Claims:We Claim:
1. A gear shift assembly (212) for an internal combustion engine (108), said gear shift assembly (212) comprising:
a shift arm (206), said shift arm (206) includes
a first shift arm (206A), and
a second shift arm (206B),
wherein a first end of said first shift arm (206A) and a first end of said second shift arm (206B) being connected to a gear shift shaft (207A) at a first pivot (207),
wherein said first shift arm (206A) comprising a second end is configured with a first cavity (214) for accommodating a stopper pin (205) mounted to a crankcase (213), and
wherein said second shift arm (206B) comprising a second end is configured with a second cavity (210) for accommodating a roller (208),
a secondary arm (203) rotatably coupled to said roller (208) at one end and engaging a pawl arm (202) at another end thereof wherein the pawl arm (202) actuates a gear cam assembly (201) of the engine (108).
2. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said second cavity (210) is oval shaped.
3. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said second cavity (210) being configured to receive said roller (208)).
4. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said secondary arm (203) being rotatably connected at a second pivot (204).
5. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said first shift arm (206A) and said second shift arm (206B) being integrated to each other as a single unit.
6. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein the shift arm (206) rotates in a first direction causing rotation of said secondary arm (203) in a second direction opposite to said first direction.
7. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein the rotation of the secondary arm (203) causes a linear movement of said pawl arm (202).
8. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said linear movement of the pawl arm (202) causes a corresponding rotation of said gear cam assembly (201).
9. The gear shift assembly (212) for an internal combustion engine (108) as claimed in claim 1, wherein said rotation of said gear cam assembly (201) is in a direction opposite to a rotational direction of said secondary arm (203).
10. A two wheeled straddle type vehicle comprising a gear shift assembly (212) as claimed in any of the preceding claims.

, Description:TECHNICAL FIELD
[0001] The present subject matter relates to a vehicle. More particularly, to a saddle type vehicle.

BACKGROUND
[0002] Straddle type vehicles such as motorcycles generally have a manual transmission system to carry the power generated by an internal combustion (1C) engine, in a controllable way, to a wheel of the vehicle. The manual transmission system comprises a system of interlocking gears such that by operating a gear shift lever manually, the driver can choose one of the several ratios of speed between the input shaft and the output shaft. To allow smooth and gradual shifting gears, a clutch is provided to isolate the engine from the transmission momentarily. When the driver releases the clutch lever manually, the plates in the clutch assembly are squeezed with each other and thus the transmission is engaged with the engine.
[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The present invention is described with reference to an exemplary embodiment of battery module for a saddle type two-wheeled vehicle colloquially called a motorcycle wherein a rider has to straddle and sit. This invention is implementable in two-wheeled vehicles/three-wheeled vehicles. The same numbers are used throughout the drawings to reference like features and components. Further, the inventive features of the invention are set forth in the appended claims.
[0005] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. It should be appreciated that the following figures may not be drawn to scale.
[0006] Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as a discussion of other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.
[0007] Figure 1 illustrates a left side view of an exemplary two wheeled motor vehicle, as per embodiment, in accordance with one example of the present subject matter.
[0008] Figure 2a illustrates a left side view of the engine assembly in a two wheeled motor vehicle, as per embodiment, in accordance with one example of the present subject matter.
[0009] Figure 2b illustrates a cut section view of the gear shift engine assembly across section A-A’, as per embodiment, in accordance with one example of the present subject matter.
[00010] Figure 3 illustrates a left side view of the gear shift assembly for the engine assembly where few parts are omitted from the figure, as per embodiment, in accordance with one example of the present subject matter.
[00011] Figure 4 illustrates a graphical representation depicting the difference of gear shift lever travel between the conventional gear shift mechanism and the present gear shift assembly layout as per embodiment, in accordance with one example of the present subject matter.
DETAILED DESCRIPTION
[00012] In the following description, numerous details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.
[00013] Conventionally, a two-wheeled vehicle is powered by an internal combustion engine (IC engine) generally disposed at the lower half of the vehicle. The engine converts chemical energy into mechanical energy by a combination of air-fuel mixture within a combustion chamber of the engine. The IC engine, among other components, has a cylinder block and the engine comprising a cylinder head disposed atop the cylinder block and receiving a reciprocating piston from bottom. On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocating motion of the piston is converted to the rotatory motion of the crankshaft. The crankshaft is housed inside a crankcase that is disposed of beneath the cylinder block.
[00014] To set the vehicle into motion, the power supplied to the crankshaft of the internal combustion engine is carried to a wheel of the vehicle, in a controllable way, through a transmission system. The transmission system for the engine of a two-wheeled motor vehicle such as a motorcycle generally comprises of a system of interlocking gears such that by operating a gear shift lever manually, the driver can choose one of the several ratios of speed between the input shaft and the output shaft. To allow smooth and gradual shifting of gears, a clutch is provided to isolate the engine from the transmission momentarily. When the driver releases the clutch lever manually, the discs in the clutch assembly are squeezed with each other and thus the transmission is engaged with the engine.
[00015] The rider can decide on the need to change the gear position based on the engine speed or vehicle indication provided on the instrument cluster. Typically, a motorcycle gear shift assembly is used for manually shifting gears by using a foot to shift the position of the gear shift lever so that the desired drive gears or the neutral position in a gearbox is engaged. Particularly, the desired drive gears or the neutral position in the gearbox is engaged by either lifting up or pushing down the gear shift lever. Thus, the gear shift lever serves as the contact point for manual shifting with the foot. A change in drive gear positions is achieved due to the transfer of motion from the gear shift lever to the gear shift shaft. The gear shift shaft is connected to the shift drum through a plurality of gear shifting components. Generally, a plurality of gear shifting components such as a pawl, a stopper, a gear shift arm, and a shift drum are housed inside a transmission housing. The gear shift shaft is connected to the gear shift arm. One end of the gear shift arm is connected to the gear shift shaft while another end is connected to the pawl. The rotation of the end connected to the gear shift shaft is restricted by the stopper.
[00016] Further, to ensure good riding ergonomics, it is essential to ensure that the gear shift lever is easily accessible to the rider. Since gears have to be shifted frequently while riding, ideally the rider should be able to reach said gear shift lever comfortably with his foot under all riding conditions.
[00017] However, it is observed that lower magnitude of leverage, which is required to create the necessary shift force, leads to the incomplete gear shift. Additionally, due to low gear shift lever travel, the rider tends to get a poor gear shift feel. More specifically, the rider tends to apply excessive force even after completion of gear shifting due to a lack of positive gear shift feel to the rider. The excessive force applied by the rider affects the durability of the parts housed inside the transmission housing. More specifically, the pivot zone between the gear shift arm and the pawl arm is prone to failure as it is acted upon with additional force during gear shifting. Further, another zone that is prone to failure is between the gear shift arm and the stopper.
[00018] To address said issues, an external gear shifting arrangement is provided outside of transmission housing with an additional linkage for ease of gear shifting. However, the external gear shifting arrangement only involves an external retrofittable linkage with least or no modification in the existing gearbox. With such an external design, inconsistency with gear shifting cannot be ruled out.
[00019] Therefore, there is a need to provide an improved gear shift assembly overcoming all the above problems & trade-offs as well as overcoming problems of the known art.
[00020] It is an object of the present invention to provide an improved gear shift assembly which provides a better gear shifting feel to the rider.
[00021] It is yet another object of the present invention to provide an improved gear shift mechanism that provides optimum leverage to create the necessary shift force to improve the durability of the gear shift components.
[00022] To this end, the present invention discloses an improved gear shift assembly for an internal combustion engine. The gear shift assembly comprising a shift arm. The shift arm includes a first shift arm, and a second shift arm. A first end of said first shift arm and a first end of said second shift arm being connected to a gear shift shaft at a first pivot. The first shift arm comprising a second end is configured with a first cavity for accommodating a stopper pin mounted to a crankcase, and said second shift arm comprising a second end is configured with a second cavity for accommodating a roller. A secondary arm rotatably coupled to said roller at one end and engaging a pawl arm at another end thereof wherein the pawl arm actuates a gear cam assembly of the engine
[00023] According to the above configuration, one of the advantages of the present invention is that the shift arm, and the secondary arm provide the improved gear shifting feel due to higher gear shift lever travel. Further, the shift arm and the secondary arm provide optimum leverage to provide sufficient shift forces while eliminating the stress experienced at the stopper pin and the pawl arm, since the shift arm and the secondary arm move in the opposite direction to each other.
[00024] As per yet another embodiment of the present invention, said second cavity is oval shaped.
[00025] As per one embodiment of the present invention, said second cavity being configured to receive said roller.
[00026] According to the above configuration, one of the advantages of the present invention being the second cavity being configured to provide a higher degree of freedom to said roller relative to the shift arm and secondary arm which in turn provides swifter movement of the pawl arm.
[00027] As per one embodiment of the present invention, wherein said secondary arm being rotatably connected at a second pivot.
[00028] As per one embodiment of the present invention, said first shift arm and said second shift arm being integrated as a single unit.
[00029] According to the above configuration, one of the advantages of the present invention, the integration of said first shift and second shift arm achieves swifter movement of the secondary arm. Further, it reduces the part count and improves the durability of said shift arm by eliminating mechanical wear and tear.
[00030] As per another embodiment of the present invention, said shift arm rotates in a first direction causing rotation of said secondary arm in a second direction opposite to said first direction.
[00031] As per yet another embodiment of the present invention, the rotation of the secondary arm causes a linear movement of said pawl arm.
[00032] As per one embodiment of the present invention, said linear movement of the pawl arm causes a corresponding rotation of a gear cam.
[00033] As per another embodiment of the present invention, said rotation of said gear cam is in a direction opposite to a rotational direction of said secondary arm.
[00034] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate the 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.
[00035] The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. As such, it is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Having thus described embodiments of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Thus, the present disclosure is limited only by the claims.
[00036] In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as one skilled in the art will appreciate, various embodiments disclosed herein can be modified or otherwise implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered as illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosure. It is to be understood that the forms of the disclosure herein shown and described are to be taken as representative embodiments. Equivalent elements, materials, processes or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.
[00037] Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, etc.) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.
[00038] Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification.
[00039] It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. Additionally, any signal hatches in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically specified.
[00040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[00041] With reference to Figure 1, a description is made of an entire schematic structure of a saddle type vehicle two-wheeled vehicle (hereinafter “vehicle”) (100). The vehicle (100) includes a body frame (101) to support different parts of said vehicle (100). A head pipe (102) is provided at a front end of the body frame (101). The head pipe (102) supports a steering shaft (not shown) rotatably in a certain range. In an upper portion of the head pipe (102), a handlebar assembly (103) is rotatably integrally connected to the steering shaft (not shown). The handlebar assembly (103) is used to steer the vehicle (100) and is connected to a front wheel (104) through the steering shaft (not shown). An upper portion of the front wheel (104) is covered by a front fender (105) which prevents mud and water from getting deflected towards the steering shaft (not shown). Further, a front fork assembly (106) is supported partially on the front fender (105) and is connected to the front wheel (104). In a front portion of the body frame (101) a fuel tank (107) is arranged immediately behind the handlebar (103) and is disposed over an internal combustion engine assembly, (hereinafter ‘engine assembly’) (108). A seat (109) is placed behind the fuel tank (107). The seat (109) includes a front rider portion and rear pillion portion. For the safety of the rider and in conformance with the traffic rules, a headlamp unit (110) and a turn signal lamp unit (111) is provided in a front portion of the vehicle (100). The headlamp unit (110) and the turn signal lamp unit (111) are housed in a headlamp housing assembly (112). Suspension systems are provided for comfortable steering of the vehicle (100) on the road. The front fork assembly (106), which forms the front suspension system, serves as a rigidity component just like the body frame (101). The front fork assembly (106) clamped to the head pipe (102) through an upper bracket (113a) and a lower bracket (113b) is capable of being moved to the left and right. Further, a rear suspension system, which is a hydraulic damped arrangement, is connected to the body frame (101). The rear suspension system comprises at least one rear suspension preferably on a left-hand side of the vehicle (100). However, in a vehicle (100) with two rear suspensions, the same may be disposed of on the left side and the right side respectively of said vehicle (100). The engine assembly (108) is mounted to a front lower portion of the body frame (101) by means of a first engine mounting bracket (not shown). The engine assembly (108) is equipped with an exhaust system that includes an exhaust pipe (not shown) connected to the engine assembly (108) and a muffler (not shown) connected to the exhaust pipe. The muffler (not shown) extends rearwards along the right side of a rear-wheel (114). Power from the engine assembly (108) is transmitted to a driven sprocket (119) through a transmission assembly (118), to drive and rotate a rear wheel (114). Particularly, the speed change is achieved by the operation of a gear shift linkage assembly (115) which is operatively connected to a gear shift shaft (207A) (as shown in figure 2). Thus, power from the engine assembly (108) is transmitted to the rear wheel (114) rotatably supported at a rear end of a swing arm (116). A rear fender (117) for covering an upper side of the rear wheel (114) is mounted to a rear portion of the body frame (101) to prevent mud and water splashed by the rotating rear wheel (114) from entering the muffler, the engine assembly (108).
[00042] Figure 2a illustrates a left side view of the engine assembly (108) in a two wheeled motor vehicle (100), as per embodiment, in accordance with one example of the present subject matter. Figure 2b illustrates a cut section view of the engine assembly (108) across A-A’, where few parts are omitted from the figure, as per embodiment, in accordance with one example of the present subject matter. For sake of brevity, Figure 2a and Figure 2b will be discussed together. The engine assembly (108) comprises a crankcase (213). The crankcase (213) being configured to support a gear shift assembly (212). The gear shift assembly (212) comprises a gear cam assembly (201), a pawl arm (202), a secondary arm (203), a second pivot (204), a roller (208), a gear shift shaft (207A) a first pivot (207), a stopper pin (205), a shift arm (206), a shim and circlip assembly (209), and a spring member (211). The one end of the gear shift shaft (207A) being connected to the shift arm (206) while the opposite end being connected to a gear shift lever (not shown). The stopper pin (205) allows the restricted rotatable movement of the shift arm (206) in a controllable manner. The shift arm (206) comprising of a first shift arm (206A) and a second shift arm (206B). More specifically, a first end of the first shift arm (206A) and a first end of the second shift arm (206B) being connected to the gear shift shaft (207A) at a first pivot (207).
[00043] As per the preferred embodiment, the first shift arm (206A) being integrated to the second shift arm (206B). As per alternative embodiment, the first shift arm (206A) being detachably attached to the second shift arm (206B) using attachment means (not shown).
[00044] As per the preferred embodiment, the first shift arm (206A) comprises of a second end having a first cavity (214) for accommodating the stopper pin (205). The stopper pin (205) is mounted to the crankcase (213). The second shift arm (206B) comprising a second end being configured to have a second cavity (210) for accommodating the roller (208). As per the preferred embodiment, the second cavity (210) being configured to have an oval shape. The oval shape permits a higher degree of freedom to the roller (208) relative to the movement of the shift arm (206) and the secondary arm (203). The higher degree of freedom of the roller (208) in turn contributes to the swifter movement of the secondary arm (203). Further, the secondary arm (203) is rotatably mounted at a second pivot (204). As per illustrated embodiment, the second pivot (204) includes a pin (215) mounted to the crankcase (213). More specifically, the secondary arm (203) being rotatably mounted to the pin (215) using the shim and circlip assembly (209). The shim and circlip assembly (209) includes a shim (209A), and a circlip (209B). The shim (209A) avoids the wear caused due to the relative motion between the rotating parts. The first end of the secondary arm (203) is rotatably coupled to said roller (208) at one end and engaging the pawl arm (202) at another end thereof. The pawl arm (202) being connected to the gear cam assembly (201). The gear cam assembly (201) includes a gear cam (201A). Additionally, the spring member (211) connects the pawl arm (202) and the secondary arm (203) to enable the quick return of the secondary arm (203) towards its original position after the completion of gear shift operation.
[00045] Fig. 3 illustrates a left side view of the gear shift assembly for the engine assembly (108), where few parts are omitted from the figure, as per embodiment, in accordance with one example of the present subject matter. During operation, while upshifting or downshifting the gear shift lever (not shown) rotates the gear shift shaft (207A) by the rider’s foot action. The rotation of the gear shift shaft (207A) rotates the shift arm (206) about the first pivot (207) in a first direction. This causes the rotation of the secondary arm (203) through the roller (208) in a second direction about the second pivot (204). The second direction is opposite to said first direction. The secondary arm (203) causes a linear movement of the pawl arm (202). This causes a corresponding rotation of the gear cam (201A). As per preferred embodiment, the rotation of said gear cam (201A) is in a direction opposite to a rotational direction of said secondary arm (203).
[00046] Fig. 4 illustrates a graphical representation depicting the difference of gear shift lever travel between the conventional gear shift mechanism and the present gear shift assembly layout as per embodiment, in accordance with one example of the present subject matter. Preferably, the vertical axis signifies the gear cam rotation in degrees while upshifting and downshifting and the horizontal axis signifies the gear shift lever rotation in degrees during upshifting and downshifting. As shown in the graph, line A represents the conventional gear shift assembly and, line B represents the proposed gear shift assembly having higher gear shift lever travel. It is evident from the graph, with reference to line C-C’ while upshifting and line D-D’ while downshifting that for the same gear cam rotation the gear shift travel is higher in the case of proposed gear shift assembly as compared to conventional gear shift assembly. This results in a better gear shifting feel to the rider and provide optimum leverage to create the necessary shift force. This further prevents incomplete gear selection.
[00047] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention.
List of Reference

100 Vehicle
101 Body frame
102 Head pipe
103 Handle bar
104 Front wheel
105 Front fender
106 Front for assembly
107 Fuel tank
108 Engine assembly
109 Seat
110 Head lamp unit
111 Turn signal lamp
112 Head lamp housing assembly
113a & 113b upper bracket & lower bracket
114 Rear wheel
115 Gear shift linkage assembly
116 Swing arm
117 Rear fender
118 Transmission assembly
119 Driven sprocket
201 Gear cam assembly
201A Gear cam
202 Pawl arm
203 Secondary arm
204 Second pivot
205 Stopper pin
206 Shift arm
206A First shift arm
206B Second shift arm
207 First pivot
207A Gear shift shaft
208 Roller
209 Shim and circlip assembly
209A Shim
209B Circlip
210 Second cavity
211 Spring member
212 Gear shift assembly
213 Crankcase
214: First cavity
215 Pin