Abstract:
A connection system to interconnect members of a vehicular steering linkage system has a first steering module and a second steering member adapted to receive the first steering module. A clearance exists between the first steering module and the second steering member. The first steering module includes a first steering member and a fastener. The fastener is adapted to secure the first and second steering members together.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a steering linkage system for motor vehicles, and, more particularly, to a system for connecting a tie rod assembly to a relay rod. 
     BACKGROUND OF THE INVENTION 
     Various types of steering linkage systems are used to control the steering of an automotive vehicle. A well known type of steering linkage system has a relay rod connected to the frame or chassis of an automobile by two pivoting members, such as a pitman arm and an idler. In this type of arrangement the relay rod shifts back and forth laterally in response to steering input from the steering wheel of the automobile via a steering gear. The pivoting members are connected to the relay rod by ball and socket assemblies. The opposite end portions of the relay rod are each connected to a steering knuckle by a tie rod assembly. The tie rod assemblies are connected to the relay rod by ball and socket assemblies. The steering knuckles turn the front wheels of the automobile to steer the automobile in response to movements of the relay rod and tie rods that connect the relay rod to the steering knuckles. The steering knuckles are connected to suspension members by ball and socket assemblies. Some steering linkage systems also include a drag link for moving the relay rod. 
     As noted, the inner end of the tie rod is typically connected to a corresponding end of the relay rod by a ball and socket assembly. FIG. 1 shows a conventional inner tie rod to relay rod connection system. Specifically, the inner tie rod  10  is attached to a distal end of the relay rod  12  via a ball and socket assembly  14 . The ball and socket assembly  14  includes a hollow cylindrical housing  16  having an upstanding threaded post  16   a , a disk portion  16   b  and a annular wall  16   c  projecting generally perpendicular from disk portion  16   b  so as to define a socket cavity. The ball and socket assembly  14  also includes a ball stud  18  having a shank segment  18   a  and a ball segment  18   b  which is retained in the cavity between a spring seat  20  and a ball seat  22 . 
     A spring (not shown) is inserted into a reduced diameter portion of the cavity with a belleville spring washer (not shown) positioned between a planar end face of housing disk portion  16   b  and a planar end face of the spring seat  20 . The surface of seat  20  is adapted to engage a portion of the spherical external surface of the ball segment  18   b . Prior to assembly of ball stud  18  into housing  16 , shank segment  18   a  is passed through a bore formed through ball seat  22  such that another portion of the spherical exterior surface of ball segment  18   b  engages a partial spherical seat surface formed in ball seat  22  and which communicates with the bore. 
     To secure the ball stud  18  within housing  16 , external threads are formed on ball seat  22  and are threaded into internal threads formed in the cavity of housing  16 . Ball seat  22  is then tightened into housing  16  until a desired torque is reached. In addition, a blind tapped hole  24  is formed in the end of the relay rod  12 . In order to fasten the tie rod to the relay rod, the upstanding threaded post  16   a  of the housing  16  is threaded into the blind tapped hole  24  in the end of the relay rod  12 . 
     A disadvantage with the system just described is that there must be a minimum straight length in the relay rod  12  adjacent to the inner tie rod  10  attachment point. In addition, that straight length cannot be larger in diameter than the distance across the outer diameter of the disc portion  16   b  of the housing  16 . These requirements are driven by the need to remove an automated tightening tool once the inner tie rod to relay rod connection has been made. Specifically, an automated wrench that is used during assembly can only be removed from the inner tie rod in one position, and thus after tightening must be slid over the relay rod in order to rotate back to its home position. 
     In addition, the design provides no allowance to compensate for the location of the inner tie rod ball in vehicle position. 
     SUMMARY OF THE INVENTION 
     The present invention provides a connection system for interconnecting members of a vehicular steering linkage system. The connection system includes a first steering module and a second steering member adapted to receive the first steering module. A clearance exists between the first steering module and the second steering member. The first steering module includes a first steering member and a fastener adapted to be secured thereto. The fastener is adapted to secure the first and second steering members together. 
    
    
     Additional features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a section view of an exemplary prior art tie rod to relay rod connection system; 
     FIG. 2 is a partial schematic plan view of a vehicle having a steering linkage system constructed in accordance with the teachings of the present invention; 
     FIG. 3 is a perspective view of a portion of the steering linkage of FIG. 2 illustrating the tie rod assembly; 
     FIG. 4 is a sectional view of a portion of the steering linkage system shown in FIG. 2 which illustrates the tie rod to relay rod connection system made in accordance with a preferred embodiment of the present invention; and 
     FIG. 5 is a partial exploded view of the tie rod to relay rod connection system shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In general, the present invention is directed to a connection system for interconnecting a first steering member to a second steering member in a vehicle steering linkage system. The embodiments shown are more particularly directed to a tie rod to relay rod fastening and adjustment system in a vehicle steering linkage system. The connection system of the present invention is adapted to provide improved performance without requiring modification of the other components associated with the vehicle steering linkage system. Thus, the connection system of the present invention may be utilized with a variety of steering linkage systems and is not intended to be limited to the particular application described below. 
     FIG. 2 is a partial schematic plan view of the front end of an automotive vehicle showing a steering linkage system  50 . The steering linkage system  50  generally comprising a relay rod  52  that is connected to the frame or chassis (not shown) of the automotive vehicle by two pivoting members, such a pitman arm  54  and an idler arm  56 . The relay rod  52 , the chassis, the pitman arm  54  and the idler arm  56  are formed so that the relay rod  52  moves laterally in response to steering input from a steering wheel (not shown) which operates a steering gear (not shown) to rotate the pitman arm  54 . The pitman arm  54  and idler arm  56  are connected to the relay rod  52  by ball and socket assemblies  58 . Each of a pair of tie rod assemblies  60  are connected to the relay rod  52  at a first end and to an associated wheel bracket  62  at a second end. The front wheels  64  are turned in response to lateral movements of the relay rod  52  via the tie rod assemblies  60 . 
     With particular reference to FIG. 3, the tie rod assembly  60  is illustrated to include a rod member  70 , ball and socket assemblies  72  and  74 , and a threaded member  76 . The rod member  70  includes a first end  78  that is coupled to the ball and socket assembly  72  and second end  80  having a threaded portion  82 . In the particular embodiment illustrated, rod member  70  also includes an adjustment segment  84 . 
     With reference to FIGS. 4-5, the construction of the connection system of the present invention is illustrated in greater detail. Tie rod assembly  60  and a fastener  90  combine to form a first steering module  92 . Ball and socket assembly  72  includes a hollow cylindrical housing  94  having an upstanding threaded post  94   a , a disk portion  94   b  and an annular wall  94   c  projecting generally perpendicular from disk portion  94   b  so as to define a socket cavity  94   d . Ball and socket assembly  72  also includes a ball stud  96  having a shank segment  96   a  and a ball segment  96   b  which is retained in cavity  94   d  between a spring seat  98  and a ball seat  100 . Spring seat  98  is shown inserted into a reduced diameter portion of cavity  94   d  with a belleville spring washer  102  positioned between a planar end face of housing disk portion  94   b  and planar end face of spring seat  98 . 
     A partial spherical seat surface extends inwardly from the opposite planar end face of spring  102  when assembled. Seat surface is adapted to engage a portion of the spherical external surface of ball segment  96   b . Prior to assembling a ball stud  96  into housing  94 , its shank segment  96   a  is passed through a bore formed through ball seat  100  such that another portion of the spherical exterior surface of ball segment  96   b  engages a partial spherical seat surface formed in ball seat  100  and which communicates with the bore. External threads are formed on ball seat  100  and are threaded into internal threads formed in cavity  94   d  of housing  94  to secure ball stud  96  within housing  94 . 
     Ball seat  100  is tightened into housing  94  until a desired torque is reached. Thereafter, a distal end of ball seat  100  is inwardly swaged or crimped to create an inward lip flange to prevent ball seat  100  from unthreading itself during use. As an alternative, a welded joint may be used in place of the flange. As a further alternative, ball seat  100  need not be threaded to housing  94  but instead may be retained therein simply by crimping of the distal end to create a lip flange. 
     A flexible seal  104  is also provided which is attached around the inner tie rod housing  94  and an inner tie rod shank segment  106  using a clamp ring or other suitable fastening means. The seal  104  prevents water and contaminants from entering the ball and socket assembly and hindering smooth operation thereof. 
     As noted, the relay rod  52  is adapted to connect with the inner tie rod  60 . To this end, a bore  110  is formed in a portion of the relay rod  52 . A mating segment of the fastener  90  is inserted through the bore  110  in the relay rod  52 . For exemplary purposes, the mating segment of the fastener  90  illustrated is shown to include a shank portion  90   a  extending from a head portion  90   b . The shank portion  90   a  is adapted to insert into the bore  110 . The shank portion  90   a  includes a shank cavity  90   a ′ having female threads. The upstanding threaded post  94   a  of the inner tie rod housing  94  has male threads adapted to mate with the female threads of the shank cavity  90   a ′. Accordingly, the fastener  90  is threaded onto the upstanding threaded post  94   a  and tightened to a suitable torque level. In this manner, the connection between the inner tie rod  60  and the relay rod  52  is made. One skilled in the art will understand that the fastener  90  may be of a type other than the hexagonal flange nut shown. One skilled in the art will also recognize that the connection system is not limited to the interconnection of a tie rod and a relay rod, but may also be applicable to other steering linkage members, such as connecting a pitman arm or idler arm to the relay rod or connecting a wheel bracket to the tie rod. 
     It should be noted that a clearance S is provided between the outer diameter of the shank  90   a  and the diameter of the bore  110  of the relay rod  52 . This clearance allows the inner tie rod housing  94  position to vary relative to the vehicle directions. As such, precise adjustment of the inner tie rod ball position can be made, thereby compensating for possible variations in other steering or vehicle frame structures. 
     It should also be noted that the inner tie rod to relay rod connection system of the present invention provides several advantages over conventional systems. For example, the present invention simplifies the machining of the relay rod, since only a bore needs to be formed in each end of the rod. In contrast, the conventional system shown in FIG. 1 requires the machining of a blind tapped hole in each end of the relay rod, thereby adding to the cost and complexity of manufacture. 
     Similarly, the present invention reduces dependence on forging and machining tolerances and provides a potential for reduced scrap. Currently, if one of the tapped holes in the relay rod is incorrectly processed, the entire relay rod is scrapped. However, if there is a processing or tolerance problem with the present invention, only one less expensive fastener would be scrapped. 
     Also, unlike the conventional system of FIG. 1, the present invention does not require a minimum straight length in the relay rod adjacent to the inner tie rod attachment point. This is advantageous since the assembly of the present invention requires less complicated assembly equipment. For example, the use of a more traditional socket type torque gun is possible rather than elaborate gear driven crowfoot designs which are currently used. Another advantage of the present invention is that compressive stresses to relay rod are applied, thereby improving the fatigue life of that portion of the relay rod. Also, the present invention provides improved clamp load due to longer bolt stretch. 
     While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalence may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within this description of the appended claims.