Description:FIELD OF THE INVENTION
[001] The present invention generally relates to a saddle type vehicle and particularly relates to a swingarm of the saddle type vehicle.

BACKGROUND OF THE INVENTION
[002] A swingarm is a mechanical device which is part of a rear suspension system of a vehicle, like two wheeled vehicles, and attaches a rear wheel of the vehicle to a frame structure of the vehicle. This allows the rear wheel to pivot up and down vertically to traverse bumps and surface undulations on the terrain the vehicle traverses on. The swingarm holds a rear axle of the vehicle firmly, allowing the vehicle to absorb bumps and suspension loads induced by weight of a rider, or loads under acceleration and braking of the vehicle. Further, the swingarm also facilitates mounting of a rear suspension of the vehicle by acting as a platform where a lower end of the rear suspension is attached to.
[003] Generally, two wheeled vehicles employ a swinging fork type swingarm having a pair of longitudinal arms connected at their one end to the rear wheel and at their other end to the frame structure of the vehicle. The pair of longitudinal arms are connected via a cross member, which also acts as a mounting base for the lower end of the rear suspension. Gussets are attached to the swingarm, at junctions between the pair of longitudinal arms and the cross member for enhanced strength of the swingarm. Gussets are conventionally welded to the pair of longitudinal arms and the cross member.
[004] Furthermore, the pair of longitudinal arms and the cross member are formed of hollow tube type structures. Generally, hollow metallic tubes of rectangular cross section or elliptical cross section are utilised. However, tubes of elliptical cross section are preferred over ones having rectangular cross section. A tube having elliptical cross section has a greater height at its centre as compared to a tube having rectangular cross section of the same weight. The swingarm constituted by tubes of greater height at the centre deflects less. Consequently, deflection or bending of the swingarm under external loads and road stresses is negligible when it is formed out of tubes having elliptical cross section.
[005] During welding of the gussets to the pair of longitudinal arms and the cross member, maintenance of required weld root gap is indispensable for achieving target durability of the swingarm’s structure. Poor quality welds affect the durability, strength and longevity of the swingarm. A constant weld root gap is also imperative for good weld quality and aesthetic appeal of the welded parts. In order to achieve a perfect weld, flat surfaces are preferred between two mating parts. Given that gussets have flat surfaces along area to be welded, maintaining a constant weld root gap while welding of gussets is comparatively easier when the pair of longitudinal arms and the cross member constitute tubes of rectangular cross section. When the pair of longitudinal arms and the cross member constitute tubes of elliptical cross section, surfaces to be welded are no longer flat and parallel to each other, due to the curved surface profile of the pair of longitudinal arms and the cross member. Thus, there is a variation in weld gap between the pair of longitudinal arms and the cross member and the corresponding gussets. This increases chances of weld root gap variation along the length of the pair of longitudinal arms and the cross member affecting weld strength and weld quality. Hence, it is desirable to immovably locate the gussets while they are being welded to the pair of longitudinal arms and the cross member to achieve a good quality weld.
[006] Thus, there is a need in the art for a swingarm, which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[007] In one aspect, the present invention is directed to a swingarm of a saddle type vehicle. The swingarm includes a pair of left and right long members substantially parallel to each other and extending in a vehicle front rear direction, and a cross member extending between the pair of left and right long members. The swingarm further includes a plurality of gussets disposed at an interface between each of the pair of left and right long members and the cross member. Each of the plurality of gussets includes at least one through hole.
[008] In an embodiment, each of the pair of left and right long members includes a front end and a rear end. The front end of each of the pair of left and right long members is adapted to be pivotally mounted to a frame structure of the vehicle. The rear end of each of the pair of left and right long members is adapted to rotatably mount a rear wheel of the vehicle.
[009] In another embodiment, the swingarm includes a first bracket mounted on the cross member. The first bracket is adapted to be coupled to a rear suspension of the vehicle.
[010] In yet another embodiment, the pair of left and right long members includes hollow tubes having one of a rectangular cross section or an oval cross section. In a further embodiment, the cross member includes hollow tubes having one of a rectangular cross section or an oval cross section.
[011] In another aspect, the one or more through holes provided in each of the plurality of gussets are adapted to locate the corresponding gusset for affixing the gusset to each of the pair of left and right long members and the cross member at the corresponding interface between each of the long members and the cross member during assembly of the swingarm.
[012] In an embodiment, each of the plurality of gussets has a substantially C shaped cross section, such that the C is opened towards an outside of the vehicle in a vehicle width direction.
[013] In another embodiment, each of the C shaped gussets is adapted to clad each of the corresponding pair of left and right long members. In a further embodiment, each of the C shaped gussets extends substantially parallel to the corresponding pair of left and right long members in the vehicle front rear direction, and curves inwardly at the interface between each of the pair of left and right long members and the cross member in the vehicle width direction to clad the cross member.
[014] In yet another embodiment, each of the C shaped gussets is affixed to the corresponding pair of left and right long members and the cross member by welding.

BRIEF DESCRIPTION OF THE DRAWINGS
[015] 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 illustrates a schematic side elevation view of an exemplary vehicle, in accordance with an embodiment of the present invention.
Figure 2 illustrates a side elevation view of a rear portion of the vehicle, in accordance with an embodiment of the present invention.
Figure 3 illustrates a top perspective view of an exemplary swingarm of the vehicle, in accordance with an embodiment of the present invention.
Figure 4 illustrates a top perspective view of another exemplary swingarm of the vehicle, in accordance with an embodiment of the present invention.
Figure 5 illustrates a top view of the swingarm of the vehicle, in accordance with an embodiment of the present invention.
Figure 6 illustrates a top exploded view of the swingarm of the vehicle, in accordance with an embodiment of the present invention.
Figure 7 illustrates a top perspective view of the swingarm of the vehicle, in accordance with an embodiment of the present invention.
Figure 8 illustrates a cross sectional elevation view of the swingarm of the vehicle, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[016] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.
[017] The present invention generally relates to a saddle type vehicle and particularly relates to a swingarm of the saddle type vehicle. In the ensuing exemplary embodiments, the saddle type vehicle 10 is a motorcycle. However, it is contemplated that the disclosure in the present invention may be applied to any automobile like a scooter or any other three-wheeled or four-wheeled vehicle capable of accommodating the present subject matter without defeating the scope of the present invention. The term ‘vehicle’ has been used below for referring to the term ‘saddle type vehicle’ in favour of brevity.
[018] Figure 1 illustrates a schematic side elevation view of an exemplary vehicle 10, in accordance with an embodiment of the present subject matter. The vehicle 10 comprises a front wheel 36, a rear wheel 38, a frame structure and a seat 44. The frame structure includes a head pipe 18, a main tube (not shown), a down tube (not shown), and seat rails (not shown). A headlamp 32 and an instrument cluster (not shown) are arranged on an upper portion of the head pipe 18. Further, the head pipe 18 supports a steering shaft (not shown) disposed inside the head pipe 18. A front suspension 22 coupled to the steering shaft 20 is provided at a front of the vehicle 10, the front wheel 36 being supported by the front suspension 22. An upper portion of the front wheel 36 is covered by a front fender 46 mounted to a lower portion of the front suspension 22. A handlebar 24 is operatively coupled to the steering shaft and can rotate about the head pipe 18 for steering the vehicle 10.
[019] The vehicle 10 includes a prime mover 12 that is adapted to provide motive force for movement of the vehicle 10. In an embodiment, the prime mover 12 is an internal combustion engine. A fuel tank 42 is mounted on the main tube. An exhaust pipe (not shown) extends vertically downward from the prime mover 12 and then extends below the prime mover 12, longitudinally along length of the vehicle 10 before terminating in a muffler (not shown). In another embodiment, the prime mover 12 is an electric motor. The down tube is positioned in front of the prime mover 12 and extends downward from the head pipe 18 in a slanting manner. The main tube of the frame member is located above the prime mover 12 and extends rearward from the head pipe 18. Seat rails are joined to the main tube and extend rearward to support the seat 44. A swingarm 100 is connected to the frame structure to swing vertically, and a rear wheel 38 is connected to a rear end 114L, 114R (shown in Figure 3) of the swingarm 100. The swingarm 100 is coupled to the vehicle 10 by a rear suspension 50 at a position rearwardly of a pivot point of the swingarm 100 on the frame structure of the vehicle 10. A taillight 54 is disposed at a rear of the seat 44. A grab rail 56 is also provided to the seat rails at a rear of the seat 44. The rear wheel 38 arranged below the seat 44 rotates by motive force generated by the prime mover 12 transmitted through a transmission (not shown). A rear fender 48 is disposed above the rear wheel 38.
[020] Figure 2 illustrates a side elevation view of a rear portion of the vehicle 10, in accordance with an embodiment of the present subject matter. A front end 112L, 112R of the swingarm 100 is pivotally mounted to the frame structure of the vehicle 10 with the aid of a pivot pin 90. The swingarm 100 is free to oscillate about the pivot pin 90. The oscillation of the swingarm 100 about the pivot pin 90 is translated into up and down vertical movement of the rear wheel 38 mounted at a rear end 114L, 114R of the swingarm 100. A rear suspension 50 is coupled to the swingarm 100 at its one end and to the frame structure of the vehicle 10 at its other end to dampen oscillations induced in the swingarm 100 by vertical movement of the rear wheel 38 under influence from road disturbances, undulations or under breaking loads. Thus, rider comfort and effective grip of a rear tyre on road surfaces are well maintained. In the illustrated embodiment, the rear suspension 50 is a monoshock type suspension unit. In an embodiment, a chain guard 80 is mounted on the swingarm 100. The chain guard 80 protects a chain which transmits motive force from the prime mover 12 and the transmission to the rear wheel 38 from mud splashes and impact from road debris. In another embodiment, a tyre hugger 60 is mounted to the swingarm 100. The tyre hugger 60 covers a front top portion of the rear tyre thereby preventing mud and debris thrown up by the rear tyre from impacting on parts of the vehicle 10 disposed forwardly of the rear wheel 38.
[021] Figure 3 illustrates a top perspective view of an exemplary swingarm 100 of the vehicle 10, in accordance with an embodiment of the present subject matter. The swingarm 100 includes a pair of left and right long members 110L, 110R disposed substantially parallel to each other. The pair of left and right long members 110L, 110R extend in a vehicle front rear direction F-R, extending rearwardly from the pivot point to an axle of the rear wheel 38. Each of the pair of left and right long members 110L, 110R includes a front end 112L, 112R and a rear end 114L, 114R which respectively constitute the front and rear ends of the swingarm 100. The front end 112L, 112R is adapted to be pivotally mounted to a frame structure of the vehicle 10. The front end 112L, 112R of each of the pair of left and right long members 110L, 110R includes receiving members adapted to receive the pivot pin 90, such that the pair of left and right long members 110L, 110R are rotatably coupled with the pivot pin 90. The rear end 114L, 114R is adapted to rotatably mount the rear wheel 38 of the vehicle 10. The rear end 114L, 114R of each of the pair of left and right long members 110L, 110R includes a through hole adapted to receive the axle of the rear wheel 38. The rear wheel axle rotates with respect to the pair of left and right long members 110L, 110R when the vehicle is in motion.
[022] The swingarm 100 further includes a cross member 120 extending between the pair of left and right long members 110L, 110R. The cross member 120 joins the pair of left and right long members 110L, 110R rigidly and strengthens the swingarm 100. In an embodiment, a first bracket 122 is mounted on the cross member 120. The first bracket 122 is adapted to be coupled to the rear suspension 50 of the vehicle 10. In the illustrated embodiment, the rear suspension 50 is attached at its upper end to the frame structure of the vehicle 10 and attached at its lower end to the first bracket 122 to operatively couple the rear suspension 50 to the swingarm 100. In an embodiment, the rear suspension 50 is detachably attached to the frame structure of the vehicle 10 and the first bracket 122 using fasteners. The cross member 120 forms an interface 115L, 115R respectively with each of the pair of left and right long members 110L, 110R at junctions where the cross member 120 joins with the pair of left and right long members 110L, 110R.
[023] Furthermore, the swingarm 100 includes a plurality of gussets 130, 140 disposed at the interface 115L, 115R between each of the pair of left and right long members 110L, 110R and the cross member 120. The plurality of gussets 130, 140 attached to the swingarm 100 at the interface 115L, 115R between each of the pair of left and right long members 110L, 110R and the cross member 120 results in enhanced strength, structural integrity and performance of the swingarm 100. In the illustrated embodiment, the gussets 140 are disposed rearwardly of the cross member 120 and the gussets 130 are disposed forwardly of the cross member 120.
[024] Figure 4 illustrates a top perspective view of another exemplary swingarm 100 of the vehicle 10, in accordance with an embodiment of the present subject matter. Referring to Figures 3 and 4, the pair of left and right long members 110L, 110R includes hollow tubes having one of a rectangular cross section C1 or an oval cross section C2. In an embodiment, the cross member 120 includes hollow tubes having one of a rectangular cross section or an oval cross section. In the illustrated embodiment shown in Figure 3, the pair of left and right long members 110L, 110R includes hollow tubes having a rectangular cross section C1. In the illustrated embodiment shown in Figure 4, the pair of left and right long members 110L, 110R includes hollow tubes having an oval cross section C2 (also shown in Figure 8). In an embodiment of the swingarm 100, the cross member 120 consisting of hollow tubes having a rectangular cross section is used with the pair of left and right long members 110L, 110R consisting of hollow tubes having an oval cross section C2 (shown in Figure 8). In another embodiment of the swingarm 100, the cross member 120 consisting of hollow tubes having an oval cross section is used with the pair of left and right long members 110L, 110R consisting of hollow tubes having a rectangular cross section C1. In yet another embodiment, the pair of left and right long members 110L, 110R and the cross member 120 both consist of hollow tubes of rectangular cross section C1. In a further embodiment, the pair of left and right long members 110L, 110R and the cross member 120 consist of hollow tubes of oval cross section C2. Tubes of oval cross section C2 are preferred over ones having rectangular cross section C1 for the pair of left and right long members 110L, 110R. A tube having oval cross section C2 has a greater height at its centre as compared to a tube of the same weight having rectangular cross section C1. The swingarm 100 constituted by tubes of greater height at the centre deflects less. Consequently, deflection or bending of the swingarm 100 under external loads and road stresses is negligible when it is formed out of tubes having oval cross section C2.
[025] Figure 5 illustrates a top view of the swingarm 100 of the vehicle 10, in accordance with an embodiment of the present subject matter. Figure 6 illustrates a top exploded view of the swingarm 100 of the vehicle 10, in accordance with an embodiment of the present subject matter. Figure 7 illustrates a top perspective view of the swingarm 100 of the vehicle 10, in accordance with an embodiment of the present subject matter. Referring to Figures 5, 6 and 7, each of the plurality of gussets 130, 140 of the swingarm 100 includes at least one through hole 135, 145. In the illustrated embodiment, each of the gussets 140 which are disposed rearwardly of the cross member 120 have two through holes 145. Further, each of the gussets 130 which are disposed forwardly of the cross member 120 have a single through hole 135. However, the number of through holes in each of the plurality of gussets 130, 140 of the swingarm 100 may be greater or lesser as the case may be. In one aspect, the through hole 135, 145 in each of the plurality of gussets 130, 140 is adapted to locate the corresponding gusset 130, 140 for affixing the gusset 130, 140 to each of the pair of left and right long members 110L, 110R and the cross member 120 at the corresponding interface 115L, 115R during assembly of the swingarm 100. In an embodiment, the through hole 135, 145 in each of the plurality of gussets 130, 140 is used to fix the plurality of gussets 130, 140 to an external fixture in order to arrest the movement of the plurality of gussets 130, 140 during assembly of the plurality of gussets 130, 140 to the swingarm 100. Conventionally, the plurality of gussets 130, 140 are affixed to the corresponding pair of left and right long members 110L, 110R and the cross member 120 at the corresponding interfaces 115L, 115R by welding. Thus, the external fixtures employ the through hole 135, 145 in each of the plurality of gussets 130, 140 to keep the plurality of gussets 130, 140 stable and stationary during welding process. This enables in achieving a constant root gap between the plurality of gussets 130, 140 and the corresponding pair of left and right long members 110L, 110R and the cross member 120 during welding, thus resulting in a perfect weld. Even as this provides consistent, strong and well finished perfect welds in the case of tubes of both rectangular and oval cross sections that constitute the pair of left and right long members 110L, 110R and/or the cross member 120, it is particularly effective when the cross section of the tubes is of an oval cross sectional shape.
[026] In an embodiment, each of the plurality of gussets 130, 140 comprises a substantially C shaped cross section, the C being opened towards an outside of the vehicle 10 in the vehicle width direction W. The C shape of the plurality of gussets 130, 140 allows them to properly overlap with the tubes of rectangular or oval cross sections which form the pair of left and right long members 110L, 110R and/or the cross member 120. In another embodiment, each of the C shaped gussets 130, 140 is adapted to clad each of the corresponding pair of left and right long members 110L, 110R. The cladding allows for more contact area between the plurality of gussets 130, 140 and the corresponding pair of left and right long members 110L, 110R and the cross member 120. This allows for greater flexibility in deciding the welding zone and the welding path. In yet another embodiment, each of the C shaped gussets 130, 140 extends substantially parallel to the corresponding pair of left and right long members 110L, 110R in the vehicle front rear direction F-R, and curves inwardly at the corresponding interface 115L, 115R between each of the pair of left and right long members 110L, 110R and the cross member 120 in the vehicle width direction W to clad the cross member 120. By cladding at least partially both the pair of left and right long members 110L, 110R and the cross member 120, better strength of the swingarm 100 is achieved.
[027] Advantageously, the present invention provides a swingarm 100 of a saddle type vehicle 10. The through hole 135, 145 in each of the plurality of gussets 130, 140 is adapted to locate the corresponding gusset 130, 140 for affixing the gusset 130, 140 to each of the pair of left and right long members 110L, 110R and the cross member 120 at the corresponding interface 115L, 115R during assembly of the swingarm 100, thereby arresting any unwanted movement of the plurality of gussets 130, 140 with respect to the pair of left and right long members 110L, 110R and the cross member 120 during assembly. This allows to maintain a precise root gap during welding of the plurality of gussets 130, 140 to the corresponding pair of left and right long members 110L, 110R and the cross member 120 and aids in achieving higher weld quality and stronger welds. Other advantages include greater durability of the swingarm, batter weld aesthetics, ease of manufacturability, and the like.
[028] 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 modifications may be made without departing from the scope of the invention as defined in the following claims. , Claims:WE CLAIM:
1. A swingarm (100) for a saddle type vehicle (10) comprising:
a pair of left and right long members (110L, 110R) substantially parallel to each other and extending in a vehicle front rear direction (F-R);
a cross member (120) extending between the pair of left and right long members (110L, 110R); and
a plurality of gussets (130, 140) disposed at an interface (115L, 115R) between each of the pair of left and right long members (110L, 110R) and the cross member (120), each of the plurality of gussets (130, 140) having at least one through hole (135, 145).

2. The swingarm (100) as claimed in claim 1, wherein each of the pair of left and right long members (110L, 110R) comprises: a front end (112L, 112R) configured to be pivotally mounted to a frame structure of the vehicle (10); and a rear end (114L, 114R) configured to rotatably mount a rear wheel (38) of the vehicle (10).

3. The swingarm (100) as claimed in claim 1 comprising a first bracket (122) mounted on the cross member (120) and configured to be coupled to a rear suspension (50) of the vehicle (10).

4. The swingarm (100) as claimed in claim 1, wherein the pair of left and right long members (110L, 110R) and the cross member (120) comprise hollow tubes of rectangular cross section (C1).

5. The swingarm (100) as claimed in claim 1, wherein the pair of left and right long members (110L, 110R) and the cross member (120) comprise hollow tubes of oval cross section (C2).

6. The swingarm (100) as claimed in claim 1, wherein the through hole (135, 145) in each of the plurality of gussets (130, 140) is configured to locate the corresponding gusset (130, 140) for affixing the gusset (130, 140) to each of the pair of left and right long members (110L, 110R) and the cross member (120) at the corresponding interface (115L, 115R) during assembly of the swingarm (100).

7. The swingarm (100) as claimed in claim 1, wherein each of the plurality of gussets (130, 140) comprises a substantially C shaped cross section, the C being opened towards an outside of the vehicle (10) in a vehicle width direction (W).

8. The swingarm (100) as claimed in claim 7, wherein each of the C shaped gussets (130, 140) is configured to clad each of the corresponding pair of left and right long members (110L, 110R).

9. The swingarm (100) as claimed in claim 8, wherein each of the C shaped gussets (130, 140) extends substantially parallel to the corresponding pair of left and right long members (110L, 110R) in the vehicle front rear direction (F-R), and curves inwardly at the interface (115L, 115R) between each of the pair of left and right long members (110L, 110R) and the cross member (120) in the vehicle width direction (W) to clad the cross member (120).

10. The swingarm (100) as claimed in claim 9, wherein each of the C shaped gussets (130, 140) is affixed to the corresponding pair of left and right long members (110L, 110R) and the cross member (120) by welding.

Dated this 22nd day of June 2022
TVS MOTOR COMPANY LIMITED
By their Agent & Attorney

(Nikhil Ranjan)
of Khaitan & Co
Reg No IN/PA-1471