Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]

TITLE OF INVENTION
Floor Structure for a Vehicle

APPLICANT
Mahindra & Mahindra Limited, an Indian company, having its address at Mahindra Research Valley, Mahindra World City, Plot No:41/1, Anjur P.O., Chengalpattu, Kanchipuram District, Tamil Nadu – 603004, India

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

FIELD OF THE INVENTION
[001] Present disclosure relates to a floor structure for a vehicle.

BACKGROUND OF THE INVENTION
[002] A floor structure or an underbody floor structure of a passenger vehicle is a part corresponding to a frame that extends along a front-rear direction of the vehicle. The floor structure serves to support mechanical and structural components such as powertrain components, a suspension system and the like.
[003] Typically, the conventional vehicles are provided with floor structure of a split-type construction wherein each part of the floor structure is stamped and thereafter each stamped part is joined together through welding joints. As such, the floor structure is formed by joining multiple sheet metal parts together.
[004] However, such a construction of the frame structure increases investment costs. Also, weight of the frame structure increases, consequently reducing performance and fuel efficiency of the vehicle. Additionally, the number of tools and equipment required for manufacturing the floor structure also increases, making the manufacturing process complex, cumbersome, and expensive, which is undesirable. Further, increase in the number of tools and equipment increases overall process time required for manufacturing the floor structure. Additionally, due to inclusion of multiple sheet metal components, tool development time required for manufacturing the floor structure increases, which is undesirable.
[005] In view of the above, there is a need for a floor structure which overcomes one or more limitations stated above.

SUMMARY OF THE INVENTION
[006] In one aspect, a floor structure for a vehicle is provided. The floor structure comprises a front floor panel extending in a front-rear direction of the vehicle, an intermediate floor panel extends rearwardly from the front floor panel and a rear floor panel extends rearwardly from the intermediate floor panel. The front floor panel and the rear floor panel are coupled to the intermediate floor panel through a first TWB line and a second TWB line respectively, to form a unibody floor structure for the vehicle.
[007] In an embodiment, each of the front floor panel, the intermediate floor panel and the rear floor panel is made of a steel of different grades and different gauges.
[008] In an embodiment, the front floor panel and the intermediate floor panel are made by one of a High Strength (HS) steel material and an Advanced High Strength Steel (AHSS) material having an Ultimate Tensile Strength of at least 400MPa, and the rear floor panel is made by a Low Strength (LS) steel material having an Ultimate Tensile Strength of maximum of 400MPa.
[009] In an embodiment, the rear floor panel is provided with a lower thickness than the front floor panel, and the intermediate floor panel is provided with a thickness greater than the front floor panel.
[010] In an embodiment, the front floor panel has a thickness of 0.55 mm to 0.8 mm, the intermediate floor panel has a thickness of 0.6mm to 1 mm and the rear floor panel has a thickness of 0.55 mm to 0.8 mm.
[011] In an embodiment, each of the first TWB line and the second TWB line comprises of a plurality of layers of steel material, and wherein each of the first TWB line and the second TWB line is provided with a thickness of 0.55 mm to 1.6 mm.
[012] In an embodiment, the front floor panel is provided with a tunnel portion about a central plane of the floor structure for accommodating one or more transmission components of the vehicle.
[013] In an embodiment, a front edge of the front floor panel is adapted to receive a lower dash assembly of the vehicle and a top surface of the front floor panel is adapted to receive one or more front seat cross member and one or more long members of the vehicle.
[014] In an embodiment, a left side of the front floor panel and a left-end side of the intermediate floor panel are adapted to receive a left sill assembly of the vehicle. Also, a right side of the front floor panel and a right-end side of the intermediate floor panel are adapted to receive a right sill assembly of the vehicle.
[015] In an embodiment, a rear rim surface of the rear floor panel is adapted to receive a rear sill assembly of the vehicle. An upper surface of the rear floor panel is adapted to receive one or more rear seat cross members of the vehicle. Also, a lower surface of the rear floor panel is adapted to receive a rear cradle assembly of the vehicle. A left-end portion of the rear floor panel is adapted to receive a left wheelhouse assembly of the vehicle and a right-end portion of the rear floor panel is adapted to receive a right wheelhouse assembly of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS
[016] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 is a front perspective view of a floor structure of a vehicle, in accordance with an exemplary embodiment of the present disclosure.
Figure 2 is a top view of the floor structure, in accordance with an exemplary embodiment of the present disclosure.
Figure 3 is a rear perspective view of the floor structure mounted with structural components of the vehicle, in accordance with an exemplary embodiment of the present disclosure.
Figure 4 is a bottom perspective view of the floor structure of Figure 3, in accordance with an exemplary embodiment of the present disclosure.
Figure 5 is a bottom view of the floor structure depicting a load path, in accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[017] The present invention provides a floor structure for a vehicle. The floor structure comprises a front floor panel, a rear floor panel and an intermediate panel. The front floor panel is coupled to an intermediate panel through a first tailored weld blank line, while the rear floor panel is coupled to the intermediate panel through a second tailored weld blank line. Such a construction makes the floor structure to be a unibody structure, thereby minimizing the tools required and joining processes required for manufacturing the floor structure. As such, the weight of the floor structure is considerably reduced, thereby improving performance and fuel efficiency of the vehicle.
[018] Figure 1 illustrates a front perspective view of a floor structure 100 for a vehicle, in accordance with an exemplary embodiment of the present invention. The floor structure 100 is adapted to be a unibody structure, thereby mitigating the drawbacks resulting from joining of multiple floor panels as made in conventional floor structures. In the present embodiment, the floor structure 100 is configured for a four wheeled vehicle (not shown). Alternatively, the floor structure 100 can be configured for any multi-wheeled vehicle, as per requirement.
[019] As shown in Figures 1 and 2, the floor structure 100 comprises a front floor panel 102, an intermediate floor panel 104 and a rear floor panel 106 extending in a front-rear direction (arrow indications provided in Figures 1 and 2) of the vehicle. In an embodiment, each of the front floor panel 102, the intermediate floor panel 104 and the rear floor panel 106 is made of steel of different grades and different gauges or thickness resulting in a reduction in overall weight of the floor structure 100.
[020] In an embodiment, the front floor panel 102 is made by one of a High Strength Steel (HS) material and an Advanced High Strength Steel (AHSS) material having an Ultimate Tensile Strength of at least 400MPa. In an embodiment, the front floor panel 102 is made by dual phase steels or a High Strength Low Alloy (HSLA) steel or a transformation induced plasticity steel having the Ultimate Tensile Strength as mentioned herein before. In an embodiment, a thickness of the front floor panel 102 is 0.55 mm to 0.8 mm. Such a construction of the front floor panel 102 mitigates the need for reinforcement members for resisting deformation in the event of a frontal collision of the vehicle, thereby enhance safety to a driver or a co-driver area of the vehicle.
[021] Further, the floor structure 100 comprises the intermediate floor panel 104 that extends longitudinally and rearwardly from the front floor panel 102. Particularly, the intermediate floor panel 104 extends rearwardly from a rear edge 102b of the front floor panel 102. The intermediate floor panel 104 is made by one of a High Strength Steel (HS) material and an Advanced High Strength Steel (AHSS) material having an Ultimate Tensile Strength of at least 400MPa. In an embodiment, the intermediate floor panel 104 is made by dual phase steels or a High Strength Low Alloy (HSLA) steel or a transformation induced plasticity steel having the Ultimate Tensile Strength as mentioned herein before. In an embodiment, the intermediate floor panel 104 has a thickness of 0.6 mm to 1 mm. The intermediate floor panel 104 is provided with a thickness greater than that of the front floor panel 102, to resist deformation in the event of the front collision of the vehicle or side impact collision. Also, the greater thickness imparts a greater torsional stiffness and a greater bending stiffness to the intermediate floor panel 104 than the front floor panel 102. Additionally, the thickness of the intermediate floor panel 104 is considered based on stiffness requirement for the floor structure 100 in the event of a side impact or side collision. In an embodiment, the torsional stiffness of the intermediate floor panel 104 is at least 11KN/mm. In another embodiment, the bending stiffness of the intermediate floor panel 104 is at least 18KN/mm. Such a construction ensures that penetration of deformation of the floor structure 100 terminates at the intermediate floor panel 104.
[022] Further, the intermediate floor panel 104 is connected to the rear edge 102b of the front floor panel 102 through a first Tailored Weld Blank (TWB) line 108. In an embodiment, the first TWB line 108 is formed by butt-joining the rear side 102b and a front-end side 104a of the intermediate floor panel 104. The butt-joining may be performed through a laser-welding technique. As such, the first TWB line 108 is formed of plurality of steel materials. In the present embodiment, the first TWB line 108 is made of HS material and/or AHSS material. In an embodiment, the first TWB line 108 is formed with a thickness of 0.55 mm to 1.6 mm and with a strength of 270MPa to 780MPa.
[023] Further, the floor structure 100 comprises the rear floor panel 106 that extends longitudinally and rearwardly from the intermediate floor panel 104. Particularly, the rear floor panel 106 extends rearwardly from a rear end side 104b of the intermediate floor panel 104. The rear floor panel 106 is made by a Low Strength Steel (HS) material having a maximum Ultimate Tensile Strength of 400MPa. In an embodiment, the rear floor panel 106 is made of interstitial free high strength steel. In an embodiment, the rear floor panel 106 has a thickness of 0.55 mm to 0.8 mm. The rear floor panel 106 is provided with a lower thickness than the front floor panel 102 and the intermediate floor panel 104, as higher strength is unnecessary at the rear floor panel 106. This is due to the fact that, in the event of a frontal crash, the deformation penetration is absorbed by the front floor panel 102 and the intermediate floor panel 104. Accordingly, thickness of the rear floor panel 106 is considered lower than the front floor panel 102 and the intermediate floor panel 104.
[024] Further, the rear floor panel 106 is connected to the rear end side 104b of the intermediate floor panel 104 through a second TWB line 110, thereby forming a unibody structure of the floor structure 100. In an embodiment, the second TWB line 110 is formed by butt-joining the rear end side 104b and a front-rim surface 106a of the rear floor panel 106. The butt-joining may be performed through a laser-welding technique. As such, the second TWB line 110 is formed of plurality of steel materials. In the present embodiment, the second TWB line 110 is made of HS material and/or AHSS material and/or the low strength steel material. In an embodiment, the second TWB line 110 is formed with a thickness of 0.55 mm to 1.6 mm and with a strength of 270MPa to 780MPa. Thus, the floor structure 100 is formed by joining the front floor panel 102, the intermediate floor panel 104 and the rear floor panel 106 through the first TWB line 108 and the second TWB line 110. The first TWB line 108 and the second TWB line 110 ensure to produce a single blank of the front floor panel 102, the intermediate floor panel 104 and the rear floor panel 106 prior to a forming process. As such, the floor structure of a split-type construction wherein each part of the floor structure is stamped and thereafter each stamped part is joined together through welding joints is eliminated in the present invention. Further, the first TWB line 108 and the second TWB line 110, make the manufacturing process of the floor structure 100 inexpensive, simple, and less laborious.
[025] Referring to Figures 3 and 4 in conjunction with Figures 1 and 2, the floor structure 100 supporting one or more structural components and/or the transmission components of the vehicle is depicted.
[026] As shown in Figure 3, the front floor panel 102 comprises a tunnel portion 112 extending from a front edge 102a and terminating at the rear edge 102b of the front floor panel 102. The tunnel portion 112 extends along a central plane X-X’ of the floor structure 100. The tunnel portion 112 is adapted to accommodate one or more transmission components of the vehicle such as a transmission housing, a propeller shaft and the like. Further, at the front edge 102a of the front floor panel 102 a lower dash assembly 114 of the vehicle is mounted. The lower dash assembly 114 is oriented vertically to the floor structure 100. The lower dash assembly 114 is adapted to separate an engine cabin 144 (shown in Figure 5) from a passenger cabin (not shown) of the vehicle. Additionally, a top surface 116 (shown in Figure 1) of the front floor panel 102 is adapted to receive one or more front seat cross members 118 and one or more long members 120 of the vehicle. The one or more front seat cross members 118 and the one or more long members 120 are provided on either side of the tunnel portion 112. The one or more front seat cross members 118 extend laterally to the floor structure 100 or to the central plane X-X’ and is adapted to support a seat member (not shown) of the vehicle. The one or more long members 120 extend along the central plane X-X’ and is adapted to act as a structural member for absorbing impact or shock loads during collision of the vehicle.
[027] Further, a left side 102c (shown in Figure 2) of the front floor panel 102 and a left-end side 104c (shown in Figure 2) of the intermediate floor panel 104 are adapted to receive a left sill assembly 122 of the vehicle. Also, a right side 102d (shown in Figure 2) of the front floor panel 102 and a right-end side 104d (shown in Figure 2) of the intermediate floor panel 104 are adapted to receive a right sill assembly 124 of the vehicle. The left sill assembly 122 and the right sill assembly 124 are also adapted to act as a structural member to the floor structure 100. In an embodiment, the left sill assembly 122 and the right sill assembly 124 are joined to the front floor panel 102 and the intermediate floor panel 104 through a welding technique. In an embodiment, on a bottom surface 148 (as shown in Figure 4) of the front floor panel 102, a front cradle assembly 146 is mounted as a structural member. The front cradle assembly 146 may be mounted onto the bottom surface 148 through the welding technique.
[028] Furthermore, a rear rim surface 106b (as shown in Figure 2) of the rear floor panel 106 is adapted to receive a rear sill assembly 126. The rear sill assembly 126 engages with the rear rim surface 106b through the welding technique. The rear sill assembly 126 is adapted to act as a structural member for the rear floor panel 106. Accordingly, the rear sill assembly 126 adds strength to the rear floor panel 106 for withstanding impact loads during a rear collision of the vehicle.
[029] On an upper surface 128 (shown in Figure 1) of the rear floor panel 106 one or more rear seat cross members 130 of the vehicle are mounted. The one or more rear seat cross members 130 are mounted onto the rear floor panel 106 through the fastening technique. The one or more rear seat cross members 130 extend laterally to the central plane X-X’ of the floor structure 100 and is adapted to support a rear seat member (not shown) of the vehicle. On a lower surface 132 (shown in Figure 4) of the rear floor panel 106 is adapted to receive a rear cradle assembly 134 of the vehicle. The rear cradle assembly 134 also acts as a structural member for the rear floor panel 106. Additionally, a left-end portion 136 of the rear floor panel 106 is adapted to receive a left wheelhouse assembly 138 of the vehicle, while a right-end portion 140 of the rear floor panel 106 is adapted to receive a right wheelhouse assembly 142 of the vehicle. The left wheelhouse assembly 138 and the right wheelhouse assembly 142 engage with the left-end portion 136 and the right-end portion 140 respectively through the welding technique. The left wheelhouse assembly 138 and the right wheelhouse assembly 142 are adapted to support a shock absorber system of the vehicle.
[030] Figure 5 is a bottom view of the floor structure 100 depicting a load path, in accordance with an exemplary embodiment of the present disclosure. In the event of the frontal collision of the vehicle, the impact load traverses (indicated through arrows) through the one or more long members 120 whereby, the engine cabin 146 would be a crumple zone where there is controlled deformation and forces from impact is absorbed immediately after the crumple zone. A portion (not shown) of the front floor panel 102 disposed behind the engine cabin 146 (along front-rear direction of the vehicle) resists the remaining impact forces. Also, the impact load dissipates or traverses through the one or more long members 120 resisting deformation of the front floor panel 102. Further, the intermediate floor panel 104 resists the remaining impact forces preventing deformation of the rear floor panel 106. The intermediate floor panel 104 also resists deformation in case of side impact collision as discussed hereienbefore. The impact forces that are being absorbed and resisted by the front floor panel 102 and the intermediate floor panel 104 respectively, thus protect the occupant cabin area, consequently, ensuring occupant safety.
[031] Advantageously, the present invention provides the floor structure which is capable of being made to the unibody structure through the first TWB line and the second TWB line. In other words, the floor structure is made as the unibody structure through joining of the front floor panel, the intermediate floor panel and the rear floor panel through the first TWB line and the second TWB line mitigates the need for prior forming or stamping process, as carried out in conventional floor structures. Accordingly, the first TWB line and the second TWB line, make the manufacturing process of the floor structure inexpensive, simple, and less laborious. Additionally, the floor structure ensures that the impact forces transferred during a collision (e.g. frontal collision) are resisted. Also, floor structure ensures that the impact forces are transferred along sides portions of the front floor panel and the intermediate floor panel, thereby ensuring occupant safety and ensure a lower NVH levels within the vehicle cabin.
[001] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.

Reference Numerals and Characters
100 – Floor structure
102 – Front floor panel
102a – Front edge of the front floor panel
102b – Rear edge of the front floor panel
104 – Intermediate floor panel
104a – Front-end side of the intermediate floor panel
104b – Rear-end side of the intermediate floor panel
106 – Rear floor panel
106a – Front rim surface of the Rear floor panel
106b – Rear rim surface of the Rear floor panel
108 – First Tailored Weld Blank line
110 – Second Tailored Weld Blank line
112 – Tunnel in the front floor panel
114 – Lower dash assembly
116 – Top surface of the front floor panel
118 – One or more front seat cross members
120 – One or more long members
122 – Left sill assembly
124 – Right sill assembly
126 – Rear sill assembly
128 – Upper surface of the rear floor panel
130 – One or more rear seat cross members
132 – Lower surface of the rear floor panel
134 – Rear cradle assembly
136 – Left-end portion of the rear floor panel
138 – Left wheelhouse assembly
140 - Right-end portion of the rear floor panel
142 - Right wheelhouse assembly
144 – Engine cabin
146 – Front cradle assembly
148 – Bottom surface of the front floor panel
X-X’ – Central plane of the floor structure
, Claims:WE CLAIM:
1. A floor structure (100) for a vehicle, the floor structure (100) comprising:
a front floor panel (102) extending in a front-rear direction of the vehicle;
an intermediate floor panel (104) extending rearwardly from the front floor panel (102); and
a rear floor panel (106) extending rearwardly from the intermediate floor panel (104),
the front floor panel (102) and the rear floor panel (106) are coupled to the intermediate floor panel (104) through a first TWB line (108) and a second TWB line (110) respectively, to form a unibody floor structure for the vehicle.

2. The floor structure (100) as claimed in claim 1, wherein each of the front floor panel (102), the intermediate floor panel (104) and the rear floor panel (106) is made of steel of different grades and different gauges.

3. The floor structure (100) as claimed in claim 2, wherein the front floor panel (102) and the intermediate floor panel (104) are made by one of a High Strength Steel (HS) material and an Advanced High Strength Steel (AHSS) material having an Ultimate Tensile Strength of at least 400MPa, and the rear floor panel (106) is made by a Low Strength Steel (HS) material having an Ultimate Tensile Strength of maximum of 400 MPa.

4. The floor structure (100) as claimed in claim 2, wherein the rear floor panel (106) is provided with a lower thickness than the front floor panel (102), and the intermediate floor panel (104) is provided with a thickness greater than the front floor panel (102).

5. The floor structure (100) as claimed in claim 4, wherein the front floor panel (102) has a thickness of 0.55 mm to 0.8 mm, the intermediate floor panel (104) has a thickness of 0.6 mm to 1 mm, and the rear floor panel (106) has a thickness of 0.55 mm to 0.8 mm.

6. The floor structure (100) as claimed in claim 1, wherein each of the first TWB line (108) and the second TWB line (110) comprises of a plurality of layers of steel material, and wherein each of the first TWB line (108) and the second TWB line (110) is provided with a thickness of 0.55 mm to 1.6 mm.

7. The floor structure (100) as claimed in claim 1, wherein the front floor panel (102) is provided with a tunnel portion (112) about a central plane (X-X’) of the floor structure (100) for accommodating one or more transmission components of the vehicle.

8. The floor structure (100) as claimed in claim 1, wherein
a front edge (102a) of the front floor panel (102) is adapted to receive a lower dash assembly (114) of the vehicle; and
a top surface (116) of the front floor panel (102) is adapted to receive one or more front seat cross member (118) and one or more long members (120) of the vehicle.

9. The floor structure (100) as claimed in claim 1, wherein
a left side (102c) of the front floor panel (102) and a left-end side (104c) of the intermediate floor panel (104) are adapted to receive a left sill assembly (122) of the vehicle; and
a right side (102d) of the front floor panel (102) and a right-end side (104d) of the intermediate floor panel (104) are adapted to receive a right sill assembly (124) of the vehicle.

10. The floor structure (100) as claimed in claim 1, wherein
a rear rim surface (106b) of the rear floor panel (106) is adapted to receive a rear sill assembly (126) of the vehicle;
an upper surface (128) of the rear floor panel (106) is adapted to receive one or more rear seat cross members (130) of the vehicle;
a lower surface (132) of the rear floor panel (106) is adapted to receive a rear cradle assembly (134) of the vehicle;
a left-end portion (136) of the rear floor panel (106) is adapted to receive a left wheelhouse assembly (138) of the vehicle; and
a right-end portion (140) of the rear floor panel (106) is adapted to receive a right wheelhouse assembly (142) of the vehicle.

Dated this 26th day of March 2024
MAHINDRA & MAHINDRA LIMITED
By their Agent & Attorney

(Janaksinh Jhala)
of Khaitan & Co
Reg No IN/PA-2193