Rebound Stopper for a Suspension Assembly of a Vehicle

FIELD OF THE INVENTION

[001] The present invention relates to a suspension assembly for a vehicle, more particularly relates to a rebound stopper disposed in the suspension assembly of the vehicle. BACKGROUND OF THE INVENTION

[002] Vehicle, such as a two-wheeled vehicle, typically has a suspension assembly to act as a shock absorber for isolating road undulations and improving road holding characteristics of the wheel with the road. One widely used suspension assembly in two wheeled vehicles is a telescopic suspension assembly having an inner tube slidably mounted with an outer tube. A spring and damper assembly is enclosed within the tubes to isolate the road undulation and shock by absorbing and dissipating energy.

[003] Typically, in conventional telescopic suspension assembly, a hydraulic damping element is coupled with the springs enclosed inside the tubes. The hydraulic damping element is usually an oil damper in which oil flows through restricted bleed holes to absorb kinetic energy from the spring motion for damping. During a return stroke the inner tube slides out of the outer tube and oil passes through tension bleed holes and generate extension damping to dissipate energy absorbed. At the end of the return stroke a rebound spring gets compressed along with oil damping to avoid jerking and enable a smooth stop at end of the return stroke. [004] However, the conventional telescopic suspension assembly is complex in construction due to the bleed holes and oil seals incorporated therein. Also, these oil seals and bleed holes are susceptible to dust accumulation and oil leakage. Dust accumulation reduces performance of the suspension assembly and heat dissipation characteristics leading to cavitation in the suspension tubes, which is undesirable.

[005] In order to overcome the aforementioned limitations, telescopic suspension assemblies without an oil damping element have been introduced. In these suspension assemblies, a single spring is provided, which is adapted to absorb energy during movement of the tubes in both compression and tension directions. Hence, performance of these suspension assemblies depends on the characteristics of the spring component mounted within the tubes. The compression stroke is limited by the compression of the spring and the extension stroke is limited by the tension of the spring. A slider is mounted at the lower end of the inner tube and a bush is mounted on the outer tube to guide the inner tube’s sliding motion within the outer tube. The slider mounted at the lower end of the inner tube acts as a stopper when it comes into contact with the upper end of the outer tube and prevents the inner tube from being disassembled from the outer tube during an extension stroke or during spring breakage thus enhancing the safety of the users.

[006] However, the telescopic suspension assemblies without the oil damping element, do not provide the smooth stop at the end of the return stroke as seen in telescopic suspensions coupled to hydraulic dampers. Also, introducing a separate rebound spring in these suspension assemblies, create heavy noise and hard stopping at end of the return stroke. Moreover, the slider mounted at the lower end of the inner tube is typically made of a plastic element to avoid jerking at the end of the return stroke. Such a slider made of a plastic element gets damaged due to constant contact or impact with the metal sides of the outer tube. Hence, such a slider made of a plastic element will have to be replaced often. Also, during maintenance when the inner tube and the outer tube requires dismantling, disassembly becomes cumbersome and such a slider made of a plastic element gets damaged and will have to be replaced. [007] In view of the above, there is a need for a suspension assembly which addresses one or more limitations stated above.

SUMMARY OF THE INVENTION

[008] In one aspect, a rebound stopper for a suspension assembly of a vehicle is disclosed. The rebound stopper includes a cylindrical structure coaxially disposed within the suspension assembly having a first tube telescopically mounted within a second tube and operable between a jounce motion and a rebound motion. The cylindrical structure includes a first surface adapted to engage with a cylinder head extending from the second tube via a cylinder rod and disposed within the first tube. A second surface is adapted to engage with an inner end surface of the first tube, such that the cylindrical structure is adapted to store energy during the jounce motion and dissipate the stored energy between the first tube and the second tube during the rebound motion for inhibiting contact of the inner end surface with the cylinder head.

[009] In an embodiment, the cylindrical structure is defined with a slot extending from the first surface to the second surface. The slot is adapted to enable coaxial disposal of the cylindrical structure with the cylinder rod of the second tube.

[010] In an embodiment, the cylindrical structure is taper in configuration, such that surface area of the first surface is larger than surface area of the second surface. [011] In an embodiment, the first surface of the cylindrical structure engages with the cylinder head via a damping member. The first surface is defined with a damping insert for supporting the damping member thereon.

[012] In an embodiment, the cylindrical structure is provided with one or more annular grooves along its surface. The one or more annular grooves are adapted to form a corrugated configuration of the cylindrical structure.

[013] In an embodiment, the cylindrical structure is made by one of a rubber material or a polyurethane material.

[014] In an embodiment, the suspension assembly is a front suspension assembly of the vehicle.

[015] In an embodiment, the second surface is engaged onto the inner end surface via a washer member.

[016] In another aspect, a suspension assembly for a vehicle is disclosed. The suspension assembly includes the first tube having an upper end mounted onto a clamping member of the vehicle and a lower end. The second tube having a first end adapted to receive the lower end for slidable engagement with the first tube and a second end mounted to a wheel of the vehicle is provided. The second tube includes a cylinder head extending from the second end via a cylinder rod and disposed within the first tube. A damper is disposed within the first tube. The damper has one end engaged to a stopper provided within the first tube and an other end engaged to the cylinder head. The damper is adapted to enable the first tube and the second tube to operate between a jounce motion and a rebound motion. The rebound stopper is coaxially disposed between the first tube and the second tube. The rebound stopper includes the cylindrical structure having the first surface adapted to engage with the cylinder head and the second surface adapted to engage with an inner end surface of the first tube. The cylindrical structure is adapted to store energy during the jounce motion and dissipate the stored energy to the first tube and the second tube during the rebound motion for inhibiting contact of the inner end surface with the cylinder head. [017] In another aspect, the vehicle is disclosed. The vehicle includes a clamping member extends from a head pipe connected to a frame member. The suspension assembly includes the first tube having an upper end mounted onto the clamping member of the vehicle and a lower end. The second tube having a first end adapted to receive the lower end for slidable engagement with the first tube and a second end mounted to a wheel of the vehicle is provided. The second tube includes the cylinder head extending from the second end via a cylinder rod and disposed within the first tube. A damper is disposed within the first tube. The damper has one end engaged to the stopper provided within the first tube and an other end engaged to the cylinder head. The damper is adapted to enable the first tube and the second tube to operate between a jounce motion and a rebound motion. The rebound stopper is coaxially disposed between the first tube and the second tube. The rebound stopper includes the cylindrical structure having the first surface adapted to engage with the cylinder head and the second surface adapted to engage with an inner end surface of the first tube. The cylindrical structure is adapted to store energy during the jounce motion and dissipate the stored energy to the first tube and the second tube during the rebound motion for inhibiting contact of the inner end surface with the cylinder head. BRIEF DESCRIPTION OF THE DRAWINGS

[018] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 is a schematic view of a vehicle, in accordance with an embodiment of the present disclosure.

Figure 2 is a schematic view of a suspension assembly of the vehicle including a rebound stopper, in accordance with an embodiment of the present disclosure.

Figure 3 is a magnified view of the portion ‘A’ of Figure 2, in accordance with an embodiment of the present disclosure.

Figure 4 is a schematic view of the rebound stopper, in accordance with an embodiment of the present disclosure. Figure 5 is a schematic view of the suspension assembly of the vehicle including the rebound stopper, in accordance with another embodiment of the present disclosure

Figure 6 is a magnified view of the portion ‘B’ of Figure 5, in accordance with an embodiment of the present disclosure.

Figure 7 is a perspective view of the rebound stopper, in accordance with an embodiment of the present disclosure.

Figure 8 is a schematic view of the suspension assembly of the vehicle including the rebound stopper, in accordance with another embodiment of the present disclosure

Figure 9 is a magnified view of the portion Ό’ of Figure 8, in accordance with an embodiment of the present disclosure. Figure 10 is a perspective view of the rebound stopper, in accordance with an embodiment of the present disclosure.

Figure 11 is a graphical representation of the operating characteristics of the rebound stopper, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[019] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.

[020] Figure 1 illustrates a schematic view of a vehicle 200, in accordance with an embodiment of the present invention. As an example, the vehicle 200 is a two-wheeled vehicle. The vehicle 200 comprises a prime mover 228 that is adapted to provide motive force for movement of the vehicle. In an embodiment, the prime mover 228 is an internal combustion engine, which is preferably a single-cylinder engine. The vehicle 200 comprises a front wheel 218, a rear wheel 230, a frame member 226, a seat 232 and a fuel tank 234. The frame member includes a head pipe 224, a main tube (not shown), a down tube (not shown), and seat rails (not shown). The head pipe 224 supports a steering shaft (not shown) and a suspension assembly 202 attached to the steering shaft through a lower bracket (not shown). The suspension assembly 202 supports the front wheel 218. Also, the suspension assembly 202 includes a rebound stopper 100 (for e.g, as shown in Figure 2), which would be described in description pertaining to Figures 2-10.

[021] Further, the upper portion of the front wheel 218 is covered by a front fender 234 mounted to the lower portion of the telescopic front suspension 202 at the end of the steering shaft. A handlebar 236 is fixed to upper bracket (not shown) and can rotate about the steering shaft for turning the vehicle. A headlight 238, a visor guard (not shown) and instrument cluster 240 is arranged on an upper portion of the head pipe 224. The frame member 226 comprises a down tube (not shown) that may be positioned in front of the prime mover 228 and extends slantingly downward from head pipe 224. The main tube of the frame member 226 is located above the prime mover 228 and extends rearward from head pipe 224.

[022] The fuel tank 234 is mounted on the main tube. Seat rails are joined to main tube and extend rearward to support the seat 232. A rear swing arm (not shown) is connected to the frame member to swing vertically, and the rear wheel 230 is connected to rear end of the rear swing arm. Generally, the rear swing arm is supported by a mono rear suspension 240 (as illustrated in the present embodiment) or through two suspensions on either side of the vehicle 200. A taillight unit 242 is disposed at the end of the vehicle 200 and at the rear of the seat assembly 232. A grab rail 244 is also provided to the seat rails. The rear wheel 230 arranged below the seat 232 rotates by the motive force of the prime mover 228 transmitted through a chain drive (not shown). [023] Further, a rear fender 246 is disposed above the rear wheel 230. An exhaust pipe 248 of the vehicle 200 extends vertically downward from the prime mover 228 and then extends below the prime mover 228, longitudinally along length of the vehicle 200 before terminating in a muffler 250. The muffler 250 is typically disposed adjoining the rear wheel 230. [024] Figure 2 illustrates the suspension assembly 202 including the rebound stopper 100, in accordance with an embodiment of the present invention. In the present embodiment, the suspension assembly 202 is a telescopic-type suspension assembly 202. The suspension assembly 202 includes a first tube 204 having an upper end 204a mounted onto a clamping member 216 (for e.g. as shown in Figure 1) and a lower end 204b. A second tube 206 having a first end 206a receives the lower end 204b for slidable engagement therebetween. As such, the first tube 204 and the second tube 206 are slidable relative to one another. In the present embodiment, the lower end 204b is inserted within the second tube 206 via the first end 206a. Thus, the first tube 204 acts as an inner tube, while the second tube 206 acts as an outer tube. In an alternate embodiment, the first tube 204 acts as the outer tube, while the second tube 206 acts as the inner tube. Further, the second tube 206 includes a second end 206b adapted to be mounted onto a wheel, optionally the front wheel 218 of the vehicle 200.

[025] Further, the second tube includes a cylinder head 208 extending from its second end 206b via a cylinder rod 210. The cylinder head 208 is disposed within the first tube 204 via the lower end 204b. Additionally, a damper 220 is disposed within the first tube 204. The damper 220 has one end 220a engaged to a stopper 222 within the first tube 204 and an other end 220b engaged to the cylinder head 208. In an embodiment, the other end 220b is engaged to an outer surface 208b of the cylinder head 208 (for e.g. as shown in Figure 3). Such a construction of the damper 220 enables the first tube 204 and the second tube 206 to be operable between a jounce motion and a rebound motion. In an embodiment, the jounce motion is a bounce or vertical motion between the first tube 204 and the second tube 206, when the wheel 218 contacts an undulation on a road surface. Thus, the suspension assembly 202 attenuates the undulations encountered by the vehicle 200 during movement. In an embodiment, the rebound motion is a recovery motion between the first tube 204 and the second tube 206 subsequent to the jounce motion.

[026] In an embodiment, construction of the cylinder head 208 and the cylinder rod 210 and the damper 220 can be interchangeably mounted between the first tube 204 and the second tube 206, as per design feasibility and requirement. [027] In an embodiment, the shape, dimensions and configuration of the first tube 204 and the second tube 206 is selected based on the damping requirements of the vehicle 200. Accordingly, the configuration of the damper 220, the cylinder head 208 and the cylinder rod 210 is selected as per design feasibility and requirement of the first tube 204 and the second tube 206.

[028] Referring to Figures 3 and 4 in conjunction with Figure 2, the rebound stopper 100 disposed in the suspension assembly 202 is depicted. The rebound stopper 100 is disposed between the first tube 204 and the second tube 206. The rebound stopper 100 is adapted to dissipate energy during the rebound motion between the tubes 204, 206, to ensure smooth stopping of the tubes 204, 206 without noise.

[029] The rebound stopper 100 includes a cylindrical structure 102 coaxially disposed within the first tube 204. In other words, an axis A-A’ of the rebound stopper 100 is mounted to be coaxial with the axis X-X’ of the first tube 204. The cylindrical structure 102 has a first surface 104 engaged to the cylinder head 208 and a second surface 106 engaged with an inner end surface 212 of the first tube 204. The cylindrical structure 102 also includes a slot 108 extending from the first surface 104 to the second surface 106. The slot 108 is adapted to receive the cylindrical rod 210 (for e.g. as shown in Figures 1 and 3) so that the cylindrical structure 102 is mounted co-axially within the first tube 204, while also enabling engagement of the first surface 104 with the cylinder head 108 on its inner surface 208a.

[030] In an embodiment, the first surface 104 and the second surface 106 are provided with mounting features such as inserts (for e.g. as shown in Figure 7) for enabling engagement with the inner surface 208a and the inner end surface 212, respectively. In an embodiment, engagement between the first surface 104 and the inner surface 208a is established by contact therebetween. Similarly, the second surface 106 and the inner end surface 212 establish engagement by contact therebetween. Alternatively, other possible techniques can be employed for establishing engagement between the first surface 104 and the inner surface 208a, and between the second surface 106 and the inner end surface 212.

[031] In an embodiment, the cylindrical structure 102 is taper in configuration, such that the surface area of the first surface 104 is larger than that of the second surface 106. The taper configuration may refer to a tapered cross-section of the cylindrical structure 102. The taper configuration provides minimal surface area to the rebound stopper 100 required for ensuring optimal structural integrity for preventing contact between the inner surface 208a and the inner end surface 212 during the rebound motion. In an embodiment, the cylindrical structure 102 is configured with a square cross-section, a rectangular cross- section and a circular cross-section as per design feasibility and requirement. Further, the cylindrical structure 102 is made by one of a rubber material or a polyurethane material The material has non-linear stiffness characteristics and optimum hysteresis properties for absorbing and dissipating the energy during the rebound motion of the suspension assembly 202. The material is selected based on the stiffness requirement in the suspension assembly 202.

[032] In an alternative embodiment, the configuration of the cylindrical structure 102 conforms to the configuration of the first tube 204. In other words, when the first tube 204 is configured with a circular cross-section, the cylindrical structure 102 is also configured with a circular cross-section. Further, to ensure stability in engagement between the second surface 106 and the inner end surface 212, a washer member 214 (for e.g. as shown in Figure 3) is provided. Also, the washer member 214 is a plate-like structure adapted to prevent misalignment between the cylindrical structure 102 and the inner end surface 212 during engagement.

[033] In an operational embodiment, the shock experienced by the wheel 218 during traversal over the road undulation is transferred to the suspension assembly 202. In this scenario, the suspension assembly 202 is operated to jounce, wherein the second tube 206 moves relative to the first tube 204. That is, the cylinder head 208 moves within the first tube 204 away from the inner side surface 212 and actuates the damper 220 for absorbing the shock.

[034] Upon dissipation of the shock, the energy absorbed by the damper 220 is released, pushing back the cylinder head 208 towards the inner end surface 212. In this scenario, the inner surface 208a contacts the first surface 104, thereby imparting a portion of the energy (/.e. kinetic energy) to the cylindrical structure 102. The energy received by the cylindrical structure 102 is absorbed, while preventing contact of the inner surface 208a with the inner end surface 212. The energy absorbed by the cylindrical structure 102 is thereafter released back to the inner surface 208a for reverting the cylinder head 208a to its initial position. As such, the rebound stopper 100 of the present invention is adapted to prevent contact of the inner surface 208a with the inner end surface 212, while ensuring smooth stopping of the tubes 204, 206 without noise.

[035] In an embodiment, the initial position (not shown) is the position of the first tube 204, the second tube 206, the cylinder head 208 and the damper 220, when no shock is experienced.

[036] Referring to Figures 6 and 7 in conjunction with Figures 2 and 3, the rebound stopper 100 with a damping member 110 is depicted, in accordance with another embodiment of the present invention. In this present embodiment, the cylindrical structure 102 is mounted with the damping member 110. The damping member 110 further smoothens the transition of the suspension assembly 202 from the rebound motion to its initial position, thereby improving the performance of the suspension assembly 202.

[037] The damping member 110 is inserted between the first surface 104 and the cylinder head 208. As such, in the present embodiment, the first surface 104 engages with the cylinder head 208 via the damping member 110 (for e.g. as shown in Figures 5 and 6). For accommodating the damping member 110, the first surface 104 is defined with a damping insert 112 (for e.g. as shown in Figure 7). As such one end of the damping insert 112 is mounted, by conventional techniques, within the damping insert 112 while the other end is engaged with the cylinder head 208. In an embodiment, the damping insert 112 is also provided onto the cylinder head 208 for accommodating the other end of the damping member 110.

[038] In the present embodiment, the damping member 110 is a spring member of a predefined stiffness, sufficient to allow operation of the suspension assembly 202. In an embodiment, the damping member 110 is a diaphragm member. In another embodiment, the dimensions, configuration, number of turns and material of the spring member are selected as per stiffness requirement of the spring member in the suspension assembly 202.

[039] In an operational embodiment, the shock experienced by the wheel 218 during traversal over the road undulation is transferred to the suspension assembly 202. In this scenario, the suspension assembly 202 is operated to jounce, wherein the second tube 206 moves relative to the first tube 204. That is, the cylinder head 208 moves within the first tube 204 away from the inner side surface 212 and actuates the damper 220 to absorb the shock received. [040] During movement of the cylinder head 208 away from the inner side surface 212, the damping member 110 is also elongated, thereby storing energy. In this scenario, the energy stored by the damper member 110 and the damper 220 act collectively with one another and ensure smooth transition to their respective initial positions, resulting in moving the cylinder head 208 towards the inner side surface 212. Due to relatively higher energy absorption by the damper 220, the damping member 110 gets compressed, when the cylinder head 208a is reverting back towards the inner side surface 212. The compression of the damping member 110 absorbs the energy from the damper 220, and thereafter releases the energy back to revert the cylinder head 208 to its initial position. Thus, contact between the inner surface 208a and the inner end surface 212 is prevented. [041] In an embodiment, when the energy released by the damper 220 is greater than the stiffness of the damping member 110, the damping member 110 compresses completely and transfers the remaining energy to the cylindrical structure 102.

[042] The energy absorbed by the damping member 110 and/or cylindrical structure 102 is thereafter released back to the inner surface 208a for reverting the cylinder head 208 to its initial position. As such, the rebound stopper 100 of the present invention is adapted to prevent contact of the inner surface 208a with the inner end surface 212, while ensuring smooth stopping of the tubes 204, 206 without noise.

[043] Figures 9 and 10 illustrate the rebound stopper 100 in accordance with another embodiment of the present disclosure. In the present embodiment, the cylindrical structure 102 is defined with one or more annular grooves 114. The grooves 114 are provided on the cylindrical structure 102 by conventional grooving techniques, such as etching. The grooves 114 form a corrugated configuration of the cylindrical structure 102. The corrugated configuration makes the cylindrical structure 102 to behave like a spring member, which smoothens the movement of the cylindrical head 208 from the rebound motion to its initial position.

[044] In an embodiment, each groove 114 are provided laterally to the axis A-A’. Alternatively, the grooves 114 can be inclined with respect to the axis A-A’. In the present embodiment, the number of grooves 114 provided on the cylindrical structure 102 is four. However, the number of grooves 114 and its dimensions on the cylindrical structure 102 is provided based on the stiffness requirement in the suspension assembly 102.

[045] In an operational embodiment, the shock experienced by the wheel 218 during traversal over the road undulation is transferred to the suspension assembly 202. In this scenario, the suspension assembly 202 is operated to jounce, wherein the second tube 206 moves relative to the first tube 204. That is, the cylinder head 208 moves within the first tube 204 away from the inner side surface 212 and actuates the damper 220 for absorbing the shock.

[046] Upon dissipation of the shock, the energy absorbed by the damper 220 is released, pushing back the cylinder head 208 towards the inner end surface 212. The inner surface 208a contacts the first surface 104, thereby imparting a portion of the energy (i.e. kinetic energy) to the cylindrical structure 102. In this scenario, the cylindrical structure 102 is deformed by absorbing the energy, particularly due to the grooves 114, which makes the cylindrical structure 102 to act as the spring member. Due to the absorption of the energy, the movement of the cylinder head 208 is impeded, thereby preventing contact between the inner surface 208a and the inner end surface 212. The energy absorbed by the cylindrical structure 102 is thereafter released back to the inner surface 208a for reverting the cylinder head 208a to its initial position. In the process, the cylindrical structure 102 also reverts to its original structure. Thus, the rebound stopper 100 of the present invention is adapted to prevent contact of the inner surface 208a with the inner end surface 212, while ensuring smooth stopping of the tubes 204, 206 without noise.

[047] Referring to Figure 11, a graphical representation of behavior of the rebound stopper 100 to load is depicted. As shown, the graph depicts displacement along the X-axis and load acting on the rebound stopper 100 along Y-axis. Thus, the graph depicted in Figure 11 is a load vs displacement curve, that depicts behavior of the rebound stopper 100 during different loading conditions.

[048] The conventional rebound stoppers (shown by curve OZ’ in Figure 11) are typically characterized with linear stiffness characteristic, wherein during a full bump condition or a critical loading condition of the suspension assembly 202, a sudden rebound is experienced. In an embodiment, the full bump condition is a condition, wherein the load acting on the damper 220 exceeds its loading capacity. The sudden rebound leads to failure of the conventional rebound stopper. The loading curve in such a scenario is depicted by the curve OZ’. Additionally, based the loading curve OZ’, it is also evident that due to the linear stiffness characteristic, the conventional rebound stoppers respond abruptly, which cause discomfort to a rider of the vehicle 200, which is undesirable.

[049] In the rebound stopper 100 of the present invention, due to the non-linear stiffness characteristic and configuration of the cylindrical structure 102, the rebound stopper 100 is loaded progressively as shown by curve OZ. Upon releasing the load, the rebound stopper 100 releases the stored energy progressively as shown by curve ZO, thereby ensuring smooth movement of the suspension assembly 202, while also preventing failure of the rebound stopper 100 during the full bump condition.

[050] Advantageously, the present invention provides the rebound stopper 100 which is adapted to prevent contact of the inner surface 208a with the inner end surface 212, while ensuring smooth stopping of the tubes 204, 206 without noise. Consequently, the rider experiences minimal or no discomfort while driving the vehicle 200. Additionally, the rebound stopper 100 is configured with a non-linear stiffness characteristic, which prevents overload thereon, thereby preventing failure of the suspension assembly 202. Additionally, the construction of the rebound stopper 100 ensures that the first tube 204 and the second tube 206 remain assembled even during failure of damper 220 during the critical loading condition.

[051] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.