FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
LIGHT WEIGHT FREE STANDING PLASTIC SEAT FRAME STRUCTURE
Applicant:
MAHINDRA & MAHINDRA LIMITED
Automotive & Farm Equipment Sector,
Mahindra Towers, Dr. G.M. Bhosale Marg, Worli, Mumbai,
MAHARASHTRA, INDIA.
Inventors:
1. NTLESH SURESH MATE, an Indian National of Cl/1003, Nandan Inspera, Near Datta Mandir, Wakad-Thergaon Road, Wakad, Pune - 411057, Maharashtra, INDIA,
2. SHRIDHAR GANPATI JOSHI, an Indian National of A16 Sunshine, Opposite Gokul Paradise, Thakur Complex, Kandivali East, Mumbai - 400101, Maharashtra, INDIA, and
3. HIMMATRAO ATMARAM PATIL, an Indian National of D103/104, Dahisar Mandakini CHSL, Rawalpada, Dahisar (East), Mumbai -400068, Maharashtra, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE USED.

Field of the Invention
The present invention relates to a seat frame structure, particularly a free standing seat frame structure for motor vehicles. More particularly, the present invention relates to a light weight free standing seat frame structure made of plastics.
Background of the Invention
At present, it is increasingly necessary in motor vehicles to reduce weight of the material being used, both from the point of view of reducing the cost, as well as for reducing the propulsive power necessary to drive the vehicle and thereby to enhance the fuel efficiency of motor vehicles.
The seat assembly in a motor vehicle includes a seat frame structure intended for seating at least one occupant. This assembly is mounted on the vehicle floor. The term "seat frame structure" includes individual seat as well as the parts of a bench seat intended for seating one occupant each. The seat frame structure is configured to support the occupant and also to incorporate various adjustment means for adapting to varying human anthropometry of the occupant/s of the motor vehicle. These adjustment means include seat . forwarding means, seat push-back means and seat back-rest reclining means.
The seat frame structure should readily be capable of incorporating these seat adjustment means, while at the same time; it should help in fulfilling the safety regulations in-force. Thus, the seat frame structure should also comply with the mandatory and/or optional standards during the durability tests

specified for the safety of the occupants and the general public. However, these additional seat adjustment means also increase the overall weight of motor vehicles. Since the seat frame structure is one of the most expensive subassembly in motor vehicles, this increased cost has a considerable effect in increasing the overall cost of motor vehicles.
Prior Art
EP 0160927 A2 describes a back rest which is of hollow plastic part constituting polypropylene and 30% glass filled fibers and is manufactured by roto mold process. It has a variable cross-section at the lower and upper sides, which is accommodated at the lower side by two sheet metal brackets spot welded together and bolted to plastic part by rivets.
Patent No. US 6378946 Bl discloses a back rest which is made of a casting. It may also be made of a suitable engineering plastic material cast from a fiber-reinforced plastics resin, or may be compression molded from a plastics sheet material. The document discloses a unique design with a single-piece, channel shaped component having a hollow shell structure to accommodate airbag, adjustable head restraint, lumbar and such features.
Patent No. US 7128373 B2 discloses a seat back of plastic part made from different plastic materials having thickness between 2 to 3 mm. It has ribs, particularly in the rear seat back frame assembly.

Disadvantages with the prior art
The existing plastic seat structures in the automobile industry are integrated single back and cushion pan part made of reinforced composite plastics, which are covered by foam pad and trim cover.
The existing plastic seat structure is mostly used in M2 or M3 category of passenger vehicles.
The existing plastic seat structure does not have any recliner adjustment for the seat back rest, because the back pan is integrated with cushion pan for a single-piece construction.
Objects of the Invention
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide an improved seat frame structure for motor vehicles.
Another object of the present invention is to provide a seat frame structure which fulfils the mandatory safety requirements for motor vehicle seats.
Yet another object of the present invention is to provide a seat frame structure which reduces carbon footprint of the motor vehicle.

Still another object of the present invention is to provide a seat frame structure which reduces the overall cost of the motor vehicle.
A further object of the present invention is to provide a seat frame structure which provides optimal comfort to the occupant/s of the motor vehicle.
A still further object of the present invention is to provide an improved ingress and egress of the occupant/s of the motor vehicle.
Other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.
Summary of the Invention
In accordance with the present invention, there is provided a seat frame structure for seat of a motor vehicle, said seat frame structure having at least one seat, said seat comprising:
- at least one profiled single-piece seat cushion pan mounted on a seat slider assembly with reinforcement plate at the front side thereof and seat belt anchorage brackets on the rear side below thereof;
- a seat back rest consisting of a single-piece main member;
- a marriage assembly including a recliner assembly welded to adapter brackets, a back portion and a profiled back cushion;

- at least one combination profiled cushion pad disposed over said seat cushion pan and said seat back rest; and
- at least one seat trim cover each disposed over said single-piece cushion pan and said seat back rest, both trim covers fitted with said combination profiled cushion pad, said trim covers covering said cushion pan and said seat back rest to provide optimum comfort to the seat occupant;
wherein said seat slider assembly, said seat belt anchorage assembly and said recliner assembly are suitably adjustable to adapt to varying human anthropometry for optimum personal comfort while sitting thereon.
Typically, the profiled single-piece seat cushion pan is made of a combination . of light-weight synthetic materials, e.g. reinforced reaction injection molded polyurethane and polyurea based plastic parts.
Typically, the back rest single-piece main member is made of light-weight synthetic materials, e.g. filament winding polyurethane and polyurea based plastic parts.
Typically, the combination profiled cushion pad comprises at least one comfort foam pad and at least one structural foam pad.
Typically, the comfort foam pad comprises polyurethane (PU) comfort foam.
Typically, the comfort foam pad comprises low density high performance structural foam pad.

Typically, the seat single-piece main member includes an integrated head restraint frame member.
Typically, the single-piece plastic member is bonded by adhesives to the back frame sheet metal adapter brackets of said marriage assembly on both the sides of said seat back rest frame, and also riveted to the said seat back rest frame.
Typically, the cushion adapter brackets are bolted to seat belt anchorage brackets on both the sides, thereby facilitating to transfer the load from said seat back frame single-piece member to said seat slider assembly.
Typically, the seat cushion trim cover is attached to said cushion pan either by J strips or by fir tree clips.
Description of the Invention
According to the present invention, the foam pad is composed of a combination of poly urethane (PU) foam and light weight poly ethylene or poly styrene foam. The back rest of the seat is composed of poly urethane and poly urea based fiber reinforced plastic materials and which is manufactured by filament winding process. The back rest structure has a substantially rectangular cross-section made of plastic, which can be accommodated with metal side members at both the sides by bonding with the help of both adhesives and rivets.

The technical advantage of the seat frame structure according to the present invention over the conventional metallic structure is development of a light weight structural part having the same impact resistance and stiffness.
It also integrates the head restraint therein, which further achieves considerable weight reduction and reduces the number of parts in back frame assembly.
The present invention offers a separate cushion pan and the back rest is not pan shaped but is in the form of a structural member made of poly urethane and poly urea based reinforced plastics.
The invention can be implemented in Ml Category of passenger vehicles as well.
The invention having a split construction also includes a recliner adjustment for the seat back rest.
. The invention offers a free standing plastic seat frame structure for a car/SUV for the first time. This free standing plastic seat frame structure is not directly fitted to the Body in white (BIW), thereby helping to reduce the load requirement that the plastic part needs to take.
The invention can be implemented in any row in the motor vehicle with modifications as per seat geometry requirements, but the basic idea of using polyurethane and polyurea based reinforced plastics for cushion and back pan remains the same.

The present invention can be used for various seating layouts, e.g. 60-40, full bench seat, foldable seat or fold and tumble seat etc., especially for seats which are normally directly mounted on the BIW.
This invention can be easily implemented for adjustable head restraint and the armrest can also be attached to the seat back rest structure.
The invention offers mechanisms for seat forward / rearward adjustment means and seat back reclining adjustment means to suit varying human anthropometry.
It also provides integrated head restraint, helping to avoid any whiplash during accidents. The seat back recliner operates by mean of a plastic knob.
The invention also leads to significant reduction in number of parts and welding and assembly fixtures.
The invention also reduces the assembly time at Just-In-Time production line.
The invention provides the same comfort and safety as compared to the conventional sheet metal structure.
The invention uses a part having solid cross-section. Moreover, the present invention facilitates bonding by using adhesives in addition to the riveting. Thus, it makes a much stronger connection between the metal and plastic parts than that obtained only by riveting.

The seat frame structure according to the present invention has a back rest member made up of single piece solid substantially rectangular cross-section which is used as the back rest integrated with the head restraint.
The present invention discloses a seat back rest constituted of a solid rectangular cross-section made of polyurethane and polyurea based fiber reinforced plastic material, which is manufactured by filament winding process.
The seat back frame assembly according to the present invention is attached to side brackets which are directly mounted on the tracks, thereby imparting it a free standing construction which is an essential feature of the present invention.
In accordance with the invention, the plastic components used in the seat frame structure are preferably made from materials supplied by DOW Chemicals and using their technical support.
This invention relates to the seat frame structure, in particular, this invention relates to the components which improve the upholstery of the seat occupant.
Brief Description of the Accompanying Drawings
The present invention will now be explained in more detail with reference to the non-limiting accompanying drawings of the seat frame structure, in which:

Figure 1 illustrates a perspective view of a conventional seat frame structure showing the main, three sub-assemblies.
Figure 2 illustrates a cross-sectional view of the conventional seat frame structure shown in Figure 1.
Figure 3 illustrates a detailed longitudinal cross-sectional view of the arrangement of the improved cushioning structure incorporated in the seat frame structure in accordance with the invention.
Figure 4 illustrates a perspective skeletal view of the improved seat frame structure in accordance with the invention as shown in the Figure 3. It represents various sub-assemblies for adjustment of the seat according to the individual human anthropometry of the occupant/s seated on the seat of the motor vehicle.
Detailed Description of the Accompanying Drawings
The seat frame structure in accordance with the present invention will now be described in detail with reference to the accompanying drawings, without limiting the scope and ambit of the disclosure in any way.
Figure 1 illustrates a perspective view of a conventional seat frame structure showing the main three sub-assemblies. These are: (a) Seat cushion structure 10, (b) Seat slider assembly 20, and (c) Seat back assembly 30. A lateral section line A-A is also indicated in Figure 1 for describing a conventional

assembly of the seat frame structure, which is described further with reference . to Figure 2 below.
Figure 2 illustrates a lateral cross-sectional view of the seat frame structure along the section line A-A shown in Figure 1. A seat trim 40 covers the seat pad 50. The seat trim 40 is supported on the seat pad 50 which in turn is placed on the seat structure 60 longitudinally disposed on both undersides of the seat.
Figure 3 illustrates a detailed longitudinal cross-sectional view of the arrangement of the seat cushion structure of the seat frame structure in accordance with the invention. This seat cushion frame structure consists of a single cushion pan 100 made of reinforced reaction injection molded polyurethane and poly urea based plastic parts. Cushion pan 100 is partially covered by a structural foam pad 110. A comfort foam pad 120 is disposed completely covering the assembly of cushion pan 100 with the structural foam pad 110. A seat trim cover 130 is disposed over this structural foam pad 110 and connected at the edges to the edges of the cushion pan 100 to seal said assembly.
Figure 4 illustrates a perspective skeletal view of the seat frame structure in accordance with the invention, representing various subassemblies for adjusting the seat according to the individual anthropometry of the occupant seated on the seat of motor vehicle. The seat back rest structure consists of a single-piece main member 170 of the back frame made of filament winding polyurethane and poly-urea based plastic parts. This main member 170 also acts as part of the integrated head restraint frame member. This plastic

member 170 is glued with the help of adhesives to the back frame sheet metal adapter brackets 180 of marriage assembly on both the sides of seat. The adapter brackets 180 are also riveted to the seat. The marriage assembly consists of a recliner assembly welded to adapter brackets 180, a back portion and a cushion. Further, the cushion adapter brackets 180 are bolted to the seat belt anchorage bracket 160 on both the sides, which facilitate to transfer the load from the seat back frame member 170 to the seat slider assembly 140. A unique feature of this concept is that the seat does not have any marriage with the cushion frame, so that it provides an easy serviceability. The seat back frame member 170 is also covered by a seat pad 120 and a seat trim cover 130 (see Figure 3). In this way, the complete seat frame structure including the seat cushion pan and the seat back rest in accordance with the present invention uses a composite foam pad, i.e. a combination of
polyurethane (PU) comfort foam 120 on the top and a low density high performance structural foam pad 110 under the comfort foam 120. The seat frame structure is configured as shown in Figure 4. The cushion pan 100 is mounted on the seat slider assembly 140 with reinforcement plate 150 at the front side and two seat belt anchorage brackets 160 on the rear side below the seat. The seat cushion pan 100 does not have marriage with the seat back rest structure configured as a plastic member 170. A cushion trim cover 130 is attached to the cushion pan 100 or single-piece main member 170, either by J strips or fir tree clips. The cushion pan 100 is configured to provide an anti-
. submarine seat which supports the occupant during any collision or frontal impact.

Working Principle of the invention
Free Standing Light Weight Plastic Seat Structure works on the principle of combining the structural parts to bear direct impact loads. The parts are made of reinforced polyurethane and poly-urea based plastic materials. The sheet metal brackets are attached to various mechanisms, which are required for facilitating the seat structure to adapt to varying human anthropometry.
The joining of plastic to the sheet metal material is achieved by using an adhesive bond. The seat back rest directly transfers the load to the seat slider assembly during a sudden impact/acceleration/deceleration. This load is not transferred to the cushion frame, thus allowing the cushion pan to be configured lighter in weight as compared to the conventional metal frame.
The complete seat structure is divided into three subassemblies:
(i) Seat slider assembly mechanism helping to move the seat structure
to and fro in longitudinal direction; (ii) Cushion assembly having plastic cushion pan and foam pads
covered by a seat trim; and (iii) Back rest assembly having a back frame assembly and foam pads
covered with seat trim. This back Frame assembly is further divided
into two subassemblies:
(a) Back marriage assembly having sheet metal parts; and
(b) Recliner mechanism helping to make rotational movement of the seat back frame assembly about a pivot. The back frame is a plastic back member joined to the back marriage assembly (back side member) using adhesive and rivets.

To make the final assembly of seat, initially the back frame assembly is placed on the upper track of the seat slider mechanism at the rear side and the reinforcing bracket sheet metal plate is placed at the front side, on which the cushion assembly is placed and fastened with the help of nuts on the studs protruding out of the slider assembly. This seat assembly is mounted on the vehicle floor using floor mounting brackets attached at the bottom of the seat slider mechanism. The shape of these mounting brackets varies from vehicle to vehicle, depending on the shape of the floor and the height of the seating reference point (SGRP) from the vehicle floor.
Technical Advantages & Economic Significance
- Light weight seat Structure with the overall weight above the seat slider assembly being reduced by approximately 25% as compared to the conventional seat structure
- Significant reduction in number of parts / subassemblies.
- Significant reduction in welding for making the seat frame structure, thereby reducing the number of fixtures and gauges for quality check of the assembly.
- Better serviceability, since the seat back has no marriage with cushion, thus it can easily be dismantled separately.
- Significant reduction in the tooling costs and assembly time.
- Reduction in the carbon footprint thereby forms part of green technology.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.
The description provided herein is purely by way of example and illustration. Various features and advantageous details are explained with reference to this non-limiting embodiment in the above description of the seat frame structure in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
Although the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible

within the spirit and scope of the present invention as described in this specification.
A person skilled in the art may make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
All such changes, variations, modifications, alterations and/or integrations in terms of materials and method used in configuring, manufacturing and assembling the novel seat frame structure adopted and arrived by any such skilled person are also comprised and embraced within the scope and spirit of the present invention, whereby it shall be distinctly understood that the entire . foregoing description and figures are treated merely illustratively and exemplarily and not as a limitation of the present invention.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We Claim:
1. A seat frame structure for seat of a motor vehicle, said seat frame
structure having at least one seat, said seat comprising:
- at least one profiled single-piece seat cushion pan mounted on a seat slider assembly with reinforcement plate at the front side thereof and seat belt anchorage brackets on the rear side below thereof;
- a seat back rest consisting of a single-piece main member;
- a marriage assembly including a recliner assembly welded to adapter brackets, a back portion and a profiled back cushion;
- at least one combination profiled cushion pad disposed over said seat cushion pan and said seat back rest; and
- at least one seat trim cover each disposed over said single-piece cushion pan and said seat back rest, both trim covers fitted with said combination profiled cushion pad, said trim covers covering said cushion pan and said seat back rest to provide optimum comfort to the seat occupant;
wherein said seat slider assembly, said seat belt anchorage assembly and said recliner assembly are suitably adjustable to adapt to varying human anthropometry for optimum personal comfort while sitting thereon.
2. Seat frame structure as claimed in claim 1, wherein said profiled single-
piece seat cushion pan is made of a combination of light-weight
synthetic materials, e.g. reinforced reaction injection molded
polyurethane and polyurea based plastic parts.

3. Seat frame structure as claimed in claim 1, wherein said back rest
single-piece main member is made of light-weight synthetic materials,
e.g. filament winding polyurethane and polyurea based plastic parts.
4. Seat frame structure as claimed in claim 1, wherein said combination profiled cushion pad comprises at least one comfort foam pad and at least one structural foam pad.
5. Seat frame structure as claimed in claim 1, wherein said comfort foam pad comprises polyurethane (PU) comfort foam.
6. Seat frame structure as claimed in claim 1, wherein said comfort foam pad comprises low density high performance structural foam pad.
7. Seat frame structure as claimed in claim 1, wherein said seat single-piece main member includes an integrated head restraint frame member.
8. Seat frame structure as claimed in claim 1, wherein said single-piece plastic member is bonded by adhesives to the back frame sheet metal adapter brackets of said marriage assembly on both the sides of said seat back rest frame, and also riveted to the said seat backrest frame.
9. Seat frame structure as claimed in claim 10, wherein said cushion adapter brackets are bolted to seat belt anchorage brackets on both the
. sides, thereby facilitating to transfer the load from said seat back frame single-piece member to said seat slider assembly.

10. Seat frame structure as claimed in claim 1, wherein said seat cushion trim cover is attached to said cushion pan either by J strips or by fir tree clips.