CLIAMS:
We claim:
1. A shift select mechanism (100) for a gear box of a vehicle, said mechanism (100) comprising:
a housing (1);
a select lever (2) positioned in a shift socket (11) of the housing (1);
a shifter shaft (3) disposed in a central bore (1a) of the housing (1), wherein the shifter shaft (3) is coupled to the select lever (2) such that the shifter shaft (3) slide axially in the central bore (1a) of the housing (1) when the select lever (2) is operated, the shifter shaft (3) is configured with
a threaded portion (3d) extending from the first end (3b) of the shifter shaft (3) up to a second predetermined distance (3e) in axial direction (A-A);
a pair of springs (6 and 7) placed concentrically to each other and provided around the shifter shaft (3), wherein the pair of springs extends from the first end (3a) of the shifter shaft to a first predetermined distance (3a) on the shifter shaft, wherein the pair of springs (6 and 7) are configured to assist the movement of shifter shaft (3) to move the select lever (2) to neutral position; and
at least one nut (10) threadingly connected to the first end (3b) of the shifter shaft (3), wherein the at least one nut (10) is configured to be threaded in axial direction (A-A) on the shifter shaft (3) to vary tension on the pair of springs (6 and 7) to adjust force on the select lever (2) through the shift shaft (3).

2. The shift select mechanism (100) as claimed in claim 1, wherein first ends (6a and 7a) of the each of the pair of springs (6 and 7) contacts a stopper element (3aa) of the shifter shaft (3) and a first stopper plate (5) provided in an inner circumference of the housing respectively.

3. The shift select mechanism (100) as claimed in claim 1, wherein a second stopper plate (8) along with the at least one nut (10) compress or extend the pair of springs (6 and 7).

4. The shift select mechanism (100) as claimed in claim 1, wherein the shifter shaft (3) comprises at least one stepped portion (3a) extending from the first end (3b) of the shifter shaft (3) up to the first predetermined distance (3c) in axial direction

5. The shift select mechanism (100) as claimed in claim 1, wherein a shift finger (4) is coupled to the shifter shaft (3).

6. The shift select mechanism (100) as claimed in claim 1 comprises an outer cap (9) for enclosing first end (3b) of the shifter shaft (3).

7. The shift select mechanism (100) as claimed in claim 4, wherein the outer cap (10) is removably connected to the housing (1).

8. The shift select mechanism (100) as claimed in claim 1, wherein the at least one nut (10) is configured to be rotated in one direction to compress the pair of springs (6 and 7) to increase the selection force on the shift lever (2).

9. The shift select mechanism (100) as claimed in claim 1, wherein the at least one nut (10) is configured to be rotated in other direction to expand the pair of springs (6 and 7) to decrease the selection force on the shift lever (2).

10. A gear box comprising a shift select mechanism as claimed in claim 1.

11. A vehicle comprising a shift select mechanism for gear box as claimed in claim 1.

Dated this 25th Day of March, 2014 GOPINATH A.S.
IN/PA 1852
OF K&S PARTNERS
AGENT FOR THE APPLICANT

,TagSPECI:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10 and rule 13]

TITLE: “A GEAR SHIFT SELECT MECHANISM FOR A GEAR BOX OF A VEHICLE”

NAME AND ADDRESS OF THE APPLICANT:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, INDIA.

Nationality: Indian

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

The present disclosure generally relates to a transmission of a vehicle. The embodiments disclose a shift select mechanism for gearbox of the vehicle.

BACKGROUND OF THE DISCLOSURE
In automotive transmission, manual gearbox is operated through gearshift lever. The operation of gearshift lever is transferred through shifter shaft to a gearshift lever/linkage in transmission for shifting the gears.

Gear shift feel is a customer touch point in all the vehicles. Good gear shifting reduces the fatigue to the user and improves the perception of the vehicle. Vehicles such as but not limiting to passenger and commercial vehicles are generally provided with 4 or more forward gears. In such vehicles, the user has to select the desired gear gate through Neutral position. While doing so, user has to overcome the selection force of the springs provided in the gearbox. The selection force depends on the springs, cable efficiency, etc. Generally, the selection forces are kept higher so that the gear shift lever returns to the neutral position after disengaging the gear.

FIG. 1 illustrates a schematic layout of a conventional shift select mechanism for a vehicle gearbox. The mechanism consists of components such as but not limiting to housing (1), select lever (2) configured in a socket provided in the housing. The select lever (2) is coupled to the shifter shaft (3) which is placed in the housing (1). The shifter shaft (3) slides in left or right direction based on the operation of the select lever (2). A shift finger (4) is connected to the shifter shaft (3), wherein the shift finger (4) comprises a finger portion, which is for operating a driver element, in particular a shift rail or shift fork. The mechanism also comprises a right select spring (6) disposed between an outer spacer (8) and a step in the shifter shaft, and a left selection spring (7) disposed concentric to the right selection spring (6) in between and inner spacer (5) and an outer spacer (8). The housing (1) comprises an integral outer portion (9) enclosing an end of the shifter shaft (3).

While selecting the gear gates on the right side, step on the shifter shaft (3) presses the right select spring (6) against outer spacer (8). Thus, it provides the selection force on the shift lever. This force helps the knob to regain its original position when gear is disengaged. Further, while selecting the gear gates on the left side, outer spacer (8) presses the left select spring (7) against inner spacer (5). Thus, it provides the selection force on the knob. This force helps the knob to regain its original position when gear is disengaged.

The conventional mechanism suffer from a drawback that selection force on the shift lever cannot be adjusted, if it is higher or lower. Also, over some time period, the spring efficiency drops and knob could not return to position on its own. However, the selection force adjustment needs to be done because over the period the spring efficiency and cable efficiency gets deteriorated and gear selection becomes difficult. Also, the perception of the drivers about the selection force, from different regions differs, which calls for different selection force.

In light of the foregoing discussion, it is observed a need for a mechanism to overcome the problems stated above.

SUMMARY OF THE DISCLOSURE
The shortcomings of the prior art are overcome and additional advantages are provided through the provision of system as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, there is provided a shift select mechanism for a gear box of a vehicle. The mechanism comprising housing, and a select lever positioned in a shift socket of the housing. Further, a shifter shaft disposed in a central bore of the housing, wherein the shifter shaft is coupled to the shift lever such that the shifter shaft slide axially in the central bore of the housing when the shift lever is operated. The shifter shaft is configured with a threaded portion extending from the first end of the shifter shaft up to a second predetermined distance in axial direction. A pair of springs are placed concentrically to each other and provided around the shifter shaft. The pair of springs extends from the first end of the shifter shaft to a first predetermined distance on the shifter shaft, and are configured to assist the movement of shifter shaft to move the shift lever to neutral position. The mechanism further includes at least one nut threadingly connected to the first end of the shifter shaft. The at least one nut is configured to be threaded in axial direction on the shifter shaft to compress or extend the pair of springs to adjust force on the shift lever through the shift shaft.

In an embodiment of the present disclosure, first ends of the each of the pair of springs contacts a stopper element of the shifter shaft and a first stopper plate provided in an inner circumference of the housing respectively.

In an embodiment of the present disclosure, a second stopper plate along with the at least one nut compress or extend the pair of springs.

In an embodiment of the present disclosure, the shifter shaft comprises at least one stepped portion extending from the first end of the shifter shaft up to the first predetermined distance in axial direction

In an embodiment of the present disclosure, a shift finger is coupled to the shifter shaft.

In an embodiment of the present disclosure, the mechanism comprises an outer cap for enclosing first end of the shifter shaft. The outer cap is removably connected to the housing.

In an embodiment of the present disclosure, the at least one nut is configured to be rotated in one direction to compress the pair of springs to increase the selection force on the shift lever, and is configured to be rotated in other direction to expand the pair of springs to decrease the selection force on the shift lever.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

OBJECTIVES OF THE DISCLOSURE

One object of the present disclosure is to provide a shift select mechanism for a gear box of a vehicle which provides an option to adjust i.e. either increase or decrease the selection force on the shift lever.

One object of the present disclosure is to provide a shift select mechanism for a gear box of a vehicle which is simple in construction and enables the user to adjust the selection force based on the requirement.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates a schematic layout of conventional shift select mechanism for a vehicle gearbox.

FIG. 2 illustrates an embodiment of a schematic layout of shift select mechanism for gearbox of a vehicle of the present disclosure.

FIG 3a illustrates shift select mechanism of FIG. 2 in which the springs are compressed by tightening the nut to increase the selection force on the shift lever.

FIG 3b illustrates shift select mechanism of FIG. 2 in which the springs are expanded by loosening the nut to decrease the selection force on the shift lever.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily 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.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the 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 disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, 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. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

To overcome the drawbacks mentioned in the background a shift select mechanism for gearbox of a vehicle is developed. In the instant system the shifter shaft is modified at its first end to accommodate the nut. The shifter shaft is provided with a threading portion up to predetermined distance to which the nut can be tightened or loosened on to the shifter shaft. The nut is configured to compress or expand the pair of springs provided on the shifter shaft to adjust the selection force on the shift lever. This adjustment can be done without completely dismantling the mechanism and/or without changing the internal components. Thus, the mechanism helps to save the time and spares required for different selection forces and improve the gear shift feel.

Reference will now be made to figures which are exemplary embodiments of the present disclosure, as illustrated in the accompanying drawings. Where ever possible referral numerals will be used to refer to the same or like parts.

In the following description the words such as above, below, left, right, middle, rear, front, clock wise and anti-clock wise are used with respect to particular orientation of the figures as depicted in the present disclosure. The words are used to explain the aspects of the present disclosure and for better understanding; however the same is not a limitation to the present disclosure.

FIG. 2 is exemplary embodiment of the present disclosure which illustrates a schematic layout of shift select mechanism also referred as top cover mechanism for gear box of a manual transmission vehicle. As illustrated in FIG. 2, the shift select mechanism (100)/top cover mechanism comprises a housing (1) which will be fixed to a vehicle floor, and is configured as housing to accommodate all the components of the shift select mechanism (100). A shift socket (11) also referred as ball socket is provided on top surface of the housing (1) for accommodating a select lever (2). Outer body of the shift socket (11) is configured in a circular form, whereas inner is configured in a hemi-sphere shape. The shift socket (11) is configured into neutral gate, and shifting gates to facilitate gear shifting in the transmission. Further, the select lever (2) is provided in the mechanism (100) to facilitate selection of gear gate. The select lever (2) comprises a spherical ball at one end, and is movably placed in the shift socket (11), and the other end is provided with a shifter knob (not shown). The select lever (2) is configured to move into the selection gates in the transmission housing for gear selection, when the driver/user operates the select lever (2).

The mechanism (100) further comprises a shifter shaft (3) disposed in a central bore (1a) of the housing (1). The shifter shaft (3) is configured with a threaded portion (3d) extending from first end (3b) of the shifter shaft (3) up to a second predetermined distance (3e) in axial direction (A-A). Threads on the threaded portion (3d) can have the configuration such as but not limiting to square threads, acme threads, triangular threads, trapezoidal threads, and any other profile which is known in the art. The shifter shaft (3) is provided with a stopper member (3aa) at a first predetermined distance (3c) from the first end (3b). In an embodiment, a portion of shifter shaft (3) between the stopper member (3aa) and the first end (3b) is configured as a stepped portion (3a). In an embodiment, the stopper member may be a step (3aa) of the stepped portion. The shifter shaft (3) is operably coupled to the shift lever (2), such that the shifter shaft (3) slide in axial direction (A-A) in the central bore (1a) of the housing (1) when the shift lever (2) is operated by the user. The shifter shaft (3) further operably coupled to the shift finger (4) for changing the gear. The shift finger (4) comprises a finger portion (not shown), which is for operating a driver element, in particular a shift rail or shift fork. In an embodiment of the present disclosure, the first predetermined distance (3c) is configured based on the maximum expansion length of the springs (6 and 7), and the second predetermined distance (3e) is configured based on the maximum compression of the springs (6 and 7).

The mechanism also comprises a pair of springs (6 and 7) arranged concentric to each other on the stepped portion (3a) of the shifter shaft (3). In an embodiment of the present disclosure, the pair of springs (6 and 7) may be compression springs. The pair of springs (6 and 7) are configured to wherein the pair of springs (6 and 7) are configured apply tension on the shifter shaft (3), and helps to assist the movement of shifter shaft (3) to move the shift lever (2) to neutral position when the gear is disengaged. The pair of springs (6 and 7) will also help in maintaining the tension on the shift lever (2) to prevent the free-play of the shift lever in neutral position. In an embodiment of the present disclosure, an inner spring (6) of the pair of springs (6 and 7) is configured as a right selection spring disposed between an second stopper plate (8) and a step (3aa) in the shifter shaft (3), and an outer spring (7) of the pair of springs (6 and 7) is configured as a left selection spring disposed concentric to the right selection spring (6) in between and a first stopper plate (5) and an outer spacer (8). The first stopper plate (5) referred herein above and below is a cup shaped member removably attached onto the inner circumference of the central bore (1a) of the housing (1). The first stopper plate (5) is configured to contact the first end (7a) of the outer spring (7). First end (6a) of the inner spring (6) is configured to contact the step (3aa) on the shifter shaft (3). The second ends (6b and 7b) of the pair of springs contacts the second stopper plate (8).

In the present disclosure, the mechanism in particular equipped with the adjustment member in the first end (3b) of the shifter shaft (3) for adjusting the tension on the shift lever by compressing and expanding the pair of springs (6 and 7). In an embodiment of the present disclosure, the adjustment member is a nut which is threadingly connected to the first end (3b) of the shifter shaft (3). The nut (10) is configured to be threaded in the threaded portion (3d) in axial direction (A-A) on the shifter shaft (3) to compress or extend the pair of springs (6 and 7) to adjust force on the shift lever (2) through the shift shaft (3). The nut is configured with internal threads, corresponds with the external threads on the threaded portion (3d) of the shifter shaft (3). Internal threads in the nut (10) can have the configuration such as but not limiting to square threads, acme threads, triangular threads, trapezoidal threads, and any other profile which is known in the art.

While selecting the gear gates on the right side, step (3aa) on the shifter shaft (3) presses the right select spring (6) against outer spacer (8). Thus, it provides the selection force on the shift lever (3). This force helps the shift lever (2) to regain its original position when gear is disengaged. Further, while selecting the gear gates on the left side, outer spacer (8) presses the left select spring (7) against inner spacer (5). Thus, it provides the selection force on the shift lever (2). This force helps the shift lever (2) to regain its original position when gear is disengaged.

The housing (1) of the mechanism (100) comprises a removable outer cap (9) for enclosing first end (3b) of the shifter shaft (3). The outer cap (10) comprises external threads (not shown) corresponds to an internal threads in the end of the housing (1). The outer cap (9) is threadingly connectable to the housing (1). This helps in centralizing the shift finger (4) whenever required.

In an embodiment of the present disclosure, the second stopper plate (8) and the nut (10) are formed as single component by configuring the nut and stopper plate as nut with integrated washer. This helps in reducing the time of assembly, and the cost of manufacturing. In an alternative embodiment, the second stopper plate (8) may not be provided and the nut (10) may be configured to act as stopper plate by increasing the total diameter of the nut (10).

FIG 3a is an exemplary embodiment of the present disclosure illustrating shift select mechanism (10) in which the pair of springs (6 and 7) is compressed by tightening-in the nut (10) to increase the selection force on the select lever (2). For increasing the tension on the shifter shaft (3), a compression of the pair of springs (6 and 7) need to be increased. To achieve this, the user or mechanic can remove the outer cap (9) from the housing (1), then the nut (10) is rotated in one direction, in an embodiment, clockwise direction to thread in axial direction (A-A) by threading the nut (10) onto the threaded portion (3d) of the shifter shaft. This helps in compressing the springs (6 and 7) to increase the tension on the shifter shaft (3) thereby on the select lever (2). The increased tension on the select lever (2) ensures the shifter shaft (3) to return to the neutral position when the gears are disengaged.

FIG 3b is an exemplary embodiment of the present disclosure illustrating shift selection mechanism (10) in which the pair of springs (6 and 7) is expanded by tightening the nut (10) to decrease the selection force on the select lever (2). For decreasing the tension on the shifter shaft (3), a compression of the pair of springs (6 and 7) need to be decreased. To achieve this, the user or mechanic can remove the outer cap (9) from the housing (1), then the nut (10) is rotated in other direction, in an embodiment, anti-clockwise direction to thread in axial direction (A-A) by threading-out the nut (10) in threaded portion (3d) of the shifter shaft (3). This helps in expanding the springs (6 and 7) to decrease the tension on the shifter shaft (3) thereby on the select lever (2). The decreased tension on the select lever (2) decreases the selection effort on the shifter shaft (3), thereby improves comfortablity of the user.

Thus, with mechanism (100) proposed in the present disclosure the gear selection feel can be improved without dismantling and changing the internal components. The select force can be adjusted by the drivers or mechanics easily, reducing the discomfort levels of the customers.

Advantages:
The present disclosure provides a shift select mechanism for a gear box of a vehicle which provides an option to adjust i.e. either increase or decrease the selection force on the shift lever. This adjustment can be done without completely dismantling the mechanism and/or without changing the internal components. Thereby saves maintenance time of the vehicle.

The present disclosure provides a shift select mechanism for a gear box of a vehicle which enables the user to adjust the selection force based on the requirement without completely removing the parts. Thus, the mechanism helps to save the time and spares required for different selection forces and improve the gear shift feel.

The present disclosure provides a shift select mechanism for a gear box which is simple in construction and easy to maintain.

The present disclosure provides a shift select mechanism for a gear box in which mechanism can be used for all gears.

Equivalents:

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals:
Reference Number Description
100 Shift select mechanism
1 Housing
1a Internal bore
2 Select lever
3 Shifter shaft
3a Stepped portion
3aa Stopper member/Step
3b First end of the shifter shaft
3c First predetermined distance
3d Threads
3e Second predetermined distance
4 Shift finger
5 First stopper plate
6 and 7 Pair of springs
6a and 7a First end pair of springs
6b and 7b Second end pair of springs
8 Second stopper plate
9 Outer cap
10 Nut