Patent Publication Number: US-2013234380-A1

Title: Spring of suspension for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2012-0022597 filed on Mar. 6, 2012, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a spring of a suspension for a vehicle which makes it possible to replace a metal spring of a suspension by a corrugated tube-shaped spring made of a complex material. 
     2. Description of Related Art 
     In general, the car body of a vehicle is supported by a suspension connected with the tires and the suspension improves riding comfort by absorbing various vibrations and shocks generated while the vehicle travels, and adjusts the overall balance of the car body in accordance with the state of the road surface. 
     Further, the suspension prevents the vehicle from inclining in one direction due to a centrifugal force by keeping drivability stable for the driver against the centrifugal force, when the vehicle turns. 
     Meanwhile, the spring disposed in the suspension is a main part that has great influence on the mechanical behavior of the suspension by providing a reaction force against vertical motion. A leaf spring formed by stacking spring metals and a coil spring wound in a coil shape are generally used as the spring of the suspension. 
     As shown in  FIG. 1 , in a suspension  1  equipped with a coil spring  10 , an insulator  12  is provided on the upper end of the coil spring  10  to be combined with a car body and the lower end of the coil spring  10  is seated on a lower seat fixed to a strut to be supported by a portion of the strut. 
     The coil spring  10  is usually made of metal and exposed to the outside due to the structural characteristic when being mounted in a vehicle, such that the coil spring  10  is commonly coated with paint to prevent corrosion. 
     As shown in  FIG. 2 , however, when the paint fall off due to various environments where the vehicle travels and the metal is exposed, a problem is generated in durability due to corrosion. 
     Further, when spring steel, which is high tension steel, is used to reduce the weight of a suspension system, brittleness of the spring is increased by addition of a silicon-based material, such that the spring may very rapidly break. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY 
     Various aspects of the present invention are directed to providing a spring of a suspension for a vehicle which makes it possible to reduce weight and vibrations by replacing a spring of a suspension by a corrugated spring made of a complex material and to providing a spring of a suspension for a vehicle which improves rigidity and non-linearity by forming a slit on the edge of the spring. 
     In an aspect of the present invention, a spring member of a suspension for a vehicle may include a spring provided to be supported between a lower seat disposed in the suspension and a car body to provide an elastic force, wherein an inner part of the spring is formed in a shape of a hollow corrugated tube. 
     The spring is made up of a compound of different materials. 
     The spring is composed of an inner layer and an outer layer, and the inner layer and the outer layer are made of different materials, respectively. 
     Elasticity of the inner layer is higher than elasticity of the outer layer. 
     At least a slit is formed on the outer side of the spring to control non-linear characteristics of the spring. 
     The at least a slit is formed perpendicular to a longitudinal axis of the spring. 
     The at least a slit is formed at a tip of ridge of the spring. 
     The at least a slit is formed in a radial direction with respect to the longitudinal axis. 
     The at least a slit is formed at every ridge of the spring, in a same line along the longitudinal axis. 
     The at least a slit is formed symmetric in a circumferential direction with respect to a longitudinal axis of the spring. 
     It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the configuration for mounting a coil spring of a suspension in the related art. 
         FIG. 2  is a view showing coat separation and fracture of the coil spring of the related art. 
         FIG. 3  is a front view showing the shape of a corrugated spring according to an exemplary embodiment of the present invention. 
         FIG. 4  is an enlarged cross-sectional view showing the structure of the inner layer and the outer layer by cutting the spring according to an exemplary embodiment of the present invention. 
         FIG. 5  is a perspective view and a plan view showing the arrangement of slits formed on the spring according to an exemplary embodiment of the present invention. 
         FIG. 6  is a diagram comparing the degrees of attenuating vibrations in the spring made of a complex material according to an exemplary embodiment of the present invention and a metal spring of the related art. 
         FIG. 7  is a diagram comparing the natural frequencies and the corresponding shapes in the spring made of a complex material according to an exemplary embodiment of the present invention and a metal spring of the related art. 
         FIG. 8  is a diagram comparing characteristics according to changes in corrugation angle, outer diameter of grooves and outer diameter of ridges in the spring according to an exemplary embodiment of the present invention. 
         FIG. 9  is a diagram comparing non-linear characteristics according to existence of slits and the number of slits in the spring according to an exemplary embodiment of the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. 
     Preferred embodiments of the present invention are described hereafter in detail with the accompanying drawings. 
       FIG. 3  is a front view showing the shape of a corrugated spring  100  according to an exemplary embodiment of the present invention. 
     As shown in the figure, the spring  100  according to an exemplary embodiment of the present invention is formed in the shape of a hollow corrugated tube and supported between a lower seat  300  disposed in a suspension and a car body  200  to provide an elastic force. 
     In detail, the spring  100  may be disposed, with the upper end supported by the car body  200  through an insulator and the lower end of the spring  100  seated and supported on the lower seat  300  disposed on a strut of a suspension. 
     That is, the corrugated spring  100  is disposed in a suspension, replacing the coil springs of the related art. The structure of the corrugated spring  100  provides a function of generating a repulsive reaction force due to elastic deformation at the ends of the corrugated structure against vertical load and returning to the original shape when the load is removed. 
     Further, when large load at a predetermined level or more is applied, the upper and lower surfaces come in contact with each other in the corrugated structure and a large repulsive reaction force is kept, such that the spring  100  performs the same operation as the metal springs of the related art. 
       FIG. 4  is an enlarged cross-sectional view showing the structure of the inner layer  110  and the outer layer  120  by cutting the spring  100  according to an exemplary embodiment of the present invention 
     As shown in the figure, the spring  100  according to an exemplary embodiment of the present invention may be manufactured with a compound of different materials. In detail, the spring  100  includes the inner layer  110  and the outer layer  120 , and the inner layer  110  and the outer layer  120  may be made of different materials. Preferably, the inner layer  110  may be made of an elastic material and the outer layer  120  may be made of a high-rigidity material. The high-rigidity material may be an alloy of different materials, or single metal. 
     That is, according to an exemplary embodiment of the present invention, a shock is reduced when the inner diameter comes in contact with the spring  100  by compression and NVH performance of the suspension is improved by high vibration attenuation force, by manufacturing the spring  100  from two materials of the inner layer  110  and the outer layer  120 , using an elastic material for reducing a vibration for the inner layer  110 . 
     Further, the spring  100  is provided with rigidity by forming the outer layer  120  of a high-rigidity complex material. 
       FIG. 5  is a perspective view and a plan view showing the arrangement of slits  130  formed on the spring  100  according to an exemplary embodiment of the present invention. 
     As shown in the figure, it is possible to control non-linear characteristics of the spring  100  by forming groove-shaped slits  130  on the outer side of the spring  100 . 
     In detail, the slits  130  may be formed perpendicular to the axis of the spring  100 . That is, the slits  130  are formed perpendicular to the central axis extending in the longitudinal direction of the spring  100 , in which the slits  130  may be radially formed on the corrugated spring  100 . 
     In this configuration, one or more slits  130  may be formed and the non-linearity characteristics depends on the number of the slits  130 , such that it is possible to adjust the number of the slits  130  in order to control non-linearity to satisfy the user&#39;s demands. 
     Further, the slits  130  may be formed at the tips of the ridges  140  of the spring  100 . Further, the slits  130  may be formed at every ridge  140  of the spring  100 , in the same lines with respect to the axis. 
     That is, the corrugated spring  100  has a structure with the ridges  140  and the grooves  150  that are alternately formed, and the slits  130  may be formed at the tips of the ridges  140  of the spring  100 . Further, the slits  130  may be formed in the same vertical line, at the ridges  140  of the spring  100 , but the present invention is not limited thereto. 
     In an exemplary embodiment of the present invention, the slits  130  are formed symmetric in a circumferential direction with respect to the longitudinal axis of the spring  100 . 
     The operation and effect of the present invention are described in detail. 
       FIG. 6  is a diagram comparing the degrees of attenuating vibrations in the spring  100  made of a complex material according to an exemplary embodiment of the present invention and a metal spring of the related art. Since a complex material generally has a damping coefficient higher than a single metal material, when the same vibration is generated, the complex material attenuates the vibration faster. That is, the spring  100  made of a complex material according to an exemplary embodiment of the present invention reduces vibration of a suspension faster than a coil spring made of metal, such that riding comfort can be improved and the vibrations of a wheel transmitted through the spring  100  is attenuated faster and transmitted to the vehicle. 
       FIG. 7  is a diagram comparing the natural frequencies and the corresponding shapes in the spring  100  made of a complex material according to an exemplary embodiment of the present invention and a metal spring of the related art. 
     That is, in the structure of the spring  100  having the same rigidity, the weight of the spring  100  made of a complex material according to an exemplary embodiment of the present invention is considerably smaller than the weight of a coil spring made of metal, such that the natural frequency of the spring  100  is higher than the metal spring (49.9 Hz→70.9 Hz). Therefore, since the possibility that the high natural frequency resonates with a low frequency band (50 Hz or less) inputted from a load while a vehicle travels is significantly low, the NVH-related performance is very excellent. 
       FIG. 8  is a diagram comparing characteristics according to changes in corrugation angle θ, outer diameter D 1  of grooves  150  and outer diameter D 2  of ridges  140  in the spring  100  according to an exemplary embodiment of the present invention wherein the corrugation angle θ, the outer diameter D 1  of the grooves  150  and the outer diameter D 2  of the ridges  140 , or the thicknesses of the inner layer  110  and the outer layer  120  change, the displacement characteristic of the spring  100  to the load changes, as shown in  FIG. 8 . Therefore, it is possible to design characteristics of the spring  100  which fit to the user&#39;s demands by changing the design variables of the spring  100 . 
       FIG. 9  is a diagram comparing non-linear characteristics according to existence of slits and the number of slits  130  in the spring  100  according to an exemplary embodiment of the present invention, in which the non-linear characteristics of the spring  100  change, as shown in the figure. Therefore, it is possible to design the spring to control the non-linear characteristic of the spring to satisfy the user&#39;s demands, using those shown in the figure. 
     According to an exemplary embodiment of the present invention, since the inner layer and the outer layer of the spring are made of different materials, respectively, the damping coefficient of the spring made of a complex material is higher than that of a metal spring and vibrations of a suspension are reduced faster, such that it is possible to improve riding comfort and to attenuate faster the vibration transmitted through the spring from a wheel. 
     Further, the weight of a spring made of a complex material is considerably smaller than the weight of a coil spring made of metal so that the natural frequency of the spring is higher than the metal spring. Therefore, the possibility that the high natural frequency resonates with a low frequency band (50 Hz or less) inputted from a load while a vehicle travels is significantly low so that the NVH-related performance is very excellent. 
     Further, it is possible to freely adjust rigidity and non-linearity of the spring by forming slits on the spring or changing the cross-sectional structure including the outer diameter of the spring or the corrugation angle so that it is possible to improve stability in driving of a vehicle by designing a spring to satisfy the characteristics of the spring that are required by a suspension. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.