Patent Application
20140196265
The present invention relates to a tool useful for effecting removal of a push rod from an internal combustion engine.
Typically, multiple stroke, internal combustion engines include push rods which are mechanically linked to valves that open and close ports to the cylinders of the engine. Most often, one end of each push rod is reciprocally driven in response to actuation by a rotating cam. The opposite end of each push rod typically engages one end of a rocker arm which is pivotally biased by a valve spring causing the opposite end of the rocker arm to engage with the push rod. Thus, as the cam rotates, the push rod reciprocates causing the rocker arm to pivot against the biasing force of a valve spring assembly and thereby open or enable closure of a valve port of the internal combustion engine.
A repair operation often necessary with respect to internal combustion engines is replacement of the intake manifold gasket which, in turn, may require removal of the intake manifold. On some engines the push rods must also be removed to allow the gasket surfaces to be cleaned prior to installation of a new gasket. Removal of push rods from an internal combustion engine, however, is not a straightforward mechanical operation. Various means must be employed in order to move the rocker arm out of engagement with the push rod so that the push rod may be effectively removed and replaced. Factors which complicate replacement may include the time and effort to remove parts of the engine in order to secure adequate access to the push rods. An effective, efficient and simple means for removal of push rods thus is an objective long sought by engine mechanics.
U.S. Pat. No. 7,409,755 entitled “Push Rod Removal Tool” issued Aug. 12, 2008, incorporated herein by reference, describes a tool designed to facilitate removal of push rods. The tool performs well in many circumstances. However, changes in engine design may inhibit the effective use of the described tool in some situations. Specifically, the described tool may be too bulky or may have a configuration which may preclude effective use in constricted spaces. This problem arises, for example, in General Motors 3.5L and 3.9L engines. Thus, there is a need for a tool which will enable efficient repair of such engines and in other similar circumstances involving space constraints.
Briefly, the present invention comprises a tool for engaging a rocker arm associated with an internal combustion engine push rod in a manner which imparts pivotal movement of the rocker arm out of engagement with the push rod so that the push rod may be easily removed and replaced. The tool is comprised of a handle joined to first and second spaced or bifurcated lever arms which are connected or joined at a distal end of the tool opposite the handle to a depending prong. A single, transverse bridging member or plate with a slot extends partially over a recess or indentation along the lower edge of the spaced lever arms adjacent the depending prong.
In use, the spaced first and second lever arms are positioned against the rocker arm support bracket and the transverse cross member or plate, attached to the first and second lever arms is positioned to engage the bottom side of one end of the rocker arm so that the tool may be manually rotated thereby pivoting or rotating the rocker arm about its support bracket axis and against the spring force of the associated engine valve spring. Rotation of the rocker arm out of engagement with the push rod is thus effected by engaging the cross member or plate of the tool with the underside of the rocker arm so that the depending prong may impact or drive the valve spring. Manipulating the tool rotates the rocker arm about its support axis thereby releasing the rocker arm from engagement with the associated push rod.
The tool handle optionally includes a means for effective extension by engagement with a socket wrench. The tool may be formed from two mirror image, flat stock strips of metal that are stamped, notched, and welded together.
Thus, it is an object of the invention to provide an improved tool capable of effecting pivotal or rotational movement to a rocker arm in order to remove the associated push rod thus facilitating necessary repair work.
A further object of the invention is to provide a tool which will provide a mechanic with a mechanical advantage upon engagement and pivoting a rocker arm of an internal combustion engine.
Yet another object of the invention is to provide a rugged, yet economical tool useful for engaging a rocker arm in order to effect removal of a push rod from an internal combustion engine.
Yet a further object of the invention is to provide a tool for use with internal combustion engines to effect removal of a push rod by engaging the rocker arm associated with the push rod while simultaneously depressing the valve spring, particularly when access space to engage the rocker arm is constrained or limited.
A further object of the invention is to provide a rocker arm engagement tool which may be comprised of an assembly of generally planar plates including a handle, an intermediate rocker arm engagement section and an end prong section and having a narrow or low profile to enable use in restricted spaces.
These and other objects, advantages and features of the invention will be set forth in the detailed description which follows.
In the detailed description which follows, reference will be made to the drawing comprised of the following figures:
A typical internal combustion engine will include a plurality of rocker arms each mounted on a transverse pivot axis or pivot shaft support bracket with one end of the rocker arm projecting transversely outwardly from the pivot axis to engage a push rod associated with the operation of a cam shaft of the internal combustion engine and wherein the oppositely projecting end of the rocker arm is biased by a valve compression spring mounted in a recess or counterbore in the cylinder head of the engine. The compression spring effectively engages or connects to the rocker arm thereby biasing it about its pivot axis into engagement with the push rod. An object of the invention is to provide a tool which will pivot the rocker arm against the compression force of the valve spring mounted on the engine block or cylinder head in a manner which enables the push rod to be moved independently away from engagement with the rocker arm enabling access and removal of the push rod.
Referring to
Frame members 10 and 12 further include, respectively, an acutely diverging connection section 21, 23 joined, respectively, to a generally parallel, spaced, medial section 25, 27. Medial sections 25, 27 are joined, respectively, to convergent sections 29, 31 which connect respectively to end sections 33, 35. The end sections 33, 35 are joined to form a terminal section comprising an end prong 37 with a distal outer end 39. The end prong 37 extends toward the lower or second edge 19, and is generally coaxial with axis 9 and is generally coplanar with the handle sections 14, 16. Further, the end prong 37 comprises or defines an outer boundary or limit of the recess 22. The medial sections 25, 27 comprise spaced side plates and are spaced in the range of ½ to about 2 inches from each other.
A slotted rocker arm lift plate 41 is attached to the lower or bottom edge 19 of the medial sections 25, 27 adjacent the diverging sections 21, 23. Plate 41 includes an axial extending, medial slot 43 with an open end 49 adjacent recess 22 and directed toward prong 37. Plate 41 further includes lateral wings 45, 47 extending outwardly from diverging sections 21, 23 and partially over the recess 22. Extension of a plane defined by plate 41 diverges slightly from the recess 22 and away from intersecting with prong 37.
As depicted in the figures, an optional feature of the invention is the inclusion of a socket opening 80 formed in the frame members 10 and 12 and, more particularly, formed in the handle sections 14, 16 of the frame members 10, 12 which are joined together. The socket opening 80 is typically a square passage or polygonal shaped passage which enables the insertion of a socket wrench 82 or other device to provide a longer lever arm or mechanical advantage during use of the tool.
Referring to
The tool of the invention may be inserted as depicted in the figures so that the handle (formed by sections 14, 16) is directed away from the push rod 78 with the plate 41 engaged with the bottom of the push rod end 76 of the rocker arm 70. The spaced medial sections 25, 27 permit a fastener 81, associated with the rocker arm pivot block or bracket 69, to be positioned between them. The prong 37 extends over the top side of rocker arm 70 and engages the valve spring end 74 of the rocker arm 70. The second or lower surface 19 of the recess 22 fits over the rocker arm 70. Plate 41 is positioned against the underside of the push rod end 76 with slot 43 fitted around push rod 78. Push rod end 76 is thereby nestled in recess 22 between plate 41 and lower edge 19.
The push rod end 76 of the rocker arm 70 may thus be driven or pivoted about axis 72 upwardly in the figures in the direction of the arrow with the pivot block or bracket 69 acting as a fulcrum in order to compress the spring 73 of the valve spring assembly. In this manner, the rocker arm 70 is lifted out of a biased position and the push rod 78 may be easily manipulated and removed from pocket or recess of rocker arm 70 and the engine block to effect repair without removal of the rocker arm 70 or pivot block 69. To reinsert the push rod 78, the reverse operation may be performed. Thus, with the construction of the present invention, the spaced medial plates 25, 27 in combination with the recess 22, slotted plate 41 and the prong 37 may be inserted in extremely constricted spaces to effect engine repair.
The shape of the recess 22, the prong 37, the dimensions of the tool, the spacing of the plates 25, 27, and various other features and elements of the invention may be amended or altered without departing from the spirit and scope of the invention. The use of mirror image members 10, 12 to form the tool is a further advantage in that the manufacture and assembly of the tool is facilitated by the use of plate stock in order to manufacture the component parts which may be easily assembled. Thus, while there has been set forth an embodiment of the invention, it is to be understood the invention is limited only by the following claims and equivalents thereof.
