FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10; Rule 13)
TITLE OF THE INVENTION
“A TWIST-BLADE TYPE SUSPENSION SYSTEM OF A VEHICLE TO
VARY A ROLL STIFFNESS”
APPLICANT(S) TATA MOTORS PASSENGER VEHICLES LIMITED
Floor 3, 4, Plot-18, Nanavati Mahalaya,
Mudhana Shetty Marg, BSE,
Fort, Mumbai - 400001
Maharashtra, India
Nationality Indian.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION OF THE INVENTION
[0001] The present invention relates to vehicle suspension, and more specifically related to a twist-blade type suspension system of a vehicle to tune a roll stiffness as per the requirement.
BACKGROUND OF THE INVENTION
[0002] A twist blade type rear suspension has a structure which encompasses a cross beam and torsion tube extending in width or lateral direction of vehicle body. A pair of right and left blades each extending in a longitudinal direction of the vehicle body and the wheel mounting knuckles are rigidly connected to the opposite side of the cross-member and torsion tube. Each of the arms (also known as twist blade) has front end connected to the vehicle body and the rear end rigidly connected to cross beam, wheel knuckle, spring seat bottoms, damper mounting brackets are rigidly connected on the cross beam at opposite side ends of the cross beam just before the wheel mounting knuckle by welding. The lower plate is connected to the cross beam from bottom side to provide the required stiffness and life. Also the panhard rod twist axle side mounting bracket is welded on the right side of the twist axle. The contemporary design having single roll stiffness value requires lots of modification leading to huge cost impact in case of change in roll stiffness is required. The structure of contemporary designs is the fully fabricated welded structure having stamped / Hydroformed child parts including stab bar which provides fixed roll stiffness and does not have provision for tuning the roll stiffness according to the vehicle or project need. The conventional design causes the limitations during vehicle ride and handling tuning and also while catering the different roll stiffness requirements of other platform vehicles through commonisation.
[0003] Hence there remains a need for an improvised design of the twist-blade type suspension system that provides liberty to tune the roll stiffness as per the

requirement without much cost impact and provide a solution to above mentioned problem.
OBJECT OF THE INVENTION
[0004] The principal object of the embodiments herein is to provide a twist-blade type suspension system of a vehicle to tune a roll stiffness as per the requirement without much cost impact.
[0005] Another object of the embodiments herein is to provide slots on a stabilizer tube to reduce the roll stiffness. The required stiffness is tuned by simply providing the slots on the stabilizer tube and is further tuned inserting the right stiffener blocks at right location of the slots.
[0006] Yet another object of the embodiments is to provide different shapes of the slots based on stabilizer slot geometry. Two types of plug has been designed as a tool kit to tune the roll stiffness with slot in plug and solid plug without slot.
SUMMARY OF THE INVENTION
[0007] In one aspect the object is satisfied by providing a twist-blade type suspension system of a vehicle to vary a roll stiffness. The twist-blade type suspension system includes a torsion tube, a pair of longitudinal arms each of which extending in a longitudinal direction of the vehicle and wheel mounting knuckles of the vehicle are rigidly connected to an opposite side of a cross-member and the torsion tube, and a stabilizer tube comprising a plurality of slots provided along a length of the stabilizer tube to tune the roll stiffness by changing a position of a stiffener frame bracket.

[0008] In an embodiment, each longitudinal arms of the pair of longitudinal arms comprises a front end connected to the vehicle body and a rear end connected to the torsion beam.
[0009] In an embodiment, the plurality of slots are provided on the stabilizer tube from a center and towards an outward direction of the vehicle at equidistance.
[0010] In an embodiment, the twist-blade type suspension system includes a plug with slot inserted into the slots provided on the stabilizer tube.
[0011] In an embodiment, the twist-blade type suspension system includes a solid plug without slot inserted into the slots provided on the stabilizer tube.
[0012] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the scope thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWING(S)
[0013] The proposed a twist-blade type suspension system are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0014] FIGS. 1 illustrates a base line design of a stabilizer tube without slots, according to embodiments as disclosed herein;

[0015] FIGS. 2a illustrates the stabilizer tube with slots, according to embodiments as disclosed herein;
[0016] FIGS. 2b illustrates shape of the slots provided on the stabilizer tube, according to embodiments as disclosed herein;
[0017] FIGS. 3a illustrates the stabilizer tube with slots and plug with slot, according to embodiments as disclosed herein;
[0018] FIGS. 3b illustrates shape of the plug with slot provided on the stabilizer tube, according to embodiments as disclosed herein;
[0019] FIGS. 4a illustrates the stabilizer tube with slots and solid plug, according to embodiments as disclosed herein; and
[0020] FIGS. 4b illustrates shape of the solid plug provided on the stabilizer tube, according to embodiments as disclosed herein.
[0021] It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawing. Further, those of ordinary skill in the art will appreciate that elements in the drawing are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimension of some of the elements in the drawing may be exaggerated relative to other elements to help to improve the understanding of aspects of the invention. Furthermore, the one or more elements may have been represented in the drawing by conventional symbols, and the drawings may show only those specific details that are pertinent to the understanding the embodiments of the invention so as not to obscure the drawing with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION OF THE INVENTION
[0022] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0023] Referring now to the drawings, and more particularly to FIGS. 1a through 4b, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0024] FIGS. 1 illustrates a twist-blade type suspension system (1) having a stabilizer tube (6) without slots, according to embodiments as disclosed herein.
[0025] The twist-blade type suspension system (1) includes a torsion tube (2), a pair of longitudinal arms (3) and the stabilizer tube (6). Each longitudinal arm (3) is extending in a longitudinal direction of the vehicle and wheel mounting knuckles (4) of the vehicle are rigidly connected to an opposite side of a cross-members (5) and the torsion tube (2). Each longitudinal arms (3) of the pair of longitudinal arms (3) includes a front end connected to the vehicle body and a rear end connected to the torsion beam. The base line design of the stabilizer tube (6) without slots is shown in the FIG. 1.

[0026] FIG. 2a illustrates the stabilizer tube (6) with slots (7), according to embodiments as disclosed herein. The stabilizer tube (6) includes a plurality of slots (7) provided along a length of the stabilizer tube (6) to tune the roll stiffness by changing a position of a stiffener frame bracket. The plurality of slots (7) are provided on the stabilizer tube (6) from a center and towards an outward direction of the vehicle at equidistance. FIG. 2b illustrates shape of the slots (7) provided on the stabilizer tube (6), according to embodiments as disclosed herein. Various slots (7) are provided on the cross stabilizer tube (6) along its length to change the position of the stiffener bracket in order to modify and achieve the required roll stiffness. During the torsional loading stabilizer tube section is tends to resist the vehicle roll motion due to its sectional properties. In order to reduce the roll stiffness contribution of the twist blade slots (7) are given on the stabilizer tube (6) starting from center and towards vehicle outwards direction at equidistance which helps to change the sectional properties of the bar and reduce the roll stiffness due to the change in the sectional properties.
[0027] A separate tool kit with insulated stiffener bracket arrangement is provided to change the roll stiffness of the twist beam as per requirement. The shape of the slots (7) is decided to defuse the stress concentration during working condition which can be finalize based on the durability run. Based on the stabilizer slot geometry two types of plug has been designed as the tool kit to tune the roll stiffness with slot in plug as shown in the FIG. 3a and plug without slot as shown in the FIG. 4a.
[0028] FIG. 3a illustrates the stabilizer tube (6) with the slots (7) and plug with slot, according to embodiments as disclosed herein. In an embodiment, the twist-blade type suspension system (1) includes a plug with slot (8) inserted into the slots (7) provided on the stabilizer tube (6). The design of the plug (8) is made with sufficient interference and locking to avoid dislodge during working condition. FIG. 3b illustrates shape of the plug with slot (8) provided on the stabilizer tube (6), according to embodiments as disclosed herein. In order to increase the roll stiffness

with respect to the slots (7) provided on the stabilizer tube (6), the plug with slots (8) is inserted in to the slots (7) provided on the stabilizer tube (6). This helps to improve the sectional properties of the bar and increase the stiffness as compare to the design illustrated in the FIGS. 2a-2b.
[0029] FIG. 4a illustrates the stabilizer tube (6) with slots and solid plug, according to embodiments as disclosed herein. In an embodiment, the twist-blade type suspension system (1) includes a solid plug without slot (9) inserted into the slots (7) provided on the stabilizer tube (6). The design of the solid plug (9) is made with sufficient interference and locking to avoid dislodge during working condition. FIG. 4b illustrates shape of the solid plug without slots (9) provided on the stabilizer tube (6), according to embodiments as disclosed herein.
[0030] To regain the roll stiffness inline or slightly better than baseline design as shown in the FIGS. 2a-2b, the solid plugs without slot (9) is inserted into the slots (7) provided on the stabilizer tube (6). This helps to improve the sectional properties of the bar and increases the stiffness as compare to the baseline design as shown in the FIGS. 2a-2b. However the stiffness is expected to increase slightly than the baseline design because of enhanced sectional properties of the stabilizer tube.
[0031] The proposed design is used to enhance performance of the vehicle as fine tuning in the roll stiffness can be easily done as per the need. The proposed stabilizer tube (6) with slots (7) can be used to achieve need of different vehicles of roll stiffness easily with minimum modifications enabling comonisation of welded structure in a vehicle platform catering different segment of vehicles.
[0032] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within

the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.
[0033] List to reference numerals:

Sr. No. Description
1 twist-blade type suspension system
2 torsion tube
3 longitudinal arms
4 wheel mounting knuckles
5 cross-members
6 stabilizer tube
7 slots
8 plug with slot
9 solid plug wit hout slot

We Claim:
1. A twist-blade type suspension system (1) of a vehicle to vary a roll stiffness,
wherein the twist-blade type suspension system (1) comprises:
a torsion tube (2);
a pair of longitudinal arms (3) each of which extending in a longitudinal direction of the vehicle and wheel mounting knuckles (4) of the vehicle are rigidly connected to an opposite side of a cross-member (5) and the torsion tube (2); and
a stabilizer tube (6) comprising a plurality of slots (7) provided along a length of the stabilizer tube (6) to tune the roll stiffness by changing a position of a stiffener frame bracket.
2. The twist-blade type suspension system (1) as claimed in claim 1, wherein each longitudinal arms (3) of the pair of longitudinal arms (3) comprises a front end connected to the vehicle body and a rear end connected to the torsion beam.
3. The twist-blade type suspension system (1) as claimed in claim 1, wherein the plurality of slots (7) are provided on the stabilizer tube (6) from a center and towards an outward direction of the vehicle at equidistance.
4. The twist-blade type suspension system (1) as claimed in claim 1, comprises a plug with slot inserted into the slots (7) provided on the stabilizer tube (6).
5. The twist-blade type suspension system (1) as claimed in claim 1, comprises a solid plug without slot inserted into the slots (7) provided on the stabilizer tube (6).