Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Reexamination Certificate
1999-10-25
2001-02-06
Rosenbaum, I Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
C029S557000
Reexamination Certificate
active
06182362
ABSTRACT:
The present invention relates to the manufacture of a multi-component camshaft assembly.
Conventionally, camshafts of internal combustion engines are made as one-piece solid components in which the cams cannot move relative to one another nor relative to the bearings. With such camshafts, the phases of the valve events and their durations are fixed and cannot be varied with the engine operating conditions. As a result, engine performance can only be optimised for some operating conditions.
To allow the timing and/or duration of valve events to be adjusted during engine operation, it has been proposed to use a multi-component camshaft assembly in which the individual cams can be rotated about the axis of the shaft by a suitable actuating mechanism disposed within the shaft. One example of such a multi-component camshaft assembly is described in EP-A-0 733 154.
Such multi-component camshaft assemblies are costly to manufacture because of the precision required in the manufacture of the individual components in order to avoid excessive build-up of tolerances.
The present invention therefore seeks to provide a method of manufacturing multi-component camshaft assembly in which the foregoing disadvantage is mitigated.
According to the present invention, there is provided a method of manufacturing a multi-component camshaft assembly having an internal mechanism for enabling relative angular movement of individual cams of the assembly, in which method the cam surfaces are machined after the individual components of the camshaft assembly have been assembled to one another.
On account of the fact that, in the present invention, the cams are not accurately machined until after the components of the camshaft assembly have been assembled to one another, tolerance build up is avoided and the camshaft assembly can be machined in the same manner as would normally be employed to machine the cams and bearings of a one-piece camshaft.
In a preferred embodiment of the invention, after the camshaft components have been assembled to one another but prior to the machining of the surfaces of the camshaft assembly, the assembly is temporarily filled with a viscous or solid material that can be removed after the cam surfaces have been machined. Such filling of the spaces within the camshaft assembly during the machining of the cam surfaces serves the dual purpose of preventing the components from moving relative to one another and of avoiding ingress of debris, metal filings and swarf into the interior spaces of the camshaft assembly. Once machining has been completed, the filling material is removed from the interior of the camshaft assembly.
The filling material may be a grease that is pumped into the interior of the camshaft using a grease gun and subsequently removed by the application of heat or by flushing with a solvent. Alternatively, the material could be a wax or low melting point metal that can be introduced into the interior of the camshaft by means of a vacuum and removed by melting.
An alternative method of preventing the ingress of debris is to pressurise the interior spaces of the camshaft assembly during the machining of the cam surfaces. A lubricant can be pumped through the mechanism while it is being worked to prevent debris from penetrating into the interior spaces. In this case, the lubricant will not act to prevent the components from moving relative to one another but this function can be achieved separately, for example by providing a clamping bolt that is tightened during the machining and subsequently released when the camshaft is assembled to an engine.
REFERENCES:
patent: 4660269 (1987-04-01), Suzuki
patent: 5195229 (1993-03-01), Hughes
patent: 5245888 (1993-09-01), Tsuzuki et al.
patent: 5724860 (1998-03-01), Sekiguchi et al.
patent: 5960660 (1999-10-01), Klaas et al.
patent: 0 733 154 (1996-09-01), None
patent: 2 152 858 (1985-08-01), None
Patent Abstracts of Japan, vol. 95, No. 8, Sep. 29, 1995.
Cuda Rosenbaum I
Mechadyne PLC
Smith-Hill and Bedell
LandOfFree
Method of manufacturing a multi-component camshaft does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing a multi-component camshaft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing a multi-component camshaft will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2589778