Appeal No. 97-1070
Application 08/100,418
detection schemes are susceptible to inaccuracies associated with transient engine operation.
Appellants further point out at page 3 of their specification that such prior art schemes fail to eliminate
error due to non-combustion related torque influencing the compression measurement. Appellants’
invention seeks to remedy the above prior art problems in that appellants seek to provide a method and
apparatus for detecting low compression pressure in an internal combustion engine which is more
durable, more accurate, and is simpler to manufacture (specification, pages 2 to 3).
As further discussed, infra, we find that the applied references, taken as a whole, fail to teach
or suggest utilizing a direct measurement of crankshaft acceleration in a running engine to predict a low
compression pressure condition as recited in the claims on appeal.
Representative claim 1 is reproduced below:
1. A method of compression pressure determination in a combustion chamber of a cylinder in a
running engine, said method comprising the steps of:
measuring acceleration of a crankshaft of said running engine, said measurement centered
proximate a maximum rate of compression of said cylinder, and providing a first acceleration variable
responsive thereto; and
providing a compression pressure variable having a magnitude indicative of a compression
pressure in the combustion chamber of the cylinder in said running engine determined dependent on an
amplitude of the measured first acceleration variable.
The following references are relied on by the examiner:
Buck et al. (Buck) 4,295,363 Oct. 20, 1981
Ina et al. (Ina) 4,517,648 May 14, 1985
Wier 5,386,723 Feb. 7, 1995
3
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