Patent Publication Number: US-2015084287-A1

Title: Dust cover for ball joint

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage Application of International Application No. PCT/JP2013/075239 filed on Sep. 19, 2013, and published in Japanese as WO 2014/057779 A1 on Apr. 17, 2014. This application claims priority to Japanese Application No. 2012-226550 filed on Oct. 12, 2012. The entire disclosures of the above applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a dust cover for a ball joint. 
     Further, the present invention relates to a dust cover for a ball joint which is used in an automobile suspension device, and a steering device. 
     DESCRIPTION OF THE CONVENTIONAL ART 
     Conventionally, as a ball joint to which a dust cover is installed for the purpose of a dust prevention and a water prevention in a ball joint coupling portion, there has been known a dust cover for a ball joint which is described in  FIGS. 4 and 5  (Japanese Unexamined Patent Document No. 2009-24834 and Japanese Unexamined Patent Document No. 2001-323923). 
     In a seal structure of this kind of dust cover for the ball joint, a spherical head portion  200  formed in one end of a ball stud  100  is retained within a socket  300 , as shown in  FIGS. 4 and 5 . 
     Further, a shaft portion  400  in the other end of the ball stud  100  is fastened and fixed to a knuckle  500 . 
     On the other hand, a one end large-diameter opening portion  90  of a dust cover made of a rubber-like elastic material is fixed and retained to an outer peripheral surface of the socket  300  by a reinforcement ring  600  which is buried in the one end large-diameter opening portion  90  and is made of a metal material, and the other end small-diameter opening portion  70  is retained to the shaft portion  400 . 
     Further, a film portion  800  is formed as a whole into a hand drum shape, the film portion  800  connecting the one end large-diameter opening portion  90  and the other end small-diameter opening portion  70 . 
     The reinforcement ring  600  is constructed by a base portion  610 , and a blade portion  620  which extends from the base portion  610  toward an outer peripheral surface of the socket  300 . 
     Further, since the blade portion  620  eats into the outer peripheral surface of the socket  300 , the dust cover is prevented from breaking away from the socket  300 . 
     Therefore, the blade portion  620  is necessarily provided with a spring elasticity. On the other hand, the base portion  610  is necessarily provided with a sufficient rigidity to prevent a sealing performance from being lowered by deformation of the base portion  610  when the large-diameter opening portion  60  is pressed into the socket  300 . 
     This kind of reinforcement ring  600  made of the metal material is manufactured by folding an outer peripheral side of an annular thin plate having a thickness Z, as shown in  FIG. 5 . 
     Accordingly, a width A in a diametrical direction of the base portion  610  is necessarily enlarged. 
     As a result, the film portion  800  in a compression side (a left side on the drawing) interferes with the one end large-diameter opening portion  90  as shown in  FIG. 4 , and a problem that the film portion  800  wears off and is damaged in an early stage has been brought about. 
     Further, in the case that the width A in the diametrical direction of the base portion  610  is sufficient, the base portion  610  can be pressed by a press fit jig P as shown in  FIG. 6 . Therefore, the dust cover can be installed to the socket  300  with no problem. However, in the case that protrusion toward an outer side in the diametrical direction of the one end large-diameter opening portion  90  is reduced for avoiding interference of the film portion  800  in the compression side with the one end large-diameter opening portion  90 , the width A in the diametrical direction of the base portion  610  is necessarily narrowed. As a result, an area at which the base portion  610  can be pressed by the press fit jig P is reduced, and a problem that it is hard to push the one end larger-diameter opening portion  90  into the socket  300  has been caused. 
     In the same manner, in recent years, it has been strongly desired to make the ball joint compact, and the diameter of the socket  300  has been made as small as possible. As a result, a space for setting a step portion of the socket  300  has been restricted, the socket  300  to which the one end large-diameter opening portion  90  is installed. 
     As a result, the area at which the base portion  610  can be pressed by the press fit jig P has been reduced, and the problem that it is hard to press the one end large-diameter opening portion  90  to the socket  300  has been brought about. 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     The present invention is made by taking the problem mentioned above into consideration, and an object of the present invention is to provide a dust cover for a ball joint which can easily compress a one end large-diameter opening portion by a socket even if a width in a diametrical direction of a base portion of a reinforcement ring becomes narrow, the reinforcement ring being buried in the one end large-diameter opening portion and being made of a metal material, and even if a compact structure of the ball joint is progressed. 
     Means for Solving the Problem 
     A dust cover for a ball joint according to the present invention is a dust cover for a ball joint structured such that a spherical head portion formed in one end of a ball stud is retained within a socket, a shaft portion in the other end of the ball stud is fastened and fixed to a knuckle, a one end large-diameter opening portion is fixed and retained to an outer peripheral surface of the socket, the one end large-diameter opening portion having a reinforcement ring made of a metal material and buried therein, and the other end small-diameter opening portion is retained to the shaft portion, having a film portion which connects the one end large-diameter opening portion and the other end small-diameter opening portion, and protrudes to an outer side and is formed approximately into a hand drum shape, and being made of a rubber-like elastic material, wherein a concave portion is provided in an outer peripheral surface of a joint portion between the one end large-diameter opening portion and the film portion. 
     Effect of the Invention 
     The present invention achieves effects described below. 
     According to the dust cover for the ball joint of the invention described in the first aspect, the dust cover for the ball joint is structured such that the concave portion is provided in the outer peripheral surface of the joint portion between the one end large-diameter opening portion and the film portion. As a result, even if the width in the diametrical direction of the base portion of the reinforcement ring becomes narrow, the reinforcement ring being buried in the one end large-diameter opening portion and being made of the metal material, and even if the compact structure of the ball joint is progressed, the one end large-diameter opening portion can be easily compressed into the socket. 
     Further, according to a dust cover for a ball joint of the invention described in a second aspect, a plurality of concave portions are uniformly provided circumferentially. It is possible to inhibit the film portion from peculiarly deforming, and it is possible to minimize reduction of a strength of the film portion. 
     Further, according to a dust cover for a ball joint of the invention described in a third aspect, the dust cover for the ball joint is particularly effectively structured such that an outer diameter of the reinforcement ring made of the metal material is equal to or smaller than a maximum outer diameter of the film portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross sectional view of a dust cover for a ball joint according to the present invention; 
         FIG. 2  is an enlarged view of a substantial part of the dust cover for the ball joint according to the present invention; 
         FIG. 3  is a vertical cross sectional view of a state of attaching a jig for installing the dust cover for the ball joint according to the present invention to a socket; 
         FIG. 4  is a vertical cross sectional view of a dust cover for a ball joint according to a prior art; 
         FIG. 5  is an enlarged view of a substantial part in  FIG. 4 ; and 
         FIG. 6  is a vertical cross sectional view of a state of attaching a jig for installing the dust cover for the ball joint according to the prior art to the socket. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     A description will be given below of an embodiment for carrying out the present invention. 
     As shown in  FIGS. 1 and 2 , a dust cover for a ball joint according to the present invention is structured such that a spherical head portion  2  formed in one end of a ball stud  1  is retained within a socket  3 , a shaft portion  4  in the other end of the ball stud  1  is fastened and fixed to a knuckle  5 , a one end large-diameter opening portion  6  is fixed and retained to an outer peripheral surface of the socket  3 , the one end large-diameter opening portion having a reinforcement ring  60  made of a metal material and buried therein, the other end small-diameter opening portion  7  is retained to the shaft portion  4 , and a film portion  8  is provided for connecting the one end large-diameter opening portion  6  and the other end small-diameter opening portion  7 , the film portion  8  protruding to an outer side and being formed approximately into a hand drum shape. 
     Further, a concave portion  91  is provided in an outer peripheral surface of a joint portion  9  between the one end large-diameter opening portion  6  and the film portion  8 . 
     As mentioned above, since the concave portion  91  is provided, the one end large-diameter opening portion  7  can be easily compressed into the socket  3  even in the mode in which the width in the diametrical direction of the ball portion  61  of the reinforcement ring  60  becomes narrow, the reinforcement ring  6  being buried in the one end large-diameter opening portion  6  and being made of the metal material, and the mode in which the compact structure of the ball joint is progressed, which are hard to be installed by the conventional installation jig P as shown in  FIG. 6 . 
     The concave portion  91  may be formed into an annular shape, however, it is preferable that a plurality of concave portions  91  are uniformly provided circumferentially since it is possible to suppress peculiar deformation of the film portion  8  and it is possible to minimize reduction of the strength of the film portion  8 . 
     Further, in the case that the dust cover for the ball joint is installed to the socket  3 , a compressing force of a split installation jig J can be transmitted to the base portion  61  of the reinforcement ring  60  made of the metal material via projections  10  and  10 , by inserting the projections  10  and  10  into the concave portions  91  and  91 , and thereafter compressing the installation jig J (moving downward in the drawing), the projections  10  and  10  being provided at leading ends of the jig J which is separated into a plurality of sections, and protruding inward in a diametrical direction, and the concave portions  91  and  91  being uniformly provided circumferentially, as shown in  FIG. 3 . 
     Therefore, even in the mode in which the width in the diametrical direction of the base portion  61  of the reinforcement ring  60  is narrowed as shown in  FIG. 3 , the one end large-diameter opening portion  6  can be easily compressed and installed to the socket  3 . 
     Further, in the case that an outer diameter X of the reinforcement ring  60  made of the metal material is equal to or smaller than a maximum outer diameter Y of the film portion  8 , the installation can not be achieved at all by the conventional installation jig P as shown in  FIG. 6 . Therefore, the mode according to the present invention is particularly effective, the mode being structured such that the concave portions  91  are provided in the outer peripheral surface of the joint portion  9  between the one end large-diameter opening portion  6  and the film portion  8 . 
     Further, the reinforcement ring  60  can employ various modes which are manufactured by a sheet metal processing and a forging process. 
     Further, the dust cover is formed by various rubber-like elastic materials. 
     Since the reinforcement ring  60  can be made compact without taking an installation performance into consideration, it is possible to further reduce risk that the film portion  8  interferes with the one end large-diameter opening portion  6 . 
     Further, it goes without saying that the present invention is not limited to the best mode for carrying out the invention mentioned above, but can employ the other various structures without deviating from the scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be used in the ball joint which is used in the suspension device and the steering device of the motor vehicle.