DESC:FIELD OF INVENTION:
[001] The present invention relates to a transmission system for a vehicle and more particularly relates to the transmission system with a provision for easy servicing and maintenance.
BACKGROUND OF INVENTION:
[002] In automotive industry, different kind of gear shifting mechanisms are used. The two well-known gear shifting mechanisms include a drum type gear shift mechanism, which uses a drum type arrangement for shifting gears, and a cross type gear shift mechanism, which uses a cross, fixed on a shaft, used to change or engage different gears. Various factors such as available space, vehicle type, available gear ratios, driving requirements, etc are considered while deciding a type of gear shift mechanism.

[003] The drum type gear shift mechanism comprises a gear shift drum having a plurality of slots engaged with at least a fork or gear shifting members used to engage the gears mounted on a transmission shaft. Whenever a gear shift is triggered either automatically or manually by a driver of the vehicle, the gear shift drum rotates by a predefined amount which is equivalent to a required gear change. The rotation of gear shift drum causes shifting of the gears through usages of the fork or the gear shifting members. This kind of arrangement increases the space. Also, the design of gear shift drum and fork is complex in nature and also a time consuming task as it requires machining and high accuracy. The components of the mechanism are made using casting process which require high precision and ultimately increases cost.

[004] The cross type gear shift mechanism, comprises an output shaft, which engages with different gears for gear engagement. The engagement between the output shaft and the gears is provided by a cross. Whenever a gear shift is triggered either automatically or manually by the driver of the vehicle, the cross engages with a prescribed gear to achieve required gear change. Further, the cross type gear shifting mechanism is simpler and less costly as compared to the drum type mechanism, hence the cross type gear shifting mechanism is considered an economic solution for gear shifting. The cross arrangement is compact and requires less machining time and cost for manufacturing. However, there are major challenges associated with the cross removal that are explained further.

[005] The cross is a metallic component which can get wear and tear after a period of time or continuous operation. Once the cross worn-out, it needs to be replaced with a new cross for a proper functioning of a transmission system. Thus, the cross replacement can become a frequent affair in some cases. During breakdown of a vehicle, which may be caused by engine malfunctioning, a user takes the vehicle to a service centre or to a local mechanic. A possible error in the cross may be the reason for the engine malfunctioning. The worn-out cross doesn’t properly engage with intended gears and the gear-shifting doesn’t happen smoothly. For example, when a user intent to shift the gear from 2nd gear to 3rd gear, it may engage 4th gear instead. Hence, in such scenarios, the cross needs to be replaced.

[006] The major challenge faced during replacement of the cross is difficulty to take out the cross from an engine assembly 100, since the cross is located deep inside a crankcase assembly, and mostly the cross is in engaged condition with a gear assembly. Further, a piston block assembly is assembled above the crankcase assembly, hence, to replace the worn-out cross, the entire engine assembly is required to be dismantled, i.e., an engine-block, a crank shaft, the gear assembly, a clutch assembly, etc. Further, dismantling the entire engine assembly is a complex, huge time consuming and tedious task, which incurs high cost. For such a task, skilled labor is required since the engine disassembly and re-assembly is a high skilled task and cannot be performed by an ordinary labor or a non-skilled labor.

[007] It is generally advised not to dismantle the entire engine assembly (100) as the engine performance doesn’t remain the same for reassembled engine as that of original engine.

[008] Considering the above scenarios and challenges faced, there is a need to re-design the cross type gear shift arrangement in order to easily remove and replace the worn-out cross without affecting the engine efficiency caused due to dismantling the entire engine assembly and without increasing cost of the engine assembly.

[009] Further, the re-designing of the cross type gear shift arrangement should be such that there is no requirement of a skilled labor for a job i.e., it can be done by a labor having an ordinary knowledge in the engine assembly.

OBJECTIVES OF INVENTION:
[010] It is an object of the present invention to provide a transmission system for an engine with a cross type gear shift mechanism with a provision for easy replacement of a cross without dismantling a complete engine assembly.

[011] Another objective is to have a provision for easy replacement of a cross in an existing vehicle/ engine design without major changes.

[012] Yet another objective of the present invention is to reduce the cost and time of service during replacement of a cross in an engine assembly.

[013] Yet another objective of the present invention is to provide ease of replacement of a cross with the help of a non-skilled labor.

[014] Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY OF INVENTION:
[015] With these objective in view, the present invention provides a transmission system for a vehicle, comprising:
an output shaft connected to a drive source through at least a gear pair for receiving power from a drive source;
a cross mounted on the output shaft and configured to engage at least a gear with the output shaft; and
at least a crankcase for mounting the output shaft along with the cross and the gear;
wherein the crankcase is provided with an opening configured for removing the cross from the transmission system.

[016] According to an embodiment, the opening on the crankcase is at least partially covered by a covering member.

[017] Preferably, the covering member is provided with an integral bearing arrangement for supporting the output shaft.

[018] According to another embodiment, the output shaft is provided with a plurality of slots configured to translate the cross along the output shaft. The plurality of slots may be a linear slots.

[019] According to another embodiment, the cross is fixed on a guide rod located inside the output shaft. Preferably, a rotating nut is provided to unmount the cross from the guide rod.

[020] According to another embodiment, the slots include at least a portion with higher dimensions compared to the slot dimension at the other portions for rotation and removal of the cross from the output shaft. Preferably, the provision is in a form of a curved portion.

[021] According to another embodiment, the crankcase is covered by a clutch cover.

[022] According to another embodiment, the drive source for the vehicle is either an engine or a motor or both.

[023] According to another embodiment, the transmission system comprises an input shaft connected to the output shaft through the gear pair, wherein the input shaft is connected to the drive source to receive power.

[024] According to present invention, a method for arrangement of a transmission system of a vehicle, comprising:
connecting an output shaft through at least a gear pair for receiving power from a drive source; engaging at least a gear with the output shaft using a cross mounted on the output shaft; providing at least a crankcase for mounting the output shaft along with the cross and the gear; removing the cross through an opening provided on the crankcase of the transmission system.

[025] The method for removal of the cross, comprises steps of dismantling a covering member, wherein the covering member partially covers the opening on the crankcase; removing a guide rod from the output shaft along with the cross.

[026] The method for removal of the cross, comprises steps of pulling out the guide rod along with the cross by translating the cross along the slots provided on output shaft; unscrewing a rotating nut for dismounting the cross from the guide rod; removing the guide rod from the output shaft; pulling out the cross by rotating through a provision of a curved portion on the output shaft and removing the cross through the opening provided on the crankcase of the transmission system.

[027] The transmission system according to the present invention can be employed on any vehicle including two-wheeled, three-wheeled and four-wheeled vehicles.

BRIEF DESCRPTION OF DRAWINGS:
[028] The above and other objects, features, and advantage of the present disclosure will be more apparent from the detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by the way of example only with reference to the accompanied drawings wherein like reference numerals represent like elements:

[029] Fig. 1 illustrates an engine assembly with a transmission system, according to an embodiment of the present disclosure;

[030] Fig. 2a illustrates a transmission system, according to an embodiment of the present disclosure;

[031] Fig. 2b illustrates the transmission system of Fig. 2a having a clutch cover removed, according to an embodiment of the present disclosure;

[032] Fig. 3a illustrates the transmission system of Fig. 2b having a clutch removed, according to an embodiment of the present disclosure;

[033] Fig. 3b illustrates an isometric view of the transmission system of Fig. 3a, according to an embodiment of the present disclosure;

[034] Fig. 4 illustrates a sectional view A-A of the Fig. 3a, according to an embodiment of the present disclosure;

[035] Fig. 5 illustrates an isometric view of an output shaft in a transmission system, according to an embodiment of the present disclosure;

[036] Figs. 6a – 6c illustrate a cross removal of the transmission system, according to an embodiment of the present disclosure;

[037] Figs. 7a – 7c illustrate a covering member of a transmission system, according to an embodiment of the present disclosure; and

[038] Fig. 8 illustrates a rear view of a vehicle with a transmission system employed therein, according to an embodiment of the present disclosure.

DETAIL DESCRIPTION OF DRAWINGS:

[039] A preferred embodiment will now be described in detail with reference to the accompanying drawings. The preferred embodiment does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

[040] It will be readily understood that components of present invention as generally described and illustrated in figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention as represented in the figures is not intended to limit the scope of the invention but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

[041] Fig. 1 illustrates an engine assembly 100 for an automotive vehicle provided with a piston block assembly 101 located above a crankcase assembly 102. The crankcase assembly 102 includes a clutch assembly 103, a transmission system 104 comprising a differential system 105, etc. The piston block assembly 101 is connected to the transmission system 104 through a conventional arrangement i.e., a piston is connected to a crankshaft (not shown), and a rotational motion of the crankshaft is transmitted to a propeller shaft through a connection of a plurality of shafts. A gearbox of transmission system 104 comprises a plurality of gear pairs that are used to connect an input shaft of the transmission system 104 to an output shaft for power transmission. Further, the clutch assembly 103 is operated to connect and disconnect the power output from the engine assembly 100 to the transmission system 104 (or drivetrain). The transmission system 104 is configured to further modulate a torque and RPM of the output shaft or a propeller shaft of the vehicle as per the user demand. In present embodiment, the transmission system 104 uses a cross type gear shift arrangement for gear engagement.

[042] Figs. 2a to 4, illustrating further details of the transmission system 104 including a cross type gear shift arrangement 400. The complete transmission system 104 is covered by a clutch cover 201 (seen in FIG. 2a). The components of transmission system 104 includes the plurality of shafts, gear pairs etc. are supported and covered by a crankcase 202. A clutch assembly 103 is supported by the crankcase 202 (seen in FIG. 2b).

[043] The transmission system 104 comprises a plurality of gears 405 mounted on an output shaft 402 (seen in FIG.4). The gears 405 mounted on the output shaft 402 engages with an input shaft (not shown) to receive power from the crankshaft (not shown). The gears 405 are engaged to the output shaft 402 using a cross 401 selectively based on power requirement of a user. The output shaft 402, along with the cross 401 and the gears 405, is mounted on the crankcase 202. The output shaft 402 of the transmission system 104 is covered and supported by a covering member 301 comprising an integral bearing 302 (seen in FIG. 3b). The cross 401 is a metallic component having four arms orthogonally protruded outwards in all four directions. The arms of the cross 401 is an engaging member which engages with respective gears 405 in the transmission system 104 as the user demands. The cross 401 at its center is mechanically fitted to an inner end 403a of a guide rod 403 and its four arms protrude from the center in four directions, 90 degrees to each other. A rotating nut 404, provided at an outer end 403b of the guide rod 403, is unscrewed to dismount the cross 401 from the inner end 403a of the guide rod 403 (seen in FIG. 4). The inner end 403a of the guide rod is provided with external threads for mounting the cross 401.

[044] As explained in the background section, the cross 401 being mounted deep inside the transmission system is difficult to take out or replace conventionally. In order to make the cross type gear shift accessible to a mechanic or the user without disturbing or opening an entire assembly, the modifications have been made as explained herein. The clutch cover 201 is unmounted by opening the fastening means such as screws or bolts. After removing the clutch cover 201, the multi-plate clutch assembly 103 is dismantled and unmounted from the crankcase 202. The removal of the clutch assembly 103, which partially covers the covering member 301, opens the accessibility to the covering member 301. The covering member 301 is provided to cover an optimized opening 303 provided on the crankcase 202. The covering member 301 is unmounted from the crankcase 202 and an opening 303 provides sufficient space for access to the cross type gear shift arrangement 400. The opening 303 provided on the crankcase 202 is utilized for cross 401 removal and replacement (seen in FIG. 3b).

[045] Figs. 5 to 6c, illustrating cross mounting and disassembly arrangement of the cross 401 from the transmission system 104 in further detail according to preferred embodiment of the present invention. In the Fig. 5, an isometric view of the output shaft 402, the guide rod 403 and the cross 401 are shown. The cross 401 is mounted on the output shaft 402 provided with a plurality of linear slots 501, at least four linear slots, which is used for translatory motion of the cross arms in the linear direction for engagement/ disengagement of gears. Also, a purpose and design of a curved portion 502 is explained herewith. The slots 501 along its length are provided with curved portion 502 forming a higher dimension compared with slot dimension at the other portions of the linear slot 501. The curved portion 502 is similar to a circular hole having enough dimension so that the arms of the cross 401 do not interfere when the cross 401 is rotated. The curved portion 502 formed along each of the linear slots 501 facilitates in easy rotation of the cross 401 about 90 degrees such that a plane of cross 401 becomes parallel to a longitudinal axis 601 of the output shaft 402.

[046] According to an embodiment, the gear is ensured to be at neutral i.e. the cross 401 is not engaged with any of the plurality of gears 405. The guide rod 403 is pulled outward towards the opening 303 and the rotating nut 404 is rotated which dismount the cross 401 located at the inner end 403a. During the pull of the guide rod 403, the cross arms longitudinally move along the output shaft 402 through the linear slots 501 on the output shaft 402. The guide rod 403 is now pulled out from the transmission system 104 and the cross 401 rests at a position where its arms are at the curved portions 502, as shown in the Fig. 6a. The cross 401 is held from its protruding arm and rotated in 90 degrees such that the plane of cross arms is parallel to the longitudinal axis 601 of the output shaft 402, as shown in the Fig. 6b. The cross 401 is now pulled out of the output shaft 402 and brought out through the opening 303, as shown in the Fig. 6c. Accordingly, a new cross is replaced following similar procedure in the reverse order.

[047] Referring to Figs. 7a to 7c, illustrating the covering member 301 in detail. The covering member 301 is provided with plurality of through holes 701 on which mechanical fastening is provided for fixing the covering member 301 onto the crankcase 202. In conventional systems, the output shaft 402 is supported by the bearings mounted within the crankcase or any other covering member, whereas in according to present invention, the covering member 301 is provided with a ball bearing arrangement 302 integrated at its inner portion. The bearing arrangement facilitates continuous rotation and supports the output shaft 402.

[048] The present invention serves following technical advancement over the existing arrangement made in the transmission system 104 for removal of the cross 401. They are listed below:

• The optimized opening provided in the crankcase 202 ensures easy accessibility of the cross 401 from outside
• The covering member 301 provided for the crankcase opening 303 along with the integrated bearing ensures rotation and mounting of the output shaft 402 are not hampered with the introduction of the opening 303.
• The provision of plurality of slots 501 in the output shaft 402, facilitates in easy and smooth movement and removal of the cross 401 from the output shaft 402.
• Eventually, the current arrangement of the transmission system 104 ensures an easy removal of the cross 401 without dismantling the entire engine which saves huge cost, time and manpower. Further the engine efficiency is also not affected.

[049] The present invention is applicable to any type of vehicle including two-wheeled, three wheeled or four wheeled vehicles including front mounted and rear mounted engine 100. Fig. 8 illustrates a three wheeled vehicle 800 with the cross type gear shift arrangement 400 mounted in the crankcase assembly 102, in which the engine 100 is mounted on the rear side of the vehicle 800. According to one of the embodiment of present invention, the system is applicable to both manual and Automated Manual Transmission (AMT) system.

[050] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics or essential characteristics. The described embodiments are to be considered in respects as illustrative and not restrictive.

[051] Although the exemplary forms of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure.

List of Reference Numerals:
100 – Engine assembly/Engine
101 – Engine head/ Piston block assembly
102 – Crankcase assembly
103 – Clutch/Clutch assembly
104 - Transmission system
105 – Differential system
201 – Clutch cover
202 – Crankcase
301 – Covering member
302 – Bearing
303 – Opening
400 – Cross type gear shift arrangement
401 – Cross or gear engaging member
402 – Output shaft
403 – Guide rod or Actuation shaft
403a – Inner end of guide rod
403b – Outer end of guide rod
404 – Rotating nut
405 – Plurality of gear
501 – Linear slots
502 – Curved portion
601 – Longitudinal axis of the output shaft
701 – Holes on the covering member
,CLAIMS:1. A transmission system (104) for a vehicle, comprising:
an output shaft (402) configured to receive power from a drive source through at least a gear pair;
a cross (401) mounted on the output shaft (402) configured to engage at least a gear (405) with the output shaft (402); and
at least a crankcase (202) for mounting the output shaft (402);
wherein the crankcase (202) is provided with an opening (303) configured for removing the cross (401).

2. The transmission system (104) as claimed in claim 1, wherein the opening (303) on the crankcase (202) is at least partially covered by a covering member (301).

3. The transmission system (104) as claimed in claim 2, wherein the covering member (301) is provided with an integral bearing arrangement (302) for supporting the output shaft (402).

4. The transmission system (104) as claimed in claim 1, wherein the output shaft (402) is provided with a plurality of slots (501) configured to translate the cross (401) along the output shaft (402).

5. The transmission system (104) as claimed in claim 4, wherein the plurality of slots (501) comprises of linear slots (501).

6. The transmission system (104) as claimed in claim 4, wherein the slots (501) include at least a portion with higher dimensions compared to the slot dimension at the other portions for rotation and removal of the cross (401) from the output shaft (402).

7. The transmission system (104) as claimed in claim 6, wherein the portion is in a form of a curved portion (502).

8. The transmission system (104) as claimed in claim 1, wherein the output shaft (402) comprises a guide rod (403) having provision for mounting the cross (401) on an inner end (403a) of the guide rod (403) and is configured to translate within output shaft (402) along with the cross (401).

9. The transmission system (104) as claimed in claim 8, wherein the inner end (403a) of the guide rod (403) is provided with external thread for mounting the cross (401).

10. The transmission system (104) as claimed in claim 8, wherein the guide rod (403) is provided with a rotating nut (404) mounted on an outer end (403b) of the guide rod (403) for dismounting the cross (401) from the inner end (403a) of the guide rod (403).

11. The transmission system (104) as claimed in claim 1, wherein the crankcase (202) is covered by a clutch cover (201).

12. The transmission system (104) as claimed in claim 1, wherein the drive source for the vehicle is either an engine or a motor or both.

13. The transmission system (104) as claimed in claim 1, wherein an input shaft is connected to the output shaft (402) through the gear pair, wherein the input shaft is connected to the drive source to receive power.

14. The transmission system (104) as claimed in claim 1, wherein the transmission system (104) is employed on vehicle including a two-wheeled, a three-wheeled or a four-wheeled vehicle.

15. A method for arrangement of a transmission system (104) of a vehicle, comprising:
connecting an output shaft (402) through at least a gear pair for receiving power from a drive source;
engaging at least a gear (405) with the output shaft (402) using a cross (401) mounted on the output shaft (402);
providing at least a crankcase (202) for mounting the output shaft (402);
removing the cross (401) through an opening (303) provided on the crankcase (202).

16. The method for arrangement of the transmission system (104) as claimed in claim 15, wherein the method of removal of the cross comprises steps of:
dismantling a covering member (301), wherein the covering member (301) partially covers the opening (303) on the crankcase (202);
removing a guide rod (403) from the output shaft (402) along with the cross (401).

17. The method for arrangement of transmission system (104) as claimed in claim 16, wherein the method of removal of the cross comprises steps of:
pulling out the guide rod (403) along with the cross (401) by translating the cross (401) along slots (501) provided on output shaft (402);
unscrewing a rotating nut (404) for dismounting the cross (401) from the guide rod (403);
removing the guide rod (403) from the output shaft (402);
pulling out the cross (401) by rotating through a provision of a curved portion (502) on the output shaft (402) and removing the cross (401) through the opening (303) provided on the crankcase (202) of the transmission system.