Abstract:
A valve train with components connected by ball and socket joints is provided with projecting assembly guides adjacent the sockets of selected joints. The assembly guides include guide surfaces angling toward the sockets to guide the ball end of a push rod or other actuator into the socket of an associated rocker arm or other component. The guide surfaces may be generally conical or comprised of multiple spaced surfaces. The assembly guides facilitate assembly of valve trains, especially where components with multiple ball and socket joints are involved.

Description:
TECHNICAL FIELD 
     This invention relates to engine valve trains and, more particularly, to valve trains with ball and socket-type joints. 
     BACKGROUND OF THE INVENTION 
     It is known in the art relating to engine valve trains to provide actuating members, such as rocker arms and push rods or other components, having ball and socket-type joint connections. In some embodiments, more than one rocker arm and/or push rod or other actuator may be utilized in a train to actuate a single valve or multiple valves. Assembly of such valve trains can require excessive time in alignment of the components. For example, connecting a push rod between a pair of rocker arms at ball and socket joints in order to insert the ball ends into the sockets may require simultaneously depressing the valve actuating rocker against the valve spring. Also, insertion of a single push rod into a rocker arm socket may prove difficult in alignment of the components. 
     SUMMARY OF THE INVENTION 
     The present invention facilitates the assembly of valve trains with ball and socket-type joints by providing, where appropriate, assembly guides to aid in inserting and aligning an actuating member, such as a push rod, with one or more sockets on a mating actuating member or members. In an exemplary embodiment, a primary push rod engages and actuates a primary rocker arm which is connected with a secondary push rod engaging and actuating a second rocker arm that directly actuates a valve. The primary push rod has a spherical or ball end which is received in a socket of the primary rocker arm to aid alignment and insertion of the push rod with the rocker arm socket. The invention provides a conical guide surrounding the socket which slopes inwardly toward the socket and, upon assembly, guides the end of the push rod into position in the socket with a minimum of manual guidance. 
     The secondary push rod must be aligned with and inserted into sockets on both the primary and the secondary rocker arms. To assist this process, the invention provides guides, each having at least one guide surface which, in a preferred embodiment, comprises a partial cone surface extending out from the lower side of each of the rocker arm sockets. In assembly, the valve actuating rocker arm is rotated in a valve opening direction and the push rod is laid upon the part-conical guide surfaces. The valve actuating rocker arm is then released and returned by the valve spring to the actuating position, causing the ends of the push rod to ride up the assembly guides and slide into the sockets on the rocker arms in its operating position. 
     These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view in fragmentary cross section of a nearly assembled exemplary valve train arrangement including assembly guides in accordance with the invention; 
     FIG. 2 is a side view in fragmentary cross section of the valve train arrangement of FIG. 1; 
     FIG. 3 is a pictorial view of the arrangement of FIGS. 1 and 2 showing a push rod in a nearly installed position; and 
     FIG. 4 is a pictorial view of an alternative rocker arm having multiple assembly guide projections adjacent to a ball socket. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail, numeral  10  generally indicates an exemplary valve train arrangement including ball and socket-type joints provided with assembly guides in accordance with the invention. 
     Valve train  10  includes a primary push rod  12  connected at a ball and socket joint  14  with a primary rocker arm  16 . Rocker arm  16  pivots on an axis  18  and includes a second socket  20  in which a ball end  22  of a secondary push rod  24  is received. A second ball end  26  of push rod  24  is received in a socket  28  of a secondary rocker arm  30  which is pivotable about a secondary axis  32 . The secondary rocker arm  30  further engages a valve stem  34  for actuating a valve which is closed by a valve spring  36 . 
     Assembly of the valve train as described, without assembly guides according to the invention, may be accomplished in any desired manner. However one possible assembly process could involve: 
     Installation of the primary push rod  12  into a cam follower, not shown; 
     Alignment of the primary push rod  12  with a socket  38  of the joint  14  and rotation of the rocker arm  16  to engage push rod  12 ; 
     Rotation of the secondary rocker arm  30  against the valve stem  34  and spring  36  to provide clearance for insertion of the secondary push rod  24 ; 
     Alignment of the secondary push rod ball ends  22 ,  26  with sockets  20 ,  28  of the primary and secondary rocker arms; and 
     Rotation of the secondary rocker arm  30  by the spring  36  back to the valve closed position to engage the ball ends of push rod  24  with their respective sockets in rocker arms  16 ,  30 . 
     The process as described requires care in aligning and maintaining alignment of the components while they are being installed in their respective ball and socket joint connections, which may lead to increased assembly time or misalignment leading to repeated attempts to complete the assembly process. 
     To facilitate assembly, sockets  20 ,  28  of rocker arms  16 ,  30  are each provided with an assembly guide  40  in the form of a protruding lip having a part conical guide surface  42  which slopes inward toward its respective socket  20  or  28 . If desired, the continuous lip of assembly guide  40  could be replaced by a plurality of rods or other individual projections, each providing a sloping surface angled toward its respective socket  22  or  28 . As shown, the assembly guides  40  are preferably cast in place as part of the rocker arms  16 ,  30 . However, they could alternatively be formed as separate components subsequently attached to their respective rocker arms in any suitable fashion. For example, they could be made of plastic and snapped into suitable projection pegs surrounding the rocker arm sockets. 
     The ball and socket joint  14  between push rod  12  and rocker arm  16  provides an example of the alternative proposal mentioned above. The rocker arm  16  includes an assembly guide  44  made as a separate component of any suitable metal or plastic material. The guide  44  is provided with an internal conical guide surface  46  and is configured with a connecting end  48  which snaps over a machined portion of the rocker arm  16  surrounding socket  38  of the joint  14 . The assembly guide  44  may, if desired, be made of lightweight plastic material in order to minimize the inertia of the valve train during actuation of the valve. 
     Assembly of the valve train described may be accomplished with the same steps previously described. However, the assembly process is made easier by the assembly guides  40 ,  44  provided. For example, the initial insertion of the push rod  12  into the socket  38  of joint  14  is made easier by the conical assembly guide surface  46  which requires less accurate alignment of the components and guides the end of the push rod  12  into position in the socket  38  as the rocker arm  16  is rotated to connect with the push rod. Likewise, installation of the secondary push rod  24  is made easier. When the rocker arm  30  is rotated against the valve spring  36 , the push rod  24  is merely placed in position with its ball ends  22 ,  26  on the guide surfaces  42  of the assembly guides  40 . The rocker arm  30  is then allowed to return to the assembled position, and the push rod ball ends are guided by the conical guide surfaces  42  up into their respective sockets  20 ,  28  of the associated rocker arms  16 ,  30 . 
     Thus, it is seen that the provision of assembly guides adjacent to the sockets of the associated ball and socket joints considerably simplifies assembly of the components of a valve train by reducing or avoiding the necessity of aligning the parts carefully and instead providing guidance of the ball components as they are inserted into their respective sockets. 
     FIG. 4 illustrates an alternative valve actuating rocker arm  50  including a ball socket  52  for receiving a ball end push rod (such as rod  24 ) or another actuating member. An assembly guide  54  is provided below the socket  52  and is formed by a pair of protrusions  56  having guide surfaces  58  angled upwardly toward the socket  52 . The assembly guide  54  is used as described earlier to support a ball end of a push rod and guide the ball end up into the socket  52  as the rocker arm  50  is pivoted toward engagement of the socket  52  with the push rod. A rocker arm may have any suitable configuration as called for by the valve train application. In this case, a valve actuating arm  60  and a socket carrying connecting arm  62  are supported by spaced bearing portions  64  for pivotally mounting the rocker arm  50  on a shaft or other supporting pivot. 
     The terms “ball” and “ball end” are used herein to indicate a socket engaging connecting portion and should be broadly interpreted to include various suitable bearing connections for engaging a socket. Such connections may, without limitation, include ring-shaped or part spherical bearings having continuous or interrupted bearing surfaces as may be appropriate. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.