DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A GEAR SHIFTING MECHANISM

Applicant:
Tata Motors Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400001,
Maharashtra, India

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

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application claims priority from Indian Patent application no. (201821045311) filed on 30th November, 2018.

TECHNICAL FIELD
[002] The present disclosure in general relates to a gear shifting mechanism. More particularly, the present disclosure relates to the gear shifting mechanism in a part time four-wheel drive vehicle. Further, the present subject matter relates to a direct shift mechanism with interlock for part time mechanical shift transfer case.

BACKGROUND
[003] It is to be noted that, in a part time mechanical shift transfer-case there are 4 modes of operation namely, 2H, 4H, N and 4Lmode. In 2H mode vehicle behaves like a standard rear wheel drive. In 4H mode power is transferred from engine to all the four wheels of the vehicle. However, there is no speed reduction occurring in transfer-case. In N mode (neutral mode), there is no power transmission to any of the wheels. In 4L mode power is transferred to all the 4 wheels and there is speed reduction occurring in the transfer-case. Depending on the terrain, which has to be traversed by the vehicle, the driver makes selection of the appropriate modes. For mode selection, a mechanical shift linkage is required. A mechanical shift transfer-case can operate in four modes namely 2H, 4H, N & 4L mode. For mode selection, a shaft or a transfer case shaft, which protrudes out of the transfer-case needs to be rotated.
[004] Consequently, in conventional designs, the mechanism lacks a smooth shifting of gears, and the conventional mechanism has more complexity in design.

SUMMARY
[005] It is to be understood, that this application is not limited to the particular systems, and methodologies described, as there can be multiple possible embodiments, which are not expressly illustrated, in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce concepts related to a gear shifting mechanism. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[006] In one implementation, a gear shifting mechanism for a vehicle is illustrated. In one embodiment, the gear shifting mechanism comprises an adapter housing, a bracket, a pin, a gear shift lever, and a shifting finger. The bracket is coupled to the adapter housing, and the bracket comprises a primary stopper and a secondary stopper. The pin is coupled to the bracket. Further, the gearshift lever is coupled to the pin, the gearshift lever pivots between the primary stopper and the secondary stopper for shifting a gear position to one of a first gear position and a second gear position. In another embodiment, the shifting finger is coupled to the gearshift lever. The shifting finger comprises a return spring, the return spring may contract, and hold the gearshift lever onto the primary stopper for a third gear position, or the return spring may retract and push the gearshift lever to the first gear position from the third gear position.

BRIEF DESCRIPTION OF DRAWINGS
[007] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.
[008] Figure 1 is an exploded view showing the gear shifting mechanism, in accordance with an embodiment of the present subject matter.
[009] Figure 2 illustrates stopper details, in accordance with an embodiment of the present subject matter.
[0010] Figure 3 illustrates mechanical shift linkage shifting position, in accordance with an embodiment of the present subject matter.
[0011] Figure 4 illustrates transfer case shifting angles, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION
[0012] Some embodiments of the present disclosure, illustrating all its features, will now be discussed in detail. The words “comprising”, “including”, and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, a gear shifting mechanism is now described. The disclosed embodiment of the gear shifting mechanism is merely exemplary of the disclosure, which may be embodied in various forms.
[0013] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure the gear shifting mechanism is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0014] As described above, there are some limitations in the conventional gear shifting mechanism. Conventionally, an all-wheel drive vehicle can have a part time or full time transfer-case. In a part time transfer-case, the driver has to select the mode in which the vehicle is to be driven. Mode selection has to be effected electrical means or mechanically by means of linkages, depends on the type of transfer-case. In conventional approach, the motion of mode selection lever is translated by means of cable shift linkage or full remote linkage. Cable shift arrangement requires the cable routing in either straight direction or bent with bigger radius (approx. 150 mm), which is very difficult to achieve from packaging point of view in a vehicle layout. Further, in this case the transfer case shaft rotation requires total included angle of 48 degrees (i.e. 16 degrees per gate) to achieve the mode selection. In such a case, it becomes very difficult or almost impossible to accommodate the cable angles with respect to cable anchoring location, otherwise, the cable shift arrangement results in partial shifting or very hard shifting.
[0015] Similarly, for full remote linkage, the transfer case shaft rotation requires total included angle of 48 degrees (i.e. 16 degrees per gate) to achieve mode selection. It was also very difficult to accommodate the transfer case shaft angles in 4-bar mechanism. Further, the multiple joints of shift links, which leads to loss of efficiency and results in partial shifting or very hard shifting. Thus there is a need overcome the limitation of the conventional gear shifting mechanism.
[0016] In one implementation, a gear shifting mechanism for a vehicle is illustrated. In one embodiment, the gear shifting mechanism comprises an adapter housing, a bracket, a pin, a gear shift lever, and a shifting finger. The bracket is coupled to the adapter housing, and the bracket comprises a primary stopper and a secondary stopper. The pin is coupled to the bracket. Further, the gearshift lever is coupled to the pin, the gearshift lever pivots between the primary stopper and the secondary stopper for shifting a gear position to one of a first gear position and a second gear position.
[0017] In another embodiment, the shifting finger is coupled to the gearshift lever. The shifting finger comprises a return spring, the return spring may contract, and hold the gearshift lever onto the primary stopper for a third gear position, or the return spring may retract and push the gearshift lever to the first gear position from the third gear position.
[0018] In one embodiment there may include an advantage, the gear shifting mechanism eliminates the design complexity due to the less number of parts in gear shifting mechanism.
[0019] Now, referring to Figures 1-4, various elements of a gear shifting mechanism for a vehicle in accordance with an embodiment of the present subject matter is illustrated. The vehicle may be a four-wheel drive vehicle or a part time four wheel drive vehicle. The part time four wheel drive vehicle is a system that may allow a driver to operate the vehicle, when necessary. Figure 1 is an exploded view showing the gear shifting mechanism 100. Figure 2 illustrates stopper details 200. Figure 3 illustrates mechanical shift linkage shifting position 300. Figure 4 illustrates transfer case shifting angles 400, in accordance with an embodiment of the present subject matter.
[0020] In one embodiment, the gear shifting mechanism comprises an adapter housing, a bracket 1, a pin 2, a gearshift lever 9, and a shifting finger 5.
[0021] In another embodiment, the bracket 1 is coupled to the adapter housing. The bracket 1 may comprise a primary stopper 3 and a secondary stopper 4. Hereinafter the primary stopper 3 and the secondary stopper 4 may be referred to as stoppers. The primary stopper 3 may be cylindrical. The secondary stopper 4 may be a plate. The secondary stopper may be coupled to the bracket by screws 22. The stoppers may be mounted to the bracket 1 by means of screws. The pin 2 is coupled to the bracket 1.
[0022] The gearshift lever 9 is coupled to the pin 2. The gearshift lever 9 may pivot between the primary stopper 3 and the secondary stopper 4 for shifting a gear position to one of a first gear position and a second gear position. To facilitate the cab drop, gearshift lever (GSL) 9 is divided in to two pieces named GSL upper (10) and GSL lower. These two part are assembled by means of two screws 23.The first gear position may be one of 2H, 4H, and 4L. The second gear position may be one of 2H, 4H, and 4L.
[0023] The shifting finger 5 is coupled to the gearshift lever 9, the shifting finger 5 comprises a return spring 20. Hereinafter may be referred to as spring. The shifting finger 5 may be mounted on the pin 2. Hereinafter the shifting finger 5 may be referred to as the finger. Two polymer bushes are used for finger 5 mounting on pin 2 to reduce the friction and improve the shift feel. A harden washer 18 and a nyloc nut 19 restrict the finger 5 to come out from the pin 2. A first igus bush 17 may be coupled to the pin 2 and the shifting finger 5, and a second igus bush 17 may be coupled to the shifting finger and the harden washer 18. A spherical bush 6 is fixed on finger 5 and it is located with its flat portion in slot of transfer case lever 7 (t-case lever).
[0024] In one example, during shifting, the spherical bush 6 moves up and down as well as inside and outside with in oblong slot on t-case lever 7. Transfer-case lever 7 is mounted on the transfer case shaft. In another example, shifting force is transferred from finger 5 to transfer-case lever 7 and shifting takes place. A rubber bellow 8 is provided to protect the spherical portion of finger 5 from underbody dust, mud ingress. A spring guide pin 21 is mounted on finger 5 to hold spring 20. This spring 20 is placed between collar pin and finger 5. The spring action acts as damper to reduce vibrations at knob.
[0025] Two polymer bushes 15 are used between finger 5 and pin 13 to reduce friction and to improve shift feel. Anti-rattle polymer bush 14 is used between finger 5 and pin 13, this helps to reduce vibrations at GSL knob 12. Thus, upon matching the holes of the gear shift lever 9 with the hole of the shifting finger 5, the pin 13, anti-rattle polymer bush 14, two polymer bushes 15, and a nyloc nut 16 is coupled to the matched holes (as shown in figure 1). A thin nut 11 may be located between the GSL knob 12 and the gear shift lever 9. The thin nut 11 may be coupled to the gearshift lever and the GSL knob 12 (as shown in figure 1).
[0026] In one implementation, in one example, for a shifting a gear position from the first gear position to the second gear position. The gearshift lever 9 hits an outer surface of the primary stopper 3, the gearshift lever 9 stop at the stopper without extra travel, thus shifting the transfer case lever 7 that in turn changes the gear position by the transfer case shaft. In one aspect, the transfer case shaft may be coupled to a bottom portion of the transfer case lever 7. In another aspect, a top portion of the transfer case lever 7 is coupled to a bottom portion of the shifting finger 5. The second gear position may be four high 4H (as shown in right side diagram of figure 2 and figure 3). However, second gear position may be one of 4H, 2H, and 4L. A driver in one of a forward or a backward direction may shift the gearshift lever 9 in order to change the gear position from first to second. In one embodiment, the shifting of gears may also take place from neutral position.
[0027] In another example, for a shifting a gear position from the second gear position to the first gear position, the gear shift lever 9 hits an outer surface of the secondary stopper 4, the gear shift lever 9 stop at the stopper without extra travel, thus shifting the transfer case lever 7 which in turn changes the gear position. The first gear position may be two high 2H (as shown in figure 3). However, first gear position may be one of 4H, 2H, and 4L. A driver in one of a forward or a backward direction may shift the gearshift lever 9 in order to change the gear position from second to first.
[0028] In one another example, for shifting a gear position from the second gear position to the third gear position. The return spring may contract and hold the gearshift lever 9 onto the primary stopper 3 for the third gear position, when the driver in one of a right or a left direction shifts the gearshift lever 9. The third gear position may be four low 4L (as shown in left side diagram of figure 2 and figure 3). The third gear position may be known as an interlock gear position. The interlock gear position may be 4L. However, third gear position may be one of 4H, 2H, and 4L. A driver in one of a right or a left direction may shift the gearshift lever in order to change the gear position from second to third.
[0029] In yet another example, for shifting a gear position from the third gear position to the first gear position, the return spring 20 retracts and pushes the gearshift lever 9 to the first gear position from the third gear position, when the gearshift lever 9 is shifted from the third gear position to the first gear position.
[0030] Further, upon shifting the gearshift lever 9 from the third gear position to the first gear position by the driver, the return spring 20 retracts and the gearshift lever 9 may hit an inner surface of the secondary stopper 4. In addition, simultaneously with the operation of hitting of the gearshift lever 9, the retracted spring pushes the gear shift lever to the first gear position (2H) (as shown in figure 3). A driver in one of a forward or a backward direction may shift the gearshift lever in order to change the gear position from third to first.
[0031] In one embodiment, the transfer case shaft rotation angles is reduced while operating or shifting the gear positions (as shown in figure 4), or the mode selections is achieved efficiently due to the design of the gear shifting mechanism 100.
[0032] Exemplary embodiments discussed above may provide certain advantages, these advantages may include the following.

[0033] Some embodiments of the gear shifting mechanism provides efficient direct shift mechanism for mode selection of part time mechanical shift transfer case.

[0034] Some embodiments of the gear shifting mechanism reduces complexity of the design.

[0035] Some embodiments of the gear shifting mechanism comprising the return spring acts as a damper for reduced vibrations at GSL knob.

[0036] Some embodiments of the gear shifting mechanism comprising the polymer bush at a spherical joint and the pin joints for dampening the powertrain vibrations to gear shift lever knob.

[0037] Some embodiments of the gear shifting mechanism provides smooth shifting of gears.
[0038] Some embodiments of the gear shifting mechanism has less number of parts in the design.

[0039] Some embodiments of the gear shifting mechanism is robust and provides long-term durability.

[0040] Some embodiments of the gear shifting mechanism is cost effective.

[0041] Some embodiments of the gear shifting mechanism is suitable for both right hand drive and left hand drive vehicles.
[0042] Although implementations for the gear shifting mechanism 100 have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as examples of implementations for the gear shifting mechanism 100.
,CLAIMS:
1. A gear shifting mechanism (100) for a vehicle, the gear shifting mechanism (100) comprises:
an adapter housing;
a bracket (1), wherein the bracket (1) is coupled to the adapter housing, and wherein the bracket (1) comprises a primary stopper (3) and a secondary stopper (4);
a pin (2), wherein the pin (2) is coupled to the bracket (1);
a gear shift lever (9), wherein the gear shift lever (9) is coupled to the pin (2), wherein the gear shift lever (9) pivots between the primary stopper (3) and the secondary stopper (4) for shifting a gear position to one of a first gear position and a second gear position; and
a shifting finger (5), wherein the shifting finger (5) is coupled to the gear shift lever (9), wherein the shifting finger (5) comprises a return spring (20), and wherein the return spring (20) is configured to:
contract and hold the gear shift lever (9) onto the primary stopper (3) for a third gear position; or
retract and push the gear shift lever (9) to the first gear position from the third gear position.

2. The gear shifting mechanism (100) as claimed in claim 1, wherein during operation, the return spring (20) is configured to contract and hold the gear shift lever (9) onto the primary stopper (3) for the third gear position, when the gear shift lever (9) is shifted from the second gear position to the third gear position.

3. The gear shifting mechanism (100) as claimed in claim 1, wherein during operation, the return spring (20) retracts and pushes the gearshift lever (9) to the first gear position from the third gear position, when the gearshift lever (9) is shifted from the third gear position to the first gear position.

4. The gear shifting mechanism (100) as claimed in claim 3, during operation, the gearshift lever (9) is configured to hit a surface of the secondary stopper (4), when the gearshift lever (9) is shifted from the third gear position to the first gear position, and the gearshift lever (9) is shifted to the first gear position based on the retraction of the return spring (20).

5. The gear shifting mechanism (100) as claimed in claim 1, wherein the primary stopper (3) is cylindrical.

6. The gear shifting mechanism (100) as claimed in claim 1, wherein the secondary stopper (4) is a plate.

7. The gear shifting mechanism (100) as claimed in claim 1, wherein the gear shifting mechanism comprises a transfer case shaft, wherein the transfer case shaft is coupled to a bottom portion of the transfer case lever (7), wherein the transfer case shaft is configured to change the gear positions based on the shifting of the gearshift lever (9).

8. The gear shifting mechanism (100) as claimed in claim 7, wherein the transfer case lever (7) comprises a top portion, wherein the top portion of the transfer case lever (7) is coupled to a bottom portion of the shifting finger (5).