Claims:
We claim:
1. A two-wheeled or three wheeled vehicle (100) comprising:
a frame assembly (101) comprising a head pipe (102) in a front portion (F);
a steering shaft (201) of a steering assembly (107) being accommodated inside the head pipe (102) to steer the vehicle (100);
one or more top insert assembly (202a) being disposed at a top portion of the head pipe (102), and one or more bottom insert assembly (202b) being disposed at a bottom portion of the head pipe (102); and
one or more locking pin (203a, 203b) being provided to align and couple the head pipe (102) with the one or more inserts (202a, 202b);
wherein the top insert (202a), the bottom insert (202b) and the one or more locking pins (203a, 203b) being configured to adjust the steering shaft (201) at different caster angles with respect to the head pipe (102).
2. The vehicle (100) as claimed in claim 1, wherein one or more top insert assembly (202a) includes an inner steering insert (202ab) and an outer steering insert (202ac).
3. The vehicle (100) as claimed in claim 1, wherein one or more bottom insert assembly (202b) includes an inner steering insert (202ba) and an outer steering insert (202bb).
4. The vehicle (100) as claimed in claim 1, wherein a one or more locking pin (203a, 203b) includes a first locking pin (203a) and a second locking pin (203b), the first locking pin (203a) being configured to align and couple the head pipe (102) with the outer steering insert (202ac) of the one or more top insert assembly (202a), and the second locking pin (203b) being configured to align and couple the outer steering insert (202ac) with the inner steering insert (202ab) of the one or more top insert assembly (202a).

5. The vehicle (100) as claimed in claim 4, wherein the first locking pin (203a) being configured to align and couple the head pipe (102) with the outer steering insert (202bb) of the one or more bottom insert assembly (202b), and the second locking pin (203b) being configured to align and couple the outer steering insert (202bb) with the inner steering insert (202ba) of the one or more bottom insert assembly (202b).
6. The vehicle (100) as claimed in claim 1, wherein one or more locking pin (203a, 203b) being disposed on both the sides of the steering shaft (201) in the top portion and in the bottom portion of the head pipe (102).
7. The vehicle (100) as claimed in claim 1, wherein the head pipe (102), the outer steering insert (202ac, 202bb), and the inner steering insert (202ab, 202ba) being provided with one or more axial groove (209a, 209b,209c,209d) to accommodate the one or more locking pins (203a, 203b).
8. The vehicle (100) as claimed in claim 7, wherein the inner surface of the head pipe (102) and the outer surface of the outer steering insert (202ac,202bb) being configured to be a shape of half cylinder so that, when the half cylinders (209d) in the inner surface of the head pipe (102) aligns with the half cylinder (209c) in the outer surface of the outer steering insert (202ac,202bb), it forms a shape of a hole shaped axial groove to accommodate the locking pin (203a).
9. The vehicle (100) as claimed in claim 7, wherein the inner surface of the outer steering inserts (202ac, 202bb) and the outer surface of the inner steering inserts (202ab,202ba), being configured to be a shape of half cylinder so that, when the half cylinders (209a) in the inner surface of the outer steering inserts (202ac, 202bb) aligns with the half cylinder (209b) in the outer surface of the inner steering insert (202ab,202ba), it forms a shape of a hole shaped axial groove to accommodate the locking pin (203b).
10. The vehicle (100) as claimed in claim 1, wherein the head pipe (102) being configured as a cast structure integrated with the locking pin (203a,203b), and the outer steering insert (202ac, 202bb) being press fitted with the head pipe (102).
11. The vehicle (100) as claimed in claim 1, wherein the top surfaces of the head pipe (102) and the one or more inserts (202a,202b) being marked with a specific caster angle values to align and lock the head pipe (102) and the one or more inserts (202a,202b) with the locking pin (203a,203b) to achieve a desired caster angle.
12. The vehicle (100) as claimed in claim 1, wherein
a first longitudinal axis (201a) of the steering shaft (201) lies inclined with respect to a second longitudinal axis (102a) of the head pipe (102),
wherein the first longitudinal axis (201a) and the second longitudinal axis (102a) being aligned with each other towards the top portion of the head pipe (102) and
the first longitudinal axis (201a) and the second longitudinal axis (102a) lies with an offset (206) towards the bottom portion of the head pipe (102).
, Description:TECHNICAL FIELD
[0001] The present subject matter relates generally to a vehicle. More particularly but not exclusively the present subject matter relates to a caster angle adjustment of the vehicle.

BACKGROUND
[0002] Generally, in a two-wheeled, a steering assembly is supported by a main frame of the vehicle. The steering assembly allows the user to steer the vehicle while riding in different direction. The handling characteristics of the two wheeled vehicle is quite closely related to a caster angle of the vehicle. The caster angle of two wheeled vehicle is generally defined by the angle of a Head Steering Pivot (HSP) tube respect to the main frame. The caster angle is the angular displacement of a steering axis from a vertical axis of a steered wheel in the two-wheeled vehicle. The purpose of caster angle is to provide a degree of self-centering for steering the wheel. This makes the vehicle easier to control and improves its directional stability. Excessive caster angle makes the steering heavier and less responsive. The head steering pivot takes the steering load along with other loads during vehicle braking /rider/ road reactions. Due to these different demanding vehicle loads, the head steering pivot is generally welded with the main frame of the vehicle. To increase the weld area & for better stress distribution, often an additional gusset is added in between the head steering pivot and the main frame. In order to achieve such stringent design requirements, the head steering pivot is mostly welded with the main frame of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The details are described with reference to an embodiment of a two-wheeled vehicle along with the accompanying figures. The same numbers are used throughout the drawings to reference similar features and components.
[0004] Figure 1 exemplarily illustrates a positioning of a head pipe and steering shaft in the known arts.
[0005] Figure 2 (a) exemplarily illustrates a side view of a two wheeled saddle type vehicle with a frame assembly with other parts of the vehicle.
[0006] Figure 2(b) exemplarily illustrates a side view of the two wheeled saddle type vehicle with the frame assembly and other parts being omitted for beverity.
[0007] Figure 3(a) exemplarily illustrates a cross-sectional view of the head pipe along with the steering shaft accommodated in the head pipe.
[0008] Figure 3(b) exemplarily illustrates the exploded cross-sectional view of the head pipe along with the steering shaft accommodated in the head pipe.
[0009] Figure 4(a) exemplarily illustrates a top perspective view of the one or more inserts along with the steering shaft.
[00010] Figure 4(b) exemplarily illustrates a top view of the one or more inserts along with the steering shaft.

DETAILED DESCRIPTION

[0001] Conventionally, the two-wheeled vehicles include a hollow tube HSP (Head Steering Pivot) welded to the main frame. The above-mentioned construction only allows to have a fixed caster angle, and any change in the caster angle can only be achieved by changing the entire frame of the two-wheeled vehicle. One solution to such a problem can be an adjustable joint between the main frame and the HSP. Any adjusting mechanism provided between the main frame and the HSP in this location is complex, has to undergo major structural loads, which in turn increases the weight and cost of the frame assembly. Therefore, there is a need for a caster angle adjustment mechanism which is light weight, simple and cost effective.
[0002] In order to meet the above requirements of keeping weight and cost of a caster adjustment mechanism under control while satisfying the structural load constraints, as a solution multiple concentric taper cylinders can be utilized. To achieve the aforesaid solution, in known arts, a head pipe in the form of a cylinder having an inclined inner surface such that the axis of the outer surface of the head pipe is made offset with the inner surface axis as shown in figure-1. If a steering shaft (201) in the form of a cylinder is made to sit inside the said head pipe (102) having an inclined inner surface, the now seated steering shaft has its axis (201a) at an offset with the axis of the outer surface of the head pipe (102a). Now, if the whole arrangement is rotated about the head pipe outer surface axis, the axis (201a) of the steering shaft (201) traces a circle on an imaginary plane perpendicular to the head pipe (102) outer surface axis (102a). Such a setup could achieve multiple axis offset in different directions along the perimeter of the traced circle. However, only two points of offset (210a, 210b) are along the vehicle centre plane and contains all the axis. The arrangement provides only two variations on the steering axis, i.e. two caster angles is achieved which are feasible along the length direction of the vehicle.
[0003] Further, the assembly of the steering shaft within the head pipe, and with the frame and its arrangement to assemble and maintain the head pipe and the steering shaft in their desired orientation is a very crucial aspect to achieve a desired caster angle. So, it is very difficult and cumbersome to align all the cylindrical axis of the head pipe and the steering shaft to get a caster angle change and which may lead to misalignment during the assembly process. This further impacts the final caster angle and may lead to offset of the steering system in sideways direction, which is highly undesirable. Also, if the offset is not accurate and the desired caster angle is not achieved, it may lead to misalignment of a front wheel and a rear wheel. This leads to other problems like improper steerability, vehicle imbalance, abnormal type wear, inconsistent handling behaviour and the like. Therefore, a simpler, safer, accurate caster angle adjusting mechanism is required which helps in easier alignment of the steering shaft during assembly of the two-wheeled vehicle. The caster angle adjusting mechanism should be such that it caters to the various requirements of platform of product variants while overcoming all above problems as well as other related problems of known art.
[0004] An objective of the present subject matter is to provide an adjustable caster angle mechanism that enables easy assembly of the parts in their desired orientation in order to achieve a caster change and which helps to maintain the caster change. The present subject matter is described using an exemplary two-wheeled vehicle, whereas the claimed subject matter is applicable to any type of two-wheeled or three-wheeled vehicle, with required changes and without deviating from the scope of invention.
[0005] As per an aspect of the present subject matter, a two-wheeled vehicle is disclosed comprising: a frame assembly comprising a head pipe in a front portion; a steering shaft of a steering assembly is accommodated inside the head pipe to steer the two-wheeled vehicle; one or more top insert assembly is disposed at a top portion of the head pipe, and one or more bottom insert assembly is disposed at a bottom portion of the head pipe; and one or more locking pin is provided to align and couple the head pipe with the one or more inserts. The top insert, the bottom insert and the one or more locking pins are configured to adjust the steering shaft at different caster angles with respect to the head pipe.
[0006] As per an aspect of the present subject matter, one or more top insert assembly includes an inner steering insert and an outer steering insert.
[0007] As per an aspect of the present subject matter, one or more bottom insert assembly includes an inner steering insert and an outer steering insert.
[0008] As per an aspect of the present subject matter, a one or more locking pin includes a first locking pin and a second locking pin, the first locking pin is configured to align and couple the head pipe with the outer steering insert of the one or more top insert assembly, and the second locking pin is configured to align and couple the outer steering insert with the inner steering insert of the one or more top insert assembly .
[0009] As per an aspect of the present subject matter, the first locking pin is configured to align and couple the head pipe with the outer steering insert of the one or more bottom insert assembly , and the second locking pin is configured to align and couple the outer steering insert with the inner steering insert of the one or more bottom insert assembly.
[00010] As per an aspect of the present subject matter, the one or more locking pin is disposed on both the sides of the steering shaft in the top portion and in the bottom portion of the head pipe.
[00011] As per an aspect of the present subject matter, the head pipe, the outer steering insert, and the inner steering insert is provided with one or more axial groove to accommodate the one or more locking pins.
[00012] As per an aspect of the present subject matter, the inner surface of the head pipe and the outer surface of the outer steering insert is configured to be a shape of half cylinder so that, when the half cylinders in the inner surface of the head pipe aligns with the half cylinder in the outer surface of the outer steering insert, it forms a shape of a hole shaped axial groove to accommodate the locking pin.
[00013] As per an aspect of the present subject matter, the inner surface of the outer steering inserts and the outer surface of the inner steering inserts are configured to have a shape of half cylinder so that, when the half cylinders in the inner surface of the outer steering inserts aligns with the half cylinder in the outer surface of the inner steering insert, it forms a shape of a hole shaped axial groove to accommodate the locking pin.
[00014] As per an aspect of the present subject matter, the head pipe is configured as a cast structure integrated with the locking pin, and the outer steering insert is press fit with the head pipe.
[00015] As per an aspect of the present subject matter, the top surfaces of the head pipe and the one or more inserts being marked with a specific caster angle values to align and lock the head pipe and the insert with the locking pin to achieve a desired caster angle.
[00016] As per an aspect of the present subject matter, a first longitudinal axis of the steering shaft lies inclined with respect to a second longitudinal axis of the head pipe, wherein the first longitudinal axis and the second longitudinal axis is aligned with each other towards the top portion of the head pipe and the first longitudinal axis and the second longitudinal axis lies with an offset towards the bottom portion of the head pipe. The embodiments of the present invention will now be described in detail with reference to an embodiment in a saddle type two wheeled vehicle along with the accompanying drawings. However, the present invention is not limited to the present embodiments. The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00017] Fig.2(a) exemplarily illustrates a side view of a two wheeled saddle type vehicle 100 with a frame assembly 101 with few other parts of the vehicle 100 for clarity. Fig.2(b) exemplarily illustrates a side view of the two wheeled saddle type vehicle 100 with the frame assembly 101 and other parts being omitted for brevity. Fig 2(a) and Fig 2(b) shall be discussed together. The two-wheeled vehicle 100 includes a frame assembly 101 having a front portion (F) and a rear portion (R). The frame assembly 101 includes a head pipe 102, a down tube 103, a centre frame member 104, and a rear frame member 105. The down tube 103 extends rearwardly in downward direction from the head pipe 102. The centre frame member 104 extends horizontally in rearward direction from an end portion of the down tube 103. The rear frame member 105 extends horizontally upward in rearward from an end portion of the centre frame member 104. The front portion (F) includes a front suspension unit 106, a steering assembly 107, and a front wheel 108. The rear portion (R) of the vehicle 100 includes a rear wheel 109, a rear suspension unit 110, and a swing arm 111. The front portion (F) of the vehicle 100 along with the front suspension unit 106 is connected to the front wheel 108. The rear portion (R) includes the rear suspension unit 110 connected to the rear frame member 105 of the vehicle 100. The swing arm 111 is connected to the frame assembly 101 of the vehicle 100 at one end in longitudinal direction of the vehicle 100 and the other end is connected to an axle of the rear wheel 109. The front portion of the frame assembly 101 supports the steering assembly 107 disposed on the head pipe 102. A steering shaft 201 (shown in fig.2(a)) of the steering assembly 107 is configured to be accommodated in the head pipe 102 to steer the vehicle 100. A gusset 112 is added to increase the weld area & for better stress distribution on the vehicle 100. A caster angle 113 is formed between an axis 114 passing through the steering assembly 107 and an axis 115 passing vertically through an axle of the front wheel 108, when viewed from the side of the vehicle 100. The purpose of caster angle 113 is to provide a degree of self-centering for steering the wheels (108, 109). This makes the vehicle easier to control and improves its directional stability. If the caster angle 113 is smaller, it is easier to change the direction of the steering shaft 201 on the roads as it reduces the steering efforts and is more comfortable for a rider to manoeuvre the vehicle 100 however at a trade-off on the straight-line stability.
[00018] Fig.3(a) exemplarily illustrates a cross-sectional view of the head pipe 102 along with the steering shaft 201 accommodated in the head pipe 102. Fig.3(b) exemplarily illustrates the exploded cross-sectional partial view of the head pipe 102 along with the steering shaft 201 accommodated in the head pipe 102. Fig.4(a) exemplarily illustrates a top perspective view of the one or more inserts (202a, 202b) (shown in fig. 3(a)) along with the steering shaft 201. Fig.4(b) exemplarily illustrates a top view of the one or more inserts (202a, 202b) (shown in fig. 3(a)) along with the steering shaft 201. Fig 3(a), Fig 3(b), Fig 4(a) and Fig 4(b) shall be discussed together. The head pipe 102 has a flaring 204 at its top and bottom which holds one or more metal inserts (202a, 202b). The one or more metal inserts (202a, 202b) holds a steering bearing 205 which helps to keep the one or more metal inserts (202a, 202b) at a desired position to attain a desired caster angle suited for proper steering of the vehicle 100. In a best embodiment, head pipe 102 is configured to have a plurality of inserts for maintaining the required caster angle. In the present embodiment, the head pipe 102 is fitted with 4 inserts (202a, 202b), 2 at each top (202ab, 202ac) and bottom (202ba, 202bb) end of the head pipe 102. There are 2 inner steering inserts (202ab, 202ba), one at the top and one at the bottom of the head pipe 102. Similarly, there are 2 outer steering inserts (202ac, 202bb) each at the top and at the bottom of the head pipe 102. The 2 inner steering inserts (202ab, 202ba) at the top and bottom have to be aligned along a single axis to maintain the caster angel axis.
[00019] The head pipe 102 and the one or more steering inserts (202a, 202b) are fitted with one or more locking pins (203a, 203b) along one or more mating surfaces of the head pipe 102, and the one or more inserts (202a, 202b) to retain the inserts in the desired orientation for maintaining the required caster angle. In a best embodiment, the head pipe 102 and the one or more steering inserts (202a, 202b) are fitted with a plurality of locking pins (203a, 203b) along one or more mating surfaces of the head pipe 102 to retain the plurality of inserts in the desired orientation for maintaining the required caster angle. In another embodiment, the one or more locking pins (203a, 203b) are placed on both the sides of the steering shaft 201 on the top portion and the bottom portion of the head pipe 102. In conventional two-wheeled vehicle, the head pipe 102 is a hollow tube, welded to the main-frame. In above-mentioned known art, the head pipe 102 has the flaring 204 at its top and bottom which holds the metal insert, wherein the metal steering inserts and the head pipe are configured with inclined mating surface to attain a fixed desired caster adjustment. So, if there is a requirement of change of caster angle from the customer side or due to the layout design requirements, then the entire frame assembly 101 has to be changed to achieve the particular desired angle. This takes a lot of time for the changes to be made and also adds up to the cost. So, in the present embodiment, a design of having one or more inserts (202a, 202b) with a locking mechanism which gives multiple axis, so that the inserts (202a, 202b) can be adjusted at multiple points to achieve different caster angle without changing the frame structure. This ensures the orientation of the inserts (202a, 202b) in the caster adjustment, enabling easy assembly of the parts in their desired orientation in order to achieve caster change, without modifying the layout of the vehicle 100. The steering shaft 201 having an axis 201a is placed inside the head pipe 102 with an inclination with the respect to the axis 102a of the head pipe 102 forming an offset 206. The first longitudinal axis (201a) of the steering shaft 201 lies inclined with respect to the second longitudinal axis (102a) of the head pipe 102. The first longitudinal axis (201a) and the second longitudinal axis (102a) are aligned with each other towards the top portion of the head pipe 102 and the first longitudinal axis (201a) and the second longitudinal axis (102a) lie with an offset 206 towards the bottom portion of the head pipe 102. This offset 206 aids in achieving a caster angle while maintaining an alignment between the front wheel 108 and the rear wheel 109 of the vehicle 100. Due to this inclination, a smaller arc area 207 is formed at the right top side of the head pipe 102 and a larger arc area 208 is formed at the left top side of the head pipe 102, as shown in fig.3(a). Similarly, this inclination results in formation of an equivalent larger arc area 208 at the right bottom side of the head pipe 102 and an equivalent smaller arc area 207 at the left bottom side of the head pipe 102.
[00020] The adjustable caster mechanism is fitted with the 2 steering insert assemblies (202a, 202b) at the top portion and the bottom portion of the head pipe 102. The one or more locking pins (203a, 203b) include a first locking pin (203a) and a second locking pin (203b). The first locking pin (203a) is disposed between the mating surface of the head pipe 102 and an outer steering insert (202ac, 202bb). Similarly, the second locking pin (203b) is assembled between the inner surface of the outer steering inserts (202ac, 202bb) and the outer surface of inner steering inserts (202ab, 202ba). The locking pins (203a, 203b) are inserted in the mating surfaces of the head pipe 102, the outer steering inserts (202ac, 202bb), and the inner steering inserts (202ab, 202ba) are machined to have one or more half cylinders. The head pipe 102 having a half cylinder (209d) in the inner surface of the head pipe 102 aligns with the half cylinder (209c) in the outer surface of the outer steering inserts (202ac, 202bb) to form a hole shaped axial groove (209) to accommodate the first locking pin (203a) Similarly, the outer steering inserts (202ac, 202bb) having the half cylinder (209a) in the inner surface of the outer steering inserts (202ac, 202bb) aligns with the half cylinder (209b) in the outer surface of the inner steering inserts (202ab, 202ba) to form a hole shaped axial groove (209) to accommodate the second locking pin (203b). The hole shaped axial groove (209a, 209b, 209c, 209d) is provided at a portion of the head pipe (102), the inner and the outer circumferential surfaces of the inserts (202a, 202b) on both the sides of the steering shaft (201). Now, by inserting the first locking pin (203a) and second locking pin (203b) into the axial groove (209), the mating components orientations is locked to each other to provide the desired caster angle. Further, the caster angle can be changed by changing the shape or depth of the steering inserts (202a, 202b), without changing the layout. By tilting the steering shaft (201) inside the head pipe (102), two caster angle is achieved but for achieving multiple cater angle points, one or more top inserts (202a) and bottom inserts (202b) are used and to align these one or more inserts (202a, 202b) with the head pipe (102), one or more locking pins (203a, 203b) are used. This provides multiple caster angle adjustment without changing the frame layout of the vehicle (100).
[00021] In an embodiment, the head pipe 102 can be made as a cast structure and the first locking pin 203a between the head pipe 102 and the outer steering insert (202ac, 202bb) could be integrated along with the head pipe 102 casting itself. Similarly, the outer steering insert (202ac, 202bb) can be made as a cast structure and the second locking pin 203b between outer steering insert (202ac, 202bb) and the inner steering insert (202ab, 202ba) could be integrated along with casting itself. In the above-mentioned embodiment, the outer steering inserts (202ac, 202bb) can be directly press fitted with the head pipe 102, eliminating the requirement of aligning opposite axial grooves 209 in the head pipe 102 and the outer steering insert (202ac, 202bb). This improves the packaging space and achieves a compact system size. In another embodiment, the bottom side orientation can be placed at the top side and vice-versa to achieve different caster angle. In another embodiment, the top surfaces of the head pipe 102 and the one or more inserts (202a, 202b) are marked with the specific caster angle values in order to simplify the alignment of the one or more inserts (202a, 202b) and the head pipe 102. Once the one or more inserts (202a, 202b) are aligned with the respective similar markings in the head pipe 102 and locked with the one or more locking pins (203a, 203b), desired caster angel could be achieved. Many other improvements and modifications may be incorporated herein without deviating from the scope of the invention.

List of Reference numerals
100: Two-wheeled saddle-type vehicle
F: Front portion of 100
R: Rear portion of 100
101: Frame assembly of 100
102: Head pipe of 101
102(a): Longitudinal axis of 102
103: Down tube of 101
104: Centre frame member of 101
105: Rear frame member of 101
106: Front suspension unit of 100
107: Steering assembly of 100
108: Front wheel of 100
109: Rear wheel of 100
110: Rear suspension unit 100
111: Swing arm of 100
112: Gusset of 101
113: Caster angle between the 114 and 115
114: Axis passing through the 107
115: Axis passing vertically through the 108
201: Steering shaft of 107
201(a): Steering shaft axis of 201
202(a): One or more top insert assembly of 201
202(ab): One or more top inner steering inserts of 202(a)
202(ac): One or more top outer steering inserts of 202(a)
202(b): One or more bottom insert assembly of 201
202(ba): One or more bottom inner steering inserts of 202(b)
202(bb): One or more bottom outer steering inserts of 202(b)
203(a): First locking pin of 201
203(b): Second locking pin of 201
204: Flaring of 102
205: Steering bearing of 201
206: offset between 102(a) and 201(a)
207: Smaller area of 102
208: Larger area of 102
209: One or more axial grooves in 102, 202a, 202b
209(a): Half cylinder to form a groove in 202(ac), 202(bb)
209(b): Half cylinder to form a groove in 202(ab), 202(ba)
209(c): Half cylinder to form a groove in 202(ac), 202(bb)
209(d): Half cylinder to form a groove in 102
210a: First offset point
210b: Second offset point
T: Top
B: Bottom
L: Left
R: Right