FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
UPPER WISHBONE OF DOUBLE WISHBONE TYPE SUSPENSION ROBUST
DESIGN"
APPLICANT
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
Arun Prakash, Shantanu Bhave, Madhusudhan Belsare, Yashwant D Bhalerao
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 describes the invention
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FIELD OF INVENTION:
The present invention relates to an arrangement of bump stopper and rebound stopper; and also design of upper wishbone of a double wishbone type suspension.
BACKGROUND:
In an automobile, suspension system prevents shocks or vibrations from road surface from being transferred to the vehicle body in order to enhance passenger comfort. The suspension system connects axle of the vehicle to the vehicle body. A double wishbone type suspension is commonly used in automobiles. The primary purpose of the double wishbone type suspension is the appropriate control and steering of the wheels of a vehicle. Double wishbone type suspension uses two wishbones per wheel of the vehicle to guide up and down motion to each wheel. Generally, an upper wishbone of the double wishbone type suspension connects sprung mass of the vehicle to unsprung mass of the vehicle. Each wishbone of double wishbone type suspension is connected to the chassis frame at one end and to the hub of the wheel at the other end. At the time of cornering and turning, load acting on the vehicle body is shared by upper wishbone as well.
Bump travel of the wheels is controlled by a bump stopper provided in the suspension system. The bump stopper is designed to control the maximum height of the bump. When an excess load from the road surface is transferred to the suspension, which is caused when the vehicle runs on an irregular or raised road, the bump stopper supplements the function of a spring of the suspension system to absorb shocks. In the case of a vehicle's turn, the bump stopper also controls roll of the vehicle.
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During maximum downward travel or full rebound of the suspension and axle, shock absorbers provide a positive stop. Without such a stop, damage to the shock absorbers of the suspension system is likely to occur. In severe cases, damage may occur to the beams or the vehicle frame. However, relying solely on the shock absorber as a positive rebound stop for the suspension system can significantly shorten the life of the shock absorber.
A rebound stopper is used to extend the life of the shock absorbers of the suspension system. The use of rebound stopper limits the impact loads imparted on the shock absorbers.
A conventional suspension system has bump stopper and rebound stopper located on different wishbones. The bump stopper may be located at the upper wishbone and the rebound stopper at the lower wishbone or vice versa. Since a torsion bar is connected at the lower wishbone, most of the vertical load is taken by the lower wishbone. If the bump stopper or the rebound stopper is mounted on the lower wishbone, the lower wishbone undergoes more stress. This can lead to the failure of the lower wishbone.
During operation of vehicle upper wishbone is subjected to multiple stresses to withstand this stresses the construction of the upper wishbone needs to be sturdy and devoid of any manufacturing defects. Upper wishbones made up of sheet metal, which results in higher weight and makes the wishbones bulky, thereby leaving less space for access for tuning the steering. Further sheet metals are welded together to from an upper
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wishbone. Quality of welding also has an influence on the likely defects and frequencies of failures of upper wishbones.
Therefore, there is a need to optimize arrangement of the bump stopper and the rebound stopper in the suspension system together with robust design of upper wishbone that overcomes the above mentioned problems.
OBJECTS OF THE INVENTION:
An object of the present invention relates to the arrangement of the bump stopper and the rebound stopper at the upper wishbone of the double wishbone suspension system.
Another object of the present invention is to reduce the stress on the lower wishbone of the double wishbone suspension system.
Yet another object of the present invention is to enhance the life of the lower wishbone of the double wishbone suspension system.
Yet another object of the present invention relates to high durability of the double wishbone suspension system.
Further object of the present invention relates to reduce the bulkiness and weight of the upper wishbone.
Still further object of the present invention relates to provide additional access space the upper wishbone.
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Still further object of the present invention relates to reduce the number of parts in the manufacture of the upper wishbone.
Still further object of the present invention is to increase the robustness of the upper wishbone.
Various modifications of the disclosed objects, as well as alternate objects of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.
DESCRIPTION:
Fig. 1 illustrates a perspective view of a double wishbone suspension system in an automobile according to one embodiment of the present invention. The double wishbone suspension system comprises an upper wishbone 102 and a lower wishbone 104. The upper wishbone 102 and the lower wishbone 104 are connected to the vehicle chassis 106 at one end and to the hub (not shown in figure) of the wheel at the other end. Ball joints 108 connect the upper wishbone 102 and the lower wishbone 104 to the hub of the wheel.
A bump stopper 110, provided at the top of the upper wishbone 102, controls the bump travel of the wheels. The bump stopper 110 is fastened to a bump stopper bracket 112 which in turn is attached to the chassis frame 106. In one embodiment, the bump stopper is made of rubber and is fastened to the bump stopper bracket by means of bolts.
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When an excess load from the road surface is transferred to the upper wishbone 102, the ball joint 108 of the upper wishbone 102 comes in contact with the bump stopper 110, thus the maximum height of the bump is controlled.
The rebound travel of the wheels is restricted by using a rebound stopper 114. The rebound stopper 114 is provided at the bottom side of the upper wishbone 102. The rebound stopper 114 is connected to a rebound bracket 116 that is attached to the chassis frame 106. In one embodiment, the bracket 116 is welded to the chassis frame 106. In the present embodiment, the rebound stopper 114 is made of rubber.
The embodiment described above can have many variations, each of which would be obvious to a person skilled in the art. The bump stopper 110 and the rebound stopper 114 can be made of any material. The rebound bracket 116 can be attached to the chassis frame 106 by any means on the basis of known engineering concepts and/or routine experimentation.
The upper wishbone as shown in fig. 2 comprises wishbone body 102, a spindle 104 and a ball joint 106 connected at the upper wishbone body 102. The upper wishbone body 102 is manufactured by forging and is designed accordingly.
Another embodiment of the present invention is illustrated in fig. 3 depicting the arrangement of bump stopper 110 and the rebound stopper 114 in the double wishbone suspension system. The bump stopper 110 is arranged at the top of the upper wishbone
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102 whereas the rebound stopper 114 is arranged at the bottom of the upper wishbone 102. The bump stopper bracket 112 and the rebound stopper bracket 116, as shown in fig. 2, are attached to the chassis frame 106 and accommodate the bump stopper 110 and the rebound stopper 114 respectively.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

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