Method and apparatus for diagnosing valve lifter malfunction...

Details Method and apparatus for diagnosing valve lifter malfunction... Method and apparatus for diagnosing valve lifter malfunction...

2007-07-24

2007-07-24

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Overhead camshaft

C123S090170, C123S090310, C123S19800E, C701S102000, C701S105000, C701S107000

Reexamination Certificate

active

11238720

ABSTRACT:
A method for diagnosing malfunctions of switching valve lifters includes sensing variations in pressure of trapped oil in a drive chamber of a hydraulic camshaft drive, such as a cam phaser, comparing peak oil pressure readings in the drive chamber resulting from the increased torque of opening the valves of various cylinders of an engine and identifying cylinders having lower than normal valve opening pressure readings, indicating failure of an associated valve lifter to properly actuate a valve of the cylinder. Apparatus for indicating such malfunctions could include a cam phaser with pressure chamber, a pressure sensor connected to indicate pressure variations in the chamber; and a pressure indicator connected to the sensor and adapted to indicate actual pressure variations for comparison with normal variations to identify low pressure peaks indicating malfunction of a switching lifter. A computer could be used to receive and act upon the malfunction indications.

REFERENCES:
patent: 5529034 (1996-06-01), Sone et al.
patent: 5537961 (1996-07-01), Shigeru et al.
patent: 6257184 (2001-07-01), Yamagishi et al.

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