FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2006
COMPLETE
Specification
(See Section 10 and Rule 13) KNEE BOLSTER
MAHINDRA & MAfflNDRA LTD.
an Indian Company,
of R&D Center, Automotive Division, 89, M.I.D.C.,
Satpur, Nashik-422 007,
Maharashtra, India.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION
The present invention relates to the field of automotive vehicle
In particular the present invention relates to an instrument panel for
automotive vehicle.
Still particularly the present invention relates to the field of knee bolster for
instrument panel.
BACKGROUND
Knee bolsters are provided in the lower portions of an instrument panel, generally facing the legs of the passengers in the front seats of the automotive vehicle. During frontal impacts, one criterion for acceptable knee bolster performance is the effectiveness of the knee bolster in transferring impact loads to an energy absorbing structure located within the instrument panel. To accomplish this objective, the force exerted on the knee bolster, by the occupant's knees, is transferred to an energy absorbing structure that is configured to collapse during impact thereby dissipating the received energy. The energy absorbing structure collapses in a controlled manner so as to limit the depth that the knees of the occupant will intrude into the instrument panel. Hence, the knee bolster is required to be effective in absorbing and therefore dampening the frontal shocks on the occupant's knees. Conventionally the energy absorbing structure is fixed to the knee bolster by means of an adhesive or a bolting means.
Several attempts have been made to provide a knee bolster capable of reducing the impact on the occupant's knees.

Accordingly, United States Patent 3897848 discloses an Occupant knee restraint including plastically deformable portions engageable by the frontal surfaces of the driver's knees to absorb kinetic energy in case of an impact. However, the construction of the occupant knee restraint of US3897848 is complicated as it required a metal base having a knee deformable side portion. The base is further required to be covered by a layer of soft foam which is further covered by an outer decorative covering. The knee deformable side portions are spot welded to the inner surface of the base.
Again, United States Patent 3907326 discloses a knee restraint including a first portion capable of absorbing energy by plastic deformation. The first portion is located on each side of the steering column of the vehicle for engagement by the frontal surfaces of the knees of the driver. A center portion is provided for interconnecting the first portions. The plastic deformation of the first portions by the frontal surfaces of the driver's knees helps in absorbing kinetic energy of the lower torso of the driver. One of the drawbacks of the US3907326 is that only the first portions of the knee restraint absorbs the impact while the center portion does not help in absorbing the impact. Hence, in the event that the knee of the driver is not positioned to opposite the first portions, the kinetic energy will not be effectively absorbed and hence can cause injury to the driver.
Further, United States Patent 4721329 discloses an elastically restoring knee bolster for motor vehicles wherein a resilient material is disposed on a backing plate which is provided on a frame. A layer of crushable material which absorbs energy caused by the impact of the occupant on the knee bolster. Resilient material is provided between the layer of crushable material and the backing plate. The knee bolster of US 4721329 is

complicated in construction and requires a number of layers in order to reduce injury caused to the occupant.
OBJECT OF THE INVENTION
An object of the present invention is to provide a knee bolster which is effective in protecting the occupant from injury due to an impact.
Another object of the present invention is to provide a knee bolster which enables in reducing injury to the occupant in the event of a collision.
Still another object of the present invention is to improve the aesthetics of the instrument panei.
Further another object of the present invention is to provide a knee bolster which is lower in cost and easy to manufacture.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a knee bolster fitted to a vehicle for absorbing energy from impact of the knees of an occupant of the vehicle during a collision, the knee bolster comprising a base fitted to a panel of the vehicle, the base having a front surface facing the knee of the occupant in its operative configuration and a foam resilient portion integrally moulded on the rear surface of the base.
Typically, the base is arcuate in shape and is formed by a pair of horizontal parallel edges and a pair of curved parallel edge.
Typically, the front surface is convex shaped while the rear surface is concave shaped.

Typically, the base is provided with a recess along one of the horizontal parallel edge of the base, the recess adapted to accommodate a steering column.
Typically, the base is provided with a covered opening for on-board diagnostics (OBD).
Typically, the rear surface of the base is provided with a plurality of ribs aligned parallel to the horizontal parallel edges and the curved parallel edge.
Typically, the plurality of ribs is positioned in a predetermined manner.
Typically, the base is fitted to the instrument panel by means of at least one self tapping screw.
Typically, the base is provided with claws adapted to engage with the panel, the claws being located on the horizontal parallel edge of the base opposite the recess.
Typically, the foam resilient portion is formed by co-moulding at least two materials in a mould of a predetermined shape, the at least two materials being polyol and isocyanide.
Typically, the rear surface of the base forms a closing surface of the mould.
Typically, the foam resilient portion is Polyurethane foam or high density foaming material.
Typically, the foam resilient portion has a density in the range of 125 to 135 kg/cubic meter.
Typically, the foam resilient portion covers at least a portion of the rear surface of the base.

In accordance with the present invention there is provided a method for manufacturing a knee bolster fitted to a lower panel of an instrument panel of a vehicle for absorbing energy from impact with the knees of an occupant of the automotive vehicle during a collision, the method comprises the step of:
a. moulding a base by injection moulding process to form a rear
surface with ribs and a front surface with a recess for
accommodating a steering column, at least one claw adapted to
engage with the instrument panel and an opening for a cover for
on-board diagnostics;
b. attaching the base formed by moulding onto the mould for
moulding foam resilient portion; and
c. injecting at least two materials into the mould to form the foam
resilient portion, the foam resilient portion being bonded to the
rear surface.
Typically, the two materials in the step of injecting are polyol and isocyanide.
BRIEF DESCRIPTION OF THE FIGURES
Other aspects of the invention will become apparent by consideration of the accompanying drawing and their description stated below, which are merely illustrative of a preferred embodiment of the invention and do not limit in any way the nature and scope of the invention.
Figure 1 illustrates a knee bolster fitted to the instrument panel of a vehicle;

Figure 2 illustrates an isometric view of the front surface of the base of the knee bolster;
Figure 3 illustrates the front surface of the base of the knee bolster;
Figure 4 illustrates an isometric view of rear side of the knee bolster showing the rear surface with the ribs and the foam resilient portion fixed to the rear surface; and
Figure 5 illustrates the rear view of the knee bolster showing the rear surface with the ribs and the foam resilient portion fixed to the rear surface.
DETAILED DESCRIPTION
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
Referring to the accompanied drawings, a knee bolster, in accordance with this invention is generally indicated by the reference numeral 10 and is particularly shown in figure 2 to figure 5 of the drawing.
Figure 1 illustrates the knee bolster (10) fitted to the instrument panel (100) of a vehicle. The knee bolster (10) is fitted to the instrument panel (100) having an upper panel (101) and a lower panel (102). The knee bolster (10) comprises a base (13) and a foam portion (20). The knee bolster (10) is fitted to the lower panel (102) of the instrument panel, typically on the driver's side of the vehicle.

The base (13) has a front surface (12), illustrated in figure 2 and figure 3, and a rear surface (15), and illustrates in figure 4 and figure 5. The base (13) is formed by injection moulding a hard synthetic material, typically plastics. The base (13) is typically arcuate in shape and has a front surface (12) and a rear surface (15). The front surface (12) is of relatively convex configuration while the rear surface (15) is of relatively concave configuration. The base (13) is defined by a pair of horizontal parallel edges (17a and 17b) connected by a pair of curved parallel edges (19a and 19b). The pair of horizontal parallel edges (17a and 17b) is parallel to the width of the instrument panel (100) of the vehicle. A recess (14) is formed along one of the horizontal parallel edge (17b) for accomniodating a steering column of a vehicle while at least one claw (16) is provided on the horizontal parallel edge (17a) opposite the horizontal parallel edge (17b) having the recess (14). The recess (14) is typically arcuate shaped. An onboard diagnostic (OBD) opening (18) is provided and is located proximal to the horizontal parallel edge (17a) having the claws (16). A removable OBD cover (21) is snap fitted to the OBD opening (18). The OBD opening (18) enables in viewing the onboard diagnostic (OBD) of a vehicle. A plurality of ribs (22) are formed on the rear surface (15) of the base (13) which are arranged in a predetermined manner such that a part of the ribs (22) are parallel to the horizontal parallel edges (17a and 17b) while another part of ribs (22) are parallel to the curved parallel edges (19a and 19b). The ribs (22) helps in increasing the strength of the knee bolster (10) and also enables, in forming an uneven surface. The knee bolster (10) is fitted to the instrument panel (100) with the help of self tapping screws (24).

A foam portion (20) is integrated with the ribs (22) on the rear surface (15) of the base (13). The foam portion (20) is a high density foaming material, typically Polyurethane foam, having a density typically in the range of 125 to 135 kg/cubic meter. The foam portion (20) is formed by the process of co-moulding a polyol and an isocyanide in a mould which is open on one side and provided with a runner. The cavity of the mould is of a predetermined shape. The open side of the mould is closed with the help of the rear surface (15) of the base (13). The polyol and the isocyanide are mixed and poured or injected in sequence into the cavity of the mould. Chemical reaction between the polyol and the isocyanide releases carbon dioxide gas in the form of bubbles. The bubbles are trapped in the matrix resulting from the chemical reaction, thus, forming the foam portion (20). The foam portion (20) is attached to the uneven surface formed by the ribs (22) on the rear surface (15) and thus get attached and integrated with the base (12) to form the knee bolster. The knee bolster (10) formed is extracted from the mould for installing onto an instrument panel (100) of a vehicle.
The foam portion (12) covers at least a portion of the rear surface (15) of the base (12) such that a predetermined distance is provided between the foam portion (12) and the pair of horizontal parallel edges (17a and 17b) and the pair of curved parallel edges (19a and 19b). The foam portion (12) is provided with a predetermined thickness and a predetermined shape. The preferable thickness of the foam portion is in the range of 16 to 40 mm.
TRIAL RESULTS
1. Test was conducted on the knee bolster of the present invention having a foam portion integrally moulded to the base and a conventional knee

bolster having a foam portion which is fixed to a base with the help of adhesive. On subjecting the knee bolster of the present invention and the conventional knee bolster to crash testing, it was found that the knee bolster of the present invention was 45-50 % more effective in absorbing shock caused by impact of the vehicle.
2. The knee bolster of the present invention was tested by subjecting knee bolster having different thickness of the foam portion to crash testing in a simulated vehicle. The knee bolster having foam portion thickness in the range of 16 to 40 mm was found to be more effective in absorbing shock caused by the crash testing of the vehicle as compared to the knee bolster having foam thickness less than 16 mm.
TECHNICAL ADVANTAGES
The product as described herein above offers several advancements over similar products disclosed in the prior art. The knee bolster besides improving the aesthetics of the instrument panel also helps in protecting the occupant in the event of an impact by reducing the injury caused to occupants.
In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated embodiments are exemplary only. The numerical values given of various physical parameters and dimensions are only approximations and it is envisaged that the values higher or lower than the numerical values assigned to the parameters, dimensions and quantities fall within the scope of the invention.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made 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 as well as other embodiments 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 knee bolster fitted to a vehicle for absorbing energy from impact of the knees of an occupant of the vehicle during a collision, said knee bolster comprising a base fitted to a panel of the vehicle, said base having a front surface facing the knee of the occupant in its operative configuration and a foam resilient portion integrally moulded on the rear surface of said base.
2. The knee bolster as claimed in claim 1, wherein said base is formed by a pair of horizontal parallel edges and a pair of curved parallel edge, said base being arcuate in shape.
3. The knee bolster as claimed in claim 1, wherein said front surface is convex shaped while the rear surface is concave shaped.
4. The knee bolster as claimed in claim 1, wherein said base is provided with a recess along one of said horizontal parallel edge of said base, said recess adapted to accommodate a steering column.
5. The knee bolster as claimed in claim 1, wherein said base is provided with a covered opening for on-board diagnostics (OBD).
6. The knee bolster as claimed in claim 1, wherein said rear surface of said base is provided with a plurality of ribs aligned parallel to said horizontal parallel edges and said curved parallel edge.
7. The knee bolster as claimed in claim 1, wherein said plurality of ribs are positioned in a predetermined manner.
8. The knee bolster as claimed in claim 1, wherein said base is fitted to the instrument panel by means of at least one self tapping screw.

9. The knee bolster as claimed in claim 1, wherein said base is provided with claws adapted to engage with the panel, said claws being located on said horizontal parallel edge of the base opposite said recess.
10.The knee bolster as claimed in claim 1, wherein said foam resilient portion being formed by co-moulding at least two materials in a mould of a predetermined shape, said at least two materials being polyol and isocyanide.
11.The knee bolster as claimed in claim 1, wherein said rear surface of said base forms a closing surface of said mould.
12.The knee bolster as claimed in claim 1, wherein said foam resilient portion is Polyurethane foam or high density foaming material.
13.The knee bolster as claimed in claim 1, wherein said foam resilient portion has a density in the range of 125 to 135 kg/cubic meter.
14.The knee bolster as claimed in claim 1, wherein said foam resilient portion covers at least a portion of the rear surface of the base.
15.A method for manufacturing a knee bolster fitted to a lower panel of an instrument panel of a vehicle for absorbing energy from impact with the knees of an occupant of the automotive vehicle during a collision, said method comprises the step of:
a. moulding a base by injection moulding process to form a rear surface with ribs and a front surface with a recess for accommodating a steering column, at least one claw adapted to engage with the instrument panel and an opening for a cover for on-board diagnostics;

b. attaching said, base formed by moulding onto the mould for
moulding foam resilient portion; and
c. injecting at least two materials into said mould to form said
foam resilient portion, said foam resilient portion being bonded
to said rear surface.
16.The method of manufacturing knee bolster wherein said at least two materials in the step of injecting are polyol and isocyanide.