Claims:WE CLAIM:
1. A saddle type vehicle (10), comprising:
a head pipe (22);
a main frame (24) extending rearwardly and downwardly from the head pipe (22), the main frame having a first end (24A) connected to the head pipe (22) and a second end (24B);
a left cross tube (110) extending in a vehicle width direction, the left cross tube (110) having a first toroidal section (112) configured to receive a left side frame (58A), and a second toroidal section (114);
a right cross tube (120) extending in the vehicle width direction, the right cross tube (120) having a first toroidal section (122) configured to receive a right side frame (58B), and a second toroidal section (124),
wherein a recess is formed between the second toroidal section (114) of the left cross tube (110) and the second toroidal section (124) of the right cross tube (120); and
the recess is configured to receive the second end (24B) of the main frame (24).

2. The saddle type vehicle (10) as claimed in claim 1, wherein the first toroidal section (112) of the left cross tube (110) and the first toroidal section (122) of the right cross tube (120) have a circular cross section.

3. The saddle type vehicle (10) as claimed in claim 1, wherein the second toroidal section (114) of the left cross tube (110) and the second toroidal section (124) of the right cross tube (120) have rounded rectangular cross section, such that length (L) of the rounded rectangular cross section extending in a vehicle up-down direction is more than the breadth (B) of the rounded rectangular cross section extending in a vehicle front-rear direction.

4. The saddle type vehicle (10) as claimed in claims 2 and 3, wherein the length (L) of the rounded rectangular cross section is greater than diameter (D) of the circular cross section, and breadth (B) of the rounded rectangular cross section is lower than diameter (D) of the circular cross section, thereby allowing a large contact area of the left cross tube (110) and the right cross tube (120) with the main frame (24).

5. The saddle type vehicle (10) as claimed in claim 1, wherein the left cross tube (110) has a tapered profile between the first toroidal section (112) and the second toroidal section (114), and the right cross tube (120) has a tapered profiled between the first toroidal section (122) and the second toroidal section (124), thereby allowing gradual transfer of load from the main frame (24) along the left cross tube (110) and the right cross tube (120).

6. The saddle type vehicle (10) as claimed in claim 1, comprising a top gusset (130) and a bottom gusset (140) for receiving the second end (24B) of the main frame (24) in the recess formed between the second toroidal section (114) of the left cross tube (110) and the second toroidal section (124) of the right cross tube (120).

7. The saddle type vehicle (10) as claimed in claim 6, wherein the bottom gusset (140) has a larger contact area with the main frame (24), the left cross tube (110) and the right cross tube (120), than contact area of the top gusset (130) with the main frame (24), the left cross tube (110) and the right cross tube (120).

8. The saddle type vehicle (10) as claimed in claim 1, wherein the cross sectional area of the left cross tube (110) is larger than the cross sectional area of the right cross tube (120).

9. The saddle type vehicle (10) as claimed in claim 1, wherein the cross sectional area of the left cross tube (110) is smaller than the cross sectional area of the right cross tube (120).

10. The saddle type vehicle (10) as claimed in claim 1, comprising an engine suspension link rubber (160) housed in the main frame (24) for supporting an engine (12), such that the engine suspension link rubber (160) partly overlaps with the left cross tube (110) or right cross tube (120) in a vehicle side view.

11. The saddle type vehicle (10) as claimed in claim 1, wherein a top portion of the second toroidal section (114) of the left cross tube (110), and a bottom portion of the second toroidal section (124) of the right cross tube (120), overlap with a central axis (A-A’) of the main frame (24) by a predetermined length in a vehicle front view.

12. The saddle type vehicle (10) as claimed in claim 1, wherein a top portion of the second toroidal section (124) of the right cross tube (120), and a bottom portion of the second toroidal section (114) of the left cross tube (110), intersect with a central axis (A-A’) of the main frame (24) a predetermined length in a vehicle front view.
, Description:FIELD OF THE INVENTION
[001] The present invention relates to a saddle type vehicle.

BACKGROUND OF THE INVENTION
[002] In conventional saddle type vehicles, manufacturers constantly attempt to reduce the vehicle weight in order to reduce vehicle emissions, improve vehicle range, increase vehicle performance, reduce rotational mass inertia of the vehicle, reduce fuel consumption of the vehicle and the like. Frame structure of a vehicle is one of the major contributors of total vehicle weight.
[003] Generally, for two-wheelers the frame structure comprises a front head pipe, a main pipe, a middle cross pipe and rear side frame assemblies. The middle cross pipe is a structure that extends in a lateral direction, which connects the rear portion of front frame region and the front portion of rear frame region. The middle cross pipe also connects the frame components on the left hand side of the two wheeler vehicle to the frame components on the right hand side of the two wheeler vehicle.
[004] Conventionally, decreasing the thickness of the frame members is most prominently used to reduce vehicle weight. However, mere reduction of the thickness of frame members leads to a reduction in strength and rigidity of the vehicle frame. The frame being the structural part of the vehicle, it bears substantial load when the vehicle is loaded. Furthermore, the frame being a simply supported structure, the parts of the frame in the middle region of the vehicle will experience more load concentration. Hence, achieving the desired weight reduction in the vehicle by reducing the thickness of the middle cross pipe is of limited scope.
[005] Further, the frame structure comprises of tubular parts and sheet metal parts. These parts, if complex, leads to increase in manufacturing costs, and has a detrimental effect on the ease of serviceability and frame durability. Conventional weight reduction methods for the vehicle frame are insufficient in decreasing the weight of the middle cross pipe, while simultaneously maintaining the required strength and design simplicity of the vehicle frame member.
[006] Thus, there is a need in the art for a saddle type vehicle which addresses the aforementioned problems.

SUMMARY OF THE INVENTION
[007] In an aspect, the present invention is directed towards a saddle type vehicle having a head pipe, and a main frame extending rearwardly and downwardly from the head pipe and having a first end connected to the head pipe and a second end. Further, a left cross tube extends in a vehicle width direction and has a first toroidal section configured to receive a left side frame, and a second toroidal section. A right cross tube extends in the vehicle width direction and has a first toroidal section configured to receive a right side frame, and a second toroidal section. Herein, a recess is formed between the second toroidal section of the left cross tube and the second toroidal section of the right cross tube, and the recess is configured to receive the second end of the main frame.
[008] In an embodiment of the invention, the first toroidal section of the left cross tube and the first toroidal section of the right cross tube have a circular cross section.
[009] In another embodiment of the invention, the second toroidal section of the left cross tube and the second toroidal section of the right cross tube have rounded rectangular cross section, such that length of the rounded rectangular cross section extending in a vehicle up-down direction is more than the breadth of the rounded rectangular cross section extending in a vehicle front-rear direction.
[010] In another embodiment of the invention, the length of the rounded rectangular cross section is greater than diameter of the circular cross section, and breadth of the rounded rectangular cross section is lower than diameter of the circular cross section, thereby allowing a large contact area of the left cross tube and the right cross tube with the main frame.
[011] In another embodiment of the invention, the left cross tube has a tapered profile between the first toroidal section and the second toroidal section, and the right cross tube has a tapered profiled between the first toroidal section and the second toroidal section, thereby allowing gradual transfer of load from the main frame along the left cross tube and the right cross tube.
[012] In a further embodiment of the invention, the saddle type vehicle has a top gusset and a bottom gusset for receiving the second end of the main frame in the recess formed between the second toroidal section of the left cross tube and the second toroidal section of the right cross tube. In an embodiment, the bottom gusset has a larger contact area with the main frame, the left cross tube and the right cross tube, than contact area of the top gusset with the main frame, the left cross tube and the right cross tube.
[013] In a further embodiment of the invention, the cross sectional area of the left cross tube is larger than the cross sectional area of the right cross tube.
[014] In a further embodiment of the invention, the cross sectional area of the left cross tube is smaller than the cross sectional area of the right cross tube.
[015] In a further embodiment of the invention, the saddle type vehicle has an engine suspension link rubber housed in the main frame for supporting an engine, such that the engine suspension link rubber partly overlaps with the left cross tube or right cross tube in a vehicle side view.
[016] In a further embodiment of the invention, a top portion of the second toroidal section of the left cross tube, and a bottom portion of the second toroidal section of the right cross tube, overlap with a central axis of the main frame by a predetermined length in a vehicle front view. In an alternative embodiment, a top portion of the second toroidal section of the right cross tube, and a bottom portion of the second toroidal section of the left cross tube, intersect with a central axis of the main frame a predetermined length in a vehicle front view.

BRIEF DESCRIPTION OF THE DRAWINGS
[017] 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 left side view of an exemplary saddle type vehicle, in accordance with an embodiment of the invention.
Figure 2 illustrates a left side view of frame of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 3 illustrates a perspective view of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 4 illustrates a perspective view of a left cross tube and a right cross tube with a main frame of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 5 illustrates a rear view of the left cross tube and the right cross tube with the main frame of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 6 illustrates a rear view of the left cross tube, in accordance with an embodiment of the invention.
Figure 7 illustrates a top view of the left cross tube, in accordance with an embodiment of the invention.
Figure 8 illustrates a left side view of the left cross tube with the main frame of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 9 illustrates a rear view of the left cross tube and the right cross tube with the main frame of the saddle type vehicle, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[018] The present invention relates to a saddle type vehicle. More particularly, the present invention relates to frame of a saddle type vehicle.
[019] Figure 1 illustrates a left-side view of an exemplary motor vehicle 10, in accordance with an embodiment of the present subject matter. The vehicle 10 comprises a frame. The frame comprises a head pipe 22 (shown in Figure 2), and a main frame 24 (shown in Figure 2), which extends rearwardly and downwardly from the head pipe 22 to a floorboard 18. One or more front suspensions 44 connect a front wheel 14 to a handlebar 20, which forms a steering assembly of the vehicle 10. The steering assembly is rotatably disposed about the head pipe 22. The main frame 24 further includes a portion extending horizontally and rearwardly in a vehicle front rear direction. Further, the frame includes a left side frame 58A (shown in Figure 2) and a right side frame 58B (shown in Figure 3) extending inclinedly rearward towards a rear portion of the vehicle 10.
[020] The vehicle 10 includes a power unit 12 that comprises at least an internal combustion (IC) engine or an electric drive source. The power unit 12 is coupled to a rear wheel 16. In one embodiment, the engine or the electric drive source is swingably connected to the frame. In one embodiment, the engine or the electric drive source is mounted to a swing arm (not shown) and the swing arm is swingably connected to the frame. Further, the vehicle 10 includes a transmission means (not shown) coupling the rear wheel 16 to the power unit 12. The transmission means includes a continuously variable transmission, an automatic transmission, or a fixed ratio transmission. A seat assembly 22 is disposed above the power unit 12 and is supported by the left side frame 58A and the right side frame 58B. The seat assembly 22 is hingedly openable. The frame defines a step-through portion ahead of the seat assembly 22. The floorboard 18 is disposed at the step-through portion, wherein a rider can operate the vehicle 10 in a seated position by resting feet on the floorboard 18. Further, the floorboard 18 is capable of carrying loads.
[021] Further, the frame is covered by plurality of body panels including a front panel 30 having a front face 30A and a rear face 30B, an under-seat cover 32, and a left and a right-side panel 33 disposed on the frame and covering the frame and parts mounted thereof.
[022] In addition, a front fender 28 is covering at least a portion of the front wheel 14. A utility box (not shown) is disposed below the seat assembly 22 and is supported by the frame. A rear fender 26 is covering at least a portion of the rear wheel 16 and is positioned upwardly of the rear wheel 16. One or more suspension(s) 46 are provided in the rear portion of the vehicle 10 for connecting the swing arm and the rear wheel 16 to the frame for damping the forces from the rear wheel 16 and the engine (not shown) from reaching the frame.
[023] Furthermore, the vehicle 10 comprises of plurality of electrical and electronic components including a headlight 36, a taillight 38, an alternator (not shown), and a starter motor (not shown).
[024] Figure 3 illustrates a perspective view of the frame of the vehicle 10. As illustrated, the saddle type vehicle 10 comprises the head pipe 22 and the main frame 24 which extends rearwardly and downwardly from the head pipe 22. The main frame has a first end 24A that connected to the head pipe 22 and a second end 24B. The saddle type vehicle 10 further comprises a left cross tube 110 that extends in a vehicle width direction. The left cross tube 110 has a first toroidal section 112 (shown in Figure 5) which is configured to receive the left side frame 58A, and a second toroidal section 114 (shown in Figure 5).
[025] The saddle type vehicle 10 further comprises a right cross tube 120 which extends in the vehicle width direction. The right cross tube 120 has a first toroidal section 122 (shown in Figure 5) which is configured to receive the right side frame 58B, and a second toroidal section 124 (shown in Figure 5). Herein, as illustrated in Figure 3 and Figure 4, a recess is formed between the second toroidal section 114 of the left cross tube 110 and the second toroidal section 124 of the right cross tube 120 and the recess is configured to receive the second end 24B of the main frame 24.
[026] As further depicted in the embodiments illustrated in Figure 3 and Figure 4, the first toroidal section 112 of the left cross tube 110 and the first toroidal section 122 of the right cross tube 120 have a circular cross section having a diameter D (shown in Figures 6 and 7). Further, the second toroidal section 114 of the left cross tube 110 and the second toroidal section 124 of the right cross tube 120 have rounded rectangular cross section, such that length L (shown in Figure 6) of the rounded rectangular cross section extending in a vehicle up-down direction is more than the breadth B (shown in Figure 7) of the rounded rectangular cross section extending in a vehicle front-rear direction.
[027] Reference is made to Figure 6 and Figure 7, which illustrate a rear view and a top view of the left cross tube 110. It is understood that the right cross tube 120 has similar characteristics, profile and dimensions as the left cross tube 110. As illustrated in Figure 6 and Figure 7, the length L of the rounded rectangular cross section of the second toroidal section 114 of the left cross tube 110 and the second toroidal section 124 of the right cross tube 120, is greater than diameter D of the circular cross section Further, the breadth B of the rounded rectangular cross section of the second toroidal section 114 of the left cross tube 110 and the second toroidal section 124 of the right cross tube 120 of the rounded rectangular cross section, is lower than diameter D of the circular cross section. Such a configuration facilitates and allows a large contact area of the left cross tube 110 and the right cross tube 120 with the main frame 24. A large contact area is not only fundamental to the structural integrity of the frame but is also vital for effective transfer of load from the main frame 24 to the left cross tube 110 and the right cross tube 120.
[028] As further illustrated in Figure 3 and Figure 4, and referenced in Figure 6 and Figure 7, the left cross tube 110 has a tapered profile between the first toroidal section 112 and the second toroidal section 114. Similarly, and the right cross tube 120 has a tapered profiled between the first toroidal section 122 and the second toroidal section 124. Such a configuration thereby allows gradual transfer of load from the main frame 24 along the left cross tube 110 and the right cross tube 120, and then on to the left side frame 58A and the right side frame 58B, thus effectively distributing the load across the entire frame.
[029] As illustrated in Figure 4, and referenced in Figure 5, the vehicle 10 comprises a top gusset 130 and a bottom gusset 140 for receiving and holding the second end 24B of the main frame 24 in the recess formed between the second toroidal section 114 of the left cross tube 110 and the second toroidal section 124 of the right cross tube 120. In an embodiment, the bottom gusset 140 has a larger contact area with the main frame 24, the left cross tube 110 and the right cross tube 120, than contact area of the top gusset 130 with the main frame 24, the left cross tube 110 and the right cross tube 120. This is because the bottom gusset 140 must be capable of bearing higher loads than the top gusset 130.
[030] In an alternative embodiment of the invention, the cross sectional area of the left cross tube 110 is larger than the cross sectional area of the right cross tube 120. In this embodiment, the rear suspension 46 is mounted on the left hand side of the vehicle, the larger cross section area of the left cross tube 110 allows for the left cross tube 110 to effectively bear loads from the rear suspension 46, thereby increasing overall structural integrity of the vehicle 10, while ensuring lower weight of the right cross tube 120.
[031] Similarly, in a further alternative embodiment, when the rear suspension 46 is mounted on the right side of the vehicle, the cross sectional area of the left cross tube 110 is smaller than the cross sectional area of the right cross tube 120. This allows for the right cross tube 120 to effectively bear loads from the rear suspension 46, thereby increasing overall structural integrity of the vehicle 10, while ensuring lower weight of the left cross tube 120.
[032] As illustrated in Figure 8, the vehicle 10 comprises an engine suspension link rubber 160 housed in the main frame 24. The engine suspension link rubber 160 is housed in the main frame 24 near the second end 24B of the main frame 24 and supports a front end of the engine 12. Further the engine suspension link rubber 160 also acts as a shock absorber between the engine 12 and the main frame 24. Since, the engine suspension link rubber 160 is a high load point, the engine suspension link rubber 160 is disposed such that the engine suspension link rubber 160 partly overlaps with the left cross tube 110 or right cross tube 120 in a vehicle side view. This allows load from the front end of the engine 12 to be directly transferred to the left cross tube 110 and the right cross tube 120.
[033] In another embodiment of the invention, as illustrated in Figure 9, a top portion of the second toroidal section 114 of the left cross tube 110, and a bottom portion of the second toroidal section 124 of the right cross tube 120, overlap with a central axis (A-A’) of the main frame 24 by a predetermined length in a vehicle front view. Correspondingly, a top portion of the second toroidal section 124 of the right cross tube 120, and a bottom portion of the second toroidal section 114 of the left cross tube 110 are adapted to be at the predetermined length from the central axis (A-A’) from the main frame 24. In that, the top portion of the second toroidal section 114 of the left cross tube 110, and the bottom portion of the second toroidal section 124 of the right cross tube 120 are welded on to the main frame 24 to create a welded joint. This configuration provides additional structural strength to the vehicle 10, especially during vehicle 10 cornering, as the offset as explained as above allows the frame to counter the lateral forces experienced by it during cornering.
[034] In an alternative embodiment, the top portion of the second toroidal section 124 of the right cross tube 120, and the bottom portion of the second toroidal section 114 of the left cross tube 110, intersect with the central axis (A-A’) of the main frame 24 a predetermined length in a vehicle front view. Correspondingly, the top portion of the second toroidal section 114 of the left cross tube 110, and the bottom portion of the second toroidal section 124 of the right cross tube 120 are adapted to be at the predetermined length from the central axis (A-A’) from the main frame 24.
[035] Advantageously, the present invention provides a saddle type vehicle which achieves a lighter frame, hence achieving vehicle weight reduction while maintaining the structural strength and integrity of the vehicle, thereby increasing vehicle durability. The reduced vehicle weight results in increase in performance of the vehicle, and makes the vehicle more fuel efficient. Further, the greater structural strength and integrity provided to the frame of the vehicle in the present invention, especially during cornering,
[036] Further, manufacturing of the left cross tube and the right cross tube as separate elements, which are smaller as opposed to a single cross tube extending on both sides of the main frame, makes it easier and more cost effective to manufacture.
[037] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.