Claims:We claim:

1. A rear-seat bench for an automobile provided with a cross-member configured in a substantially trapezoidal section (a-b-c-d) comprising:

- a top side and a base side disposed parallel to each other;

- the top side being shorter than the base side;

wherein the angle included between the front face and the base side being smaller than the angle included between the rear face and the base side thereof and the front top edge and the rear bottom edges have rounded profiles.

2. The rear-seat bench as claimed in claim 1, wherein the trapezoidal section (a-b-c-d) is made out of two metal strips from a metal sheet of 2 mm thickness.

3. The rear-seat bench as claimed in claim 1, wherein the metal strips are bent substantially in ‘L’ shape, wherein the inclined side of the metal strip makes the top shorter parallel side of the trapezoidal-section, which configures the front face of the trapezoidal section, is bent with an included angle greater than the inclined side of the metal strip making the longer parallel base side of the trapezoidal-section, which configures the rear face of the trapezoidal-section.

4. The rear-seat bench as claimed in claim 1, wherein the shorter parallel top side of the trapezoidal-section is welded from below by protruding the rear edge thereof from the top edge of the inclined side of the longer parallel base side of the trapezoidal-section by a predetermined distance and the lower edge of the front face of the trapezoidal-section is welded on and protruding by a predetermined distance from the front lower edge of the longer parallel base side of the trapezoidal-section.

5. The rear-seat bench as claimed in claim 1, wherein the width of the longer parallel base side of the trapezoidal-section is approximately 1.5 times to 2 times the width of the shorter parallel top side of the trapezoidal-section, preferably 1.6 times.

6. The rear-seat bench as claimed in claim 1, wherein the angle included between the rear face and the base side of the trapezoidal-section is approximately 1.2 times to 1.8 times the angle included between the front face and the base side of the trapezoidal-section, preferably 1.5 times.

7. The rear-seat bench as claimed in anyone of the claims 1 to 6, wherein the weight of the trapezoidal-section of the cross member is approximately 2 kg per meter length thereof.

8. A rear-seat bench for an automobile provided with a cross-member made of a substantially trapezoidal-cross-section, the cross member comprising:

- an upper metal strip configuring a top side bent with an inclined front face and a lower metal strip configuring a base side bent with an inclined rear face, the top side and the base side disposed parallel to each other, and the width of the base side approximately 1.5 times to 2 times the width of the top side, preferably 1.6 times; the front top edge of the bend in upper metal strip and the rear bottom edges of the bend in lower metal strip having rounded profiles;

- the angle included between the front face and the base side configured smaller than the angle included between the rear face and the base side, preferably the angle included between the rear face and the base side approximately 1.2 times to 1.8 times the angle included between the front face and the base side, preferably 1.5 times; and

- the weight of the trapezoidal-section of the cross member is approximately 2 kg per meter length.

9. The rear-seat bench as claimed in claim 8, wherein the upper and lower metal strips cut from a metal sheet of approximately 2 mm thickness and bent and welded to each other to form the cross member of trapezoidal-section; the rear edge of the shorter top side welded by protruding beyond the top edge of the inclined rear face of the trapezoidal-section by a predetermined distance and the lower edge of the base side welded under the lower edge of the front face by protruding by a predetermined distance from the front lower edge of the inclined front face of the trapezoidal-section.

10. A method for manufacturing a cross-member configured in a substantially trapezoidal section (a-b-c-d) for the rear-seat bench of an automobile, the method comprising the steps of:

- shearing a pair of strips of predetermined length and width from a metal sheet of approximately 2 mm thickness;

- drilling holes at predetermined locations for fixing seatbelt anchorage fitments of the rear-seat bench;

- bending each metal strips by a predetermined included angle to obtain the top strip and base side strip;

- placing the metal strip having shorter top side over the bottom metal strip having longer base side by keeping the short side (ab) and long side (dc) parallel to each other and maintaining a predetermined offset of the base side front edge from the front face lower edge and of the rear face top edge from the rear edge of the top side for configuring welding areas on the top and bottom metal strips for welding the with each other; and

- welding at the welding areas configured between the top side metal strip and bottom side metal strips for making the trapezoidal section cross-member for rear-seat bench of the automobile.

Dated: this 12th day of August, 2015. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention relates to the automobile seat bench structure, particularly to the rear-seat bench structure of automobiles, and more particularly to the light-weight cross-member of an automobile rear-seat bench structure.

BACKGROUND OF THE INVENTION

According to the Automotive Industry Standards (AIS), one of the most-critical safety-related assemblies in the present day high-speed automobiles is the seats, seat belts their anchorage and the seat structure stability and robustness in the event of an accident, whereby the automobile is prone to be subjected to a sudden acceleration/deceleration. Automotive Industry Standards AIS-015 particularly recommends several load-tests for seat-belt anchorage in rear-seat bench structures.

DISADVANTAGES WITH THE PRIOR ART

The major challenge in the rear engine passenger vehicle is the lack of enough space for accommodating seat belt anchorage points in the body-in-weight (BIW) because of the requirement of providing a serviceable opening lid for the rear-engine. Therefore, all middle seat belt anchorage points need to be accommodated on the rear seat itself. Since the existing rear-seat bench structures do not have sufficient strength to take this huge anchoring load, there is an existing requirement to configure a robust rear-seat bench structure for absorbing this additional load due to provisioning of the seat-belt anchorage points on the rear-seat bench structure, and that too without any failure during the statutory tests AIS-015 for the rear-seat bench structure. Therefore, the present invention strives to eliminate the disadvantages associated with the conventional rear-seat bench structures. These are described as under:

The conventional rear-seat bench structure includes a cross-member for carrying loads during an impact of the automobile against any moving and/or stationary obstacle. This load may be as high as 50kN and most of this load has to be borne by the rear-seat cross-member and not the BIW. At present, these cross-members are made of a square hollow section, e.g. 40 mm x 40 mm with 3 mm thickness having a or even a circular hollow (tubular) section, e.g. Mahindra Xylo, having a tube-section weight of 3.6 kg for cross-member length of about 1.2 meter, it comes to about 3 kg per meter. The existing square cross-sections do not result in a favourable contact due to sharp edges, when tested with a dummy, so the conventional square cross- member sections also substantially uncomfortable to the rear-seat passengers.

DESCRIPTION OF THE PRESENT INVENTION

Therefore, the inventors have explores various alternative cross-sections for cross-member for rear-seat bench structure and have arrived at the optimal performance during seat structure testing according to the AIS-015, with a cross-member of a trapezoidal section made of 2 mm thick metal sheet with the upper parallel side of about 30 to 35 mm and the lower side of about 45 to 50 mm. The upper and lower parallel sides are joined with each other by inclined sides welded at the straight ends thereof. The front inclined side makes an steeper angle than the rear side. The front top edge and rear bottom edges also finished rounded for seating comfort of the rear-seat bench occupants. This typical trapezoidal section has also demonstrated a good strength to weight ratio as compared to the rectangular and tubular sections discussed above. In addition, the cross-member of trapezoidal section weighs only about 2 to 2.2 kg per meter, which is significantly lower than the existing square and tubular cross-sections having a weight of about 3 to 3.5 kg per meter.

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 a robust cross-member section for an automobile rear-seat bench structure.

Another object of the present invention is to provide a light-weight cross-member section for an automobile rear-seat bench structure.

Still another object of the present invention is to provide a rear-seat bench structure with seat-belt anchorage points disposed on the rear-seat bench structure itself.

Yet another object of the present invention is to provide an automobile rear-seat bench structure, which is favourable to dummy contact during testing as per the relevant statutory standard AIS-015.

A further object of the present invention is to provide an automobile rear-seat bench structure, which is also more comfortable to the rear-seat passengers.

Still further object of the present invention is to provide an automobile rear-seat bench structure, which consumes less material in comparison to the existing rear-seat bench structures.

Yet further object of the present invention is to provide an automobile rear-seat bench structure, which is cheaper and easy to manufacture.

These and 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 however are 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 rear-seat bench for an automobile provided with a cross-member configured in a substantially trapezoidal section (a-b-c-d) comprising:

- a top side and a base side disposed parallel to each other;

- the top side being shorter than the base side;

wherein the angle included between the front face and the base side being smaller than the angle included between the rear face and the base side thereof and the front top edge and the rear bottom edges have rounded profiles.

Typically, the trapezoidal section (a-b-c-d) is made out of two metal strips from a metal sheet of 2 mm thickness.

Typically, the metal strips are bent substantially in ‘L’ shape, wherein the inclined side of the metal strip makes the top shorter parallel side of the trapezoidal-section, which configures the front face of the trapezoidal section, is bent with an included angle greater than the inclined side of the metal strip making the longer parallel base side of the trapezoidal-section, which configures the rear face of the trapezoidal-section.

Typically, the shorter parallel top side of the trapezoidal-section is welded from below by protruding the rear edge thereof from the top edge of the inclined side of the longer parallel base side of the trapezoidal-section by a predetermined distance and the lower edge of the front face of the trapezoidal-section is welded on and protruding by a predetermined distance from the front lower edge of the longer parallel base side of the trapezoidal-section.

Typically, the width of the longer parallel base side of the trapezoidal-section is approximately 1.5 times to 2 times the width of the shorter parallel top side of the trapezoidal-section, preferably 1.6 times.

Typically, the angle included between the rear face and the base side of the trapezoidal-section is approximately 1.2 times to 1.8 times the angle included between the front face and the base side of the trapezoidal-section, preferably 1.5 times.

Typically, the weight of the trapezoidal-section of the cross member is approximately 2 kg per meter length thereof.

The present invention also provides a rear-seat bench for an automobile provided with a cross-member made of a substantially trapezoidal-cross-section, the cross member comprising:

- an upper metal strip configuring a top side bent with an inclined front face and a lower metal strip configuring a base side bent with an inclined rear face, the top side and the base side disposed parallel to each other, and the width of the base side approximately 1.5 times to 2 times the width of the top side, preferably 1.6 times; the front top edge of the bend in upper metal strip and the rear bottom edges of the bend in lower metal strip having rounded profiles;

- the angle included between the front face and the base side configured smaller than the angle included between the rear face and the base side, preferably the angle included between the rear face and the base side approximately 1.2 times to 1.8 times the angle included between the front face and the base side, preferably 1.5 times; and

- the weight of the trapezoidal-section of the cross member is approximately 2 kg per meter length.

Typically, the upper and lower metal strips cut from a metal sheet of approximately 2 mm thickness and bent and welded to each other to form the cross member of trapezoidal-section; the rear edge of the shorter top side welded by protruding beyond the top edge of the inclined rear face of the trapezoidal-section by a predetermined distance and the lower edge of the base side welded under the lower edge of the front face by protruding by a predetermined distance from the front lower edge of the inclined front face of the trapezoidal-section.

The invention also provides a method for manufacturing a cross-member configured in a substantially trapezoidal section (a-b-c-d) for the rear-seat bench of an automobile, the method comprising the steps of:

- shearing a pair of strips of predetermined length and width from a metal sheet of approximately 2 mm thickness;

- drilling holes at predetermined locations for fixing fitments of the rear-seat bench;

- bending each metal strips by a predetermined included angle to obtain the top strip and base side strip;

- placing the metal strip having shorter top side over the bottom metal strip having longer base side by keeping the short side (ab) and long side (dc) parallel to each other and maintaining a predetermined offset of the base side front edge from the front face lower edge and of the rear face top edge from the rear edge of the top side for configuring welding areas on the top and bottom metal strips for welding the with each other; and

- welding at the welding areas configured between the top side metal strip and bottom side metal strips for making the trapezoidal section cross-member for rear-seat bench of the automobile.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1 shows a top-view of a rear-seat bench structure manufactured with a seat-belt anchorage arrangement configured thereon in accordance with the invention during testing according to the relevant statutory standard AIS-015.

Figure 2 shows a perspective view from rear-side of the existing tubular cross-member for rear-seat bench structure in a SUV model manufactured by the applicant.

Figure 3 shows a perspective view of the load description in the statutory load-test for seat-belt anchorage according to the relevant standard AIS-015.

Figure 4 shows a perspective view of the post-deformation pattern the seat cross-member after the statutory load-test conducted according to the relevant standard AIS-015.

Figure 5 shows a perspective view of an exemplary embodiment of the rear-seat bench structure according to the present invention.

Figure 6 shows a detailed enlarged view of the cross-member for the rear-seat bench structure according to the present invention as shown in Figure 5.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a top-view of a rear-seat bench structure manufactured with a seat-belt anchorage arrangement configured thereon in accordance with the invention to be used during the seat-belt anchorage load-test according to the relevant statutory standard AIS-015. A triple seat bench is supported by a cross member 10 and provided with back-rest 36 and side-brackets 38. The seat bench consists of three seats 12, 14 and 16 provided with three anchorage points 22, 24 and 26 respectively, which can be attached to the seat only for testing purposes. The anchorage arrangement consists of front cross-bar 30 and rear cross-bar 32 disposed parallel to the cross member 10. Seat belts 18 are fixed on two anchorage brackets 42 and 44 to be pulled by means of tension elements, e.g. wires to apply predetermined standard loads mandatory for the seat-belt anchorage test. Since the anchorage points 22, 24 and 26 are attached to the seats themselves, this rear-seat bench structure can be made very compact, particularly for rear-engine vehicles, which have very limited space available behind the rear-seat bench.

Figure 2 shows a perspective view from rear-side of the existing tubular cross-member for rear-seat bench structure in a SUV model, e.g. Mahindra Xylo manufactured by the applicant. The figure illustrates a tubular cross member 10’ disposed between the side brackets 38’ and under the seat back rest 36’. However, such tubular cross members or conventional square cross members have heavier sections, e.g. 40 mm x 40 mm and are made from 3 mm thick metal sheets weighing substantially more, so their manufacturing cost is significantly high. However, the seat-belt anchorage testing structure required for this rear-seat bench is very complex and therefore expensive.
Therefore, the inventors have conducted extensive tests to improve the cross member design for rear-seat bench structure for weight reduction as well as for achieving an excellent strength to weight ratio in comparison to the currently available and used cross members.

Accordingly, an optimized solution is arrived at in the form of a trapezoidal-section cross member (Figure 5 and 6), which not only reduces the weight of the cross member and thus reduces the overall weight of the rear-seat bench structure, but which also achieves a substantially superior strength to weight ratio, which is desirable. This trapezoidal-section cross member satisfies the load tests prescribed under AIS-015, eases out the dummy contact and in addition, the rear-seat passengers find this rear-seat bench much more comfortable as well.

Figure 3 shows a perspective view of the load description in the statutory loads applied according to the relevant standard AIS-015 during seat-belt anchorage testing. The seat-bench rear-side is fixed by a plurality of holding or retaining elements, e.g. wires or cables on the rear cross-bar 32 of the seat-anchorage arrangement and the seat-anchorage points 22, 24 and 26 as well as brackets 42 and 44 are connected to front cross-bar 30 via a plurality of tension elements a1, a2, a3 and b1, b2 respectively. As shown in Figure, the seat anchorage points 22, 26 and brackets 42, 44 are applied with a load of 13.5 kN load each and the middle seat anchorage point 24 is applied with a 22.25 kN load. The application of these loads simulates an acceleration of 20 times the seat mass multiplied by ‘g’ being applied on the front anchorage-bar A of the overall seat-anchorage arrangement.

Figure 4 shows a perspective view of the pattern obtained post-deformation of a typical square seat cross-member (not visible) after conducting the statutory load-test according to the relevant standard AIS-015.

Figure 5 shows a perspective view of an exemplary embodiment of the rear-seat bench structure which includes a trapezoidal-section cross member 110 according to the present invention, which is disposed between the side brackets 130 and under the back rest 136.

Figure 6 shows a detailed enlarged view of the cross-member 110 for the rear-seat bench structure shown in Figure 5. The substantially horizontally disposed upper P and lower side Q of the cross member 110 are parallel to each other and the other two sides R and S make an angle with sides P and Q, thereby configuring a substantially trapezoidal section, which has proved to be of low-weight in comparison to the currently available square or tubular cross-members. The figure also illustrates in the inset, an enlarged side view a-b-c-d of the cross-member 110, which is self-explanatory. This also means that the strength to weight ratio of this trapezoidal-section cross member 110 is much favourable than the conventional ones. Moreover, due to use of a thinner material of 2 mm thick metal sheet and lesser cross-sectional area of the cross member 110, the manufacturing cost thereof is also substantially reduced, contributing in lower cost of the overall rear-seat bench structure.

The exemplary optimized trapezoidal-section shown here is obtained by shearing a pair of strips from a metal sheet of 2 mm thickness. These are pierced at predetermined places and bent to obtain a substantially ‘L’ shaped profile, in which the respective long sides of each ‘L’ shaped bent strip makes an angle of about 95 to 1200 with their respective short sides. Subsequently, these two metal sheets are welded together by keeping their shorter sides parallel to each other to make the trapezoidal-section of the cross member 110. In a preferred embodiment, the base side has a width of about 45 to 50 mm and the top side has a width of about 30 to 35 mm width which are welded together with their respective short-sides disposed parallel to each other. Therefore, the cross-member of a trapezoidal-section is obtained, the front side of which has a less inclined face than the rear-side thereof. This configuration is found to be particularly advantageous during the seat-belt anchorage test as per AIS-015. Moreover, the rounded edges, i.e. the front top rounded edge ‘a’ and rear bottom rounded edge ‘c’ provide a better comfort to the seat bench occupants.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The rear-seat bench cross member with a plurality of seat belt anchorage points built-in thereon configured in accordance with the present invention has the following technical advantages:

- Low weight

- Higher Strength to Weight ratio

- Ease of Dummy Contact

- More comfort for the rear-seat passengers

- Anchorage points built-in on the cross member itself, thereby eliminating disadvantageous space constraints in rear-engine automobiles

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. Although, only the preferred embodiments have been described herein, the skilled person in the art would readily recognize to apply these embodiments with any modification possible within the spirit and scope of the present invention as described in this specification.

Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description 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.

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.