Abstract:
The present invention relates to a rear suspension system of a coupled torsion beam which comprises a torsion beam and trailing arms connected to ends of the torsion beam by welding, wherein a gap with a predetermined length is formed between the torsion beam and the trailing arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0123617 filed in the Korean Intellectual Property Office on Nov. 2, 2012, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a rear suspension system of a coupled torsion beam. More particularly, the present invention relates to a rear suspension system of a coupled torsion beam of which a connecting structure of a torsion beam and a trailing arm is improved. 
         [0004]    (b) Description of the Related Art 
         [0005]    Generally, even though the suspension system of a torsion beam axle type (CTBA; Coupled Torsion Beam Axle) has simple components and narrow performance in a design, it has high driving stability compared to the low production cost and the light mass such that it can be mainly applied to a smaller car and a semi-mid-size car. 
         [0006]    In the suspension system of the torsion beam axle type, as shown in  FIG. 1 , a torsion beam  101  is disposed in width direction of a vehicle body, and a trailing arm  105  that is mounted with a carrier  103  for connecting a wheel and a tire is connected thereto. 
         [0007]    Each trailing arm  105  is provided with a shock absorber  107  and a bushing  109  for being connected to a vehicle body and a spring  113  is mounted between a spring seat  111  and the vehicle body. 
         [0008]    The wheel moves according to the torsion deformation of the torsion beam  101  in the middle of the suspension system of the torsion beam axle type according to the conventional art, and the wheel is induced to toe-in by the deformation of the torsion beam  101 , the position of the trailing arm  105 , and the characteristic of the mounting bushing  109 . 
         [0009]    Referring to  FIG. 2 , in the rear suspension system of a coupled torsion beam, the trailing arm  105  may be formed by connecting an inner arm  106   a  and an outer arm  106   b  by welding to be formed as tubular shape for high performance and light weight. 
         [0010]    The torsion beam  101  may be “V” shape and be connected to trailing arm  105  for high performance and light weight. 
         [0011]    However, when the rear suspension system of a coupled torsion beam absorbs twisting the torsion beam  101 , warping may be generated and thus concentrated stress may be applied to a connecting portion  1  of the torsion beam  101  and the trailing arm  105 . 
         [0012]    Thus, if the torsion beam  101  is twisted in driving of a vehicle, the warping formed to the connecting portion  1  of the torsion beam  101  and the trailing arm  105  may influence fatigue life of the suspension system. 
         [0013]    As solving the problem, increasing thickness where the warping may be applied may be considered, however entire weight of the suspension system is increased. 
         [0014]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention has been made in an effort to provide a rear suspension system of a coupled torsion beam having advantages of reducing concentrated stress, which may be generated during absorbing twisting of a torsion beam, applied to a connecting portion of a torsion beam and a trailing arm. 
         [0016]    A rear suspension system of a coupled torsion beam according to an exemplary embodiment of the present invention may include a torsion beam and trailing arms connected to ends of the torsion beam by welding, wherein a gap with a predetermined length is formed between the torsion beam and the trailing arm. 
         [0017]    A cross section of the torsion beam may be shaped as “V”. 
         [0018]    An attaching portion may be formed to each end of the torsion beam for the trailing arm to be connected thereto. 
         [0019]    The gap may be formed between the trailing arm and the attaching portion. 
         [0020]    A cross section of the torsion beam may be shaped as “V” and the torsion beam comprises a slated first surface and a slanted second surface. 
         [0021]    The attaching portion supporting the trailing arm may be formed to the first and the second surface of the torsion beam respectively. 
         [0022]    A connecting portion may be formed to each end of the torsion beam for connecting the first and the second surface and is connected with an upper portion of the trailing arm, and the connecting portion may be formed as flat. 
         [0023]    The attaching portion may include an open portion where the trailing arm is inserted therethrough, a supporting portion faced with the trailing arm, and a protrude portion supporting a lower portion of the trailing arm, and the gap may be formed between the supporting portion and the trailing arm. 
         [0024]    The connecting portion and the upper portion of the trailing arm may be connected by welding so as to form a first welding portion, and the protrude portion and the lower portion of the trailing arm may be connected by welding so as to form a second welding portion. 
         [0025]    The trailing arm may be formed by connecting an inner arm and an outer arm shaped as “C” respectively by welding so as to form tubular shape. 
         [0026]    The rear suspension system may further include a reinforcement bracket, and the reinforcement bracket may be welded to each end of the torsion beam and the trailing arm. 
         [0027]    A rear suspension system of a coupled torsion beam according to an exemplary embodiment of the present invention may include a torsion beam and trailing arms connected to ends of the torsion beam by welding, wherein an attaching portion is formed to each end of the torsion beam for the trailing arm to be connected thereto, and a gap is formed between the trailing arm and the attaching portion. 
         [0028]    The rear suspension system may further include a reinforcement bracket, and the reinforcement bracket may be welded to each end of the torsion beam and the trailing arm. 
         [0029]    The trailing arm may be formed by connecting an inner arm and an outer arm shaped as “C” respectively by welding so as to form tubular shape. 
         [0030]    A cross section of the torsion beam may be shaped as “V” and the torsion beam may include a slated first surface and a slanted second surface, a connecting portion may be formed to each end of the torsion beam for connecting the first and the second surface and be connected with an upper portion of the trailing arm, the connecting portion may be formed as flat, the attaching portion may include an open portion where the trailing arm is inserted therethrough, a supporting portion faced with the trailing arm, and a protrude portion supporting a lower portion of the trailing arm, and the gap may be formed between the supporting portion and the trailing arm. 
         [0031]    In exemplary embodiments of the present invention, concentrated stress formed to a connecting portion of the torsion beam and the trailing arm due to warping generated in absorbing twisting of a torsion beam, may be dispersed to the first and the second welding portion through the gap formed between the trailing arm and the attaching portion. 
         [0032]    Thus, according to an exemplary embodiment of the present invention, the warping effect generated in absorbing twisting moment between the torsion beam and the trailing arm may be minimized so that fatigue life of the entire suspension system may be improved. 
         [0033]    Also, according to an exemplary embodiment of the present invention, since warping stress which would be applied to the connecting portion of the torsion beam and the trailing arm may be disposed to the first and the second welding portion, thus thickness of the torsion beam and the trailing arm may be reduced and weight of the entire suspension system may be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which: 
           [0035]      FIG. 1  is a perspective view of a rear suspension system of a coupled torsion beam according to a conventional art. 
           [0036]      FIG. 2  is a perspective view of a connection structure of a torsion beam and a trailing arm of a rear suspension system of a coupled torsion beam according to a conventional art. 
           [0037]      FIG. 3  is a perspective view of a rear suspension system of a coupled torsion beam according to an exemplary embodiment of the present invention. 
           [0038]      FIG. 4  is an exploded perspective view of  FIG. 3 . 
           [0039]      FIG. 5  is cross-sectional view along line V-V of  FIG. 3 . 
           [0040]      FIG. 6  is front view of  FIG. 3 . 
           [0041]      FIG. 7  is an exploded perspective view of a rear suspension system of a coupled torsion beam according to a modified exemplary embodiment of the present invention. 
           [0000]    
         
           
                 
               
                 
                 
                 
               
             
                 
                     
                 
                 
                   &lt;Description of symbols&gt; 
                 
                 
                     
                 
               
               
                 
                     
                 
               
            
             
                 
                     
                   10, 110: torsion beam 
                   11: first surface 
                 
                 
                     
                   12: second surface 
                   30, 130: trailing arm 
                 
                 
                     
                   31, 131: inner arm 
                   33, 133: outer arm 
                 
                 
                     
                   50: attaching portion 
                   51a: open portion 
                 
                 
                     
                   51b: supporting portion 
                   51c: protrude portion 
                 
                 
                     
                   55: connecting portion 
                   170: reinforcement bracket 
                 
                 
                     
                   G: gap 
                   W1: first welding portion 
                 
                 
                     
                   W2: second welding portion 
                 
                 
                     
                     
                 
               
            
           
         
       
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0042]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0043]    The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
         [0044]    Further, in the drawings, a size and thickness of each element are randomly represented for better understanding and ease of description, and the present invention is not limited thereto and the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. 
         [0045]    In the following detailed description, in order to distinguish constituent elements of the same name, the constituent elements have names of a first, a second, and a third, and the first, the second, and the third are not limited to order thereof. 
         [0046]    In the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
         [0047]      FIG. 3  is a perspective view of a rear suspension system of a coupled torsion beam according to an exemplary embodiment of the present invention, 
         [0048]      FIG. 4  is an exploded perspective view of  FIG. 3 ,  FIG. 5  is cross-sectional view along line V-V of  FIG. 3 , and  FIG. 6  is front view of  FIG. 3 . 
         [0049]      FIG. 3  to referring to  FIG. 6 , a rear suspension system of a coupled torsion beam  100  according to an exemplary embodiment of the present invention includes a torsion beam  10  and a trailing arm  30  connected to each end of the torsion beam  10  by welding. 
         [0050]    The rear suspension system of the coupled torsion beam  100  according to an exemplary embodiment of the present invention may alleviate warping effect generated in absorbing twisting moment of the torsion beam  10 , and thus concentrated stress which may be applied to a connecting portion of the torsion beam  10  and the trailing arm  30  may be minimized 
         [0051]    A cross section of the torsion beam  10  is shaped as “V”. And the torsion beam  10  includes a slated first surface  11  and a slanted second surface  12 . 
         [0052]    A bushing case may be mounted to an end of the trailing arm  30  for connecting with a vehicle body, and a plurality of mounting bracket may be mounted to the other end of the trailing arm  30  for mounting a carrier, a spring, a shock absorber and so on. 
         [0053]    The trailing arm  30  includes an inner arm  31  and an outer arm  33 . That is, the trailing arm  30  is formed by connecting the inner arm  31  and the outer arm  33  shaped as “C” respectively by welding so as to form tubular shape. In this case, a part of the outer arm  33  is inserted into the inner arm  31 . 
         [0054]    In an exemplary embodiment of the present invention, the inner arm  31  is defined as a portion which is connected to each end of the torsion beam  10  and the outer arm  33  is defined as a portion which is partially inserted into the inner arm  31 . 
         [0055]    In an exemplary embodiment of the present invention, a predetermined gap G is formed where the torsion beam  10  and trailing arm  30  are connected to each other. 
         [0056]    An attaching portion  50  is formed to each end of the torsion beam  10  for supporting the trailing arm  30 . The attaching portion  50  may be formed to each end of the first and the second surface  11  and  12  of the torsion beam  10  respectively. 
         [0057]    A connecting portion  55  is formed to each end of the torsion beam  10  for connecting the first and the second surface  11  and  12  and is connected with an upper portion of the inner arm  31 . The connecting portion  55  may be formed as flat corresponding to a lower portion of the attaching portion  50  for supporting the upper portion of the inner arm  31 . 
         [0058]    So, the attaching portion  50  may support the upper and lower portion of the trailing arm  30 , which is the inner arm  31 . 
         [0059]    The attaching portion  50  include an open portion  51  a where the inner arm  31  is inserted therethrough, a supporting portion  51   b  faced with the inner arm  31 , and a protrude portion  51   c  supporting a lower portion of the inner arm  31 . 
         [0060]    The gap G is formed to the connecting portion of the torsion beam  10  and the trailing arm  30 , that is, the gap G is formed between the trailing arm  30  and the attaching portion  50 . More precisely, the gap G is formed between the supporting portion  51   b  and a side of the inner arm  31 . 
         [0061]    In an exemplary embodiment of the present invention, the gap G may be about 3 mm. 
         [0062]    The connecting portion  55  and the upper portion of the inner arm  31  are connected by welding so as to form a first welding portion W 1  and the protrude portion  51   c  of the attaching portion  50  and the lower portion of the inner arm  31  are connected by welding so as to form a second welding portion W 2 . 
         [0063]    As described above, according to the rear suspension system of the coupled torsion beam  100  of the exemplary embodiment of the present invention, the attaching portion  50  is formed to each end of the torsion beam  10  for connecting the trailing arm  30  thereto, and the predetermined gap G is formed between the trailing arm  30  and the attaching portion  50 . 
         [0064]    So, in exemplary embodiments of the present invention, concentrated stress, formed to a connecting portion of the torsion beam  10  and the trailing arm  30  due to the warping effect generated in absorbing twisting of the torsion beam  10 , may be dispersed to the first and the second welding portion W 1  and W 2  through the gap G formed between the trailing arm  30  and the attaching portion  50 . 
         [0065]    Thus, the warping effect generated in absorbing twisting moment generated in the connecting portion of the torsion beam  10  and the trailing arm  30  may be minimized so that fatigue life of the entire suspension system  100  may be improved. 
         [0066]    Also, according to the exemplary embodiment of the present invention, since warping stress which would be applied to the connecting portion of the torsion beam  10  and the trailing arm  30  may be disposed to the first and the second welding portion W 1  and W 2 , thus thickness of the torsion beam  10  and the trailing arm  30  may be reduced and weight of the entire suspension system  100  may be reduced. 
         [0067]      FIG. 7  is an exploded perspective view of a rear suspension system of a coupled torsion beam according to a modified exemplary embodiment of the present invention. 
         [0068]    Referring to  FIG. 7 , a rear suspension system of a coupled torsion beam  200  according to a modified exemplary embodiment of the present invention further includes a reinforcement bracket  170  which is connected to each end of a torsion beam  110  and a trailing arm  130 . 
         [0069]    The reinforcement bracket  170  is connected to each end of the torsion beam  110  and the trailing arm  130  by welding. The reinforcement bracket  170  is formed as “C” shape, and supports each end of the trailing arm  130  and the torsion beam  110 . 
         [0070]    The reinforcement bracket  170  wraps an outer arm  133  and an inner arm  131  and is connected to each end of the torsion beam  110  and the outer arm  133  and the inner arm  131  by welding. 
         [0071]    Because the reinforcement bracket  170  is connected to each end of the torsion beam  110  and the outer arm  133  and the inner arm  131  by welding, concentrated stress formed to a connecting portion of the torsion beam  110  and the trailing arm  130  due to warping generated in absorbing twisting of the torsion beam  110 , may be dispersed to the first and the second welding portion W 1  and W 2  more smoothly. Thus, the warping effect generated in absorbing twisting moment generated in the connecting portion of the torsion beam  110  and the trailing arm  130  may be minimized so that fatigue life of the entire suspension system  200  may be improved. 
         [0072]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.