TUBULAR ROCKER SHAFT WITH MULTIPLE INTERNAL COMPARTMENTS
A rocker shaft having at least two transversely formed interior compartments is provided each of which is devised for, and capable of, containing fluid at differing pressures. A multiplicity of generally radially directed holes present along the length of the rocker shaft communicate hydraulic fluid to the compartments via passageways present in the rocker arms, or valve deactivating rocker arm sections mounted thereon. Plugs installed within the rocker shaft at locations on either side of the holes provide compartmented regions within the shaft, each region of which has the capacity to contain hydraulic fluid at different pressures. The rocker shaft is capped at each end. Hydraulic fluid may be provided to the rocker shaft interior in a number of ways, such as through additional holes aligned with passageways provided in the cylinder head or through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.
The present invention relates to a generally tubular rocker shaft, the interior of which is partitioned transversely into at least two regions or compartments to contain hydraulic fluid, usually engine oil with each of the partitioned compartments devised to contain fluid at different pressures. For engine applications where more than two compartments are required, plugs may be installed within the shaft to create additional compartments. Each end of the rocker shaft is closed or capped to provide a multiplicity of separate regions within the tubular shaft, each region of which is capable withstanding a different hydraulic pressure.
BACKGROUND OF THE INVENTIONIn known prior art rocker shaft constructions containing more than one interior compartment, the interior of the rocker shaft tubular bore is longitudinally partitioned. Configurations of this kind are difficult to manufacture because of the requirement that two or more small diameter holes extending from end to end must be drilled into the rocker shaft as descriped for example in U.S. Pat. No. 5,592,907. Alternatively, a second tube or divider must be installed within the rocker shaft for example, as described in U.S. Pat. No. 6,598,578. With reference to the latter patent, apparently a rather complex manufacturing method is required wherein a kidney-shaped tube is slideably installed into the rocker shaft bore and the assembly is drawn through a mandrel to deform the rocker shaft around the kidney-shaped tube, mechanically closing the clearance between the rocker shaft bore and the kidney-shaped tube to form two separate longitudinal oil passages. Oil communication holes are then made through the rocker shaft and the internal kidney-shaped tube, contaminating the interior of the rocker shaft and the tube with particulates from the hole making process. Another disadvantage of this structure is that it cannot be used when valve deactivating rocker arms of two different cylinders are mounted on a rocker shaft assembly, especially wherein one passageway is used for lubricating oil and the other passageway for hydraulic fluid to engage or disengage the deactivating mechanism. Dependant upon an engine's firing order and the engine operating stratagem used to provide acceptable noise, vibration, and harshness (NVH), exhaust emissions, and other engine operating parameters, valve deactivating rocker arms on the same rocker shaft must be able to be separately engaged or disengaged. A transversely compartmented rocker shaft arrangement that overcomes such disadvantages, as provided by the present invention, is clearly desirable.
SUMMARY OF THE INVENTIONAccording to the invention a generally hollow rocker shaft is provided with an interior that is transversely partitioned into at least two longitudinal regions to contain hydraulic fluid, usually engine oil, with provisions to contain the fluid at different pressures within each of the regions. Plugs may be installed within the shaft at suitably spaced locations to create more than two compartments. The ends of the rocker shaft are closed as by capping to provide a multiplicity of separate compartmented regions within the shaft; each of these regions is capable of supporting a different hydraulic pressure. The compartment forming partitions or plugs are located and supported during the installation by means of a temporary dowel inserted through generally radially directed holes through the rocker shaft wall(s). The partitions or plugs may be configured so as to reduce the volume within some or all of the partitioned regions and such as to locate the sealing portion of the plug away from the radially formed holes in the rocker shaft wall(s).
Engines that employ cylinder deactivation to conserve fuel typically do so by deactivating the individual valves of the cylinders. This invention describes a rocker shaft assembly for a cylinder deactivating engine equipped with an overhead valve train which incorporates center pivoting rockers arms mounted on said rocker shaft.
A number of the rocker arms are configured to deactivate valves. These valve deactivating rocker arms comprise valve actuation and cam follower sections linked together by a hydraulically actuated locking pin. In valve train mechanisms which utilize deactivating rocker arms for different cylinders on a common rocker shaft, it is typically necessary to selectively deactivate or re-activate these rocker arms in synchronization with the engine cylinder firing order by changing the pressure of the hydraulic fluid supplied to individual rocker arms to control the motion of the locking pin. The present invention provides the means to compartmentalize the rocker shaft interior so as to isolate the pressure supplied to one rocker arm from others. Means are also provided by the invention to isolate the pressure supplied to one section of a valve deactivating rocker arm from another section.
Referring to the drawing,
Shown in
The above described advantages of the transversely compartmented rocker shaft of the invention are not meant to limit the scope of the invention. Although the invention has been described with respect to preferred embodiments, many variations and modifications will become apparent to those skilled in the art. It is therefore intended that the claims be interpreted as broadly as possible in view of the prior art, to include all such variations and modifications.
Claims
1. A longitudinal rocker shaft having a generally hollow interior with plugged ends and containing at least two transverse isolated fluid confining compartments formed by intermittently plugging the interior of the shaft with plugs inserted and secured at locations within the shaft to provide the desired predetermined compartment size.
2. The rocker shaft of claim 1 comprising a tubular member.
3. The rocker shaft of claim 1 configured such that hydraulic fluid is introduced to at least one of said compartments through holes provided by a cylinder head.
4. The rocker shaft of claim 1 wherein fluid is introduced to the rocker shaft compartments through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.
5. The rocker shaft of claim 1 wherein said compartments are formed by tubular plugs slideably inserted within the rocker shaft bore.
6. The rocker shaft of claim 1 wherein said compartments are formed by an insert having a distal closed end.
7. The rocker shaft of claim 5 wherein said tubular plugs are secured in place by an interference fit insert introduced into said tubular plugs.
8. The rocker shaft of claim 7 wherein the insert comprises a ball.
9. The rocker shaft of claim 1 provided with passageways for introducing fluid to said compartments through holes that are aligned with passageways of an associated cylinder head.
10. The rocker shaft of claim 1 provided with passageways for introducing fluid to said compartments through clearance openings between rocker shaft fasteners and rocker shaft mounting holes.
11. The rocker shaft of claim 1 wherein the inserted plugs are sized so as to seal and minimize the compartment volume.
Type: Application
Filed: Jun 8, 2007
Publication Date: Dec 11, 2008
Inventors: THOMAS C. EDELMAYER (Canton, MI), Daniel M. Olin (Westland, MI), Thomas E. Rome, SR. (Burlington, MI)
Application Number: 11/760,251