FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Lower control arm of a Vehicle Suspension System
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Sandip Kulkarni, Ravi Rao, Prasad Jadhav, Rahul Sarode
all Indian nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention

FIELD OF INVENTION
This invention relates to a lower control arm of a vehicle suspension system for an independent suspension system of a vehicle and more particularly to a lower control arm made up of sheet metal.
BACKGROUND OF INVENTION
McPherson type of suspension for conventional vehicles typically includes a suspension system which has a lower control arm attached to the wheel of the vehicle incorporating vertical hydraulic dampener struts. As the vehicle is driven, the wheel bounces up and down in response to bumps in the road and during cornering. As this is going on, the travel of the wheel is controlled by lower control arms as it pivots about axes. The typical control arm is generally triangular shaped with a ball joint assembly at the apex of the control arm and pivots bar bushings at the ends of the arm for mounting the control arm to a pivot bar assembly. In the past, the modulus sections between the bushings and the ball joint have been solid sections of cast iron or cast aluminum. It was believed that the traditional cast metal sections were necessary to maintain the integrity of the control arm under the.stresses of the suspension system. More recently, the modulus section has been constructed of a steel forging. Although these control arm constructions were strong enough to withstand the stress loads they also were very heavy consequently increasing the overall weight of the vehicle and carbon foot print. Because of the higher weight the cost and effect on fuel efficiency is also adverse, which necessitates different design and different manufacturing method.
In the existing proposals there is always a compromise between reducing the weight of the control arm and increase the stiffness. There have been few cases of reduction in weight achieved with sheet metal two piece control arm being welded to each other. However, stiffness of the control arm needs to be increased to withstand against the higher loads, this need usually comes when the same design of the control

arm has to be used for vehicle higher versions. To fulfill such a requirement, either . additional reinforcement is to be used or thickness of the components needs to be increased which again has a comparable weight of steel forged control arm. These necessary changes require a lot of design efforts and testing cycles which adds to the cost of the part.
OBJECT OF THE INVENTION
The main object of the invention is to obviate the above mentioned drawbacks. Another object of the invention is to provide a control arm made of sheet metal having requisite stiffness and low weight.
SUMMARY OE THE INVENTION
The embodiments herein provide a lower control arm for vehicle suspension system. The lower control arm comprises a major shell having a bushing aperture at first vertex and a second vertex, and a ball joint receptacle at third vertex. A first and second minor shells to act as reinforcement by supporting said major shell. The first and second minor reinforcement shells acts as a closing plate for said major shells. At least one irregular hole with smooth contour is provided on said major shell, first minor shell and second minor shell considering a load path and force behavior in particular direction to reduce weight.
According to present invention an arc like structure extends between the third vertex and second vertex, a wedge shaped profile extends between said first vertex and second vertex and a linear edge extends between said third vertex and first vertex. The aperture provided at second vertex and first vertex is for horizontal and vertical bushing. The first minor shell is bent from one side and its bent edge is joined with said major shell such that the bending area acts as a gusset to offer stiffness to the complete assembly. The second minor shell overlaps on the bending edge of first bottom reinforcement shell to provide additional stiffness. A cutout is provided on

the first minor shell to accommodate ball joint housing profile and a curve section is provided for front pivot mounting.
An edge of said second minor shell is connected with side wall of major shell to form a closing section from one side. A plurality of ribs is provided on said major shell to stiffen the shell. A cutout is provided on said second minor shell to accommodate rear pivot housing profile. An bottom edge 16a of. said second minor shell is connected with bent surface 15 of said first minor shell to offer additional stiffness for the assembly similarly a side edges 16b & 16c of said second minor shell is joined with the side wall of major shell to form closed section. The irregular hole in said major shell includes an elongated oval shaped hole provided in a path between said first vertex and third vertex, a circular hole is provided between said first vertex and middle of the arc region between said second vertex and third vertex and an elongated oval shaped hole is provided in a path between said first vertex and second vertex. The irregular hole in said first minor shell is elongated oval shaped and provided on the middle region along longitudinal direction. The irregular hole in said second minor shell includes a circular hole towards said bottom edge and an oval shaped hole above said circular hole.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully understood by reference to the following detailed description of a preferred embodiment of the present invention when read in conjunction with the accompanying drawing, in which:
FIG. A is an elevated perspective view of lower control arm complete which includes three major parts with front & rear bush & ball joint for a vehicle suspension system.
FIG. B is a view of part 'A' which is nothing but the upper part of the control arm.

FIG. C shows a perspective view of part 'B' which acts as a reinforcement as well as the gusset at key result area.
Fig. D shows a perspective view of Part 'C which also acts as a reinforcement & also serve the purpose of closing plate.
Fig. E shows the assembly of part 'A' & part 'B' which are welded together.
Fig F is nothing but the complete assembly of three major parts. All three parts are welded together to form a rigid close structure.
Fig. G is a cross sectional view of lower control arm.
DETAILED DESCRIPTION OF THE INVENTION
The present invention overcomes the disadvantages of the prior known control arms for vehicle suspension systems where there is always a compromise between weight and stiffness. Here the topology optimized sheet-metal design of lower control arm has been evaluated to identify the required material distribution. The present invention has a triangular three pieces configuration where a typical control arm has only two pieces. Such a unique three pieces construction gives comparatively better stiffness in all three directions with a great advantage in optimizing the component weight.
According to present invention, the independent suspension allows each wheel on the same axle to move vertically (i.e. reacting to a bump in the road) independently of each other. An independent suspension system for a vehicle driving axle is disclosed which includes a leading lower control arm which pivots about an axis. This control arm is a nearly fiat and roughly triangular member, which pivots in two places. The broad end of the triangle attaches at the frame and pivots on a bushing. The narrow end attaches to the steering knuckle and pivots on a ball joint. Here the

topology optimized sheet-metal design of lower control arm has been evaluated to identify the required material distribution. Consequently a significant improvement in stiffness with a considerable weight reduction is achieved. Moreover gusset is used at required section to improve the performance of control arm.
The embodiments herein provide a lower control arm for vehicle suspension system. The lower control arm comprises a major shell 'A' having a bushing aperture 6, 9 at first vertex 1 and a second vertex 2, and a ball joint receptacle aperture 4 at third vertex 3. A first 'B' and second minor shells 'C to act as reinforcement by supporting said major shell 'A', the first and second minor reinforcement shells acts as a closing plate for said major shells. At least one irregular hole with smooth contour is provided on said major shell, first minor shell and second minor shell considering a load path and force behavior in particular direction to reduce weight.
According to present invention a broad arc like structure extends between the third vertex and second vertex, a wedge shaped profile extends between said first vertex and second vertex and a linear edge extends between said third vertex and first vertex. The aperture provided at second vertex and first vertex is for horizontal and vertical bushing. The first minor shell is bent from one side and its bent edge is joined with said major shell such that the bending area acts as a gusset to offer stiffness to the complete assembly. The second minor shell 'C'overlaps on the bending edge 15 of first bottom reinforcement shell 'B' to provide additional stiffness. A cutout 11 is provided on the first minor shell 'B' to accommodate ball joint 1 housing profile and a curve section 14 is provided for front pivot mounting.
An edge of said second minor shell is connected with side wall of major shell to form a closing section from one side. A plurality of ribs 10a, 10b, 10c is provided on said major shell 'A' to stiffen the shell. A cutout 18 is provided on said second minor shell 'C to accommodate rear pivot housing profile. An bottom edge 16a of said second minor shell is connected with bent surface 15 of said first minor shell to

offer additional stiffness for the assembly similarly a side edges 16b & 16c of said second minor shell is joined with the side wall of major shell to form closed section. The irregular hole in said major shell 'A' includes an elongated oval shaped hole 5 provided in a path between said first vertex ] and third vertex 3, a circular hole 7 is provided between said first vertex 1 and middle of the arc region between said second vertex 2 and third vertex 3 and an elongated oval shaped hole 8 is provided in a path between said first vertex 1 and second vertex 2. The irregular hole in said first minor shell 'B' is elongated oval shaped 12 and provided on the middle region along longitudinal direction. The irregular hole in said second minor shell 'C includes a circular hole 17 towards said bottom edge 16a and an oval shaped hole 19 above said circular hole.
The control arm of the present invention also includes a modulus section having a substantially triangular section which reduces the overall weight of the control arm while maintaining strength in key stress areas of all the sections. All three pieces are formed through a stamping process & welded to each other through seam weld to form the triangular cross-section. Here weight reduction is being achieved through three piece construction with a minimum required thickness. Whereas stiffness is concern, minimum material distribution'required from stiffness point of view is being evaluated. One of the three parts is designed in such a way that it acts as a gusset too at key stress area & offers a better stiffness for the complete component,
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Now Referring to Fig. A. there is an inclined view of a control arm embodying the principles of the present invention. The control arm is preferably a forming part of a suspension system of a vehicle. As is typical of such components, the control arm has a substantially box shaped configuration with bushing apertures formed at the

ends 1 & 2 of the arms and a ball joint receptacle formed at the apex 3 of the control arm. Typical modern control arms are having two piece of construction where major shell act as a major component and other acts as a boxing or closing plate. In the present invention three parts (refer Fig. 'G') are used to form an optimized geometry where part 'A' is a major shell. The Part 'B' is a first minor shell and acts as a . reinforcement and offer support to the major shell. It also acts as a gusset at the key stress area which is located by considering all forces behaviors as well as the minimum material condition required. Part 'C is a second minor shell and act as reinforcement as well as serve the purpose of closing or boxing plate. Fig 'G' shows cross-sectional view of lower control arm where part 'B' is welded with part 'A' at all mating edges. The Part 'B' is bent from one side and its bent edge is welded with the part 'A' surface in such a way that the bending area act as a gusset which offers better stiffness to the complete assembly. Part 'C is overlapped on the bending edge of part 'B' which gives additional advantage.
The control arm of the present invention is formed of an integral metal stamping to ensure the required structural strength for the suspension system, However, unlike the prior known control arms which incorporate a solid construction, the present invention comprises triangular section which offers better stiffness. The control arm major shell (part 'A') shown in FIG. B is typical triangular section with three holes 5, 7 and 8 given for weight reduction purpose considering the minimum material requirements. The sections 6 and 9 are given for horizontal and vertical bushing mounting respectively where as section 4 is given for ball joint connection. A ribs 10a, 10b, 10c are provided from all three sides of the major shell which stiffens the part.
FIG. C shows profile of part 'B' which act as a reinforcement as well as the closing plate for major shell. Hole 12 is given for weight reduction purpose, the location of the hole is decided considering load path and forces behavior in particular direction.

The cutout ] 1 is given to accommodate ball joint housing profile whereas section 14 is given for front pivot mounting. The edge 13 joins with side wall of part 'A' and forms a closing section from one side after welding. One end 15 of part 'B' is bent in such a way that bent portion act as a gusset. Edge of bent portion is welded with the surface of part 'A' and offers a great stiffness against the major forces at key result areas. FIG. D shows the view of part 'C which also act as a reinforcement and serve the purpose of closing plate. The holes 17 and 19 are given for weight reduction purpose where the locations of the holes are decided considering load path and forces behavior in particular direction. The cutout 18 is given to accommodate rear pivot housing profile. The edge 16a rests over bent surface 15 of part 'B' and welded over there to offer additional stiffness for the assembly. The edges 16b and 16 c joins with the side wall of part 'A' & forms closed section after welding.
FIG. E shows the assembly of part 'A' & part 'B\ Part 'B" is formed in such a way that it converts 'C section into box (rectangular) section which offers better moment of inertia & ultimately the better stiffness to the assembly. Fig. F is nothing but the three part assembly where one edge of part 'C is overlapped on part 'B' which gives additional advantage.
ADVANTAGE:
• The present invention provides a three piece construction of lower control arm for independent suspension system made of sheet metal having requisite stiffness and low weight.
• An atleast one irregular hole with smooth contour is provided on said major shell, first minor shell and second minor shell considering a load path and force behavior in particular direction to reduce the weight.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration

only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim
1. A lower control arm for vehicle suspension system, comprising;
a major shell having a bushing aperture at first vertex and a second vertex and a ball
joint receptacle at third vertex;
a first and second minor shells to act as reinforcement by supporting said major shell
and act as a closing plate for said major shells;
at least one irregular hole with smooth contour provided on said major shell, first and
second minor reinforcement shells considering load path and force behavior in
particular direction to reduce weight.
2. The lower control arm according to claim 1, wherein an arc like structure extends between said third vertex and said second vertex, a wedge shaped.profile extends between said first vertex and said second vertex and a linear edge extends between said third vertex and first vertex.
3. The lower control arm according to claim 1, wherein said aperture provided at said second vertex and said first vertex is for horizontal and vertical bushing.
4. The lower control arm according to claim 1, wherein said first minor shell is bent from one side and its bent edge is joined with said major shell such that bending area acts as a gusset to offer stiffness to complete assembly.
5. The lower control arm according to claim 1 and 4, wherein said second minor shell overlaps on the bending edge of first bottom reinforcement shell to provide additional stiffness.

6. The lower control arm according to claim 1, wherein a cutout 11 is provided on said first minor shell to accommodate ball joint housing profile and a curve section is provided for front pivot mounting.
7. The lower control arm according to claim 1, wherein an edge of said second minor shell is connected with side wall of major shell to form a closing section from one side.
8. The lower control arm according to claim 1, wherein plurality of ribs are provided on said major shell to stiffen the shell.
9. The lower control arm according to claim 1, wherein a cutout is provided on said second minor shell to accommodate rear pivot housing profile.

10. The lower control arm according to claim 1, wherein an bottom edge 16a of said second minor shell is connected with bent surface 15 of said first minor shell 'B! to offer additional stiffness for the assembly similarly a side edges 16b & 16c of said second minor shell is joined with the side wall of major shell to form closed section.
11. The lower control arm according to claim 1, wherein said atleast one irregular hole in said major shell includes an elongated oval shaped hole provided in a path between said first vertex and third vertex, a circular hole provided between said first vertex and middle of the arc region between said second vertex and third vertex and an elongated oval shaped hole provided in a path between said first vertex and second vertex.
12. The lower control arm according to claim 1, wherein said irregular hole in said first minor shell is elongated oval shaped and provided on a middle region along longitudinal direction.

13. The lower control arm according to claim 1, wherein said irregular hole in said second minor shell includes circular hole towards said bottom edge, and an oval shaped hole above said circular hole,