Internal-combustion engines – Poppet valve operating mechanism – Cam
Reexamination Certificate
2003-11-07
2004-08-24
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Cam
C123S090160, C074S567000
Reexamination Certificate
active
06779502
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a cam system for valve position monitoring. In particular, the present invention relates to an improved cam system for valve position monitoring, wherein a cam having a plurality of unevenly spaced pairs of evenly pitched adjacent cam teeth is positioned on a rotatable shaft having evenly pitched external splines, thereby locking only one set of cam teeth onto a spline. This results in a number of possible discrete angular cam positions greater than the number of splines thereby obtaining higher angular resolution and a reduced vertical height.
2. Description of Background Art
The prior art uses a sliding spline with a compression spring to secure a cam or cams to a rotatable shaft where the shaft is coupled to a valve shaft whereby each shaft cooperates with the other in rotational movement.
BRIEF SUMMARY OF INVENTION
In view of the foregoing, the present invention has been made, and an object of the present invention is to provide a cam system of a valve position monitor, which is capable of reducing the needed parts count, improves resolution accuracy of discrete valve positions and decreases the required height of a valve position monitor.
To achieve the above object, a cam system includes a shaft member whereby at least one cam member is slidably fitted onto the shaft member causing the outer diameter of the shaft member to come into intimate contact with inner diameter of a cam member so that the axis of the cam member coincides with the axis of the shaft member. The size and pitch of adjoining cam pair teeth cooperates with the size and pitch of the individual splines of the shaft member.
However, each regular pitch cam teeth pair is located in a slightly offset circumferential position along the inner diameter of the cam member relative to where a regular pitch spacing would locate each tooth with respect to all the vacant teeth positions on the inner diameter of the cam member between each cam teeth pair. This thereby provides a capability of an incremental discrete angular resolution of the cam member in relation to the shaft member that is smaller than the spline pitch and the cam teeth pitch as well as a number of discrete cam member positions on the shaft member greater than the number of splines on the shaft member. When a cam teeth pair is urged by a contiguous leaf spring into full engagement with a shaft member spline, the remaining cam teeth pairs are only partially engaged with contiguous splines thereby causing any partially engaged teeth to provide an additional normal and securing force between the inner diameter of the cam member and the outer diameter of the shaft member.
Further scope of applicability of the present invention will become apparent from the detailed description given hereafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only and are not limitative of the present invention, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: 3878822 (1975-04-01), Beal
patent: 4504838 (1985-03-01), Tamai et al.
patent: 5704257 (1998-01-01), Kottke et al.
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