Gm Global Technolgoy Operations, Inc.

Daniel R Cuatt

Mark A Shost

Michael James Fox

Thomas H Lichti

Bohdan Michael Lyko

Ronald A Waydelis

Ivan R Samalot

John S Lylak, Jr

Thomas Howard Lichti

Internal combustion engine variable valve timing control with a camshaft phaser for varying rotational phase between a camshaft and a crankshaft in response to a control command determined through a hybrid control strategy without resort to direct temperature measurement. For a range of phase errors requiring high response compensation, a control strategy emphasizing rapid response, such as a bang-bang strategy, is deployed. For a range of phase errors requiring high accuracy compensation, a control strategy emphasizing high precision, such as a proportional-plus-integral strategy, is deployed. The phase error ranges are updated periodically to account for changes in operating conditions. The control command includes an offset which varies in response to a periodically estimated control deadband to affirmatively account for the deadband with each issued control command.

Closed-loop camshaft phaser control

A variable cam phaser has drive and driven members connected by helical splines of an annular phase control piston and a lash control piston, axial motion of which varies the angular phase relation between the drive and driven members. A single wave spring received in a groove in one of the pistons biases them apart to take up lash in the splines. A return spring biases the phase control piston to an initial phase setting. Pre-timing of the members is provided for by a driven (or drive) member comprising two components, a hub flange that supports the other member and a splined hub carried by and initially rotatable on a tubular protrusion of the hub flange. After assembly of the phasing mechanism, the hub is rotated on the hub flange to pre-time the initial phasing of the members. An end of the tubular protrusion is then deformed into a flange engaging an annular shoulder on the hub to lock the hub and hub flange members together and maintain the pre-timing. An annular cover is then installed and retained by a retaining ring to close a hydraulic pressure chamber and help support the members. Upon assembly to a camshaft, a center bolt clamps the cover, hub and hub flange to the camshaft and relieves the locking means from operational torque loads.

Variable cam phaser and method of assembly

A self-contained lash adjuster includes a closed end cylinder body and a plunger in the cylinder defining a pressure chamber at the closed end of the cylinder and an internal reservoir connected with the chamber by a one-way passage in the plunger. A diaphragm sealing the reservoir is loaded by a spring piston to pressurize the reservoir and apply a differential pressure extending force to the plunger. The plunger is preferably made in two parts with the diaphragm in the lower part defining the chamber and the piston in the upper part distal from the chamber. The two-part construction permits leakdown testing before permanent installation of the diaphragm. A seal in the lower part beyond a return port seals the plunger walls to the cylinder. Installation during assembly of excess fluid for make-up is controlled by positioning of the plunger lower part during filling in a hyper extended position beyond the fully extended position to which the plunger is limited after full assembly of the lash adjuster.

Self-contained hydraulic lash adjuster with pressurizing diaphragm

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Henrietta, NY, United States of America

Daniel R Cuatt