FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A bush assembly structure for vehicle suspension
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
Soheb Ahmed, Mandar Hajare, & Pawan Awthankar
All are 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 and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to suspension assembly for frame assemblies of vehicles, and more particularly to an improved bush assembly structure for vehicle suspension with provisions for direct mounting of lower link suspension bushes, and thereby reducing the vibration and noise level in the vehicle.
BACKGROUND OF THE INVENTION
The automotive suspension mechanism uses vibration isolating bushes at a portion connecting the car body and the suspension with a view to attenuating and absorbing the shocks. This vibration isolating bushes are generally provided with a shaft member such as an inner cylinder, an outer cylinder arranged at spacing outside of the shaft member, and a rubbery elastic member interposed between the shaft member and the outer cylinder to bind the two elastically. Satisfactory level of vehicle suspension can be obtained by optimizing the damping force against the relative movement of the vehicle body and the wheel assembly with respect to the road conditions and the vehicle driving conditions.
Suspension bush assembly is usually either done directly on vehicle body or on a subframe assembly through attachment brackets on which suspension bushes are bolted. The subframe assembly is removable section of a vehicle frame that fastens under the bottom of the vehicle body. Subframe assembly is usually mounted at the bottom of a vehicle body at the front or the rear. For example in a front engine type vehicle, front suspension and steering systems are mounted on a subframe at the front side of the vehicle body.
The primary requirement from the suspension bush assembly structure is to provide sufficient strength and stiffness. Strength of the structure is paramount since the subframe assembly is subjected to very large mechanical stresses due to the forces

of the vehicle transferred to the subframe assembly from the suspension. Stiffness of the structure is required in order to not only have effective isolation of road induced vibrations but also help in reducing lateral compliance at wheel center which helps is achieving better vehicle dynamics.
Conventionally the suspension bush assembly structure is typically made of sheet metal formed brackets welded to the longitudinal members of subframe or directly to the vehicle body. In other conventional designs of subframe, suspension bush assembly structure is integrated between large sheet metal stampings. The individual components in these conventional designs are usually metallic pieces which are generally stamped then welded together.
However, the conventional suspension assembly requires external attachments and brackets for mounting the suspension system with the car body of the vehicle. Further, this external linkages leads to the bending moment due to the lateral loads of the suspension and the road shocks are not directly taken to the suspension assembly of the assembly. Moreover the conventional suspension assembly does not have consistency in reducing the vibration and noise level in the vehicle. The increased number of parts for achieving the vehicle suspension will also degrade the vehicle dynamics and increase the cost of suspension for the vehicle.
With respect to the conventional suspension arrangement, it is necessary to provide an improved assembly structure for vehicle suspension free from the above-mentioned disadvantages and the short comings involved in the conventional arrangements.
Therefore, it is necessary and desirable and advantages to have a suspension arrangement having direct mounting of suspension elements provided inside the body of suspension assembly structure and eliminating the requirement of external

brackets, and thereby improving both strength and stiffness of the suspension and the vehicle dynamics.
OBJECTS OF THIS INVENTION
The main objective of the present invention is provide a vehicle suspension arrangement having direct mounting of suspension elements inside the body of suspension assembly structure and eliminating the requirement of external brackets.
Another object of the present invention is to increase both the strength and stiffness of the suspension assembly and improving the level of vehicle dynamics.
Another object of the present invention is to provide a suspension bush assembly structure for a vehicle with provisions for mountings for suspension lower link bushes.
Yet another object of the present invention is to provide the suspension bush assembly structure for a vehicle with high dimensional accuracies for suspension mounting hard points.
Further object of the present invention is to provide the suspension bush assembly structure for a vehicle with means for attaching lower link assembly of suspension system with a stiffer joint, thereby reducing vibration and noise as well as helping in reducing lateral compliances.
Further object of the present invention is to provide a suspension bush assembly structure having lesser number of parts and eliminate the need for additional brackets for suspension attachment locations.

Still further object of the present invention is to provide a subframe assembly which is having reduced weld related distortions.
Another object of the present invention is to provide a subframe assembly for a vehicle which is simple in construction, cost effective and having minimum weight.
SUMMARY OF INVENTION
The present invention which achieves the objectives relates to a suspension bush assembly structure for vehicle suspension with provisions for direct mounting of lower link suspension bushes, and reducing the vibration and noise level in the vehicle. The suspension bush assembly structure includes a frame member having relief holes formed at each side of the frame member. The relief holes are formed in frame member, such that the relief holes formed in one side of the frame member is substantially parallel to the relief holes formed on the other side of the frame member.
A set of lower link assembly, each having front pin and rear pin arranged to respectively connect with the each side of the frame member. The lower link assembly and the frame member are connected through cylindrical sleeves placed inside the relief holes of the frame member. Suspension bushes are inserted inside the cylindrical sleeves placed in the frame member such that the two link assemblies are secured on the suspension bushes provided on the frame member through the cylindrical sleeves. The cylindrical sleeves are located and welded inside the relief holes provided on frame member.
A cross member is welded at the open side of the frame member for assembly requirements and providing required level rigidity in suspension assembly. The link assemblies are bolted on the suspension bushes using bush assembly nuts. The

cylindrical sleeves are welded in the relief holes provided on the each sides of the frame member thus forming provision for suspension bush assembly. Further, the body mounting sleeves are provided at each corner of frame member for mounting the suspension bush assembly structure on the vehicle body. A rack and pinion bracket is welded on the front side of the frame member of the suspension assembly.
The suspension bush assembly according to the present invention allows for mounting the suspension lower link attachments directly inside the body of suspension bush assembly structure, thus eliminating the requirement of welded brackets. This helps to improve both the strength and the stiffness of the suspension attachment hard point. Further, due to the elimination of welded brackets there is no bending moment arm created due to lateral loads of suspension and the loads are directly transferred to the body of suspension bush assembly structure. This further helps to achieve better strength and rigidity. The reduced level of bending moment arm enables to reduce the lateral compliances at wheel center and thus helping to improve the vehicle handling performance as well as noise and vibration performance.
BRIEF DESRIPTION OF DRAWINGS
Referring now to the drawings wherein the showings are for the purpose of illustration of the invention only, and not for the purpose of limiting the same.
Fig. 1 shows an isometric top view of suspension bush assembly structure with suspension lower link assembly in accordance to the exemplary embodiment of the present invention.
Fig. 2 shows an isometric bottom view of suspension bush assembly structure with suspension lower link assembly in accordance to the present invention.

Fig. 3 shows an exploded isometric top view of suspension bush assembly structure with suspension lower link assembly in accordance to the present invention.
Fig. 4 shows an isometric bottom view of alternate embodiment of suspension bush assembly structure with suspension lower link assembly in accordance to the present invention.
Fig. 5 shows an exploded isometric bottom view of alternate embodiment of suspension bush assembly structure with suspension lower link assembly in accordance to the present invention.
DETAILED DESCRIPTION
The present invention relates to improved bush assembly structure for vehicle suspension with provisions for direct mounting of suspension lower link bushes, and thereby improving the vehicle handling performance as well as noise and the vibration performance.
Fig. 1 to 3 shows various views of the suspension bush assembly structure with suspension lower link assembly in accordance to the exemplary embodiment of the present invention. The suspension bush assembly structure comprises of frame member (2) generally a U shaped tubular member with relief holes (13) formed on the each sides of the frame member (2). The relief holes are formed in frame member (2), such that the relief holes (13) formed on the one side of the frame member is substantially parallel to the relief holes formed on the other side of the frame member.
The arrangement further includes cylindrical sleeves (4) which are placed inside the relief holes (13) of the frame member (2) to receive and accommodate bushes for

providing improved vehicle suspension. The cylindrical sleeves (4) are welded inside the relief holes (13) provided on frame member. A cross member (3) is welded at the open side of the frame member (2) for assembly requirements and providing required level of rigidity in suspension bush assembly.
A set of lower link assembly (5, 6), each having front pin (9) and rear pin (10) is arranged to respectively connect with the left hand side and the right hand side of the frame member (2). The left hand side (LH) lower link assembly (5) and the right hand side (RH) lower link assembly (6) and the frame member (2) are respectively connected through the cylindrical sleeves (4) placed inside the relief holes (13) of the frame member (2). Suspension bushes (8) are inserted inside the cylindrical sleeves (4) placed in the frame member (2) such that the lower link assemblies (5, 6) are secured on the suspension bushes (8) provided on the frame member (2) through the cylindrical sleeves (4).
The front pin (9) and rear pin (10) of lower link assembly (5, 6) are respectively bolted on the suspension bushes (8) using bush assembly nuts (12), thus forming the assembly of LH lower link assembly (5) and RH lower link assembly (6) with the suspension bush assembly structure. The cylindrical sleeves (4) are welded in the relief holes (13) provided in the each sides of the frame member (2), thus forming provision for suspension bush assembly. Further, body mounting sleeves (11) are provided at each corner of the U shaped tubular frame member (2) for mounting the suspension bush assembly structure on the vehicle body. A rack and pinion bracket (7) is placed and welded on the front side of the frame member (2) of the suspension assembly. Further, the cylindrical sleeves (4) can be formed of a metal, and the suspension bushings (8) can be resilient bushes and formed of polymer.
Fig. 4 and 5 shows various views of an alternate embodiment of suspension bush assembly structure with suspension lower link assembly in accordance to the present invention, wherein an integrated cross member with bushing provision is

provided with access relief provided at each ends of integrated cross member with bushing provision. The suspension bush assembly structure comprises of frame member (2) generally a U shaped tubular frame member having front relief holes (13) and rear relief holes (13a) formed on the each sides of the frame member (2). The relief holes (13, 13a) are formed in frame member (2), such that the relief holes formed on the one side of the frame member (2) is substantially parallel to the relief holes formed on the other side of the frame member (2).
A set of lower link assemblies (5, 6), each having front pin (9) and rear pin (10) is arranged to respectively connect with the left hand side and the right hand side of the of the frame member (2). The left hand side (LH) lower link assembly (5) and the right hand side (RH) lower link assembly (6) and the frame members (2) are respectively connected through cylindrical sleeves (4) placed inside the front relief holes (13) of the frame member (2). The cylindrical sleeves (4) are placed inside the front relief holes (13) of the frame member (2) to receive and accommodate the suspension bushes for providing improved vehicle suspension. The cylindrical sleeves (4) are welded inside the front relief holes (13) provided on frame member (2).
An integrated cross member (3) having bushing provisions (14) for receiving suspension bushes (8) and access relief (15) for connecting with the frame member (2) is arranged to connect with the frame member (2). The ends of the cross member (3) are placed inside the rear relief holes (13a) formed in the frame member (2). The rear pin (10) of the LH lower link assembly (5) and RH lower link assembly (6) is secured through bushing provisions (14) provided on the cross member (3) and the frame member (2).
Suspension bushes (8) are inserted inside the cylindrical sleeves (4) placed in the frame member (2), such that the front pin (9) of the lower link assembly (5, 6) is secured on the suspension bushes (8) provided on the frame member (2). Further

the suspension bushings (8) are assembled with the bushing provisions (14) provided on the cross member (3) to secure the rear pin (10) of the lower link assembly (5, 6) with the cross member (3). The suspension bushes (8) for front pin (9) of lower link assembly (5, 6) are assembled inside the cylindrical sleeves (4) provided in front relief holes (13) on each side of frame member (2). The suspension bushes (8) for rear pin (10) of lower link assembly (5, 6) are assembled inside the each ends of the cross member (3).
Body mounting sleeves (11) are provided at each corner of U shaped frame member (2) for mounting the suspension bush assembly structure on the vehicle body. A rack and pinion bracket (7) is placed and welded on the front side of the frame member (2) of the suspension assembly. The integrated cross member (3) includes provisions for inserting the ends of the cross member (3) into the relief holes (13a) in the frame member (2) and bolting the rear pin (10) of the lower link assembly (5, 6) through the rear relief holes (13a).
The front pin (9) and rear pin (10) of LH lower link assembly (5) and RH lower link assembly (6) are respectively bolted on the suspension bushes (8) using bush assembly nuts (12), thus forming the assembly of LH lower link assembly (5) and RH lower link assembly (6) with the suspension bush assembly structure. The cylindrical sleeves (4) are welded in the relief holes (13) provided in the each sides of the frame member (2), thus forming provision for suspension bush assembly. Further, the cylindrical sleeves (4) disposed on each of the suspension bushings (8) can be formed of a metal. The suspension bushings (8) can be resilient bushes and made of a polymer.
The suspension bush assembly according to the present invention allows for mounting the suspension lower link attachments directly inside the body of suspension bush assembly structure, thus eliminating the requirement of external elements. It is clear from above description that suspension lower link attachments

are directly provided inside the body of suspension bush assembly structure thus eliminating the requirement of welded brackets. This helps to improve both strength and stiffness of the suspension attachment hard point. Additionally, due to elimination of welded brackets there is no bending moment arm created due to lateral loads of suspension and the said loads are directly transferred body of suspension bush assembly structure. This further helps to achieve better strength and rigidity. Reduced bending moment arm in turn also means that the lateral compliances at wheel center are reduced thus helping vehicle handling performance as well as noise and vibration performance.
Reduced number of parts helps to reduce welding length requirements which mean lesser weld related distortions and stronger subassembly. Welding reduction also helps to achieve better dimensional control during assembly resulting into consistent performance in series production. Lesser number of parts also translates into reduced complexities in manufacturing and assembly. All the vehicle body attachments are designed to have orientation in vertical direction providing ease of assembly in series production line as well as assembly/disassembly during service.
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 suspension assembly for a vehicle, the assembly comprises,
a frame member (2) having relief holes (13) formed at each side of the frame member, a set of lower link assembly (5, 6) each having front pin (9) and rear pin
(10) arranged to respectively connect with the each side of the frame member (2)
through cylindrical sleeves (4) placed inside the relief holes (13) of the frame
member (2);
wherein suspension bushes (8) are inserted inside the cylindrical sleeves (4) such that the link assembly (5, 6) is secured on the suspension bushes (8) provided on the frame member (2) through the cylindrical sleeves (4).
2. The suspension assembly as claimed in claim 1, wherein a cross member (3) is welded at the open side of the frame member (2).
3. The suspension assembly as claimed in claim 1, wherein the cylindrical sleeves (4) are located and welded inside the relief holes (13) provided on frame member (2).
4. The suspension assembly as claimed in claim 1, wherein body mounting sleeves
(11) are provided at each corner of frame member (2) for mounting the suspension
bush assembly structure on the vehicle body.
5. The suspension assembly as claimed in claim 1, wherein a rack and pinion bracket (7) is welded on the front side of the frame member (2) of the suspension assembly.
6. The suspension assembly as claimed in claim 1, wherein the lower link assembly (5, 6) are bolted on the suspension bushes (8) using bush assembly nuts (12).

7. The suspension assembly as claimed in claim 1, wherein each of the relief holes (13) includes an axis and said axes are substantially parallel.
8. The suspension assembly as claimed in claim 1, wherein the cylindrical sleeves (4) disposed on each of the suspension bushings (8) is formed of a metal.
9. The suspension assembly as claimed in claim 1, wherein the suspension bushings (8) are resilient bushes and made of a polymer.

10. The suspension assembly as claimed in claim 1, wherein the frame member (2) is a U shaped tubular member, U Tube closed cross section formed by stamping two halves or one piece bend tube.
11. A suspension assembly for a vehicle, the assembly comprises,
A frame member (2) having front relief holes (13) and rear relief holes (13a) formed at each side of the frame member (2), wherein cylindrical sleeves (4) are placed inside the front relief holes (13) of the frame member (2); a set of lower link assembly (5, 6) each having front pin (9) and rear pin (10) are arranged to respectively connect with the each side of the frame member (2);
wherein suspension bushes (8) are inserted inside the cylindrical sleeves (4) such that the front pin (9) of the link assembly (5, 6) is secured on the suspension bushes (8) provided on the frame member (2);
a cross member (3) having bushing provision (14) for receiving suspension bushes (8) and access relief (15) for connecting with the frame member (2) is arranged to connect with the frame member (2);
wherein the ends of the cross member (3) are placed inside the rear relief holes (13a) and the rear pin (10) of the link assembly (5, 6) is secured on the suspension bushes (8) placed on the bushing provisions (14) provided on the cross member (3).

12. The suspension assembly as claimed in claim 11, wherein the cylindrical sleeves (4) are located and welded inside the front relief holes (13) provided on frame member (2).
13. The suspension assembly as claimed in claim 11, wherein rack and pinion bracket (7) is welded on the front side of frame member (2).
14. The suspension assembly as claimed in claim 11, wherein the link assembly is bolted on the suspension bushes (8) and in bushing provisions (14) using bush assembly nuts (12).
15. The suspension assembly as claimed in claim 11, wherein body mounting sleeves (11) are provided at each corner of the frame member (2) for mounting the suspension bush assembly on the vehicle body.
16. The suspension assembly as claimed in claim 11, wherein the suspension bushes (8) for front pin (9) of lower link assembly (5, 6) are assembled inside the cylindrical sleeves (4) provided in front relief holes (13) on each side of frame member (2).
17. The suspension assembly as claimed in claim 11, wherein the suspension bushes (8) for rear pin (10) of lower link assembly (5, 6) are assembled inside the each ends of the cross member (3).

18. The suspension assembly as claimed in claim 11, wherein the cylindrical sleeve (4) disposed on each of the suspension (8) bushings is formed of a metal.
19. The suspension assembly as claimed in claim 11, wherein each of the relief holes (13 and 13a) includes an axis and said axes are substantially parallel.

20. The suspension assembly as claimed in claim 11, wherein the suspension bushings (8) are resilient bushes and made of a polymer.
21. The suspension assembly as claimed in claim 11, wherein the frame member (2) is a U shaped tubular member, U Tube closed cross section formed by stamping two halves or one piece bend tube.
22. A vehicle having the suspension assembly, as claimed in any one of the preceding claims.