FIELD OF INVENTION:
[001] The present subject matter described herein, relates to gear shifting system of manual gear transmission system of a vehicle and, in particular, to compact gear shifting system for shifting the gears in the manual gear box.
BACKGROUND AND PRIOR ART:
[002] Gear shift system is an integral part of manual and semi-automatic transmission which enable driver to shift gear as per requirement during driving of the vehicle. In the automatic transmission, I shape pattern for gear shifting is followed. Generally, H shape gear shifting pattern is present in the manual transmission mode. Both, I shape and H shape gear shifting pattern are restricted in their movement beyond specific direction.
[003] Fig. 1 illustrates conventional manual gear shift system for selecting and shifting the gears in the vehicle. The conventional manual gear shift system has gear box, gear knob, Gear Shift Lever Assembly (GSLA), and gear boot. Conventionally, the gear knob moves in H pattern to select the required gears in the gear box. Driver engages and disengages the gear by applying force on the gear knob of the GSLA. The driver applies the force on the gear knob 102 for engaging and disengaging the gear. Shifting mechanism of conventional gear is very common and person skilled in the art knows how the gears are selected and shifted in the gear box. Therefore, detailed description of the gear shifting mechanism in the conventional gear shift system is not provided in the present description to avoid ambiguity and bring clarity in the present subject matter.
[004] Fig. 2 illustrates structure of the existing gear shift tower in the gear shift system. During the select motion the load is applied on Select lever pin 2-a which causes boss select lever 3 to move in vertical direction. As the Shift Lever 1 and Shaft 15, are connected to Boss shift lever 3 with the help of Pin spring 6 of shift lever 1, and second Pin spring 7, they also move in vertical direction. The Shaft 15 moves in vertical direction in Linear bearing 16 available in Case gear shift guide 8 and a boss available in Transmission Case (not shown in the figure).
[005] Lever detent 9 and Lever gear shift and Select (LGSS) 12 are also connected to Shaft 15 with the help of third Pin spring 10 and fourth Pin spring (4) 11 so with the movement of shaft, they too move in vertical direction. Detent pin 13 and Bolt interlock 14 are fitted in Case gear shift guide 8 and are engaged to ramp profile of Lever detent 9 and H pattern on LGSS 12, respectively.
[006] The Detent pin 13 and the Lever detent 9 combination provides necessary loads during the gear shifting operation. Also Bolt interlock 14 and the LGSS 12 combination helps in controlling the gear shift stroke.
[007] The existing gear shift tower has various parts which may the shift tower heavier and costly. Further, the existing gar shift tower has lower efficiency due to large number of parts.
SUMMARY OF THE INVENTION:
[008] The subject matter disclosed herein relates to a combat gear shift system having compact gear shift tower for selecting and shifting gears in gearbox of vehicle. The shift tower assembly includes a case gear shift guide having flat profile defining an opening to receive a shaft, a select lever, and an arm extend in vertical downward direction (Y’) from lower surface of the flat profile of the case gear shift guide to receive a detent pin. The arm defines an opening at end to receive lower end of the shaft and branches into another arm to receive a bolt interlock. The shaft has shift lever at upper end which defines a shift lever pin at one end and a receiving profile at other end. The select lever has a shift lever pin configured to receive inputs from select knob and boss select lever. The boss select lever is engaged with receiving profile of the shift lever for vertical motion. The shaft is configured to be received by a Lever gear shift and Select (LGSS) by a pin spring and the bolt interlock at lower end. The LGSS is supported by the detent pin provided on the arm and the bolt interlock provided on the other arm. The lower end of the shaft rotates and linearly moves about the opening based on actuation of the shift lever. The select lever pin rotates upon load from the select knob causing the boss select lever to push the shift lever and the shaft in vertical linear motion in the case gear shift guide. Further, the detent pin moves on the LGSS profile to control loads. The bolt interlock controls stroke of the LGSS by moving inside grooves provided in the LGSS. The present compact gear shift system has less number of parts which results in cost and efficiency.
[009] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. 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 figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0011] Fig. 1 illustrates conventional manual gear shift system for selecting and shifting the gears in the vehicle;
[0012] Fig. 2 illustrates structure of the existing shift tower; and
[0013] Fig. 3 illustrates structure of compact shift tower, in accordance with an embodiment of the present subject matter; and
[0014] Fig. 4 illustrates exploded view of the compact shift tower, in accordance with an embodiment of the present subject matter.
[0015] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0016] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0017] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0018] Fig. 3 illustrates structure of present compact shift tower, in accordance with the present subject matter. In the present shift tower 100, boss shift lever 4, cover dust 5, first Pin spring 6, second Pin spring 7, lever detent 9, and pin spring 10 as shown in the figure 2 have been eliminated by replacing the whole structure with simple lever having groove or receiving profile to hold boss select lever 3.
[0019] Referring to figure 4, the shift tower 100 is shown in exploded mode. The assembly of the shift tower 100 includes a case gear shift guide 8, a shaft 15, a select lever 2 and a shift lever 1. The case gear shift guide 8 has flat profile 8a which defines an opening 8b to receive the shaft 15. The opening 8b of the case gear shift guide 8 has a linear bearing 16 at the lower surface 8e to allow the vertical linear motion of the shaft 15. The flat profile 8a of the case gear shift guide 8 is substantially in rectangular shape having mounting holes at corners to mount the case gear shift guide 8 on housing. The case gear shift guide 8 has an extended arm 8c which extend in vertical upward direction Y from upper surface 8d of the flat profile 8a to receive the select lever 2. The extended arm 8c has U shape profile to receive the select lever 2 through a pin 2b. The select lever 2 is pivotally mounted in the extended arm 8c. The select lever 2 pivotally rotates about the pin 2b in the extended arm 8c upon application of force on select lever pin 2a.
[0020] Further, the case gear shift guide 8 has an extended arm 8f which extend in vertical downward direction Y’ from lower surface 8e of the flat profile 8a. The extended arm 8f extends vertically to receive a detent pin 13 and defines an opening 8g at end to receive lower end 15b of the shaft 15. The extended arm 8f branches into another arm 8h from the end of the extended arm 8f to receive a bolt interlock 14. The arm 8f extend substantially parallel from the lower surface 8e of the case gear shift guide 8 to the shaft 15 to receive the detent pin 13 which is substantially opposite to the Lever gear shift and Select (LGSS) 12 mounted on the shaft 15. The case gear shift guide 8 can be made from a single mold.
[0021] The shaft 15 is a solid cylindrical shaft. The shaft 15 has a shift lever 1 at upper end 15a. The shift lever 1 is welded on the shaft 15 at upper end 15a. The shift lever 1 includes a shift lever pin 1a at one end and a receiving profile 1b groove shape profile at other end. The select lever 2 is mounted on the case gear shift guide 8. The select lever 2 includes a select lever pin 2a configured to receive inputs from select knob and a boss select lever 3. The boss select lever 3 is engaged with the receiving profile 1b of the shift lever 1.
[0022] At the lower end 15b of the shaft 15 after the case gear shift guide 8, the shaft 15 configured to be received by a LGSS 12 by a pin spring 11 and the bolt interlock 14. The LGSS 12 is positively mounted on the shaft 15 by the pin spring 11. The LGSS 12 has lever detent surface 12a which engages with the detent pin 13 mounted on the extended arm 8f of the case gear shift guide 8. The detent pin 13 applies direct pressure on the LGSS 12 to control the load. By providing the detent surface 12a of the LGSS 12, the requirement of the lever detent has been eliminated. The detent pin 13 provided on the extended arm 8f and the bolt interlock 14 provided on the branch arm 8h controls the motion of the LGSS 12 during shifting and selecting of gears. The lower end 15b of the shaft 15 is mounted on the opening 8g. The opening 8g allows rotation and linearly movement of the shaft 15 about the opening 8g based on actuation of the shift lever 1 and the select lever 2.
[0023] Upon load from the select knob on the select lever pin 2-a, the select lever 2 rotates about the pin 2b. The select lever 2 moves the boss select lever 3 to push the receiving profile 1b in vertical linear direction. Upon push from the boss select lever 3, the shift lever 1 and the shaft 15 moves in vertical linear motion in the case gear shift guide 8 through the linear bearing 16 for selecting the gears. During select and shift operation, the detent pin 13 moves on the detent surface of the LGSS 12 to control loads. The bolt interlock 14 moves in H pattern defined on the LGSS 12 to control the stroke. The H pattern is provided in the forms of grooves. The select lever 2 provides vertical linear motion and the shift lever 1 provides angular motion to the shaft 15 about the case gear shift guide 8.
[0024] The linear bearing 16 is shifted below making the shift tower compact. The Lever detent 9 and third Pin spring 10 have also been eliminated by using a new part having feature of both lever detent and LGSS. Refer fig. 5 and 6, this has been done by providing the detent surface or detent profile 12a of the lever detent on one of the faces of the LGSS 12 with LGSS finger 12b and H pattern 12c intact as per original design. So feature 12-a works as lever detent and feature 12b and 12c do the LGSS function. During the select motion, the complete LGSS 12 moves in vertical direction and in the shift motion, the LGSS rotates about the central axis. In the H pattern 12c, bolt interlock butting is provided at the end of the H profile grooves to control the strokes. Also in the present system, the Shaft 15 is mounted in Case gear shift guide 8 instead of mounting in transmission case.
[0025] The present system has several advantages over the existing shift tower.
[0026] 1. Present shift tower is having lesser cost as number of parts is less.
[0027] 2. Present shift tower is having better accuracy and efficiency.
[0028] 3. Present shift tower can be common
[0029] 4. Present shift tower enables case designer freedom due to elimination of shift tower mounting.
[0030] 5. The linear bearing has been moved below making the tower compact.
[0031] 6. The present shift tower is compact as over all tower height is lesser as compare to conventional tower.
[0032] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/device of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

We claim:
1. A shift tower assembly (100) for gear shift system in manual transmission, the shift tower (100) comprising:
a case gear shift guide (8) having flat profile (8a) defining an opening (8b) to receive a shaft (15), an extended arm (8c) extend in vertical upward direction (Y) from the flat profile (8a) to receive select lever (2), and an arm (8f) extend in vertical downward direction (Y’) from lower surface (8d) of the flat profile (8a) of the case gear shift guide (8) to receive a detent pin (13), wherein the arm (8f) defines an opening (8g) at end to receive lower end (15b) of the shaft (15) and branches into another arm (8h) to receive a bolt interlock (14);
the shaft (15) has shift lever (1) at upper end, wherein the shift lever (1) define a shift lever pin (1a) at one end and a receiving profile (1b) at other end ;
the select lever (2) has a shift lever pin (2a) configured to receive inputs from select knob and boss select lever (3), wherein the boss select lever (3) is engaged with the receiving profile (1b) of the shift lever (1);
the shaft (15) configured to be received by a Lever gear shift and Select (LGSS) (12) by a pin spring (11) and the bolt interlock (14) at lower end, the LGSS (12) is coupled with the detent pin (13) provided on the arm (8f) and the bolt interlock (14) provided on the other arm (8h), the lower end (15b) of the shaft (15) rotates and linearly moves about the opening (8g) based on actuation of the shift lever (1);
wherein, the select lever pin (2a) rotates upon load from the select knob causing the boss select lever (3) to push the shift lever (1) and the shaft (15) in vertical linear motion in the case gear shift guide (8),
wherein the detent pin (13) moves on the LGSS (12) profile to control loads and the bolt interlock (14) controls stroke of the LGSS (12) by moving inside grooves provided in the LGSS (12).
2. The shift tower assembly (100) as claimed in claim 1, wherein the opening (8b) of the case gear shift guide (8) has a linear bearing (16) at the lower surface to allow the vertical linear motion of the shaft (15).

3. The shift tower assembly (100) as claimed in claim 1, wherein the extended arm (8c) has U shape profile to receive the select lever (2) through a pin (2b).

4. The shift tower assembly (100) as claimed in claim 1, wherein the select lever (2) provides vertical linear motion and the shift lever (1) provides angular motion to the shaft (15).

5. The shift tower assembly (100) as claimed in claim 1, wherein the shift lever (1) is welded on the shaft (15) at upper end (15a).

6. The shift tower assembly (100) as claimed in claim 1, wherein the arm (8f) extend from the lower surface (8e) of the case gear shift guide (8) substantially parallel to the shaft (15) to received the detent pin (13) which is substantially opposite to the LGSS (12) mounted on the shaft (15).

7. The shift tower assembly (100) as claimed in claim 1, wherein the lower end (15b) of the shaft (15) is rotatably mounted in the opening provided at the arm (8f).

8. The shift tower assembly (100) as claimed in claim 1, wherein the LGSS (12) has lever detent surface (12a) for movement of detent pin (13) to apply direct pressure on the LGSS (12) to control the load.

9. The shift tower assembly (100) as claimed in claim 1, wherein the bolt interlock (14) configured to control the stroke of the shift lever (1) by moving in H pattern (12c) defined on the LGSS (12).

10. The shift tower assembly (100) as claimed in claim 1, wherein the LGSS (12) has integrated detent surface (12a) and H pattern (12c).