TECHNICAL FIELD
[0001] The present subject matter relates generally to a suspension assembly for a vehicle. More particularly, the present invention relates to a mechanism for the rear suspension assembly of the vehicle.
BACKGROUND
[0002] Generally,' in a saddle type two or three-wheeled vehicle, one or more suspension assembly is provided each at a front end and at a rear side of the vehicle. The one or more suspension assembly is provided in a vehicle to absorb and dissipate road shocks experienced by die vehicle while operating on the roads. The suspension assembly provided in the vehicle prevents the shocks and vibrations from reaching the rider or the pillion, thereby providing ride comfort to the rider as well as to the pillion. Generally, the suspension assembly is mounted to a vehicle body frame at one end and another end is mounted to a swing arm of the vehicle. BRIEF DESCRIPTION OF DRAWINGS
[0003] The above and other features, aspects and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings, where:
[0004] Figure 1 shows a left side perspective view of the scooter type vehicle. [0005] Figure 2 illustrates a left side view of a rear portion of the vehicle. ■ [0006] Figure 3 illustrates a suspension assembly of the two-wheeled vehicle in accordance with another embodiment.
[0007] Figure 4 illustrates a top perspective view of a preload adjuster according to an embodiment of the present invention.
[0008] Figure 5 illustrates a bottom perspective view of the preload adjuster according to an embodiment of the present invention.
[0009] Figure 6 illustrates a front view of the sectional view of the preload adjuster taken along axial direction X-Y axis of the preload adjuster. [00010] Figure 7 illustrates a front view of the preload adjuster according to an embodiment of the present invention.

DETAILED DESCRIPTION
[00011] A suspension assembly is used in the motorcycle to absorb the external road shocks and provide better ride comfort. The suspension assembly is also important for safe riding and better handling of the vehicle. The suspension assembly in the vehicle includes at least one front suspension and at least one rear suspension. In a typical motorcycle type vehicle, a pair of front forks is used in the front suspension assembly and an elastic member is a primary member that constitutes the rear suspension assembly. The pair of front forks and the rear suspension assembly comprises the elastic member of suitable stiffness value and damping oil of suitable damping value. Typically, a coil spring is used as a spring element. External shocks caused by uneven road conditions is transferred to the pair of front forks and the rear suspension assembly which is taken up by the elastic member, which results in the compression and decompression motion of the elastic member. This, prevents the transfer of the external shocks and other forces to a rider seated on the vehicle or a frame assembly of the vehicle.
[00012] The pair of front forks connects a steering handlebar to a front wheel, and the rear suspension assembly connects between the rear wheel and the rear portion of the vehicle. The pair of front forks and the rear suspension assembly ensures optimum ride comfort by enabling suitable adjustment of the stiffness of the elastic member disposed inside the pair of front forks and in the rear suspension assembly, adjustment of damping characteristics of the damping oil and also preload provided to the elastic member. In an embodiment, the pair of front forks may be replaced with suitable other type of suspension assembly like a trailing arm with hydraulic shock absorbers, etc.
[00013] The pre-load in the elastic member of the rear suspension assembly refers to an initial compression of the elastic member, for example, a spring compared to its normal decompressed state. The amount of pre-load provided to the elastic member varies with the response of the vehicle in being able to effectively isolate the rider from external shocks and bumps on the road. Therefore, the optimum

preload provided greatly affects the ride comfort of the vehicle. Increasing the amount of pre-load on the elastic member increases the initial loading in the spring. Hence, the compression that may occur due to the weight of the rider, weight of the pillion rider and the weight of the vehicle itself is decreased, resulting in increasing the distance of the rider from the ground. The optimal tuning of the pre-load provides a less responsive ride i.e. the effect of the external shocks due to uneven road condition is comparatively reduced as compared to that of a lesser pre-load in the elastic member.
[00014] Similarly, decreasing the amount of pre-load in the elastic member may result in more compression of the spring in static condition due to the weight of the rider and the weight of the vehicle. Thus, in turn, the distance of the rider or the pillion rider from the ground is decreased and resulting in providing a more responsive ride as compared to a higher pre-load tuning in the elastic member. An increase in pre-load in the elastic member leads to higher load withstand capacity of the rear suspension assembly in a static and dynamic condition of the vehicle and also influences the dynamic handling performance as well as stability of the vehicle.
[00015] Further, a number of factors affect the optimum value of pre-load to be set for a given elastic member. The factors include, an excess of pre-load may result in bottoming of the elastic member, which is strictly not desirable for the safety and ride comfort of the rider and the pillion rider or passengers. In addition, if the pre¬load is provided below a certain limit then it may result in a very responsive ride. Under these circumstances, the amount offeree transferred to the rider or the pillion rider and the vehicle may not be desirable.
[00016] Further, the user of the vehicle would like to adjust the pre-load of the elastic member to suit the performance of the vehicle according to his/her requirement. The amount of-the desired pre-load to be provided to the elastic member is dependent on the type and condition of the road and payload on the vehicle. Typically, the conventional rear suspension assembly has the preload of the elastic member tuned to provide an optimal ride comfort. However, given the

fact that the payload of a vehicle changes significantly from solo ride condition to a dual ride condition and in addition to payload, it is obvious that the vehicle stance will change owing to the changes in load exerted on the vehicle. Often, the preload is tuned for a solo condition which results in a trade-off of the optimum preload required for dual riding condition. Under such a circumstance of dual riding condition, the rear suspension and rear part of the vehicle tend to compress more than the front and resulting in an inclined stance of the vehicle thus to an inferior ride condition and vehicle handling performance of the vehicle. Additionally, the changes in the vehicle stance also causes the changes in headlight focus point from solo ride condition to a dual riding condition. All of the above creates a necessity to provide a mechanism which allows the user to modify the amount of pre-load on the elastic member as desired by him/her. The change in the stance of the vehicle also influences the squat behavior of the vehicle thereby impacting the stability performance of the vehicle.
[00017] The amount of pre-load in the elastic member has to be designed suitably to avoid bottoming or topping of the elastic member. If the elastic member is undergoing bottoming condition, then the user of the vehicle will feel the elastic member to be a solid medium between the wheel and user and further, this may result in transferring of all the external shocks and forces from the road to the user. This results in a poor ride comfort. Hence, it is important to have an optimum amount of pre-load in the elastic member to avoid the bottoming or topping of the elastic member.
[00018] Typically, the rear suspension assembly includes a shock absorber and a swing arm assembly unit for a motor cycle. Whereas scooter rear suspension consists of at least one shock absorber, an engine, and a toggle link as part of the rear suspension assembly. Typically, the rear suspension assembly includes a damper assembly, an elastic member and a preload adjustment mechanism to isolate the vehicle from the external impacts occurring due to uneven roads. The damper assembly includes damping oil and damping generating mechanism for isolating shocks from wheel assembly. Further, a damper body is welded to a stopper

member at an outer circumferential surface. Further, the rear suspension assembly typically includes the preload adjustor mechanism to adjust the initial elastic member pre-compression according to the requirements of the rider and terrain conditions. The preload adjuster mechanism includes a preload adjuster configured with plurality of angled portions for providing desired pre-compression to the elastic member. Further, the preload adjuster also includes provisions for operating through various tools. The above said angled portions in the preload adjustor rests on the stopper member provided in the damper body. Further, one end of the elastic member rests on the preload adjustor in an axial direction and the other end rests on the end of the rear suspension assembly, which includes a mounting portion enabling attachment of the rear suspension assembly to the frame assembly of the vehicle.
[00019] In one of the known arts of providing preload to the elastic member to the rear suspension assembly through usage of toots, the preload adjustor includes a hole configured to receive the tool. The mechanism of providing preload through the preload adjuster includes operating the preload adjuster through suitable tools to provide rotational movement to the preload adjustor. The rotation movement provided to the preload adjuster results in compression or decompression of the elastic member. The requirement of compression or decompression of the elastic member by providing preload is as per the requirement of the user based on road terrain and the payload.In this particular instance, under certain circumstances, it may be possible that the rear suspension assembly is packaged amidst various other vehicular components and covered partially by certain body panels. The accessibility of the preload adjuster in the rear suspension that is partially covered becomes difficult. In particular, after accessing the preload, adjuster to provide rotational movement to the preload adjuster, the hole used to access the preload adjuster has now undergone displacement or rotation and may be hidden by the body panels. Under such a condition, if the user desires to provide further preload to the elastic member, it may not be possible and further the user is left with no other options but to compromise on his ride conditions leading to poor vehicle

handling and poor ride comfort. The user may also be left with another undesirable option of taking the vehicle to the service center for making the desired preload adjustments by dismantling vehicular parts to access and adjust the pre-load setting of the vehicle. This is often inconvenient and undesirable to the user and leads to discomfort. Additionally, in a scooter type vehicle with swinging type engine and side body panels, the typical shock absorber with a provision for a hole on a boss of the preload adjuster is difficult to access. Also, turning the adjuster to achieve the desired rotation is cumbersome since the tool tends to foul with the vehicular body parts leading to potential damage to the parts. Also, there exists a problem of coating feel due to the fouling and adjustment action which can lead to corrosion and poor aesthetic appeal. Owing to such hassles, the user is unable to effectively use the preload adjustment feature or adjust the pre-load itself and ends up going to service center which is undesirable and costly.
[00020] Further, the ejection of the tool out of the hole in the preload adjuster is difficult. The tool ejection requires more space in the layout of the vehicle for the tool to be removed out of the preload adjuster after completion of the adjustment action.
[00021] Furthermore, the process of producing the preload adjuster with the hole to accommodate the tool is produced through the process of casting/forging/ pressing. The process includes inserting a rod-like structure or provision into the die during die casting process. The rod-like structure is inserted into the die before pouring of the molten metal into the die and the same is used to create the required hole in the preload adjuster. However, to address the problem of the hole being hidden by the body panels after certain rotation, the provision of creating multiple holes in the casting/forging/pressing is not feasible due to requirement of insertion of multiple rod-like structures to create multiple holes which is uneconomical and not aesthetically pleasing. This leads to a complex design changes in the die, becomes a time consuming process and is economically not significant. Further, the same procedure of inserting multiple rod-like structures into the die cannot be incorporated for mass production conditions due to the complexity involved.

Further, the procedure includes one more additional process, like machining, which results in increased cost of the preload adjuster and the entire rear suspension assembly. Furthermore, in the above said mechanism of producing the preload adjuster with hole, the ejection of die after the process of casting is difficult due to presence of a circular hole that holds an entire portion of the die. This requires other suitable process to eject the die out of the suitable hole.
[00022] Further, the stopper member is fixedly attached on to the outer diametrical surface of the damper body. The stopper member holds the preload adjuster in desired position. However, during welding of the stopper member onto the outer diametrical surface of the damper body, the damper body tends to undergo deformation and attains a slightly varying outer diameter around the region comprising the stopper member. The uneven outer diametrical surface tends to have friction with the inner diametrical surface of the conventional preload adjuster. The friction between the damper body and the conventional preload adjuster leads to wear out of a protective coating provided on the outer diametrical surface of the damper body to protect the damper from corrosion. This further affects the normal functioning of the damper body potentially leading to undesirable corrosion and poor aesthetics.
[00023] In another known art the shock absorber preload adjuster is provided with multiple vertical ribs on an outer surface for adjustment of the preload. However, in this type of construction, for the purpose of operating the preload adjuster in order to provide preload to the shock absorber, plurality of ribs have to be handheld together and then the preload adjuster can be operated. The problem of the plurality of ribs being concealed by the surrounding parts and other body panels upon operation still persists. Further, the above said construction is only to provide preload manually and the same design is not suitable for high preload requirements owing to limited structural strength and stability.
[00024] In another known art, the preload adjuster includes multiple holes configured to receive a tool enabling operability of the preload adjuster. However,

such a preload adjuster is made up of a sheet metal material including different parts comprising an exclusive member for bearing holes and then welded into another member including cam profile. Separate parts as explained above may not be desirable for a preload adjuster as it includes operating under rotational movement and being a stress bearing member, the preload adjuster may be prone to include loosened joints. Further, the preload adjuster made up of sheet metal is costlier than the conventional preload adjuster.
[00025] Further, in another known art, the preload adjuster includes plurality of'C shaped provisions to enable operability to the preload adjuster. However, such a 'C shaped provision includes open ended sides and may lead to slippage of tool while operating the preload adjuster and may be detrimental to the person operating the preload adjuster.
[00026] Therefore, a preload adjuster capable of providing preload as desired by the user and capable of overcoming problems known in the art, is required.
[00027] According to an embodiment of the present invention, the rear suspension assembly includes two mounting portions disposed at opposite ends of the rear suspension assembly. A damper body is disposed in between the two mounting portions. An elastic member is concentrically disposed around the damper body. At least one stopper member is disposed on an outer circumferential surface of the damper body. The at least one stopper member acts as a support for holding the preload adjuster in its position on the outer diametrical surface of the damper body. The preload adjuster includes an accommodating surface to accommodate one end of the elastic member. The accommodating surface is configured to include enough surface area for supporting the one end of the elastic member, such that the elastic member rests on the accommodating surface and outwardly to the damper body.
[00028] According to an embodiment of the present invention, the preload adjuster is disposed in any of the ends of the suspension assembly. The preload adjuster is mounted between the mounting portion and the elastic member. Two ends of the suspension assembly are rigidly mounted in the vehicle. Whereas, the preload

adjuster is configured to undergo rotational movement against the outer surface of the damper body. The rotational movement of the preload adjuster is transferred as a linear movement of the elastic member disposed abuttingly above the preload adjuster.
[00029] According to an embodiment of the present invention, the preload adjuster includes at least two grooves extending outwardly in the circumferential direction on the accommodating surface. The at least two grooves includes a relief at one end in the axial direction. The relief at one end facilitates easy ejection of the die during casting process. Furthermore, the other end of the at least two grooves is closed along the axial direction to provide required support to a preload adjustor tool during operating the preload adjuster.
[00030] According to an embodiment of the present invention, the bottom side of the elastic member rests on the opening end of the preload adjustor in assembled condition of the rear suspension assembly. Therefore, the one side open end is now covered by the elastic member and this provides better support to the preload adjustor tool by avoiding slippage of the tool out of the at least two grooves.
[00031] Further, according to another embodiment of the present invention, the side opposite to the accommodating surface in the preload adjustor includes plurality of angular portions. These angular portions allow traversing of the at least one stopper member there through during rotational movement of the preload adjuster. The angular portions are configured at an angle of approximately 15degrees~25degrees " of cam angle to enable better operability of the preload adjuster. In particular, the preload adjuster with the above said cam angle requires lesser torque to provide the desired preload as compared to the conventional preload adjuster.
[00032] According to another embodiment of the present invention, the inner diametrical surface of the preload adjuster includes varying diametrical surface. The inner diametrical surface of the preload adjuster that comes in contact with the outer diametrical surface of the damper body near the at least one stopper member includes a slightly higher diameter to accommodate the varying dimensions of the

damper body. Thereby preventing friction between the outer diametrical surface of the damper body and the inner diametrical surface of the preload adjuster. The damper body does not undergo frequent corrosion due to the proposed preload adjuster and the normal functioning of the rear suspension assembly is ensured through this.
[00033) These and other advantages of the present invention are described in the detailed description of the figures of an embodiment in a scooter type motor vehicle provided below.
[00034] Figure 1 shows a left side perspective view of the scooter type vehicle. The vehicle 100 has a body frame assembly made up of several tubes welded together which usually supports the body of said vehicle. The vehicle 100 has a steerable front wheel 101 and a driven rear wheel 102. The vehicle frame assembly of the vehicle 100 is an elongated structure, which typically extends from a forward end to a rearward end of the vehicle. It is generally convex in shape, as viewed from a side elevation view. The frame assembly includes a head tube 104, a main frame 111 and also may have a sub-frame. The sub-frame is attached to the main frame 111 using appropriate joining mechanism. The frame assembly is covered by a plurality of vehicle body covers including a front panel 103, a rear cover (not shown), a left front bottom panel 105, and a pair of side panels 106. [00035] A handlebar assembly 109 and a seat assembly 302 are supported at opposing ends of the vehicle frame assembly and a generally open area is defined there between known as floorboard 108 which functions as a step through space. A seat assembly 302 for a driver and a pillion is placed forward to a fuel tank (not shown) and rear side of floorboard 108. A front fender 107 is provided above the front wheel 101 to avoid the vehicle 100 and its occupants from being splashed with mud. Likewise, a rear fender 112 is placed between the fuel tank and the rear wheel 102, and to the outer side in the radial direction of the rear wheel 102. The rear fender 112 inhibits rain water or the like from being thrown up by the rear wheel 102. A front cover assembly 115 is disposed rearwardly to the floorboard 108.

[00036] Suspensions are provided for comfortable steering of the vehicle 100 on the road. A front suspension assembly 116 is connected to a front fork (not shown). The rear suspension assembly 117 comprises of at least one rear suspension preferably on the left side of the vehicle. However, a vehicle with two rear suspensions, namely on the left side and the right side is also possible. For the safety of the user, a headlamp assembly 110 in the front portion of the vehicle and a taillight assembly 114 in the rear portion of the vehicle 100 is also provided. For the utility of the rider, a secondary storage assembly 118 is disposed in front of the front cover assembly 115.
[00037] Figure 2 illustrates a left side view of a rear portion of the vehicle. According to an embodiment of the present invention, the rear suspension assembly 117 includes two mounting portions disposed at two opposite ends. The two opposite ends include a first end 201 and a second end 202. The first end 201 is attached to at least a portion of the frame assembly 106. The second end 202 is attached to at least a portion of the swing arm assembly 113 including a powertrain assembly of the vehicle. In the present embodiment, an air filter assembly 207 is disposed above the swing arm assembly 113 and at a close proximity to the rear suspension assembly 117. Under the assembled condition, most of the bottom portion of the rear suspension assembly 117 is concealed by the air filter assembly 207. The bottom portion of the rear suspension assembly 117 includes the preload adjuster 206 disposed at the second end of the rear suspension assembly 117. The suspension assembly 117 and the partial portion of the swing arm assembly 113 are exposed in the present view. However, most portion of the suspension assembly 117 would be concealed by the body panel of the vehicle. The bottom portion of the suspension assembly 117 comprising the preload adjuster 206 would be exposed • and available for accessibility.
[00038] Figure 3 illustrates a suspension assembly of the two-wheeled vehicle in accordance with another embodiment. The typical suspension assembly 117 includes two mounting portions comprising the first end 201 and the second end 202. The first end 201 includes the first mounting portion 201a and the second end 202 includes the second mounting portion 202a configured to be mounted to at least

a portion of the frame assembly and the swing arm assembly. Further, the rear suspension assembly 117 includes an elastic member 203 and orifices to control the flow of oil through an internal reciprocating member 204. The reciprocating member 204 includes a damper body 205 filled with damping fluid. The suspension assembly 117 is mounted in the two-wheeled vehicle such that the first end 201 is bolted to the vehicle body frame and the second end 202 is bolted to the swing arm. Further, the suspension assembly 117 includes a preload adjuster 206 disposed at any of the first end 201 and the second end 202, however, in the present embodiment, the preload adjuster 206 is disposed at the second end 202 and particularly between one end of the elastic member 203 and the second end 202.
[00039] Figure 4 illustrates a top perspective view of a preload adjuster according to an embodiment of the present invention. The preload adjuster is preferably circular in shape with a hollow inner body for being disposed around the damper body (not shown). The preload adjuster 206 includes at least two grooves 301 extending outwardly along a circumferential direction in an accommodating surface 302. The at least two grooves 301 comprise each groove configured with a relief 301r at one end in the axial direction. The relief 30lr at one end of the preload adjuster 206 is an open ended side and facilitates easy ejection of the die during the process of making the preload adjuster, for example during die casting of the preload adjuster 206 the open ended relief 301 r facilitates easy ejection of the portion of the die intact with the relief 30 lr of the preload adjuster 206. The easy ejection of the die during the casting process facilitates a configuration with flexibility of having required number of grooves as desired for the purpose of engaging the tool with the preload adjuster 206. to provide preload to the rear suspension assembly. The production of multiple grooves in the preload adjuster results in a simple die according to the proposed invention.
[00040] According to another embodiment of die present invention, the at least two grooves 301 includes each groove configured with a closed end along the axial direction XY to provide required support to the preload adjustor tool during operating the preload adjuster 206. In a preferred embodiment, the elastic member

(not shown) is resting on the open ended relief 30lr side of the preload adjuster 206. The portion of the elastic member resting on the relief 301r provides required support to the tool being accommodated in the at least two grooves 301 and prevents slippage of the tool from the at least two grooves 301 while operating the preload adjuster 206. Further, the presence of at least two grooves 301 provides the flexibility of providing desired preload to the rear suspension assembly (not shown). The preload adjuster 206 can be operated multiple times by accessing any visible groove of the at least two grooves 301. The probability of the groove from the at least two grooves 301 being concealed by the other vehicular parts and the body panels is being greatly reduced by the proposed invention along with improved operability of the preload adjuster 206.
[00041] Therefore, the user does not have the need to take the vehicle to the service center to perform the simple operation of providing preload to the rear suspension assembly as provided in the proposed invention.
[00042] Figure 5 illustrates a bottom perspective view of the preload adjuster according to an embodiment of the present invention. Further, according to another embodiment of the present invention, the preload adjuster 206 includes an extension member 402 configured to facilitate manual operability of the preload adjuster 206 without the need of any external preload adjuster tool. In particular, the circumstance may arise when the load on the vehicle is considerably lesser, for "example around 15kgs- 20kgs, the user can comfortably provide preload as desired by using the extension member 402. The extension member 402 is an integral portion of the preload adjuster 206. The extension member 402 according to another embodiment can be provided at any desired location along the accommodating surface 302 of the preload adjuster 206.
[00043] Figure 6 illustrates a front view of the sectional view of the preload adjuster taken along axial direction X-Y axis of the preload adjuster. The preload adjuster 206 includes a first inner diametrical surface Dl of the accommodating surface 302 and a second inner diametrical surface D2 of the plurality of angular portions 401. According to another embodiment of the present invention, the

second inner diametrical surface D2 is greater than the first inner diametrical surface Dl. The bigger second inner diametrical surface D2 of the plurality of angular portions 401 allows desired rotation of that particular portion of the plurality of angular portions 401 around the damper body without having any friction there between. Thereby preventing any damage to the damper body.
[00044] Figure 7 illustrates a front view of the preload adjuster according to an embodiment of the present invention. The side opposite to the accommodating surface 302 includes plurality of angular portions 401 extending downwardly along the axial direction XY. The plurality of angular portions 401 are configured to include a cam angle of approximately 15degrees~25degrees. The optimum cam angle as given in the proposed invention facilitates operation of the preload adjuster 206 with minimum torque and less efforts by the person operating the preload adjuster 206 either manually or through suitable tools,
[00045] Although the subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.