Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2016
COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE OF INVENTION
A Lower Control Arm for a Vehicle

APPLICANT
MAHINDRA ELECTRIC AUTOMOBILE LIMITED, an Indian company, having its address at Mahindra Tower, Pandurang Budhkar Marg, Nr. Doordarshan Kendra, Worli, Mumbai, Mumbai City, Maharashtra 400018, India.

PREAMBLE TO THE DESCRIPTION
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
FIELD OF THE INVENTION
[001] The present invention relates to a lower control arm for a vehicle.

BACKGROUND OF THE INVENTION
[002] A lower control arm, also known as a spring link, is one of the links in a multi-link suspension system in vehicles. The lower control arm connects a sub-frame of a vehicle and a hub that carries a wheel in the vehicle. The lower control arm regulates the vertical travel of the wheel and ensures that the wheel remains in contact with the ground.
[003] The lower control arm accommodates a spring to store compressive forces when the wheel moves upwards as the vehicle traverses over a bump and aids in the suspension. The spring also ensures that the wheel is brought back to its original position once the compressive forces are removed. Since the spring supports the entire weight of the vehicle and stores the energy during compression when the vehicle traverses a bump or a speed breaker, the reaction exerted by the spring onto the lower control arm is huge. Thus, it is the onus of the lower control arm to take the reaction forces without plastic deformation due to the high stresses experienced. Also, the lower control arm must be of lower weight in order to reduce the un-sprung mass. Since these requirements are contradictory, the lower control arm design poses a huge design challenge to make the part stiff enough to take the road loads and the spring reaction and also to ensure that it is lighter in weight. The reaction force exerted by the spring onto the lower control arm is extremely high in case of sport utility vehicles whose wheel travels are higher and thus the reactions from the spring are higher due to higher compression. The design of the lower control arm gets further challenging when the vehicle is a 7-seater instead of a 5-seater passenger car as the vehicle weight is higher and the spring stiffness is therefore high. The challenge to design a durable lower control arm is further enhanced multi-fold in the case of heavier vehicles like trucks, or electric vehicles wherein the vehicle weight inherently is higher due to the big underfloor battery for long range and mileage. Such higher loads will require the spring to be of longer length and larger coil diameter. Conventional lower control arms are not designed to adapt to such larger dimensions of the spring.
[004] Further in the conventional lower control arm design, the compression spring is placed on the top portion of the control arm. In such designs, springs of higher lengths cannot be accommodated.
[005] The lower control arms of the prior art are made of aluminium and by casting process. For lower control arms of higher stiffness, the casting process will increase the weight of the lower control arm. Also, the costs associated with aluminium casting are high.
[006] Hence there is a need in the art for the lower control arm for a vehicle which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[007] Accordingly, the present invention in one aspect provides a lower control arm for a vehicle, the lower control arm comprising a base member extending between a vehicle side mounting end and a wheel side mounting end, a pair of side walls extending from the base member and spaced apart from one another, a spring seat region disposed between the side walls, the spring seat region has an enlarged region between the side walls compared to regions adjacent to the vehicle side mounting end and the wheel side mounting end, a bottom reinforcement member adapted to the base member in the spring seat region, the bottom reinforcement member having a spring resting face to allow a lower end of the compression spring to be mounted thereon and a top reinforcement member disposed above the bottom reinforcement member, the top reinforcement member adapted to the side walls of the spring seat region and having an opening for allowing the lower end of the compression spring to be mounted on the bottom reinforcement member, the bottom reinforcement member and the top reinforcement member being rigid reinforcement members preventing buckling of the base member.
[008] In an embodiment of the invention, the bottom reinforcement member is adapted to the base member via spot welding, and the top reinforcement member is adapted to the side walls via welding.
[009] In another embodiment of the invention, the bottom reinforcement member is a sheet metal plate corresponding with the base member in the spring seat region, the bottom reinforcement member having a raised portion at its center, and the sheet metal plate at its outer periphery adjacent to the side walls having a pair of extensions bending upwardly.
[010] In another embodiment of the invention, the upper edges of each of the side walls are bent outwardly to form an inverted c-shaped or u-shaped flange.
[011] In yet another embodiment of the invention, the top reinforcement member is a sheet metal plate extending from a first end to a second end, the first end adjacent to the spring seat region whereby the opening is formed by bending the plate inwards, and at the second end, the metal plate is adapted on the side walls adjacent to the vehicle side mounting end.
[012] In a further embodiment of the invention, the lower control arm is provided with a panel reinforcement extending between the side walls disposed adjacent to the vehicle side mounting end.
[013] In another embodiment of the invention, the lower control arm is provided with a tab extending from one of the side walls, the tab allows a stabilizer link to be mounted.
[014] In yet another embodiment of the invention, a reinforcement member extending from the side wall is coupled with the tab.
[015] In yet another embodiment of the invention, the tab is disposed at a position offset/eccentric with respect to longitudinal axis of the lower control arm.
[016] In a further embodiment of the invention, the base member has a dimple at the spring seat region.
[017] In yet another embodiment of the invention, the spring resting face is at a depth of 50mm to 60mm below the top edge of lower control arm allowing the compression spring to be mounted at a depth of 50 mm to 60 mm below the top edge of the lower control arm.
[018] In a further embodiment of the invention, the base member and the side walls have thickness in the range of 2 mm to 2.5 mm, and the reinforcement members have a thickness in the range of 2 mm to 2.5 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

[019] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows a lower control arm for a vehicle, in accordance with an embodiment of the invention.
Figure 2 shows an exploded view of the lower control arm for the vehicle, in accordance with an embodiment of the invention.
Figure 3 shows a cut sectional view of the lower control arm for the vehicle, in accordance with an embodiment of the invention.
Figure 4 shows an assembled view of a rear suspension of the vehicle comprising the lower control arm, in accordance with an embodiment of the invention.
Figure 5 shows the forces acting on the lower control arm, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[020] The present invention is directed towards a lower control arm for a vehicle with reinforcement features to mitigate high stresses and loads due to extreme articulation angles of a rear suspension system. The reinforcement features aid in construction of a lightweight lower control arm. The lower control arm of the present invention is able to accommodate a spring of longer length and larger diameter than lower control arms of the prior art.
[021] Figures 1 through 3 show a lower control arm 100 for a vehicle in accordance with an embodiment of the invention. The lower control arm 100 is designed for a rear suspension of large size vehicles such as SUVs or electric SUVs or truck type vehicles or other type of vehicles which are inherently heavy.
[022] The lower control arm 100 comprises a base member 104, a pair of side walls 106, a spring seat region 116, a bottom reinforcement member 112, and a top reinforcement member 110. In an embodiment, the base member 104 and the side walls 106 of the lower control arm 100 are made from sheet metal. The fabrication of the lower control arm 100 from sheet metal ensures that minimum weight and thickness is maintained without compromising on the stiffness of the lower control arm 100. In an embodiment of the invention, the thickness of the base member 104 and the side walls 106 are in the range of 2 mm to 2.5 mm which is almost 50% less than the thickness of aluminium casted parts of prior art. The weight of the lower control arm 100 of the present invention is 20% to 30% lesser compared to prior art.
[023] The base member 104 and pair of side walls 106 extend between a vehicle side mounting end 102 and a wheel side mounting end 118. At the vehicle side mounting end 102, a cylindrical sleeve 126 is provided for mounting the lower control arm 100 to a sub-frame of the vehicle. The lower control arm 100 is hinged to the sub-frame via the cylindrical sleeve 126. The cylindrical sleeve 126 can also have a bush inserted into it to facilitate its connection to the sub frame. At the wheel side mounting end 118, the lower control arm 100 is adapted to a knuckle or a hub which supports the wheel in the vehicle. The side walls 106 at the wheel side mounting end 118 has holes to enable the lower control 100 to be adapted to the knuckle or hub, whereby the lower control arm 100 can be mounted to the knuckle or hub by a mounting pin.
[024] The spring seat region 116 as shown is disposed between the side walls 106 at an intermediate region of the lower control arm 100. The spring seat region 116 has an enlarged region between the side walls 106 compared to regions adjacent to the vehicle side mounting end 102 and the wheel side mounting end 118. As shown, the enlarged region is circular which corresponds with shape of a compression spring S.
[025] In an embodiment, the lower control arm 100 of the present invention comprises plurality of reinforcement features to prevent plastic deformation or buckling failure of the lower control arm 100. The reinforcement features comprise the bottom reinforcement member 112, the top reinforcement member 110 and a panel reinforcement 108. The bottom reinforcement member 112 is adapted to the base member 104 in the spring seat region 116. A lower end of the compression spring S is received on the bottom reinforcement member 112.
[026] In an embodiment, the bottom reinforcement member 112 is a sheet metal plate corresponding to the base member 104 in the spring seat region 116. The bottom reinforcement member 112 has a thickness in the range of 2 mm to 2.5 mm. The bottom reinforcement member 112 has a pair of extensions 122 at its outer periphery adjacent to the side walls 106. The pair of extensions 122 helps to distribute part of the forces to the side walls 106. The bottom reinforcement member 112 is spot welded to the base member 104. The spot weld feature allows the bottom reinforcement member 112 to be welded onto the base member 104 which would not have been possible otherwise with conventional welding. The spot welding ensures that the bottom reinforcement member 112 is rigidly fixed to the base member 104. The bottom reinforcement member 112 provides local thickening for the base member 104 where most of the spring forces acts on the lower control arm 100. The local thickening due to the bottom reinforcement member 112 obviates the need for a thicker base member 104. The local thickening helps to provide the requisite stiffness for the lower control arm 100 without considerably increasing the weight of the control arm 100.
[027] In an embodiment, the bottom reinforcement member 112 has a spring resting face 112a to receive the lower end of the compression spring S. Further, the bottom reinforcement member 112 is provided with a raised portion 112b at its centre which helps in alignment of the compression spring S on the lower control arm 100. As discussed hereinbefore, the bottom reinforcement member 112 is adapted to the base member 104. Accordingly, the compression spring S is mounted well below the top edge of the lower control arm 100. In an embodiment of the invention, the spring resting face 112a is at a depth of 50mm to 60mm below the top edge of lower control arm 100. Accordingly, the compression spring S is mounted at a depth of 50 mm to 60 mm below the top edge of the lower control arm 100. Such deep seating/mounting of the compression spring S allows a longer compression spring S to be used along with the lower control arm 100.
[028] The top reinforcement member 110 is disposed above the bottom reinforcement member 112. The top reinforcement member 110 is adapted to the side walls 106 of the spring seat region 116.
[029] The top reinforcement member 110 is made from sheet metal and is welded on top edge of the side walls 106. The top reinforcement member 110 has a thickness in the range of 2 mm to 2.5 mm. The top reinforcement member 110 is a sheet metal plate extending between a first end 110a and second end 110b. The first end 110a is adjacent to the spring seat region 116 and the second end 110b is adjacent to the vehicle side mounting end 102. Further, the top reinforcement member 110 has an opening O. The opening O is a circular opening and is aligned with the bottom reinforcement member 112 such that the compression spring S can be introduced into the spring seat region 116. The opening O is formed by bending the plate of the top reinforcement member 110 inwards. The bending of the edges of the opening O also provides additional stiffness to the top reinforcement member 110 as the bend edges of the opening O will resist buckling of the lower control arm 100.
[030] The top reinforcement member 110 acts as a rigid member and holds the side walls 106 together and mitigates the buckling tendency which may be caused due to the enlarged region at the spring seat region 116. The top reinforcement member 110 enables wider construction of the lower control arm 100 at spring seat region 116 to accommodate higher spring diameter and also enables proper clearances with the compression spring S which requires larger articulation space due to the placement at increased depth and due to the longer length. In an embodiment of the present invention, the spring seat region 116 has a width of 150 mm, at its widest portion, allowing a compression spring S of diameter 125 mm to be mounted on the lower control arm 100. The diameter of the opening O of the top reinforcement member 110 will correspond with width of the spring seat region 116. With the present invention, the lower end of the compression spring S is mounted at a depth of 50 mm to 60 mm from the top edge of the lower control arm 100. Thus, the present invention allows a longer and larger coil diameter compression spring S to be used with the lower control arm 100. The use of longer and larger diameter compression spring S is crucial when the lower control arm 100 is used in SUVs, seven-seater vehicles, electric vehicles etc.
[031] Further, longer springs allow the use of compression spring S of higher pitch to reduce the contact between the coils in the compressed condition. Reduced contact between the coils increases the life of the compression spring S. Also, longer and larger diameter springs ensures that the compression spring S has sufficient stiffness to take up heavier loads.
[032] Further, the panel reinforcement 108 is provided near to the vehicle side mounting end 102 of the lower control arm 100. The panel reinforcement 108 extends between the side walls 106. In an embodiment of the invention, the panel reinforcement 108, at its end away from the vehicle side mounting end 102, is disposed at a position below the second end 110b of the top reinforcement member 110.
[033] The panel reinforcement 108 is a sheet metal plate welded to the side walls 106. The panel reinforcement 108 has a thickness in the range of 2 mm to 2.5 mm. In an embodiment of the invention, the panel reinforcement 108 has one of its ends disposed adjacent to the vehicle side mounting end 102 and the other end is bent downwards at a position between the vehicle side mounting end 102 and the spring seat region 116.
[034] The panel reinforcement 108 provides additional stiffness to the lower control arm 100 at the vehicle side mounting end 102.
[035] Figure 3 shows the cut sectional view of the lower control arm 100, in accordance with an embodiment of the invention. In an embodiment of the invention as shown in figure 3 the upper edges of each of the side walls 106 are bent outwardly to form an inverted c-shaped or u-shaped flange. The bending of the upper edges of the side walls 106 provides additional stiffness to the lower control arm 100 and prevents buckling of the lower control arm 100. The flanged upper edges of the side walls 106 also acts as a resting face for the edges of the top reinforcement member 110. The side walls 106 and the top reinforcement member 110 can be welded to each other at the flanged upper edge portion of side walls 106.
[036] Further, as shown in figure 1 to 3, a tab 114 extends from one of the side walls 106. The tab 114 allows for a stabilizer link 406 to be mounted to the lower control arm 100. The stabiliser link 406 is part of an Anti-Roll Bar (ARB) arrangement in the vehicle which prevents rolling motion of the vehicle. A reinforcement member 124 is also provided extending from the side wall 106 to support the tab 114. The reinforcement member 124 is a sheet metal piece which is coupled to the tab 114. The end of the reinforcement member 124 which is disposed on the side walls 106 is flanged to provide additional support and stiffness to the tab 114.
[037] Further, the tab 114 is disposed at a position offset/eccentric with respect to the longitudinal axis of the lower control arm 100. The offset/eccentric positioning of the tab 114 allows for meeting the packaging requirements of the vehicle and helps to accommodate for the inability in the novel construction of the lower control arm 100 to provide for axial positioning of the stabiliser link 406. A support washer is welded to the tab 114 to provide additional stiffness at the connecting portion of the stabilizer link 406.
[038] Further, as shown in figure 3, on bottom face of the base member 104, a dimple D is provided. The dimple D acts as a reinforcement and distributes buckling loads from the compression spring S and the mounting ends (102, 118).
[039] Figure 4 shows an assembled view of a suspension 400 of the vehicle comprising a pair of the lower control arms 100 of the present invention. The suspension 400 of the vehicle will have the lower control arm 100 at both the left-hand and right-hand sides. As shown, a damper 402 may also be attached to the lower control arm 100 at an axial location. The damper 402 and compression spring S will be disposed on the lower control arms 100 of both the left-hand and right-hand sides. The stabilizer links 406 attached to the tabs 114 on each of the lower control arms 100 in the assembly will be connected to the opposite end of a stabilizer bar 404 of the ARB arrangement.
[040] During operation of the vehicle, various forces act on the lower control arm 100 under different conditions such as full bump or rebound condition of vehicle. Figure 5 depicts various forces acting on the lower control arm 100 during operation of a vehicle. Force F1 on the lower control arm 100 is due to wheel articulation wherein the forces from the wheel are transferred to the lower control arm 100 via knuckle. Similarly, a force F2 which is a reaction force is experienced at the chassis end of the lower control arm 100 during the wheel articulation. The top reinforcement member 110 acts as a rigid member to counter-act the forces F1 and F2 and mitigates the buckling tendency of the lower control arm 100. Also, during wheel articulation, the compression spring S exerts a force F3 on the lower control arm 100 due to the spring stiffness. The bottom reinforcement member 112 acts as a thickening feature at the base member 104, of the spring seat region 116, where the force F3 acts to deform and buckle the lower control arm 100. The bottom reinforcement member 112 also aids in mitigating the buckling tendency caused by the forces F1 and F2. The dimple D acts as a reinforcement and distributes the buckling forces F1, F2 and F3. Thus, the stresses on the lower control arm 100 are reduced considerably as the loads are taken up by higher load carrying area because of the reinforcement features. Also, damper 402 and ARB exert forces F4 and F5 on the lower control arm 100 during wheel articulation as depicted in Figure 5. The reinforcement member 124 provides additional support to tab 114 to counter the force F5 from the ARB arrangement. The force F4 from the damper 402 is also countered by the lower control arm 100 and the reinforcement features discussed herein. Thus, several forces act on the lower control arm 100 and the magnitude of the forces are very high, especially in 7-seater vehicle with higher articulation angles/strokes or a battery-powered vehicle. The lower control arm 100 overcomes these forces and moments of higher magnitude. The lower control arm 100 is also durable which was possible only due to the reinforcement features as described hereinbefore.
[041] Advantageously, the present invention provides a lighter construction for the lower control arm without compromising on the stiffness of the lower control arm. The lower control arm of the present invention can take heavier loads produced in SUVs, seven-seater vehicles, or electric vehicles without buckling failure. The present invention also provides for longer and larger diameter spring to be used with the lower control arm. The different reinforcement members used in the present invention are positioned at critical positions where the stresses are maximum on the lower control arm. The reinforcement members redistribute the concentrated forces to larger load carrying area of the lower control arm and thus prevents the buckling or plastic deformation of lower control arm. Also, the lower control arm and the reinforcement members can be easily manufactured using press working of sheet metal and joined using welding operation. The lower control arm of the present invention also allows for the mounting of a stabilizer bar to it at an offset position. The spring life is also improved as contact between the coils of the links are reduced using longer springs.
[042] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.
, Claims:WE CLAIM:
1. A lower control arm (100) for a vehicle, the lower control arm (100) comprising:
a base member (104) extending between a vehicle side mounting end (102) and a wheel side mounting end (118);
a pair of side walls (106) extending from the base member (104) and spaced apart from one another;
a spring seat region (116) disposed between the side walls (106), the spring seat region (116) has an enlarged region between the side walls (106) compared to regions adjacent to the vehicle side mounting end (102) and the wheel side mounting end (118);
a bottom reinforcement member (112) adapted to the base member (104) in the spring seat region (116), the bottom reinforcement member (112) having a spring resting face (112a) to allow a lower end of the compression spring (S) to be mounted thereon; and
a top reinforcement member (110) disposed above the bottom reinforcement member (112), the top reinforcement member (110) adapted to the side walls (106) of the spring seat region (116) and having an opening (O) for allowing the lower end of the compression spring (S) to be mounted on the bottom reinforcement member (112), the bottom reinforcement member (112) and the top reinforcement member (110) being rigid reinforcement members preventing buckling of the base member (104).

2. The lower control arm (100) as claimed in claim 1, wherein the bottom reinforcement member (112) is adapted to the base member (104) via spot welding, and the top reinforcement member (110) is adapted to the side walls (106) via welding.

3. The lower control arm (100) as claimed in claim 1, wherein the bottom reinforcement member (112) is a sheet metal plate corresponding with the base member (104) in the spring seat region (116), the bottom reinforcement member (112) having a raised portion (112b) at its center, and the sheet metal plate at its outer periphery adjacent to the side walls (106) having a pair of extensions (122) bending upwardly.

4. The lower control arm (100) as claimed in claim 1, wherein the upper edges of each of the side walls (106) are bent outwardly to form an inverted c-shaped or u-shaped flange.

5. The lower control arm (100) as claimed in claim 1, wherein the top reinforcement member (110) is a sheet metal plate extending from a first end (110a) to a second end (110b), the first end (110a) adjacent to the spring seat region (116) whereby the opening (O) is formed by bending the plate inwards, and at the second end (110b) the metal plate is adapted on the side walls (106) adjacent to the vehicle side mounting end (102).

6. The lower control arm (100) as claimed in claim 1, having a panel reinforcement (108) extending between the side walls (106) disposed adjacent to the vehicle side mounting end (102).

7. The lower control arm (100) as claimed in claim 1, having a tab (114) extending from one of the side walls (106), the tab (114) allows a stabilizer link (406) to be mounted.

8. The lower control arm (100) as claimed in claim 7, wherein a reinforcement member (124) extending from the side wall (106) is coupled with the tab (114).

9. The lower control arm (100) as claimed in claim 7 or 8, wherein the tab (114) is disposed at a position offset/eccentric with respect to longitudinal axis of the lower control arm (100).

10. The lower control arm (100) as claimed in claim 1, wherein the base member (104) has a dimple (D) at the spring seat region (116).

11. The lower control arm (100) as claimed in claim 1, wherein the spring resting face (112a) is at a depth of 50mm to 60mm below the top edge of lower control arm (100) allowing the compression spring (S) to be mounted at a depth of 50 mm to 60 mm below the top edge of the lower control arm (100).

12. The lower control arm (100) as claimed in claim 1, wherein the base member (104) and the side walls (106) have thickness in the range of 2 mm to 2.5 mm, and the reinforcement members have a thickness in the range of 2 mm to 2.5 mm.

Dated this 20th day of October 2023

MAHINDRA ELECTRIC AUTOMOBILE LIMITED
By their Agent & Attorney

(Janaksinh Jhala)
of Khaitan & Co
Reg No IN/PA-2193