FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
MOUNTING STRUCTURE FOR SUSPENSION BUSHES IN A RIGID AXLE
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
Mr. Mandar Hajare & Mr. Soheb Ahmed
all Indian national
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 mounting structure of bushes for a vehicle suspension system and more particularly relates to a mounting structure for suspension bushes in a rigid axle suspension system to bare the multi direction twisting forces exerted at the suspension during vehicle driving.
BACKGROUND OF THE INVENTION
The conventional dependent rear suspensions system normally used in vehicle is three link rigid axle type suspensions with panhard rod. This suspension system comprises of two trailing arms pivoted to front plane of vehicle. The rear ends of the trailing arms are connected to rigid axle on each side via two suspension bushes. The suspension bushes are connected to the rigid axle through a mounting structure comprising of support plates welded to the rigid axle. The rigid axle has an axle mounting plate secured at the end which carries a rear wheel hub unit. A vertically extending damper and spring are provided at each end of rigid link. It has, however been recognized that in this suspensions system, the mounting structure for the two rear end bushes of the trailing arm suffer from defects like low rigidity and strength and weld related distortions leading to structural bending/geometric distortion and durability failure. The situation becomes more complicated if the vehicle is rear wheel driven with rear powertrain. Further, a primary requirement of the suspension is to minimize the load path travelled from wheel contact patch to suspension and BIW joinery and to shield the suspension structure failures loop holes.
OBJECTIVE OF THE INVENTION
The main object of this invention is to provide a mounting structure for suspension bushes in a rigid axle type suspension system to provide sufficient rigidity and strength in order to improve durability of suspension system for a vehicle.

Another object of this invention is to provide a mounting structure for suspension bushes in a rigid axle type suspension system with improved geometric integrity.
Yet another object of this invention is to provide a mounting structure for suspension bushes in a rigid axle type suspension system with reduced weld related distortions.
Yet another object of this invention is to provide a mounting structure for suspension bushes in a rigid axle type suspension system having improved joinery between support plates.
Yet another object of this invention is to provide a mounting structure for suspension bushes in a rigid axle type suspension system which is simple in construction and cost effective.
Yet another objective of this invention is to have minimum part count for the suspension bush mounting structure with reduction in durability and fatigue failures of bush mounting suspension structure parts while enduring dynamic loads.
Further objects and features of the disclosure will become apparent from the following detailed description when considered in conjunction with the drawings.
SUMMARY OF THE INVENTION
The embodiments herein provide a mounting structure for suspension bushes in a rigid axle suspension system to bare the multi direction twisting forces exerted at the suspension during vehicle driving. The mounting structure comprises a bottom plate for supporting a rigid axle of said suspension system. A support plate is connected below said bottom plate for mounting with said suspension bushes on a trailing link assembly. An axle mounting plate is provided for connecting with one end of said rigid axle. A spring seat is connected above said bottom plate towards one end and other end connected to the rigid axle to form a box like structure. A pandhard rod bracket is connected to the rigid axle for mounting with an external link and a damper sleeve is provided on the rigid axle for mounting with a shock absorber.

The mounting structure according to present invention is provided on both the end of said rigid axle of suspension system for vehicles with rear engine mounting. The axle mounting plate includes a hole for connecting with one end of said rigid axle. The support plate and bottom plate is continuous to endure multi direction twisting forces exerted at the suspension during vehicle driving. The support plate has an inner profile corresponding to that of the profile of said trailing link for connecting it with middle pivot bush and rear pivot bush region on said trailing assembly. The bottom plate and spring seat forms a box like structure to provide maximum space for drive shaft envelop. According to another embodiment of the present invention the support plate may have collar like structure.
The mounting structure for suspension bushes in a rigid axle suspension system is provided to bare the multi direction twisting forces exerted at the suspension during vehicle driving to improve durability and rigidity of the suspension system. The mounting structure according to present invention improves dimensional accuracy and repeatability of the suspension system in series production. The design also helps to avoid the winding up of rigid axle beam around the wheel centre in braking, acceleration and to provide compliance to body during roll moment. The bottom plate and support plate also help in improving stiffness in lateral direction and under vertical loads of the suspension. The spring seat and bottom plate form a box like structure to give maximum space for drive shaft envelop.
BRIEF DESCRIPTION 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 a three link rigid axle system in accordance with this invention.
FIG. 2 shows an isometric exploded view of right hand side of a three link rigid axle system in accordance with this invention.

FIG. 3 shows isometric exploded view of an alternate scheme of right hand side of three link rigid axle system in accordance with this invention.
FIG. 4 shows another isometric view of the mounting structure, in accordance with this invention.
FIG. 5 shows an isometric view of a single piece structure for mounting of trailing arm bushes and wheel hub for rigid axle suspension, in accordance with an embodiment of the present invention.
FIG. 6 shows an isometric exploded view of the single piece structure for mounting of trailing arm bushes and wheel hub for rigid axle suspension, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
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,
The embodiments herein provide, a mounting structure for suspension bushes in a rigid axle suspension system to bare the multi direction twisting forces exerted at the suspension during vehicle driving. The mounting structure 1 comprises a bottom plate 12 for supporting a rigid axle 2 of said suspension system. A support plate 7 is connected below said bottom plate 12 for mounting with said suspension bushes 5,6 on a trailing link assembly 3. An axle mounting plate 13 is provided for connecting with one end of said rigid axle 2. A spring seat 16 is connected above said bottom plate 12 towards one end and other end connected to the rigid axle 2 to form a box like structure. A pandhard rod bracket 14 is connected to the rigid axle 2 for mounting with an external link (not shown in figure) and a damper sleeve 15 is provided on rigid axle for mounting with a shock absorber (not shown in figure).

The mounting structure 1 according to present invention is provided on both the ends of said rigid axle 2 of suspension system for vehicles with rear engine mounting. The axle mounting plate 13 includes a hole 18 for connecting with one end of said rigid axle 2. The support plate 7 and bottom plate 12 is continuous to endure multi direction twisting forces exerted at the suspension during vehicle driving. The support plate 7 has an inner profile 19 corresponding to that of the profile of said trailing link 3 for connecting it with middle pivot bush 5 and rear pivot bush 6 regions on said trailing assembly 3. The bottom plate 12 and spring seat 16 forms a box like structure to provide maximum space for drive shaft envelops. According to another embodiment of the present invention the support plate may have collar like structure 20 to save the material and to reduce the weight.
Referring to figures 1 to 4, the rigid axle suspension comprises of rigid axle 2, trailing link assembly 3, spring seat 16, bottom plate 12, support plate 7, damper sleeve 15, axle mounting plate 13 provided on each side of rigid axle wherein said mounting structure for suspension bushes consists of support plate 7, spring seat 16 and axle mounting plate 13 welded to rigid axle 2. The unitary support plate 7 is welded to the bottom surface of bottom plate 12 and bottom plate 12 is welded to spring seat 16, rigid axle 2 and axle mounting plate 13. The said spring seat 16 is also welded to rigid axle 2 and axle mounting plate 13. Each ends of the said rigid axle 2 is located inside axle mounting plate 13 and welded. The trailing link assembly 3 is connected to the mounting structure for suspension bushes through middle pivot bush 5 and rear pivot bush 6 mounted between unitary support plate 7. The front pivot bush 4, middle pivot bush 5 and rear pivot bush 6 are assembled inside front pivot bush sleeve 9, middle pivot bush sleeve 10 and rear pivot bush sleeve 11 respectively. The said front pivot bush sleeve 9, middle pivot bush sleeve 10 and rear pivot bush sleeve 11 are welded on to the said trailing link assembly 3. The other end of trailing arm assembly 3 is connected to vehicle body through front pivot bush 4. Damper sleeve 15 is inserted in rigid axle 2 on each side of rigid axle 2 and welded. The panhard rod bracket 14 is also welded to rigid axle 2. Figure 3 embodies alternate design for support plate 7 shaped in the form of integrated support plate 8.
During vehicle running on rough roads various forces act on suspension. The load path of these forces is complicated if the vehicle is rear wheel driven. The twisting forces have to be endured

by the joint between the suspension bush mountings, spring mounting and axle mounting. In accordance with this invention, spring seat 16, bottom plate 12, unitary support plate 7 and axle mounting plate 13 form a rigid and strong box structure not only for mounting of suspension bushes but also for spring mounting. The design of unitary support plate 7 and bottom plate 12 is such that it provides continual joinery to endure multi direction twisting forces which are exerted at the suspension during vehicle driving. This continual joinery design endures the loads, not only improving the durability of the suspension system but also increasing rigidity. The design also helps to reduce welding joinery requirements between spring seat 16, bottom plate 12, unitary support plate 7 and axle mounting plate 13 thus preventing weld related distortion and which in turn helps in achieving improved dimensional accuracy and repeatability of the suspension system in series production. The design also helps to avoid the winding up (torsional moment) of rigid axle beam around the wheel centre in braking, acceleration and to provide compliance to body during roll moment. Bottom plate 12 and unitary support plate 7 or integrated support plate 8 also help in improving stiffness in lateral direction and under vertical loads of the suspension. The spring seat 16 and bottom plate 12 are shaped such that it gives maximum space for drive shaft envelop.
Referring now to another embodiment, best illustrated in FJG. 5 and 6, the structure provides very simple mounting arrangement for suspension bushes in a rigid axle suspension. The mounting structure comprises a plate 100 with two inbuilt two projecting Pins 400 and 500. The Plate 100 provided for supporting the rigid axle 2 and a spring seat 200. In one embodiment, the plate 100 inbuilt projecting pins 400, 500 include threading at the ends to hold assembly trailing arm.
The design of the mounting structure, in this embodiment helps to provide a better dimensional and suspension geometry control, as wheel hub and suspension trailing arm are mounted on the single part. Suspension bushes of the trailing arm assembly are mounted on pins 400 and 500 respectively, of the plate 100. The other end of the plate 100 supports the rigid axle 2 of the said suspension system. A spring seat 200 is connected above said plate 100 towards one end and other end connected to the rigid axle 2. The space available below the spring seat 200 and the plate 100 pins 400,500 for drive shaft envelop.

ADVANTAGE:
• The mounting structure for suspension bushes in a rigid axle suspension system is provided to bare the multi direction twisting forces exerted at the suspension during vehicle driving to improve durability and rigidity of the suspension system.
• The mounting structure according to present invention improves dimensional accuracy and repeatability of the suspension system in series production. The design also helps to avoid the winding up (torsional moment) of rigid axle beam around the wheel centre in braking, acceleration and to provide compliance to body during roll moment.
• The bottom plate and unitary support plate or integrated support plate is provided for improving the stiffness in lateral direction and under vertical loads of the suspension system.
• The spring seat and bottom plate form a box like structure to give maximum space for drive shaft envelop.
• The mounting structure 3, according to another embodiment includes a minimum part count; hence reflects in reduction in the load path.
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 mounting structure for suspension bushes in a rigid axle suspension system, comprising;
a bottom plate 12 for supporting a rigid axle 2;
a support plate 7 connected below said bottom plate 12 for mounting with said
suspension bushes 5,6 on a trailing link assembly 3;
an axle mounting plate 13 provided for connecting with one end of said rigid axle; said
axle mounting plate 13 further connected with said bottom plate and support plate 7;
a spring seat 16 connected above said bottom plate towards one end and other end
connected to said rigid axle 2 to form a box like structure;
a pandhard rod bracket 14 connected to said rigid axle for mounting with an external link;
and
a damper sleeve 15 provided on said rigid axle for mounting with a shock absorber.
2. The mounting structure according to claim 1, wherein said mounting structure 1 is provided on both the end of said rigid axle of suspension system for vehicles with rear engine mounting.
3. The mounting structure according to claim 1, wherein said axle mounting plate 13 having a hole 18 for connecting with one end of said rigid axle 2.
4. The mounting structure according to claim 1, wherein said support plate 7 may includes collar like structure 20.
5. The mounting structure according to claim 1, wherein said support plate 7 and bottom plate 12 is continuous to endure multi direction twisting forces exerted at the suspension during vehicle driving.
6. The mounting structure according to claim 1, wherein said support plate having an inner profile 19 corresponding to that of the profile of said trailing link 3 for connecting it with middle pivot bush 5 and rear pivot bush 6 region on said trailing link assembly 3.

7. The mounting structure according to claim 1, wherein said bottom plate spring seat forms a box like structure to provide maximum space for drive shaft envelop.
8. The mounting structure according to claim 1, wherein said bottom plate, support plate, axle mounting plate, spring seat and pandhard rod bracket are connected by welding means such as arc welding, spot welding etc.
9. A mounting structure for suspension bushes in a rigid axle suspension system, the mounting structure comprising:
a plate 100 with inbuilt projecting pins 400, 500 for supporting the rigid axle 2 and a spring seat 200.
10. The mounting structure as claimed in claim 9 wherein the plate 100 with inbuilt projecting
pins 400, 500 includes threading at the ends to hold assembly trailing arm.