Claims:WE CLAIM:
1. A gearshift mechanism (100) for a saddle-type vehicle (10), comprising:
a gearshift shaft protruding outwardly in a vehicle-width direction from a crankcase (102);
a lever arm (110) fixedly connected to the gearshift shaft;
a gearshift lever (120) mounted pivotally on the crankcase (102) rearwardly from the lever arm (110) in a vehicle side view;
a first linkage member (130) connected to the lever arm (110);
a second linkage member (140) connected to the gearshift lever (120); and
an adjustable stud linkage member (150), the stud linkage member (150) having a first end (150A) threadedly connected to the first linkage member (130), and a second end (150B) threadedly connected to the second linkage member (140), such that rotation of the stud linkage member (150) causes the first linkage member (130) and the second linkage member (140) to move in and out of the stud linkage member (150), thereby adjusting the gearshift lever (120).

2. The gearshift mechanism (100) as claimed in claim 1, wherein the first linkage member (130) has a head end (130A) configured to be pivotally connected to the lever arm (110), and a tail end (130B) provided with outer threads configured to be threadedly connected to the stud linkage member (150).

3. The gearshift mechanism (100) as claimed in claim 1, wherein the second linkage member (140) has a head end (140A) configured to be pivotally connected to the gearshift lever (120), and a tail end (140B) provided with outer threads configured to be threadedly connected to the stud linkage member (150).

4. The gearshift mechanism (100) as claimed in claim 2, wherein the first end (150A) of the stud linkage member (150) is provided with inner threads that are configured to engage with outer threads provided on the tail end (130B) of first linkage member (130).

5. The gearshift mechanism (100) as claimed in claim 3, wherein the second end (150B) of the stud linkage member (150) is provided with inner threads that are configured to engage with outer threads provided on the tail end (140B) of second linkage member (140).

6. The gearshift mechanism (100) as claimed in claim 1, wherein the stud linkage member (150) has a substantially hollow cylindrical cross section.

7. The gearshift mechanism (100) as claimed in claim 6, wherein the stud linkage member (150) comprises a cut out portion (152) between the first end (150A) and the second end (150B), for rotating the stud linkage member (150).

8. The gearshift mechanism (100) as claimed in claim 1, wherein when the stud linkage member (150) is rotated in the clockwise direction, the first linkage member (130) and the second linkage member (140) move out of the stud linkage member (150), thereby increasing the inclination of the gearshift lever (120) from a rider footrest (160).

9. The gearshift mechanism (100) as claimed in claim 1, wherein when the stud linkage member (150) is rotated in the anti-clockwise direction, the first linkage member (130) and the second linkage member (140) move into the stud linkage member (150), thereby decreasing the inclination of the gearshift lever (120) from a rider footrest (160).

10. The gearshift mechanism (100) as claimed in claim 1, wherein the gearshift shaft is connected to a plurality of pins (172) provided on a star index (174), the star index (174) being mounted on a camshaft of an engine (12) to facilitate operation of the gearshift mechanism (100).

Dated this 24th day of March 2022
TVS MOTOR COMPANY LIMITED
By their Agent & Attorney

(Nikhil Ranjan)
of Khaitan & Co
Reg No IN/PA-1471 , Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

TITLE OF INVENTION
A Gearshift Mechanism for a Saddle-type Vehicle

APPLICANT
TVS MOTOR COMPANY LIMITED, an Indian company, having its address at “Chaitanya”, No.12 Khader Nawaz Khan Road, Nungambakkam, Chennai 600 006, Tamil Nadu, India.

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
[001] The present invention relates to a gearshift mechanism for a saddle-type motor vehicle.

BACKGROUND OF THE INVENTION
[002] In conventional saddle-type vehicles, gear shifting is performed by means of a gear shifting lever operated by one foot of a rider with toe of the rider resting on one end of the gear shifting lever and heel of the rider resting on other end of the gear shifting lever. Generally, for an upshift operation, the rider pushes the heel down and for a downshift operation, the rider pushes the toe down.
[003] However, such gear shifting assemblies are non-adjustable and hold goods if used only for a single type of gear shift pedal position or vehicle platform. Different types of vehicles have a variety of ergonomics and vehicle requirements, depending upon the style and the technical requirement of the vehicle itself. Also, the ergonomics varies from region to region based on geographical region, vehicle riding practices, road conditions, and the like. In such scenarios, a regular fixed type of gear shift mechanism will not be suited for each type of geographical location as well as the different types of vehicles itself.
[004] Even though conventional vehicles are designed to fit an average ergonomics, as determined by the manufacturer, still there persists an issue as a large number of vehicle riders are comfortable with a defined pedal position for the gear shift mechanism. The reasons can be the height of the rider, or the uncomfortable position of the legs, and the like, which is ergonomically not comfortable to the rider.
[005] Attempts have been made to address this problem by providing a design in which the pedal position can be adjusted by rotating the whole lever system in clockwise or anti clockwise direction with respect to a gearshift shaft axis, since both the components are connected through splines. Disadvantage of this adjustment is that the position cannot be customized as per the rider’s comfort and the adjustment only provides a fixed degree of lever range.
[006] Further, in existing designs for ergonomic adjustments, all the parts have to be kept in control within a very strict range of manufacturing tolerance, leading to higher manufacturing cost.
[007] Thus, there is a need in the art for a gearshift mechanism which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[008] In one aspect, the present invention is directed towards a gearshift mechanism for a saddle-type vehicle having a gearshift shaft protruding outwardly in a vehicle-width direction from a crankcase, a lever arm fixedly connected to the gearshift shaft, a gearshift lever mounted pivotally on the crankcase rearwardly from the lever arm in a vehicle side view, a first linkage member connected to the lever arm, a second linkage member connected to the gearshift lever and an adjustable stud linkage member. The stud linkage member has a first end threadedly connected to the first linkage member, and a second end threadedly connected to the second linkage member, such that rotation of the stud linkage member causes the first linkage member and the second linkage member to move in and out of the stud linkage member, thereby adjusting the gearshift lever.
[009] In an embodiment of the invention, the first linkage member has a head end configured to be pivotally connected to the lever arm, and a tail end provided with outer threads configured to be threadedly connected to the stud linkage member.
[010] In another embodiment of the invention, the second linkage member has a head end configured to be pivotally connected to the gearshift lever, and a tail end provided with outer threads configured to be threadedly connected to the stud linkage member.
[011] In a further embodiment of the invention, the first end of the stud linkage member is provided with inner threads that are configured to engage with outer threads provided on the tail end of first linkage member.
[012] In a further embodiment of the invention, the second end of the stud linkage member is provided with inner threads that are configured to engage with outer threads provided on the tail end of second linkage member.
[013] In a further embodiment of the invention, the stud linkage member has a substantially hollow cylindrical cross section.
[014] In another embodiment of the invention, the stud linkage member has a cut out portion between the first end and the second end, for rotating the stud linkage member.
[015] In a further embodiment of the invention, when the stud linkage member is rotated in the clockwise direction, the first linkage member and the second linkage member move out of the stud linkage member, thereby increasing the inclination of the gearshift lever from a rider foot rest.
[016] In a further embodiment of the invention, when the stud linkage member is rotated in the anti-clockwise direction, the first linkage member and the second linkage member moves in to the stud linkage member, thereby decreasing the inclination of the gearshift lever from a rider foot rest.

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 shows an exemplary saddle type motor vehicle in accordance with an embodiment of the invention.
Figure 2 shows a gearshift mechanism for the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 3 shows a side view of the gearshift mechanism, in accordance with an embodiment of the invention.
Figure 4 shows a side view of the saddle type vehicle, in accordance with an embodiment of the invention.
Figure 5 shows an exploded view of the gearshift mechanism, in accordance with an embodiment of the invention.
Figure 6 shows a side view of an adjustable stud linkage member of the gearshift mechanism, in accordance with an embodiment of the invention.
Figure 7 shows a sectional view of the adjustable stud linkage member, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[018] The present invention relates to a gearshift mechanism for a saddle type vehicle.
[019] Figure 1 illustrates an exemplary saddle-type vehicle, in accordance with an embodiment of the invention. The saddle type vehicle 10 comprises an IC engine 12 that is vertically disposed. Preferably, the IC engine 12 is a single-cylinder type IC engine. The saddle type vehicle 10 further comprises a front wheel 14, a rear wheel 16, a frame member (not shown), a seat 18 and a fuel tank 20. The frame member includes a head pipe 22, a main frame, rear down tubes, and seat rails. The head pipe 22 supports a steering shaft (not shown) and two telescopic front suspensions 26 attached to the steering shaft through a lower bracket (not shown). The two telescopic front suspensions 26 support the front wheel 14. The upper portion of the front wheel 14 is covered by a front fender 28 mounted to the lower portion of the telescopic front suspension 26 at the end of the steering shaft. A handlebar 30 is fixed to upper bracket (not shown) and can rotate to both sides. A head light 32, a visor guard (not shown) and instrument cluster (not shown) are arranged on an upper portion of the head pipe 22. The frame member comprises a down tube 44 that may be located in front of the IC engine 12 and extends slantingly downward from the head pipe 22. The main frame of the frame member is located above the IC engine 12 and extends rearward from head pipe 22. The front of the IC engine 12 is to the down tubes 44 and a rear of the IC engine 12 is mounted at the rear portion of the main frame. In an embodiment, the IC engine 12 is mounted vertically, with a cylinder block (not shown) extending vertically above a crankcase 102 (shown in Figure 4). In an alternative embodiment, the IC engine 12 is mounted horizontally (not shown) with the cylinder block extending horizontally forwardly from the crankcase 102. In an embodiment, the cylinder block is disposed rearwardly of the downtube.
[020] The fuel tank 20 is mounted on the horizontal portion of the main frame. The seat rails are joined to main frame and extends rearward to support a seat assembly 18. A rear swing arm 34 is connected to the frame member to swing vertically, and a rear wheel 16 is connected to rear end of the rear swing arm 34. Generally, the rear swing arm 34 is supported by a mono rear suspension 36 or through two suspensions on either side of the saddle type vehicle 10 (as illustrated in the present embodiment). A taillight unit 33 is disposed at the end of the saddle type vehicle 10 and at the rear of the seat assembly 18. A grab rail 37 is also provided on the rear of the seat rails. The rear wheel 16 arranged below seat 18 rotates by the driving force of the IC engine 12 transmitted through a chain drive (not shown) from the IC engine 12. A rear fender 38 is disposed above the rear wheel 16.
[021] Further, an exhaust pipe (not shown) of the vehicle extends vertically downward from the IC engine 12 up to a point and then extends below the IC engine 12, longitudinally along the vehicle length before terminating in a muffler (not shown). The muffler (not shown) is typically disposed adjoining the rear wheel 16.
[022] Figure 2 illustrates a gearshift mechanism 100 for the saddle type vehicle 10, in accordance with an embodiment of the invention. The gearshift mechanism 100 has a gearshift shaft (not shown) that protrudes outwardly in a vehicle-width direction from the crankcase 102. The gearshift shaft is generally further connected to a shift drum which converts the motion of the gearshift shaft to a horizontal motion for a shift fork (not shown). The shift fork moves the gear pairs horizontally to engage and disengage the gear pairs with output shaft of the engine 12.
[023] In an alternative embodiment, the gearshift shaft is further connected to a plurality of pins 172 (shown in Figure 8) provided on a star index 174 (shown in Figure 8). The star index 174 is disposed on the crankcase 102 and is mounted on the camshaft of the engine 12. Herein, the outer periphery of the star index 174 has a substantial shape of a star. In this embodiment, both the pins 172 and the star index 174 are integrated type and are made in same part, and effectively lock and unlock the gear shifting mechanism 100. The star index 174 converts the motion of the gearshift shaft to a horizontal motion for the shift fork. Integration of the pins 172 and the star index 174 to form a single piece part results in ease of manufacturing and cost reduction.
[024] As illustrated in Figure 2, the gearshift mechanism 100 has a lever arm 110 that is fixedly connected to the gearshift shaft. Further, the gearshift mechanism 100 has a gearshift lever 120 that is mounted pivotally on the crankcase 102. In that, the gearshift lever 120 is mounted on the crankcase 102 rearwardly from the lever arm 110 in a vehicle side view, as opposed to the conventional configuration wherein the gearshift lever 120 is directly mounted upon the gearshift shaft. In an embodiment, the gearshift lever 120 has a foot peg 122 (shown in Figure 3) disposed towards the front of the gearshift lever 120. The rider operates the gearshift lever 120 by pushing the foot peg 122 of the gearshift lever 120 down by bottom of the toe or pushing the foot peg 122 of the gearshift lever 120 up by top of the toe for an upshift or a downshift operation as required.
[025] As further illustrated in Figure 2 and Figure 3, the gearshift lever 120 is connected to the lever arm 110 by means of a first linkage member 130, a second linkage member 140 and an adjustable stud linkage member 150. Herein, the first linkage member 130 is connected to the lever arm 110 and the second linkage member 140 is connected to the gearshift lever 120. The stud linkage member 150 has a first end 150A (shown in Figure 5) that is threadedly connected to the first linkage member 130, and a second end 150B (shown in Figure 5) that is threadedly connected to the second linkage member 140. Herein, rotation of the stud linkage member 150 causes the first linkage member 130 and the second linkage member 140 to move in and out of the stud linkage member 150. This results in the total length of the first linkage member 130, the second linkage member 140 and the stud linkage member 150 between the lever arm 110 and the gearshift lever 120 to be increased or decreased. Since movement of the lever arm 110 is restricted, this causes movement of the gearshift lever 120, thereby adjusting the gearshift lever 120 by changing of the inclination of the gearshift lever 120.
[026] As illustrated in Figure 5, the first linkage member 130 has a head end 130A that is configured to be pivotally connected to the lever arm 110. Further, the first linkage member 130 has a tail end 130B that is provided with outer threads that are configured to be threadedly connected to the stud linkage member 150. As further illustrated in Figure 5, the second linkage member 140 has a head end 140A that is configured to be pivotally connected to the gearshift lever 120, and a tail end 140B provided with outer threads that are configured to be threadedly connected to the stud linkage member 150.
[027] Reference is made to Figure 6 and Figure 7, wherein as illustrated the first end 150A of the stud linkage member 150 is provided with inner threads that are configured to engage with outer threads provided on the tail end 130B of first linkage member 130. The second end 150B of the stud linkage member 150 is provided with inner threads that are configured to engage with outer threads provided on the tail end 140B of second linkage member 140.
[028] Further as illustrated in Figure 6 and 7, the stud linkage member 150 has a substantially hollow cylindrical cross section. To facilitate rotation of the stud linkage member 150, the stud linkage member 150 has a cut out portion 152 between the first end 150A and the second end 150B. The cut out portion 152 is provided such that a flat portion is provided on the cylindrical cross section, wherein any tool or fingers of the rider can engage with the flat cut out portion 152, thereby providing for easier rotation of the stud linkage member 150.
[029] In the gearshift mechanism 100 of the present invention, if a user requires that inclination of the gearshift lever 120 be increased with respect to a footrest 160 (shown in Figure 3) for better ergonomics, the user shall rotate the stud linkage member 150 in a clockwise direction. The outer threads on the first linkage member 130 and the second linkage member 140, and the inner threads on the stud linkage member 150 are configured such that clockwise rotation of the stud linkage member 150 causes the first linkage member 130 and the second linkage member 140 to move out of the stud linkage member 150, thereby increasing the inclination of the gearshift lever 120 from the rider footrest 160.
[030] Similarly, if the user requires that inclination of the gearshift lever 120 be decreased with respect to the footrest 160 for better ergonomics, the user shall rotate the stud linkage member 150 in an anti-clockwise direction. The outer threads on the first linkage member 130 and the second linkage member 140, and the inner threads on the stud linkage member 150 are configured such that anti-clockwise rotation of the stud linkage member 150 causes the first linkage member 130 and the second linkage member 140 to move into the stud linkage member 150, thereby decreasing the inclination of the gearshift lever 120 from the rider footrest 160.
[031] Advantageously, the present invention provides for a gearshift mechanism in which a rider is capable of adjusting the inclination of the gearshift lever according to their requirement with respect to their preferred ergonomics in relation to rider height, geographical location, riding conditions, and the like. Better ergonomics ensure that the rider is comfortable while riding the saddle type vehicle, as riding stance and position are improved.
[032] Further, in the present invention, the values of inclination of the gearshift lever that can be achieved by the rider are not limited to discrete values, but any value between a tolerance range can be achieved. Further, mounting of the gearshift lever on the crankcase ensures that any change in the frame of the vehicle does not affect the gearshift mechanism, thus ensuring that the gearshift mechanism of the present invention can be used in a wide range of vehicles without major modifications.
[033] Furthermore, since the gearshift mechanism of the present invention does not require any complex components for adjusting the gearshift lever and thus is easy to manufacture and has better serviceability.
[034] 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.