FORM 2
The Patent Act 1970 (39 OF1970)
The Patent Rules, 2005
COMPLETE SPECIFICATION (See Section 10; rule 13)
TITLE OF THE INVENTION
SUBFRAME FOR A FRONT OR REAR CHASSIS SECTION OF A
MOTOR VEHICLE
APPLICANT(S) TATA MOTORS LIMITED
an Indian company
Bombay house, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001,
Maharashtra, India.
and
TATA MOTORS EUROPEAN TECHNICAL CENTRE Plc
an United Kingdom company
18 Grosvenor Place, London, SW1X 7HS, London
United Kingdom
The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
[0001] The present disclosure relates to a subframe for a motor vehicle, and more particularly, to a subframe for a front or rear chassis section of the motor vehicle for increasing structural stiffness, reducing weight and minimizing the need for welding.
BACKGROUND OF THE INVENTION
[0002] A generic subframe connected via a plurality of bearing receptacles on a body for a motor vehicle is well known. The conventional subframe provides structural connection between the body and suspension components. FIG. 1 illustrates conventional metal welded subframe, according to prior art. The conventional metal welded subframe shown in the FIG. 1 comprises the following properties:
Number of sub-components (panels) = 23
Length of the welds = 5765 mm
Number of fixings = 15 (Body 4, C-mount 1, LCA 4, ARB 4, Stg Gear 2)
Typical Subframe range of weight = 10 to 16 kg.
[0003] The disadvantage of the conventionally known subframe is a number of components used and welding requirements. The conventionally known subframe comprises a significant number of components welded together, which increases the weight of the subframe. The high space and welding requirements are created by the construction shown in the prior art. Thus, there remains a need for a subframe of a front or rear chassis section of the motor vehicle to increase structural stiffness, reduce weight and minimize the need for welding.

OBJECT OF THE INVENTION
[0004] The principal object of the embodiments herein is to provide subframe for a front or rear chassis section of a motor vehicle to increase structural stiffness, reduce weight and minimize the need for welding.
[0005] Another object of the embodiments herein is to provide the subframe comprising a top shear panel, a bottom shear panel and a plastic matrix sandwiched between the top shear panel and the bottom shear panel that acts as a central reinforcement to knit the top shear panel and the bottom shear panel together. This enables a more weight efficient structure and provides greater stiffness.
[0006] Another object of the embodiments herein is to provide a plastic matrix that encapsulates a steering gear and makes a frame section deeper using the steering gear to aid stiffness of the steel structure which is enclosed by the top and bottom surfaces.
SUMMARY OF THE INVENTION
[0007] In one aspect object is satisfied by providing a subframe for a front or rear chassis section of a motor vehicle. The subframe comprises a top shear panel, a bottom shear panel and a plastic matrix. The top shear panel and the bottom shear panel extend in a longitudinal direction of the motor vehicle. The first shear panel and the second shear panel are spaced apart from each other. The plastic matrix is sandwiched between the top shear panel and the bottom shear panel and acts as a central reinforcement to knit the top shear panel and the bottom shear panel together.

[0008] In an embodiment, the top shear panel and the bottom shear panel are made of a structural material, for example steel, aluminium or carbon fibre.
[0009] In an embodiment, the top shear panel and the bottom shear panel are connected at the force nodal points and symmetrically positioned to form an open or closed frame construction.
[0010] In an embodiment, the plastic matrix provides a free space and a location for a steering gear, wherein the free space is provided in midsection of the central reinforcement.
[0011] In an embodiment, the plastic matrix encapsulates the steering gear and makes a section of the subframe deeper using the steering gear to aid stiffness of the top shear panel and the bottom shear panel.
[0012] In an embodiment, the top shear panel and the bottom shear panel locate the steering gear and the plastic matrix.
[0013] In an embodiment, the top shear panel and the bottom shear panel are designed using a Finite Element (FE) technique that defines load paths for a duty cycle of the motor vehicle.
[0014] In an embodiment, the top shear panel and the bottom shear panel are connected at the force nodal points and symmetrically positioned to form a closed frame construction.
[0015] In an embodiment, the plastic matrix comprises an upper core and a lower core. The upper core and lower core comprising compressor limiters.

[0016] 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 spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0017] The subframe is 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:
[0018] FIG. 1 illustrates conventional metal welded subframe, according to prior art;
[0019] FIG. 2 illustrates a subframe for a front or rear chassis section of a motor vehicle, according to an embodiment as disclosed herein;
[0020] FIG. 3 illustrates an exploded view of the subframe as illustrated in the FIG. 1, according to an embodiment as disclosed herein;
[0021] FIGS. 4a-4b illustrates a section view of the subframe applied on the motor vehicle, according to an embodiment as disclosed herein; and
[0022] FIG. 5 illustrates a location of the subframe on the motor vehicle, according to an embodiment as disclosed herein.
DETAILED DESCRIPTION OF THE INVENTION
[0023] 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.
[0024] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those, which are particularly set out in the accompanying drawings. Although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.
[0025] Referring now to the drawings, and more particularly to FIGS. 2 through 5, there are shown preferred embodiments.
[0026] FIG. 2 illustrates a subframe (Item 1) for a front or rear chassis section of a motor vehicle and FIG. 3 illustrates an exploded view of the subframe (Item 1) as illustrated in the FIG. 1, according to an embodiment as disclosed herein according to an embodiment as disclosed herein. The subframe (Item 1) comprises a top shear panel (2), a bottom shear panel (3) and a plastic matrix (4) sandwiched between the top shear panel (2) and the bottom shear panel (3). The top shear panel (2) and the bottom shear panel (3) are spaced apart

from each other. The plastic matrix (4) comprises an upper core (5) and a lower core (6). The upper core (5) and lower core (6) comprising compressor limiters (7). The plastic matrix (4) acts as a central reinforcement to knit the top shear panel (2) and the bottom shear panel (3) together. This enables greater weight efficiency in the structure and provides greater stiffness. Using force loading software, existing fixings are revised and used at the force nodal points and symmetrically positioned.
[0027] In an embodiment, the top shear panel (2) and the bottom shear panel (3) are made of steel or structural alternative. The top shear panel (2) and the bottom shear panel (3) are designed using a Finite Element (FE) technique that defines load paths for a duty cycle of the motor vehicle. The top shear panel (2) and the bottom shear panel (3) are connected at the force nodal points and symmetrically positioned to form an open or closed frame construction. Unlike the conventional subframe, the proposed subframe (Item 1) overcomes the conventional subframe assembly that requires fabrication prior to structural connection with the body structure and the suspension components.
[0028] In an embodiment, the plastic matrix (4) encapsulates the steering gear and makes a section of the subframe (Item 1) deeper using the steering gear to aid stiffness of the structure, which is enclosed by the top shear panel (2) and the bottom shear panel (3). Then they are brought together to connect the control arms to the body. As the steering rack fixings are now in double shear from its current single shear, the fixings are now more efficient aiding the structural strength of the assembly.
[0029] In an embodiment, the plastic matrix (4) provides a free space and a location for a steering gear. The free space is provided in midsection of the central reinforcement. In an embodiment, the top shear panel (2) and the bottom shear panel (3) locate the steering gear and the plastic matrix (4).

[0030] In an embodiment, the top shear panel (2) and the bottom shear panel (3) are connected at the force nodal points and symmetrically positioned to form an open or closed frame construction.
[0031] FIGS. 2 and 3 illustrates a construction view of the subframe (Item 1), according to an embodiment as disclosed herein. Unlike conventional subframe, the proposed subframe (Item 1) has the following features:
Number of sub-components (panels) = 3
Length of the welds = 0 mm
Number of fixings = 15 (Body 4, C-mount 1, LCA 4, ARB 4, Stg Gear 2)
Weighted estimation as = -10% saving.
[0032] The subframe utilizes fixings for existing major components (steering gear, lower control arm & c mount) to clamp the top shear panel (2), the bottom shear panel (3) and the plastic matrix (4) together to make one assembly and to fix this to the body.
[0033] Figure 4 shows typical location of compression limiters (7) within the plastic matrix (4). This comprises of upper core (5) and lower core (6).
[0034] FIG. 5 illustrates a location of the subframe (Item 1) on the motor vehicle, according to an embodiment as disclosed herein.
[0035] 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 spirit and scope of the embodiments as described herein.

We Claim:
1. A subframe (Item 1) for a front or rear chassis section of a motor vehicle,
the subframe (Item 1) comprising:
a top shear panel (2) and a bottom shear panel (3) extending in a longitudinal direction of the motor vehicle, wherein the top shear panel (2) and the bottom shear panel (3) are spaced apart from each other; and
a plastic matrix (4), sandwiched between the top shear panel (2) and the bottom shear panel (3), acts as a central reinforcement to knit the top shear panel (2) and the bottom shear panel (3) together.
2. The subframe (Item 1) as claimed in claim 1, wherein the top shear panel (2) and the bottom shear panel (3) are made of steel or equivalent structural material.
3. The subframe (Item 1) as claimed in the claim 1, wherein the top shear panel (2) and the bottom shear panel (3) are connected at the force nodal points and symmetrically positioned to form an open or closed frame construction.
4. The subframe (Item 1) as claimed in claim 1, wherein the plastic matrix (4) provides a free space and a location for a steering gear, wherein the free space is provided in midsection of the central reinforcement.
5. The subframe (Item 1) as claimed in claim 4, wherein the plastic matrix (4) encapsulates the steering gear and makes a section of the subframe (Item 1) deeper using the steering gear to aid stiffness of the top shear panel (2) and the bottom shear panel (3).
6. The subframe (Item 1) as claimed in claim 4, wherein the top shear panel (2) and the bottom shear panel (3) locate the steering gear and the plastic matrix (4).

7. The subframe (Item 1) as claimed in claim 1, wherein the top shear panel (2) and the bottom shear panel (3) are designed using a Finite Element (FE) technique that defines load paths for a duty cycle of the motor vehicle.
8. The subframe (Item 1) as claimed in the claim 1, wherein the top shear panel (2) and the bottom shear panel (3) are connected at the force nodal points and symmetrically positioned to form an open or closed frame construction.
9. The subframe (Item 1) as claimed in the claim 1, wherein the plastic matrix (4) comprises an upper core (5) and a lower core (6), and wherein the upper core (5) and lower core (6) comprising compressor limiters (7).