[001] The present subject matter described herein, relates to structure of floor panel of vehicle, and in particular, to structure of rear floor panel for improvement in torsional stiffness. More particularly, the present subject matter relates to improvement in torsional stiffness in rear floor front portion of the rear floor panel of the vehicle over which bed behind driver seat is mounted.
BACKGROUND AND PRIOR ART:
[002] In the vehicle running condition when a vehicle encounters a bump, it experiences the twisting effect. As a result, it gives an undesirable feeling to the person sitting inside the vehicle. Torsional stiffness of Body In White (BIW) is an important parameter which directly controls this twisting effect and improves the handling performance of the vehicle. Higher the torsional stiffness of the BIW better would be the handling performance of the vehicle. In controlling the torsional stiffness of the structure, the floor of the BIW plays an important role. Better the stiffness of the floor panels better would be the overall torsional stiffness of the BIW structure.
[003] Further, this stiffness can be achieved either by proposing increase in panel thickness of the floor area or reinforcement addition in sensitive floor areas of the BIW. However, these proposals cause cost and weight addition that would hamper the cost targets and overall fuel efficiency of the vehicle and thus, the vehicle manufacturer would avoid these solutions to attain the desired performance.
[004] Referring to figure 1 below, in the existing design, when the vehicle is subjected to twist loads in case of uneven roads in the actual running condition, the floor tends to bend at the center. The current design of the rear floor front area is such that it causes bending in the vertical direction due to the continuity of the profile at the encircled region. Referring to figure 1, the panel floor 100 includes a center floor portion 101 between the driver seat and rear occupant's seat, a rear

floor front portion 102, rear floor portion 103 and side quarter panel 104. On the rear floor front portion 102, a bed that is seat for the rear occupants is mounted.
[005] Referring to figure 2, the rear floor front portion 102 has a plurality of
beads structure 102a 102f which extend in longitudinal direction Y. The
longitudinal direction Y indicates direction of vehicle length. The plurality of
beads structures 102a 102f is provided in vehicle width direction, i.e.,
transverse direction X. During running condition of the vehicle, the vehicle has torsional movement which tends to bring a twist effect to the structure.
[006] In order to cater the torsional movement and noise in the vehicle cabin, several technical improvements are made. However each improvement has some drawbacks.
[007] The floor panel of an automobile or the like is provided with beads that laterally and longitudinally intersect each other. This can increase the rigidity of the floor panel against the bending mode of a car body in the side-to-side and back-and-forth directions and reduce a vibration/noise. Since loads concentrate to a portion where a lateral bead and a longitudinal bead intersect, a starting point for bending is formed.
[008] In another method, a high board thickness of the floor panel is provided which result in increased weight of the vehicle. Further, some technologies provide reinforcement in the panel floor which also result in increase in weight of the floor which is not desirable.
[009] In the current automotive environment, automakers or vehicle makers are striving hard to introduce innovative ideas in order to reduce weight and cost of the vehicle keeping the aesthetics and performance of the vehicle unaffected. The design of the rear floor front area is an important parameter that contributes in the overall torsional stiffness of the vehicle. In order to improve the torsional stiffness of the vehicle, either the thickness of the panels in the rear floor front area may be increased or reinforcements can be provided to provide the appropriate strength.

However, addition of these make vehicle heavy and costly, due to which either of the above solutions would be non-recommended.
[0010] Technical problem in the existing rear floor panel is high deformation in rear floor front panel due to torsional load. In order to achieve the present objective or solution for the present technical problem, the inventor of the present invention faces the several major technical issues, such as weight and cost. Hence, keeping the stringent cost targets intact the inventors of the present subj ect matter or present invention propose a new design and structure of the rear floor panel by studying the section of the sheet metal components in the main floor area. The inventors gone through various iterations to achieve the present design and structure. Therefore, the inventors have invested their labour, time, and intellect to develop the present invention to solve the above mentioned technical problem. The present design and structure of the rear floor panel helps in improving the torsional stiffness of vehicle and provides strength to the floor of the BIW when the vehicle is subjected to torsional loads in running conditions. Further, detailed explanation is given in the drawings and detail description of the invention.
OBJECTS OF THE INVENTION:
[0011] The principal objective of the present invention is to provide a rear floor panel structure to provide torsional stiffness in vertical direction Z along height of the vehicle.
[0012] Another object of the present subject matter is to provide a rear floor panel structure with torsional stiffness without adding any extra weight or reinforcement and cost.
[0013] Another object of the present subject matter is to provide rear floor panel structure having a plurality of beads with variable configuration to provide stiffness in longitudinal direction Y and transverse direction X.
SUMMARY OF THE INVENTION:
[0014] The subject matter disclosed herein relates to rear floor panel structure of a vehicle for improving torsional stiffness. The rear floor panel structure has a rear

floor front panel structure configured to receive a bed for occupants and a rear floor rear panel structure configured to receive a spare tyre. Further, the rear floor rear panel structure defines luggage room or boot area of the vehicle. The rear floor front panel structure is provided with a step running across width of the vehicle in transverse direction (X) to provide stiffness towards vertical direction (Z). Further, the rear floor front panel structure is provided with a plurality of beads to make the rear floor front panel structure stiff in directions X and Y.
[0015] 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
[0016] 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:
[0017] Fig. 1 illustrates structure of rear floor as known in the art;
[0018] Fig. 2 illustrates structure of rear floor panel as known in the art;
[0019] Fig. 3 illustrates structure of rear floor panel, in accordance with an embodiment of the present subject matter;
[0020] Fig. 4 illustrates structure of rear floor front panel as shown in the figure 3, in accordance with an embodiment of the present subject matter; and

[0021] Fig. 5a and 5b illustrate cross section comparison A-A and B-B of structure of rear floor front panel as shown in the figure 4 and 2, in accordance with an embodiment of the present subject matter.
[0022] The figures depict embodiments of the present subject matter for the 5 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:
10 [0023] The subject matter disclosed herein relates to rear floor panel structure of a vehicle for improving torsional stiffness. The rear floor panel structure has a rear floor front panel structure configured to receive a bed for occupants and a rear floor rear panel structure configured to receive a spare tyre. Further, the rear floor rear panel structure defines luggage room or boot area of the vehicle. The rear
15 floor front panel structure is provided with a step running across width of the vehicle in transverse direction (X) to provide stiffness towards vertical direction (Z). Further, the rear floor front panel structure is provided with a plurality of beads to make the rear floor front panel structure stiff in directions X and Y.
[0024] It should be noted that the description and figures merely illustrate the
20 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
25 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
30 construed as being without limitation to such specifically recited examples and
6

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 5 figures.
[0025] 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 10 various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0026] In the current automotive environment, automakers are striving hard to introduce innovative ideas in order to reduce weight and cost of the vehicle keeping the aesthetics and performance of the vehicle unaffected. In the same line,
15 a new modified design and structure of the rear floor front area has been proposed in the present subject matter which results in improved vehicle handling performance by increasing the torsional stiffness of the vehicle. The design of the rear floor front area is an important parameter that contributes in the overall torsional stiffness of the vehicle. In order to improve the torsional stiffness of the
20 vehicle, either the thickness of the panels in the rear floor front area may be increased or reinforcements can be provided to provide the appropriate strength. However, with these additions cost of the vehicle is increased, due to which either of the above solutions would be non-recommended. Hence, keeping the stringent cost targets intact, a new design and structure has been proposed by the inventors
25 investing lot of time, labour, and intellect in studying the section of the sheet metal components in the main floor area. The optimized section is disclosed in the present description after performing various iterations by the inventors. The present design and structure helps in improving the torsional stiffness of vehicle and provides strength to the floor of the BIW when the vehicle is subjected to
30 torsional loads in running conditions.
7

[0027] In the present design and structure of rear floor panel structure, section modifications are made in the main floor area as compared to the current designs. The new section provides better stiffness in the region which restricts the deformation about bending line A-A and increases the torsional stiffness of the 5 vehicle.
[0028] Referring to figure 3, a rear floor panel structure 300 of the vehicle is disclosed. The rear floor panel structure 300 has rear floor front panel structure 301 and rear floor rear panel structure 302. The rear floor front panel structure 301 is configured to receive a bed for rear occupants of the vehicle. The bed applies
10 pressure due to weight on the rear floor front panel structure 301. Further, the occupant’s seating on the bed feels the torsional movement during a bump. The rear floor rear panel structure 302 is configured to receive a spare tyre of the vehicle. Above the spare tyre, the rear floor rear panel structure 302 defines boot space for the vehicle to receive luggage. In the earlier designs and structure, the
15 rear floor front panel structure 301 faces torsional movement during a bump in vehicle running condition. In the present subject matter, a step is provided at the rear floor front panel structure 301 running across the width of the vehicle to control bending of the panel during bump.
[0029] Referring figure 4 which illustrates section structure of the rear floor front 20 panel structure 400. The rear floor front panel structure 400 (301 as referred in figure 3) is an elevated portion of the rear floor panel structure 300 to receive the bed for rear occupants. The rear floor front panel structure 400 is provided with a step 404 running across the width of the vehicle in transverse direction X to provide stiffness towards vertical direction Z and to control bending of the panel 25 during bump. Further, height and angle of the step 404 depends on the size and configuration of the vehicle. For example, height of the step 404 of hatch back vehicle is different from the sedan type vehicle.
[0030] In an embodiment of the present subject matter, a plurality of beads 401,
402, 403 is arranged on the rear floor front panel structure 400 to provide stiffness
30 to the rear floor front panel structure 400 in longitudinal direction Y and in
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transverse direction X. Further, the plurality of beads 401, 402, 403 is provided in variable configurations, such as rectangular, triangular, pentagon, hexagon. Furthermore, the plurality of beads 401, 402, 403 is provided asymmetrically along the step 404 without any connection with the step 404 to avoid any crack in 5 the rear floor front panel structure 400. The plurality of beads 401, 402, 403 is provided at a predetermined and optimized distance from the step in longitudinal direction Y for torsional stiffness. The plurality of beads 401, 402, 403 is arranged on the rear floor front panel structure 400 in vehicle width direction X to cater noise and vibrations in directions X and Y.
10 [0031] In an embodiment of the present subject matter, the step 404 is provided substantially in middle position of the rear floor front panel structure 400 having width W to provide torsional stiffness in direction Z.
[0032] In an embodiment of the present subject matter, the step 404 and the plurality of beads 401, 402, 403 are provided by a simple press machine.
15 [0033] In an embodiment of the present subject matter, number, shape, and configuration of the plurality of beads 401, 402, 403 can be optimized based on the shape, size, and configuration of the vehicle. For example, a hatch back type vehicle may have different plurality of beads 401, 402, 403 with number and configuration than the sedan type of vehicle.
20 [0034] In an embodiment of the present subject matter, the plurality of beads 401, 402, 403 is run on the rear floor front panel structure 400 in vehicle longitudinal direction Y. In other terms, the length of the plurality of beads 401, 402, 403 run in the longitudinal direction Y.
[0035] In an embodiment of the present subject matter, the rear floor front panel 25 structure 400 is made of metal.
[0036] Referring back to figure 4, cross section A-A and B-B are provided to analyze the section view of the rear floor front panel structure 400 along with step 404 and the plurality of beads 401, 402, 403. By comparing cross sectional view A-A and B-B of figure 2 and figure 4 in the figure 5a and 5b respectively, the
9

cross sectional view A-A of the figure 2 and figure 4 illustrate that the present structure of the rear floor front panel structure has a step whereas the existing design has a flat profile. In the existing design of rear floor front portion as shown in figure 2 and in figure 5a and 5b, the flat profile of the panel does not provide 5 adequate stiffness to it. As a result, high bending in the vertical direction is observed when subjected to twist loads. However, by providing the step in the rear floor front panel structure, the stiffness of the panel is increased. As a result, during vehicle running condition, deformation in the present rear floor front panel structure is less than deformation in the existing design of rear floor front portion 10 as shown in figure 2. The present rear floor front panel structure provides better handling performance without adding weight and cost.
[0037] The term “vehicle” or “Automobile” as used throughout this detailed description and in the claims refers to any moving vehicle that is capable of carrying one or more human occupants or Goods and is powered by any form of 15 energy. The term “vehicle” is a motor vehicle which includes, but is not limited to: cars, trucks, vans, minivans, hatchback, sedan, MUVs, and SUVs.
[0038] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps
20 or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated
25 embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the
30 practice of the methods herein. The use of “comprising” or “including” also
10

contemplates embodiments that "consist essentially of or "consist of the recited feature.
[0039] 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/component 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:
A rear floor panel structure (300) of a vehicle for improving torsional stiffness, the rear floor panel structure (300) comprising:
a rear floor front panel structure (400) configured to receive a bed for occupants,
characterized in that
the rear floor front panel structure (400) is provided with a step (404) running across width of the vehicle in transverse direction (X) to provide stiffness towards vertical direction (Z).
The rear floor panel structure (300) as claimed in claim 1, wherein a plurality of beads (401, 402, 403) is provided on the rear floor front panel structure (400).
The rear floor panel structure (300) as claimed in claim 1, wherein a plurality of beads (401, 402, 403) is arranged along the step (404) to provide stiffness to the rear floor front panel structure (400) in the longitudinal direction Y and in transverse direction X.
The rear floor panel structure (300) as claimed in claim 3, wherein the plurality of beads (401, 402, 403) is in variable configurations.
The rear floor panel structure (300) as claimed in claim 5, wherein the variable configurations are selected from a group of polygon shapes, the polygon shapes are triangular, rectangular, pentagon, and hexagon.
The rear floor panel structure (300) as claimed in claim 4, wherein the plurality of beads (401, 402, 403) is provided at a predetermined distance from the step (404) in longitudinal direction for improving torsional stiffness.

The rear floor panel structure (300) as claimed in claim 4, wherein the plurality of beads (401, 402, 403) is arranged on the rear floor front panel structure (400) in vehicle width direction X.
The rear floor panel structure (300) as claimed in claim 4, wherein the rear floor front panel structure (400) is made of metal.
The rear floor panel structure (300) as claimed in claim 1, wherein the step (404) is provided substantially at middle portion of the rear floor front panel structure (400) in vehicle width direction (X).