DESC:TECHNICAL FIELD
[0001] The present invention generally relates to a suspension system for a three wheeled vehicle. More particularly, the present invention relates to a roll stability bar for resisting the vehicle roll forces during vehicle cornering.

BACKGROUND
[0001] In many countries of the world, a three wheeled vehicle is a significant mode of public transportation. It is vastly used as a point to point mode of transport in rural and urban areas. Generally, a three-wheeled vehicle has a driver compartment in a front portion and a passenger/load compartment in a rear portion. In case of a passenger vehicle, the rear compartment comprises of a passenger seat. In the posterior portion of the rear compartment an internal combustion (IC) engine is provided, which powers the vehicle. A driver operates the vehicle from the first compartment. A driver seat is provided in the front compartment so that the driver operates the vehicle in a sitting position. The suspension structure for three wheeled vehicle normally employs separate trailing arm with rear suspension system to support the body on the two rear wheel assemblies. The three wheeled vehicle is subjected to tilt and/or roll while negotiating a turn on the road, or when one of the rear wheel is subjected to road shocks causing relative motion between the two rear wheels, and this causes instability in the three wheeled vehicle. Additionally, this may cause discomfort to both passenger and driver alike. Since, the primary usage of three wheeled vehicle is transportation, there is a need to design of the suspension system to reduce vehicle tilt and/or vehicle roll for better stability and improved comfort of passengers alike.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0003] Fig. 1a illustrates the left side perspective view of an exemplary three wheeled vehicle, in accordance with an embodiment of the present invention.
[0004] Fig. 1b illustrates the rear side perspective view of the exemplary three wheeled vehicle, in accordance with the embodiment of the present invention.
[0005] Fig. 2a illustrates the isometric view of the frame assembly of the exemplary three wheeled vehicle showing the roll stability bar, in accordance with the embodiment of the present invention.
[0006] Fig. 2b illustrates the rear perspective view of the frame assembly of the exemplary three wheeled vehicle showing the roll stability bar, in accordance with the embodiment of the present invention.
[0007] Fig. 3a illustrates the exploded view indicating the connection assembly of trailing arm suspension structure and the roll stability bar, in accordance with the embodiment of the present invention.
[0008] Fig. 3b illustrates the side perspective view of an enlarged section of the exemplary three wheeled vehicle showing the trailing arm suspension structure, in accordance with the embodiment of the present invention.
[0009] Fig. 4 illustrates a top perspective view of an enlarged section of the exemplary three wheeled vehicle showing the trailing arm suspension structure and the roll stability bar, in accordance with the embodiment of the present invention.
[00010] Fig. 5a illustrates the isometric view of the roll stability bar, in accordance with the embodiment of the present invention.
[00011] Fig. 5b illustrates the isometric view of an enlarged section of the pivot connection of the trailing arm suspension structure to the frame of the exemplary three wheeled vehicle, in accordance with the embodiment of the present invention.
[00012] Fig. 6a illustrates the isometric view of the frame assembly of the three wheeled vehicle showing the roll stability bar, in accordance with another embodiment of the present invention.
[00013] Fig. 6b illustrates the isometric view of the roll stability bar, in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION
[00014] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. In the ensuing exemplary embodiments, the vehicle is a three wheeled vehicle. However it is contemplated that the disclosure in the present invention may be applied to any automobile capable of accommodating the present subject matter without defeating the spirit of the present invention. The detailed explanation of the constitution of parts other than the present invention which constitutes an essential part has been omitted at suitable places.
[00015] When an automobile executes a turn, especially during fast cornering and sudden turns the automobile is subjected to vehicle roll over forces due to load transfer of the automobile towards the outside of the turn. Even when the automobile encounters bumps, potholes or road shocks on one side of the wheel, the two sides of the automobile are subject to relative motion. Additionally, if the automobile is loaded heavily on one side in the lateral direction then, lateral weight transfer occurs in fast cornering resulting in vehicle roll over forces acting on it. A three wheeled vehicle is always less stable as compared to four wheeled vehicle. During cornering, a three wheeled vehicle cannot bank like a two wheeled vehicle, hence it is subjected to vehicle roll over forces like any other four or more wheeled vehicle. But, since three wheeled vehicle is supported by three wheels, the points of contact on the ground is only at three points, hence during fast cornering or uneven road shocks the three wheeled vehicle is more unstable and offers less resistance to vehicle roll over forces. This excessive vehicle body roll is most detrimental from the point of view of the three wheeled vehicle stability, and safety of passengers and driver. Hence, it is very essential that the three wheeled vehicle suspension system is designed to reduce vehicle roll over forces.
[00016] When the three wheeled vehicle executes a fast cornering, the centrifugal forces generated acts sideways at the centre of gravity of the three wheeled vehicle away from the centre of the corner. The centre of gravity is always some distance above the ground, hence the centre of gravity moves away from the centre of the corner and weight is removed from the inside tyres and added to the outside tyres. This weight transfer causes the outer tyre suspension to compress and inner tyre suspension to extend. This generates vehicle roll over forces.
[00017] The dynamic behavior of the three wheeled vehicle while entering, executing and exiting a corner depends on a number of factors including roll stiffness, and resistance to lateral (or side-to-side) weight transfer by the two independent rear suspension systems. The rear suspension system includes helical springs, damper system and suspension geometry which all play critical roles in controlling weight transfer and limiting body roll. Generally, three wheeled vehicles have trailing arm independent rear suspension system. Since the three wheeled vehicle is supported only by a single front wheel and two rear wheels, the vehicle is subjected to vehicle roll over forces very easily. The stability of the three wheeled vehicle during cornering is a big issue due to lesser stability and independent rear suspension. Additionally, if in the three wheeled vehicle, the passengers are seated on any one side of the vehicle, or in case of a carrying goods, if goods are stacked towards any one side, then the centre of gravity of the three wheeled vehicle is shifted from the centre. This imbalance of weight towards any one side of vehicle will cause additional instability during cornering. In order to reduce vehicle roll over forces, we need to have harder or more stiffer suspension systems which can enhance the stability. But this reduces drive comfort, reduces the ability of the rear suspension systems to absorb road shocks. Hence, a good effective solution is to implement a roll stability bar system in such three wheeled vehicle.
[00018] The roll stability bar is a metal bar which joins the two independent rear trailing arm suspension structure of the three wheeled vehicle. The primary function of the roll stability bars is to reduce vehicle roll by adding to the roll resistance. When the three wheeled vehicle is heading into a fast cornering, the centrifugal forces cause relative motion between the two trailing arm suspension structures causing the rear wheel on the inner side of the turn to be lifted of the ground. The roll stability bar, gives a moment onto the vehicle body which tries to tilt back the vehicle body in its basic position. The roll stability bar is able to give an opposite moment due to twisting action when relative motion is applied at the two ends of the trailing arm suspension. It is this twisting that provides the resistance to the suspension movement due to vehicle roll over forces. This mechanism controls vehicle roll over forces while still allowing each corner of the vehicle’s trailing arm suspension structure to act independently.
[00019] The roll stability bar functions by twisting, hence the torsional stiffness/ torsional rigidity determines its lever force and the extent to which it limits vehicle roll. This torsional rigidity or torsional stiffness is a function of its diameter, the stiffness of the material used and whether it is solid or hollow, the length of the trailing arms that connect the bar to the suspension, and the geometry of the bar as determined by its mounting points.
[00020] In conventional roll stability bar systems, the roll stability bar is connected to the two ends of the linking arm of the rear independent suspension system. Additionally, the roll stability bar passes through two pivot points under the chassis, usually on the sub-frame and is attached to the same point on the opposite suspension setup. Generally, roll stability bar is designed to have end portions and central portion. The end portions are arranged longitudinally while the central portion is transverse forming a U-shaped system. This arrangement not only contributes to the complexity in design but also contributes to weight and usage of additional brackets is required to secure the roll stability bar. Additionally, the roll stability bar is also subjected to an accessory bending load as the roll stability bar is rigidly attached to the linking arm of the rear suspension at both sides and the bar is parallel to the imaginary axis through which the rear suspension is pivoted. Also, attachment of roll stability bar using additional attachments such as brackets and pivots gives rise to difficulty in access to engine assembly parts and difficulty in serviceability. Additionally, the geometry of the roll stability bar and the types of its end connections depend engine layout, axle layout and transmission shaft layout. The three wheeled vehicle has the IC engine assembly and all associated vehicular parts located towards the rear of the vehicle. Hence, due to space and layout constraints, it is difficult to adopt conventional roll stability bar systems. Due to the above drawbacks, there is a need to provide a roll stability bar capable of alleviating the above mentioned drawbacks.
[00021] Hence, it is an object of the present invention to provide a roll stability bar capable of being designed to reduce the vehicle roll more effectively.
[00022] Another object of the present invention is to avoid the use of additional elements such as brackets to secure the roll stability bar.
[00023] Another objective of the present invention is that, the contours of the roll stability bar is designed such that, IC engine assembly components and other vehicular components can be accommodated easily.
[00024] Another object of this invention is a roll stability bar which is fixedly attached to the location where the two trailing arm suspension structure are pivoted to the S-shaped chassis frame to avoid the roll stability bar from being subjected to bending forces.
[00025] Another object of this invention is the roll stability bar which provides roll stability at a constant rate throughout the vehicle range of motion.
[00026] Another object of the present invention is to propose a device as aforesaid which is simple in its construction, economical in use and effective in operation.
[00027] With the above design changes, the following advantages can be obtained such as reduced number of elements, ease of serviceability, better vehicle roll reduction characteristics, use of existing brackets in the three wheeled vehicle, no lag in its effectiveness and will therefore add roll stability as soon as the vehicle body and chassis begin to lean or tilt, and providing variation in contours to accommodate other systems in the three wheeled vehicle such as hand-start system.
[00028] According to the present invention to attain the above mentioned objectives, a first characteristic of the present invention provides a three wheeled vehicle, said three wheeled vehicle comprising: a S-shaped frame assembly; a pair of trailing arms, each of said pair of trailing arms spaced apart and disposed on either side of a longitudinal axis of the S-shaped frame assembly, and each of said pair of trailing arms comprises a forward end portion configured to be pivotally attached to the rear of the S-shaped frame assembly; and a roll stability bar; characterized in that, the roll stability bar is fixedly attached between the pair of trailing arms at the forward end portion of each of said pair of trailing arms.
[00029] In addition to the configuration of the first characteristic, the second characteristic of the present invention is the three-wheeled vehicle wherein the pair of trailing arm suspension structures further comprises a pair of trailing arm brackets, each attached to the forward end positions, and configured to be pivotally supported by the S-shaped frame assembly.
[00030] In addition to the configuration of the second characteristic, the third characteristic of the present invention is the three wheeled vehicle wherein the roll stability bar further comprises of two attachment points in the form of roll stability brackets, each attached to both the end portions of the roll stability bar, and configured to be fixedly attached to the pair of trailing arm brackets at the location where the pair of trailing arms are pivotally supported by the S-shaped frame assembly.
[00031] In addition to the configuration of the third characteristic, the forth characteristic of the present invention is the three wheeled vehicle wherein the attachment of the roll stability bar to the pair of trailing arms is effected by attaching the each of the attachment points to its corresponding trailing arm brackets through fasteners.
[00032] In addition to the configuration of the forth characteristic, the fifth characteristic of the present invention is the three wheeled vehicle wherein the each of the two attachment points have slotted holes and the trailing arm brackets have circular holes for inserting and securing the fasteners.
[00033] In addition to the configuration of the third characteristic, the sixth characteristic of the present invention is the three wheeled vehicle wherein the three wheeled vehicle further comprises: two rear wheels, each of said rear wheel attached to the rearward position of the each of the said pair of trailing arms; and two rear elastic members and damper systems, each attached to each of said pair of trailing arms at one end, and attached to the S-shaped frame assembly at the other end.
[00034] In addition to any of first to sixth characteristic, the seventh characteristic of the present invention is the three wheeled vehicle wherein the profile of the roll stability bar is concavely curved at a substantially right-hand side and left-hand side of the longitudinal axis of the roll stability bar, and the concavity is oriented downward to the direction of the three wheeled vehicle.
[00035] The present invention along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.
[00036] Fig. 1a illustrates a side perspective view of an exemplary three-wheeled vehicle (100) (hereafter vehicle), in accordance with an embodiment of the present invention. The vehicle (100) has a frame assembly (Fig. 2), which includes a head tube (205), and a main frame assembly (201, 202 and 203) extending rearward from the head tube (205). The vehicle (100) has a front cowl (105) positioned in the anterior portion of the head tube (205). A wind shield (108) is mounted to the front cowl (105). A floorboard (113) is extending from the bottom portion of the front cowl (105) to the rearward direction of the vehicle (100), supported by the main frame assembly. A steering shaft (207) is rotatably inserted inside the head tube (205) and handle bar assembly (107) is supported at one end of the steering shaft (207), positioned behind the front cowl (105). A steering assembly comprises a front wheel (104) connected to the handle bar assembly (107) through one or more front suspension(s) (210), and the front suspension(s) (210) is connected to the other end of the steering shaft (207). A front fender (106) is placed above the front wheel (104), covering at least a portion of the front wheel (104). A bottom portion of a rear panel (101) is connected to the posterior portion of the floorboard (113). A hood (109) connects a top portion of the front cowl (105) and a top portion of the rear panel (101). Two or more rear wheels (102 and 103) are connected to a trailing arm suspension structure (Fig. 3a and Fig. 3b) through one or more suspension(s) (209). The trailing arm suspension structure (Fig. 3a and Fig. 3b) is in turn pivoted to the main frame assembly by means of brackets (302). The vehicle (100) is longitudinally divided into two portions along the line (X-X’); a front portion F has a driver’s seat assembly (114 and 115) while a rear portion R has a long passenger seat (112) with a seating capacity of three or more passengers. A partition wall is positioned along the line (X-X’) extending in the lateral direction of the vehicle (100). The driver’s seat assembly comprises a seat base (115) and a fixed backrest (114) fixed to the partition wall (X-X’). The vehicle (100) can be used as a passenger carrier vehicle or a load carrier vehicle. In case of a load carrier vehicle, the rear portion comprises of load carriage.
[00037] Fig. 1b illustrates the rear side perspective view of the vehicle (100), in accordance with the embodiment of the present invention. An IC engine assembly is mounted to the frame assembly between the main tubes (201) in posterior portion of the vehicle (100). The IC engine assembly comprises of an IC engine (116), a transmission system (not shown), and a final drive system (120) which functionally connects the IC engine (116) to the rear wheels for transmitting power. The entire IC engine assembly is enclosed by the rear panel (101) having a rear door (not shown) to access the IC engine assembly and other vehicular components. Owing to its bigger size, it occupies a significant space in the rear panel (101) due to which the available space for other components is limited. The rear panel (101) further encloses other systems such as air induction system (119), exhaust system including muffler (117), cooling and lubrication system (not shown), and fuel tank and fuel supply system (not shown) mounted on the posterior portion of the vehicle (100) within the rear panel (101).
[00038] Fig. 2a illustrates the isometric view of the frame assembly of the vehicle (100) showing the roll stability bar (301), in accordance with the embodiment of the present invention. The frame assembly comprises of a head tube (205), a down tube (204), two side long members (201a and 201b), one central long member (202) and three cross members (212, 203 and 208). The head tube (205) receives the steering tube (207) and supports the handlebar assembly (107), front steering assembly, the front cowl (105) and other elements such as dashboard with instrument cluster (not shown). The down tube (204) is integrally attached to the head tube (205) at one end and extends downward towards the rear of the vehicle (100). The other end of the down tube (204) is connected to the central long member (202). The down tube (204) not only connects the head tube (205) to other parts of the frame assembly but also hollow to accommodate various wires and tubes (not shown) which connect the front part of the vehicle (100) to the rear. The central portion of the frame assembly comprises of a central long member (202) disposed on the center, and two side long members namely, a right-hand side long member (201a) (hereafter RH long member) and a left-hand side long member (201b) (hereafter LH long member) one on each side of vehicle (100). Both the central long member (202) and side long members (201a and 201b) extend from the front to the rear of the vehicle (100) in the longitudinal direction of the vehicle (100). Towards the rear of the vehicle (100), the side long members (201a and 201b) are curved vertically with respect to the longitudinal axis of the vehicle for a certain distance before again curving horizontally towards the rear of the vehicle forming an S-shaped structure. The side long members (201a and 201b) can be made up of one integral portion or can be assembled from multiple parts to form the entire S-shaped structure. A gusset plate (304b) connects angularly the bottom horizontal portion to the upper horizontal portion of the side long members to provide additional strength and stiffness to the side long members (201a and 201b) and frame assembly in general. The frame assembly also comprises three cross members (212, 203 and 208) which span along the lateral axis of the vehicle connecting the RH long member with the LH long member forming a ladder type frame assembly. The three cross members are the front cross member (212), the central cross member (203) and rear cross member (208). The front cross member (212) along with the down tube (204) supports the front cowl (105). The floorboard (113) is supported by the frame assembly in the bottom to support the driver the passengers respectively and extends from the front cross member (212) to till the rear cross member (208). The central cross member (203) also supports the partition wall (X-X’) which separates the driver side from the passenger side. The rear side of the side long members (201a and 201b) support the IC engine assembly and all other vehicular components. It also supports the rear panel (101).
[00039] Fig. 2b illustrates the rear perspective view of the frame assembly of the exemplary vehicle (100) showing the roll stability bar (301), in accordance with the embodiment of the present invention. The rear cross member (208) spans across the two side long members (201a and 201b) and its both ends are welded at the beginning of the curved portions at the bottom of the S-shaped structure of the side long members (201a and 201b). One of the main functions of the rear cross member (208) is too support two rear trailing arm suspension structures (see Fig. 3b). The trailing arm suspension structure pivoted to the rear cross member (208) at both ends trailing arm brackets (302 and 303) and swingably supported by rear suspension(s) (209) at the other end. The roll stability bar (301) spans along the entire lateral axis of the vehicle connecting the two trailing arms (400) at its pivot locations on its forward end portion (400a) (attached to the inner trailing arm brackets (302) on the rear cross member (208). The advantage of connecting the roll stability bar (301) at the pivot points of the trailing arms (400) to the rear cross member (208) is that, the roll stability bar (301) is subjected only to pure torsional load, and is not subjected to bending loads. Additionally, the roll stability bar (301) need not be separately attached to the frame assembly. A part of the left-hand side of the cross member (208) as referenced from the longitudinal axis is slightly curved (208a) towards the top and has a semi-circular profile. This curved profile provides sufficient hollow space below it. Similarly, a corresponding part of the left-hand side of the roll stability bar (301) as referenced from the longitudinal axis is slightly curved towards the bottom and has a semi-circular profile. This curved profile provides sufficient hollow space above it. The curved space formed between the two hollow spaces can accommodate vehicular elements such as a hand-start rod (not shown) of a hand-start system which connects the driver compartment to the IC engine assembly which is located substantially above the trailing arm suspension structure (300) towards the rear of the vehicle (100).
[00040] Fig. 3a. illustrates the exploded view indicating the connection assembly of trailing arm suspension structure (300) and the roll stability bar (301), in accordance with the embodiment of the present invention. The trailing arm suspension structure (300) comprises of a trailing arm (400), a pivot tube (403) with its profile being hollow and two rubber bushings (not shown) on either ends and disposed inside the hollow pivot tube (403). The trailing arm has a forward end (400a) and a rearward end (400b). The trailing arm is made up of two sections, the inner member (402) and outer member (401). Both inner member (402) and outer member (401) form a V-shape profile with the two ends meeting on rearward end portion (400b), and the other ends welded to the pivot tube (403) at the forward end portion (400a). This arrangement provides sufficient strength and load distribution when the trailing arm (400) oscillates laterally when subjected to lateral load. The rear cross member (208) has in its end portion on either side of the vehicle (100), an inner support bracket (302) and a outer support bracket (303) between which the pivot tube (403) of the trailing arm is pivotally mounted through the rubber bushing assembly (not shown) by attaching fasteners (not shown). On the inner side of this attachment, a trailing arm bracket (404) is welded to the end of the pivot tube (403). The trailing arm bracket (403) has a opening (410) at its centre through which fasteners (not shown) pivotally mount the pivot tube (403) on the inner support bracket (302). The trailing arm suspension structure (300) further comprises an rear axle sleeve (not shown) welded at the rear end portion (400b) of the trailing arm where the inner member (402) and outer member meet (401). The rear axle sleeve (not shown) is hollow, and a plurality of bearings is disposed on the inner portion of the rear axle sleeve (not shown), through which a rear axle (not shown) passes. While on one end of the rear axle (not shown) the hub of the rear wheel (103) is attached, a universal bipode joint (408) is attached to the rear axle (not shown) at the other end. The universal bipode joint (408) is capable of receiving a propeller shaft (not shown) from the IC engine (116). Hence, the IC engine (116) transmits rotary motion through the propeller shaft (not shown) to the universal bipode joint (408) which rotates the rear axle (not shown) and this rotary motion is subsequently transmitted to the rear wheel (103).
[00041] Fig. 3b illustrates the side perspective view of an enlarged section of the exemplary three wheeled vehicle showing the trailing arm suspension structure (300), in accordance with the embodiment of the present invention. The rear axle sleeve (not shown) also comprises suspension bracket (305) fixedly attached to it, to which an elastic member and dampener suspension element such as rear suspension (209) is pivotally connected. The upper portions of the rear suspension (209) are pivotally anchored to the end portion brackets (211) located on the rear portion of the side long members (201). In this manner, the trailing suspension structure (300) allows up and down movement of the rear axle relative to the rear cross member through oscillatory movement of the trailing arms and the rear suspension provides the necessary energy absorbing and damping forces to this oscillatory movement.
[00042] It will be noted that the trailing arm suspension structure (300) includes a pair of trailing arms which are operatively associated with opposite end portions of the vehicle and it is to be understood that the attachment of the forward ends of both trailing arms to the opposite end portions of the rear cross member is identical. In addition, the rear ends of the trailing arms are identically mounted on the corresponding opposite end portions of the rear axle.
[00043] Fig. 4 illustrates a top perspective view of an enlarged section of the exemplary three wheeled vehicle showing the trailing arm suspension structure (300) and the roll stability bar, in accordance with the embodiment of the present invention. In accordance with the embodiment of the present invention, the roll stability bar (301) has a hollow cylinder shaped tubular profile having two attachment points (405a and 405b) welded on either side. Each of the two attachment points (405a and 405b) are attached to the two ends of the trailing arm suspension structure (300) without any attachment to the frame assembly of the vehicle (100).
[00044] Fig. 5a illustrates the isometric view of the roll stability bar arrangement. It is seen that, the roll stability bar (301) is curved downward from a semicircular profile in the vertical plane of the vehicle at two opposite sides as taken from a central portion (301a) of the roll stability bar (301). This curved semicircular profile is provided to accommodate vehicular components of the vehicle such a hand-start system (not shown), wiring harness (not shown) and hydraulic brake lines (not shown). The roll stability bar (301) is attached to the trailing arm brackets (404a and 404b) directly without securing it to the frame assembly of the vehicle (100). Further, the central portion (301a) and the two attachment points (405a, 405b) all lies on a single plane. This has the advantage that, when there is relative motion between the two trailing arm suspension structure (300), the entire torsional load on one trailing arm suspension structure (300) acting on one direction is transferred to the other trailing arm suspension structure (300) acting on the other direction and no torsional forces is transferred to the frame assembly. By suitable design of rear suspension structures and design of roll stability bar, this entire combined system will have ability to resist vehicle roll forces without transferring any of the forces to the frame assembly. This will ensure that not only the safety of the driver, but also that the roll forces acting on the roll stability bar are not transferred to the passengers and thus providing for a more comfortable ride. Further, the rolls stability need not have bent tube structure and hence eliminates the need of additional manufacturing processes, reduces assembly difficulties and lesser failure of the roll stability bar after prolonged use.
[00045] Fig. 5b illustrates the isometric view of an enlarged section of the pivot connection of the trailing arm suspension structure (300) to the frame of the exemplary three wheeled vehicle, in accordance with the embodiment of the present invention. The roll stability bar (301) has roll stability brackets (405a and 405b) welded at both its ends, and the roll stability bar (301) is securely attached to the trailing arm brackets (404a and 404b) at both ends in the same location in which the forward portions of the trailing arm is pivotally anchored to the inner support brackets (302). The trailing arm bracket (404) and the attachment points (405) comprise of three portions perpendicular to each other in three dimensional plane. The trailing arm bracket (404) is exactly a mirror image of the attachment point (405) such that its corresponding portions mate together. Attachment of the trailing arm bracket (404) and the attachment point (405) is effected by two sets of fasteners. One set of fasteners (406) on the longitudinal axis of the vehicle and the other set of fasteners (407) on the vertical axis of the vehicle (100). This arrangement ensures that longitudinal displacement of one trailing arm relative to the other trailing arm is prevented by the roll stability bar (301). Additionally, there are plurality of holes provided on the trailing arm brackets (404a and 404b) and the two attachment points (405a and 405b) to accommodate the plurality of fasteners (406 and 407). In the present embodiment, the plurality of holes present on the trailing arm brackets (404a and (404b) have a circular profile, and the plurality of holes present on the two attachment points (405a and 405b) has a slotted profile. The slotted hole profile are so provided to take care of the tolerances in dimensions during manufacturing of the roll stability bar and the frame assembly, and this tolerances can be adjusted during the fastening assembly of the roll stability bar to the frame assembly.
[00046] Fig. 6a illustrates the isometric view of the frame assembly of the three wheeled vehicle showing the roll stability bar, in accordance with another embodiment of the present invention. Fig. 6b illustrates the isometric view of the roll stability bar, in accordance with the other embodiment. In this embodiment, the roll stability bar (601) is a straight bar with no variations in its geometry. As mentioned above, due to IC engine assembly, there are constraints in accommodating vehicular components such as hand-start rod (not shown) which is part of the hand-start assembly of the IC engine. But in other embodiments such as a three wheeled vehicle comprising a IC engine running on compression ignition principle and using diesel as fuel, such vehicular components are not required. In addition, such IC engine can be placed such that, no vehicular components interfere with the functioning of the roll stability bar, in this case, the roll stability bar (601) with a straight geometry is used. This design ensures that less material is utilized; and easier manufacturing process and lesser weight is achieved.
[00047] Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.
,CLAIMS:We Claim:
1. A suspension system for a three-wheeled vehicle (100), said three wheeled vehicle (100) comprising:
plurality of cross members (212, 203 and 208) including a rear cross member (208), said plurality of cross members (212, 203 and 208) forming part of a frame assembly (200) of the three-wheeled vehicle (100);
a right rear wheel (102) and a left rear wheel (103) disposed on either side towards the rear of the frame assembly (200), said right rear wheel (102) and the left rear wheel (103) each swingably connected to the rear cross member (208) through a trailing arm suspension structure (300); and
said trailing arm suspension structure (300) comprising:
a pair of trailing arms (400), each of said pair of trailing arms (400) comprises a forward end portion (400a) configured to be pivoted to the rear cross member (208), and a rearward end portion (400b) secured to the each of said right rear wheel (102) and said left rear wheel (103), and said rearward end portion (400b) of each of the trailing arm (400) connected to the frame assembly (200) through a rear suspension (209);
wherein,
a roll stability bar (301) having two attachment points (405a, 405b) at either end and a central portion (301a), said each of the two attachment points (405a, 405b) fixedly attached between each of said pair of trailing arms (400) at the forward end portion (400a) thereof, and said each of the two attachment points (405a, 405b) and the central portion (301a) are oriented in a single plane.

2. The suspension system for the three-wheeled vehicle (100) as claimed in claim 1, wherein the frame assembly (200) comprises a head tube (205), a pair of main tubes (201a, 201b, and 202), and plurality of cross members (212, 203 and 208) spanning along the lateral axis of the vehicle connecting said pair of main tubes (201a, 201b, and 202);
3. The suspension system for the three-wheeled vehicle (100) as claimed in claim 1, wherein the forward end portion (400a) of each of said trailing arm (400) comprises a pivot tube (403) capable to being pivotally secured between a pair of support brackets (302, 303), said pivot tube (403) comprising a trailing arm bracket (404a, 404b) fixedly attached and disposed at an inner end of the pivot tube (403), and said two attachment points (405a, 405b) at either end of the roll stability bar (301) configured to be fixedly attached to the pair of trailing arm brackets (404a, 405b).
4. The suspension system for the three-wheeled vehicle (100) as claimed in claim 3, wherein the attachment of the pair of trailing arm brackets (404a, 404b) and the two attachment points (405a, 405b) at either end of the roll stability bar (301) is effected by plurality of fasteners.
5. The suspension system for the three-wheeled vehicle (100) as claimed in claim 4, wherein the two attachment points (405a, 405b) have slotted holes and the pair of trailing arm brackets (404a, 405b) have circular holes for inserting and securing the fasteners.
6. The suspension system for the three-wheeled vehicle (100) as claimed in claim 1, wherein the roll stability bar (301) comprises a left curved portion (409a) and a right curved portion (409b) disposed either side of the central portion (301a), said left curved portion (409a) and right curved portion (409b) configured to be concavely and downwardly curved to the direction of the three-wheeled vehicle (100).
7. The suspension system for the three wheeled vehicle (100) as claimed in claim 1, wherein the trailing arm (400) further comprising an inner member (402) and an outer member (401), said inner member (402) and said outer member (401) converging on the rearward end (400b) of the trailing arm (400), and said pivot tube (403) is fixed to the two ends of said inner member (402) and said outer member (401).
8. The suspension system for the three-wheeled vehicle (100) as claimed in claim 1, wherein the rearward end portion (400b) of the trailing arm (400) supports a wheel axle, said wheel axle supporting the rear wheels (102, 103).