Description:“Bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile”.
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FIELD OF INVENTION
[001] This invention is related to bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile. The bushing of stabilizer bar is provided for stabilizer bar 10 connected directly to lower arm.
BACKGROUND/PRIOR ART
[002] Currently available stabilizer bar type front suspension system 15 as illustrated in fig.1 includes strut (1) and shaft (2), which are connected to tire (7) through knuckle (3). A stabilizer bar (5) is in connection with lower arm (4) by means of bushing (6). The stabilizer bar (5) performs the following functions:-
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- Controls roll of the vehicle on both sides.
- Controls the front movement of tire.
- Controls movement of vehicle in braking and acceleration.
- Reduction of body lean of occupant.
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[003] Further, said lower arm (4) is provided in connection with the tire (7) with the help of said knuckle (3). A stabilizer mount bushing (8) with stabilizer bracket is employed in order to mount the bar (5) 5 onto vehicle body.
[004] There is a washer for each pair of bushings on either side thereof.
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[005] In addition to the above, a pin with lock nut is provided next to the washer for locking with the stabilizer bar.
[006] Thus, in conventional stabilizer bar type suspension system, stabilizer bar (5) is mounted directly to suspension arm (for eg. lower 15 arm) (4). The bushing (6) is a cylindrical member made of resilient material (ex: rubber). During forward or backward movement of vehicle in longitudinal direction, the bushing undergoes axial compression. Further, while taking turn longitudinal and lateral forces are exerted on the bushing, hence the bushing undergoes 20 compression in both axial and radial direction.
[007] As a result, jerk is felt by the users thereby affecting NVH characteristics (particularly vibration) of vehicle.
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[008] Thus, the above said bushing (6) used in suspension system plays an important role in NVH of vehicle and at the same time avoids metal to metal contact.
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[009] The road vibration through tire transmits to cabin via stabilizer 5 bar and mounting thereof, which eventually causes floor vibration in front cabin due to direct mounting of the stabilizer bar on cabin floor.
[0010] To improve in NVH level of vehicle, bush stiffness (both axial and radial) plays an important role. The stiffness includes static and 10 dynamic stiffness. Static stiffness refers to the stiffness when the vehicle is in static condition, whereas dynamic stiffness refers to the stiffness when the vehicle is in movement or even if not in movement but loaded by some load (live or dead). In order to change stiffness of bushing, balancing is needed to be achieved between both static and 15 dynamic stiffness accordingly. Change in static stiffness changes dynamic stiffness and vice versa.
[0011] According to another disclosure made in prior art, a bushing has been proposed, which is implemented for mounting the stabilizer 20 bar onto the vehicle body. The bushing is a cylindrical part with a through hole at the centre for securing onto the bar, wherein two voids are provided opposite to each other throughout the bushing in longitudinal direction in various shapes.
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[0012] According to another embodiment of aforesaid disclosure, a molded insert can be embedded in the bushing longitudinally from one end to another, wherein the molded insert can be a pair of semi 5 circular parts.
[0013] The aforesaid provision can control stiffness of bushing in radial direction only.
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[0014] Thus, the suggested technologies can’t cater to the requirement of the present invention, for which it has been devised. Hence, the invention has been introduced as the various provisions are effected to control stiffness of bush only in radial direction with existence of no solution in automobile industry to control the stiffness in radial as 15 well as axial direction with plays significant role in respect of NVH characteristics (particularly vibration).
OBJECTS OF THE INVENTION
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[0015] Principal object of the invention is to propose bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile.
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[0016] Another object of the invention is to propose bushing of 5 stabilizer bar with variable bi-directional stiffness for front suspension system in automobile which overcomes disadvantages of prior art(s).
[0017] Further object of this invention is to propose bushing of 10 stabilizer bar with variable bi-directional stiffness for front suspension system in automobile which satisfies NVH characteristics of vehicle by avoiding jerk thereby making the users comfortable.
SUMMARY OF INVENTION 15
[0018] According to this invention there is provided a bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile comprising a singly structured cylindrical piece provided with a plurality of inserts therewithin, 20 wherein each of the inserts begins from one end of the bushing to be extended in axial direction upto an intermediate point thereof.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
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[0019] Further objects and advantages of this invention will be more 5 apparent from the ensuing description when read in conjunction with the accompanying drawings of exemplary embodiments of invention and wherein:
Fig. 1 shows: Conventional stabilizer bar type front suspension 10 system.
Fig. 2 shows: A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile of invention. 15
Fig. 2A shows: Sectional view of fig. 2.
Fig. 2B shows: Another embodiment of present invention.
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Fig. 3 shows: Multiple parts of bushing during manufacturing in accordance with present invention.
Fig. 4 shows: Mounting of bushing on vehicle according to invention. 25
Fig. 5 shows: A pair of bushings (bushing as in fig. 2) on one side of vehicle.
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DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS 5
[0020] The invention is pertinent to a bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile. In order to control the dynamic stiffness of the bushing of stabilizer bar without affecting static stiffness, an insert (which is 10 30~40% less than bush length) is placed in bushing of resilient material such as rubber.
[0021] Now, reference may be made to fig. 2, wherein the bushing (1') forms a single cylindrical structural piece embedded with said insert 15 (2'). The insert is plural in number. The bushing can be made of a soft material and the insert is formed by a hard material such as metal.
[0022] The bushing is secured to the stabilizer bar (3') on both left 20 hand side and right hand side in the front of vehicle.
[0023] Referring to fig. 4, the bushing (1') is placed between two washers (4A, 4B), one of the washers (4A) is adjoined to the bushing (1') and another washer (4B) is located away from said bushing. 25 Similarly arrangement has been made for another bushing directed away from the bushing (1'). Each of the washers is pinned to the bar by means of a respective pin and lock nut. Fig. 4 indicates the following:-
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1'- Bushing
4A, 4B-Washer
B1- Lock Nut for washer (4B)
3'- Stabilizer Bar
6'- Lower Arm 10
7'- Stabilizer Mount
8'- Stabilizer Bracket
[0024] Here, the bushing is provided in a pair between two washers (4A, 4B) adjoined therewith wherein starting end of the insert is 15 extended towards the adjoined washer. The provision is made in a similar manner on both Right Hand Side and Left Hand Side of vehicle as in fig. 5.
[0025] In accordance with new design of the instant invention, the 20 insert constituting a metal strip begins from one end (edge) of bushing facing the washer (4B) and ends at an intermediate point (P) of the bushing as best seen in fig. 2. The insert is extended in the axial direction of the bushing itself.
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[0026] Referring to fig. 2A, the insert is two in number. According to 5 another embodiment as in fig. 2B, the insert is three in number. Thus, the number of said molded insert can vary as per need. The insert is having curved surface.
[0027] As can be observed, the inserts maintain a gap therebetween 10 when seen in the sectional view of the whole bushing (fig. 2A and 2B) because the bushing is divided in multiple parts (Z1, Z2) during manufacturing as in fig. 3.
[0028] Positioning of these inserts (metal strips) are such that while in 15 compression initial compression is soft and after certain deflection the stiffness is increased due to presence of metal strips. The bushing stabilizer bar comes into action in twist, hence instead of continuous metal strip ring, multiple metal strips are inserted in bushing.
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[0029] Thus, the placement of the insert in a part of the whole length of said bushing is made so as to have required compression in the course of movement of the stabilizer bar i.e. initial soft stiffness with gradual increase in the stiffness.
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[0030] The length of metal insert is determined by the distance of travel after which compression of bushing is required so as to meet
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desired comfort level of users. Considering initial soft entry of bush stiffness followed by sudden increase in stiffness, length of metal 5
[0031] strip is preferably less than bush length by 30%~40%. Considering the load on the bushing during forward & reverse movement, width of the metal insert (length of curvature) is preferably more than 50% of metal insert length to satisfy desired 10 buckling load criteria.
[0032] Material of insert is selected relying on the following factors:-
- Heat resistant during molding 15
- Sufficient load carrying capacity i.e. possessing enough compressive strength.
[0033] The material is such as Ferrous (Fe) without restricting scope of the invention to the same. Thus, other materials readily apparent 20 to a person skilled in the art are understood to be within perview of the invention.
Advantageous Features
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[0034] - Stiffness control of bushing in dual direction i.e. axial and radial.
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- Satisfy NVH characteristics of vehicle.
- Avoids jerk to users thereby making the travel comfortable. 5
[0035] It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present 10 invention, which is further set forth under the following claims:-

Claims:WE CLAIM:
1. A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile comprising a singly structured cylindrical piece provided with a plurality of inserts therewithin, wherein each of the inserts begins from one end of the bushing to be extended in axial direction upto an 10 intermediate point thereof.
2. A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile as claimed in claim 1 wherein the length of insert is governed by the distance of 15 travel after which compression of the bushing is required so as to meet desired comfort level of users.
3. A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile as claimed in claim 20 1 or 2 wherein the material of said insert is a hard material, which is heat resistant during manufacturing with sufficient load carrying capacity possessing enough compressive strength.
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4. A bushing of stabilizer bar with variable bi-directional stiffness 5 for front suspension system in automobile as claimed in any of the preceding claims wherein the bushing is made of resilient material such as rubber and the insert is metal such as Ferrous.
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5. A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile as claimed in any of the preceding claims wherein the bushing in a pair is placed between two washers adjoined therewith wherein starting end of the insert is extended towards the adjoined washer. 15
6. A bushing of stabilizer bar with variable bi-directional stiffness for front suspension system in automobile as claimed in any of the preceding claims wherein the placement of the insert having curved surface in a part of the whole length of said 20 bushing is made so as to have the required compression of bushing during movement of the stabilizer bar i.e. initial soft stiffness followed by gradual increase in the stiffness.
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7. A bushing of stabilizer bar with variable bi-directional stiffness 5 for front suspension system in automobile as claimed in any of the preceding claims is associated with the advantageous features such as herein described.
8. A bushing of stabilizer bar with variable bi-directional stiffness 10 for front suspension system in automobile substantially as herein described with reference to the accompanying drawings.