditional rigid fork designs. This improves the motorcycle's handling, stability, and responsiveness, particularly during cornering and acceleration.

[0037] The girder forks 102 of the proposed girder fork suspension system ensure absorption of shocks and vibrations encountered during off-road riding, thereby improving the bike’s handling and comfort over rough terrain. The girder forks 102 reduce the impact of bumps and obstacles, and helps maintain control and stability, especially when navigating challenging trails. Such enhanced performance allows riders to navigate technical terrain with ease, as the suspension helps to keep the wheels in contact with the ground, thereby improving traction and control. The girder fork 102 helps reduce fatigue and discomfort, especially during long rides by minimizing the jolts and vibrations transmitted to the rider’s hands, arms and upper body. Hence, the girder forks 102 contribute to a safer and capable riding experience, particularly in off-road or rugged environments.

[0038] The proposed girder fork suspension system has a girder fork linkage system, which is a mechanism that connects the girder fork 102 to the motorcycle's frame or chassis. It consists of various linkages and pivot points that allow the fork to move up and down in response to bumps and uneven terrain. The girder fork linkage system helps improve suspension performance by enhancing the suspension's ability to absorb shocks and vibrations based on optimization of the movement of the aluminium girder fork 102. This results in a smoother and more controlled ride, especially over rough terrain. Tuning the flexibility of the girder fork linkage systems often allow for adjustments to the suspension characteristics, such as compression and rebound damping, preload, and overall stiffness. This provides riders with the ability to fine-tune the motorcycle's suspension to suit their preferences and riding.

[0039] Each girder fork leg 102 is connected to at least one upper link and one lower link 203, 303, the upper and lower links 203, 303 being pivotally mounted to a steering yoke or yokes attached to the vehicle headstock. These upper and lower links 203, 303, together with the girder fork legs 102 and the steering yokes, form a closed kinematic chain that defines the path of the front wheel axle during suspension compression and rebound, allowing the axle to follow a controlled trajectory which can be configured to provide desired anti-dive, braking, or handling characteristics.

[0040] By incorporating linkages into the suspension system, girder forks 102 can help reduce unsprung mass compared to traditional rigid fork designs. This can improve the motorcycle's handling, stability, and responsiveness, particularly during cornering and acceleration. Further, the girder fork linkage systems of the proposed suspension system are designed to optimize the motorcycle’s ground clearance by adjusting the fork’s geometry during compression and rebound. This can be beneficial for off-road riding or aggressive cornering on the tracks.

[0041] The girder fork legs 102 are manufactured from aluminium or aluminium alloy, such as 6082-T6, in order to reduce the mass of the suspension system relative to conventional steel girder or telescopic forks. The use of aluminium for the girder fork legs contributes to a reduction in unsprung mass, thereby improving the responsiveness of the suspension to road irregularities and enhancing the handling, stability and cornering performance of the electric two-wheeler vehicle. In some embodiments, the aluminium girder fork legs may be forged or machined to achieve the desired strength, stiffness and geometry while maintaining low weight.

[0042] The positioning and orientation of the dual shocks 104-1, 104-2 relative to the girder fork legs 102 and lower linkages is chosen to obtain a favourable motion ratio between wheel travel and damper stroke. In one preferred embodiment, a 60 mm shock stroke corresponds to approximately 100 mm of vertical wheel travel, allowing the use of compact and lightweight spring and damper units while still delivering a generous suspension travel suitable for both urban and light off-road usage. By carefully tuning the mounting points and lever arms, the designer can obtain progressive or near-linear response characteristics as desired.

[0043] The arrangement also frees packaging space in front of the headstock compared to conventional girder fork layouts in which a single, centrally mounted shock absorber is often placed ahead of the steering axis. By distributing the shock absorbers 104-1, 104-2 to either side, the central region ahead of the headstock can be used for headlamp assemblies, fairing structures, storage compartments or electronic modules without interference from a centrally mounted spring / damper unit. This configuration improves the aesthetic appearance of the front end, enables more flexible styling options, and can assist in achieving a more compact or aerodynamically optimized vehicle profile.

[0044] In operation, vertical movement of the front wheel caused by bumps or undulations in the riding surface is transmitted through the axle and associated lower links to the girder fork legs 102, which rotate about their pivot connections to the upper and lower links 203, 303. This motion compresses or extends the dual shocks 104-1, 104-2, which in turn provide both energy absorption via the springs and damping via hydraulic or other damper mechanisms. The overall kinematics provided by the geometry are selected such that the wheel path, effective wheel rate and damping characteristics yield improved ride comfort, reduced rider fatigue, and enhanced traction on both smooth and rough terrain.

[0045] Figs. 2 and 3 illustrate a cross-sectional view through a lower suspension link representing a bearing arrangement to girder sides and lower yoke respectively, in accordance with an embodiment of the present invention. The bearing arrangement of the girder fork linkage uses needle roller bearings 202, 302 to ensure durability under load, smooth movement and wear resistance. For axial location float control washers 207, 307 are used between the upper or lower girder link 203, 303 and spacers 204, 308. This is an adequate way of restricting axial movement of the swingarm while allowing free movement in rotation, and has the benefit of taking up a small amount of axial space compared to adding an additional rolling element bearing (deep groove or needle roller thrust bearing).

[0046] Fig. 2 illustrates a cross-sectional view through a lower suspension link of the girder fork suspension system, focusing on a bearing arrangement between the lower suspension link and the girder sides, in accordance with an embodiment of the present invention. In this figure, a lower girder link 203, 303 extends laterally between the left and right girder fork legs 102, and is pivotally connected to each girder leg via a respective bearingassembly incorporating needle roller bearings 202, 302 and associated axial location components.

[0047] Each bearing assembly includes at least one needle roller bearing 202, 302 that is press-fitted or otherwise mounted within a bore formed in the lower link 203, 303 or in an associated sleeve 206, 304 or housing. The corresponding end of the girder fork leg 102, or a pivot pin associated therewith, is received within the inner race or bore of the needle roller bearing 202, 302, thereby allowing relative rotation between the lower link 203, 303 and the girder leg 102 about a substantially horizontal pivot axis that extends laterally across the vehicle. Needle roller bearings 202, 302 are selected for this interface due to their high static radial load capacity relative to size, which is particularly advantageous in packaging-constrained suspension linkages where high loads must be transmitted through compact components.

[0048] The bearing arrangement further comprises spacers 204, 308 and float control washers 207, 307 disposed between the lower link 203, 303 and adjacent components. In one embodiment, spacer 204, 308 is located between the inner side of the bearing and a seal 205, 305 positioned to protect the bearing from environmental contaminants, while spacer 204, 308 is located on the opposite side of the link to control lateral clearances. The float control washer 207, 307 is positioned between the lower link 203, 303 and spacer 204, 308, and is dimensioned such that it restricts axial (lateral) movement of the lower link 203, 303 relative to the girder leg 102, while still allowing free rotational movement about the pivot axis.

[0049] By placing the float control washer 207, 307 and related axial control components behind the seals 205, 305, the design ensures that the surfaces responsible for limiting axial float are shielded from dirt, water and other contaminants. This configuration reduces the risk of premature wear, corrosion or binding in the axial control surfaces, thereby improving longterm durability and maintaining smooth rotational operation of the pivot joint over the service life of the vehicle. The arrangement also minimizes the axial space required for the combined bearing and axial control features, compared to designs that rely on additional rolling-element thrust bearings or thicker collar components.

[0050] The spacers 204, 308 are configured with simple geometries that reduce the impact of manufacturing tolerances on the overall axial stack-up. By appropriately selecting thethicknesses of these spacers 204, 308, the designer can set the desired amount of free float or preload in the lateral direction, ensuring that the lower link 203, 303 is neither excessively loose nor overly constrained between the left and right bearing assemblies. This contributes to more consistent assembly quality, easier manufacturing, and improved repeatability of suspension kinematics across multiple production units.

[0051] In some embodiments, the float control washer 207, 307 is located radially on the outer diameter of the lower link 203, 303 such that it does not interfere with the ground sleeve206, 304 or the running surfaces of the needle roller bearing 202. This specific positioning avoids contact between the washer 207, 307 and the rotating or sliding surfaces of the bearing, thereby preventing additional friction or wear in the primary rotational interface while still delivering effective axial location. The overall arrangement is therefore compact, robust and suitable for the high load and motion demands imposed on the lower link-to-girder connection during riding.

[0052] The bearing arrangement has the benefit of keeping the axial movement control method behind the seals 205, 305 hence preventing dirt ingress and premature wear. The spacers 204, 308 are a simple design which reduces the effect of tolerances on the axial stackup and the amount of free float of the swingarm in the lateral direction. The float control washers207, 307 are prevented from interfering with the ground sleeves 206, 304 by locating the on the outer diameter on the link 203, 303.

[0053] Needle roller bearings 202, 302 have a high static radial load capacity for their size, making them a good choice where package space is critical, as compared to other rolling element bearing types. In certain embodiments, the need roller bearing may be replaced with a solid polymer or metal bushing. Further, in the proposed suspension system, spring and damper units (FSU’s) are mounted between the girder fork leg and the lower link 203, 303. This gives a favourable motion ratio which reduces the size of the FSU required to give the required wheel travel, saving weight. In the developed vehicle a 60mm stroke FSU gives 100mm of wheel travel. In some embodiments, a single FSU may be used instead of two FSUs to save weight by keeping it mounted in the same location, but only on one side. In another embodiment, the single FSU may be mounted between a lower link 203, 303 and an upper yoke.

[0054] The suspension system constitutes a part of the structural member of the electric two-wheeler vehicle, which impacts the kerb weight of such vehicles. Hence the aluminium girder fork suspension system proposed in the present invention results in a reduction in the kerb weight of the two-wheeler electric vehicle due to the use of aluminium in creating the girder fork. The reduced density of aluminium as compared to materials such as steel which are conventionally used in the structural member, including suspension system, leads to a reduced weight of the proposed girder fork system, and subsequently, a reduced kerb weight. In certain embodiments of the present invention, aluminium alloy 6082-T6 is selected for its high strength compared to other aluminium alloys. Its high elongation allows it to absorb a high amount of energy in an impact scenario. Aluminum alloy 6082 has good formability, allowing it to be shaped and deformed easily under heat and pressure during forging. Aluminum 6082 can be forged at relatively low temperatures compared to some other metals, reducing energy consumption and minimizing thermal stresses during the forging process. The forging process helps create a uniform grain structure in the material, improving the mechanical properties and overall performance of the forged components.

[0055] The aluminum alloy 6082 offers several benefits due to its unique combination of properties. Aluminum 6082 has excellent strength, comparable to many steels, making it suitable for applications where strength is crucial, such as structural components in aerospace, automotive, and marine industries. Despite its high strength, aluminum 6082 is lightweight, which is advantageous for applications where weight reduction is important. Aluminum 6082 exhibits good resistance to corrosion, particularly in atmospheric environments. This makes it suitable for outdoor applications where exposure to moisture and other environmental factors is common.

[0056] The tensile strength of aluminium alloy 6082 typically ranges from 124-290 MPa (18-42 ksi), depending on temper and thickness. The yield strength typically ranges from 55- 240 MPa (8-35 ksi), depending on temper and thickness. Elongation typically ranges from 8- 25%, depending on temper and thickness. Hardness varies depending on temper, with values typically ranging from 30 to 95 on the Brinell hardness scale (BHN). Modulus of Elasticity is approximately 68.9 GPa. Density of the alloy is approximately 2.70 g / cm3(0.0975 lb / in3) and melting point is approximately 582-651°C (1080-1204°F), depending on alloy composition. Thermal conductivity is approximately 167 W / m K (1160 BTU in / h ft2 OF) at room temperature and electrical conductivity is approximately 43-57% IACS (InternationalAnnealed Copper Standard), depending on temper and alloy composition. Coefficient of thermal expansion of the aluminum alloy 6082 is approximately 23.6 pm / m°C (13.1 pin / in°F) for 0-100°C (32-212°F) range. Specific heat capacity is approximately 0.896 J / g°C (0.214 BTU / lb°F) at room temperature.

[0057] The impact of use of aluminium in the proposed girder fork suspension system hence leads to optimization of the kerb weight of the electric two-wheeler vehicles based on a decreased weight of the structural member of the vehicles. The reduction in kerb weight due to the incorporation of aluminium in the proposed girder fork suspension system leads to an increase in the range, and decrease in the energy expended for propulsion of the electric twowheeler vehicles.

[0058] The use of dual shock 104-1, 104-2 on either leg of the girder fork 102 ensure that torsional twisting of the electric two-wheeler vehicle is reduced. This proposed novel layout of the present invention also frees up packaging space in front of the headstock (the usual place to package the shock where there is only one on a girder fork). It improves aesthetics since the headlight position can be moved further back. While girder forks 102 have a classic aesthetic, modem interpretations of this suspension design incorporate advanced materials and manufacturing techniques. This blending of classic styling with modem technology can appeal to riders looking for a combination of timeless elegance and contemporary performance. Overall, girder forks 102 can be visually striking and aesthetically pleasing, adding character, style, and individuality to motorcycles and bicycles.

[0059] Fig. 3 illustrates a cross-sectional view through a lower suspension link similar to that shown in Fig. 2, but focusing on a bearing arrangement between the lower link 203, 303 and a lower yoke or lower clamp associated with the steering assembly, in accordance with an embodiment of the present invention. In this configuration, the lower link 203, 303 is pivotally connected to a lower yoke or bracket that forms part of the steering head assembly, allowing the lower link 203, 303 to rotate relative to the vehicle frame about a pivot axis parallel to that of the girder-to-link connection.

[0060] The interface between the lower link 203, 303 and the lower yoke includes a needle roller bearing 202, 302, analogous to the bearing 202, 302. The lower yoke may carry a ground sleeve 206, 304 that serves as the inner or outer race for the needle roller bearing 202, 302,while the lower link 203, 303 incorporates a corresponding bore or housing. This arrangement permits smooth rotational movement of the lower link 203, 303 relative to the lower yoke under suspension articulation, while transmitting vertical and braking loads from the wheel and links into the vehicle frame.

[0061] The assembly in Fig. 3 includes spacers 204, 308 and float control washers 207, 307 that provide axial location and limit unwanted lateral float of the lower link 203, 303 with respect to the lower yoke. The float control washers 207, 307 are positioned between the lower link 203, 303 and spacers 204, 308, and may be supported on the outer diameter of the link 203, 303 so as to avoid interference with the ground sleeve 206, 304 and the running surfaces of the needle 202, 302 roller bearing. This positioning ensures that axial control is decoupled from the primary bearing interface, maintaining low friction in rotation while still constraining axial movement.

[0062] Seals 205, 305 are provided at appropriate axial positions in the assembly to protect the bearing 302 and associated components from the ingress of dirt, water or other contaminants. By locating the axial float control washers 207, 307 and spacers 204, 308 behind the seals 205, 305, the design minimizes the exposure of these components to environmental conditions that could lead to accelerated wear, corrosion or contamination-induced binding. This configuration supports long-term reliability and reduces maintenance requirements for the suspension pivots.

[0063] The bearing and axial control scheme is particularly beneficial where available axial space is limited, as in compact electric two-wheeler frames. The use of needle roller bearings 202, 302 and slim float control washers 207, 307 instead of more voluminous thrust bearings or stepped collars allows the lower link-to-yoke joint to fit within a constrained envelope while still handling the required static and dynamic loads. This compactness facilitates integration of the girder fork linkage with existing frame geometries and headstock designs without requiring substantial redesign of the main chassis.

[0064] In some embodiments, the lower yoke and associated ground sleeve 206, 304 may be integrally formed or rigidly fixed to a steering stem that passes through the headstock bearings, thereby ensuring that loads transmitted through the lower link 303 are efficiently carried into the main frame of the electric two-wheeler. The combined function of the bearing arrangement of Fig. 3 and that of Fig. 2 is to create a stable, low-friction parallelogram or multi -link structure that accurately guides the motion of the front wheel while managing radial and axial loads in a controlled manner. Together, these arrangements contribute to the improved handling, durability and kerb-weight reduction objectives of the present invention.

[0065] The proposed aluminium girder fork suspension system constitutes a part of the structural member of the electric two-wheeler vehicle, which impacts the kerb weight of such vehicles. Hence the aluminum girder fork suspension system proposed in the present invention results in a reduction in the kerb weight of the two-wheeler electric vehicle due to the use of aluminum in creating the girder fork 102. The reduced density of aluminum as compared to materials such as steel which are conventionally used in the structural member, including suspension system, leads to a reduced weight of the proposed girder fork 102 system, and subsequently, a reduced kerb weight.

[0066] The impact of use of aluminum in the proposed girder fork suspension system hence leads to optimization of the kerb weight of the electric two-wheeler vehicles based on a decreased weight of the structural member of the vehicles. The reduction in kerb weight due to the incorporation of aluminum in the proposed girder fork suspension system leads to an increase in the range, and decrease in the energy expended for propulsion of the electric twowheeler vehicles.

[0067] The use of dual shock 104-1, 104-2 on either leg of the girder fork 102 ensure that torsional twisting of the electric two-wheeler vehicle is reduced. In addition to the incorporation of dual shocks 104-1, 104-2 in the present invention, the proposed novel layout of the present invention saves space in front of the headstock of the two-wheeler electric vehicle, which ensures that the angle of the girder arms presents a more aesthetic look.

[0068] The methods, systems, devices, graphs, and / or tables discussed herein are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative embodiments, the methods may be performed in an order different from that described, and / or various stages may be added, omitted, and / or combined. Also, features described with respect to certain embodiments may be combined in various other embodiments. Different aspects and elements of the embodiments may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims. Additionally, thetechniques discussed herein may provide differing results with different types of context awareness classifiers.

[0069] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly or conventionally understood. As used herein, the articles “a” and “an” refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. “About” and / or “approximately” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, encompasses variations of +20% or +10%, +5%, or +0.1% from the specified value, as such variations are appropriate to in the context of the systems, devices, circuits, methods, and other implementations described herein. “Substantially” as used herein when referring to a measurable value such as an amount, a temporal duration, a physical attribute (such as frequency), and the like, also encompasses variations of ±20% or ±10%, ±5%, or ±0.1% from the specified value, as such variations are appropriate to in the context of the systems, devices, circuits, methods, and other implementations described herein.

[0070] As used herein, including in the claims, “and” as used in a list of items prefaced by “at least one of’ or “one or more of’ indicates that any combination of the listed items may be used. For example, a list of “at least one of A, B, and C” includes any of the combinations A or B or C or AB or AC or BC and / or ABC (i.e., A and B and C). Furthermore, to the extent more than one occurrence or use of the items A, B, or C is possible, multiple uses of A, B, and / or C may form part of the contemplated combinations. For example, a list of “at least one of A, B, and C” may also include AA, AAB, AAA, BB, etc.

[0071] While illustrative and presently preferred embodiments of the disclosed systems, methods, and / or machine-readable media have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art. While the principles of the disclosure have been described above in connection with specific apparatuses and methods, it is to be clearly understood that this description is made only by way of example and not as limitation on the scope of the disclosure.

Claims

We Claim:

1. A suspension system for a two-wheeler vehicle, comprising: a girder fork 102 structure having at least two legs pivotally connected via a linkage system 203, 303 to a steering head or chassis; at least one shock absorber 104-1, 104-2 mounted on each leg of the girder fork 102; a linkage system including upper and lower links 203, 303 pivotally connected to the girder fork 102 and vehicle chassis; and a plurality of needle roller bearings 202, 302 at pivot joints of the linkage system203, 303, wherein the linkage system 203, 303 provides vertical wheel compliance while constraining lateral and fore-aft movement through pivot joints.

2. The system as claimed in claim 1, wherein said girder fork 102 structure is formed from a lightweight metal alloy having density at least less than 3.0 g / cm3.

3. The system as claimed in claim 1, comprising dual shock absorbers 104-1, 104-2, one on each leg of the girder fork 102.

4. The system as claimed in claim 1, wherein spring and damper units are mounted between the girder fork legs and lower links 203, 303, providing a motion.

5. The system as claimed in claim 1, wherein the pivot bearings include float control washers 207, 307 between girder links and spacers 204, 308 for axial location, positioned behind seals 205, 305.

6. The system as claimed in claim 1, wherein the needle roller bearings 202, 302 are replaceable with solid polymer or metal bushings.

7. The system as claimed in claim 4, wherein said single spring and damper unit is used, mounted on one side between girder fork leg and lower link 203, 303, or between lower link 203, 303 and upper yoke.

8. An electric two-wheeler vehicle comprising the girder fork suspension system as claimed in any preceding claim, wherein the system reduces kerb weight compared to steel -based girder forks 102 while maintaining structural integrity.

9. The vehicle as claimed in claim 8, wherein the girder fork 102 configuration frees packaging space ahead of the headstock.

10. An electric two-wheeler vehicle comprising the suspension system of any preceding claim, wherein: the girder fork 102 reduces unsprung mass; dual shock layout enables forward headlight positioning; and overall kerb weight reduction enhances vehicle range by at least 5%.

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