FIELD

This application provides methods and systems for controlling cylinder deactivation.

BACKGROUND

Vehicles using all six cylinders in all operating conditions suffer from inefficiencies. For example, when stoichiometric air to fuel ratios are required for engine operation, such as in gasoline systems, there are operating conditions where excessive fuel consumption occurs. Full fueling to all cylinders in low load, idle, coast, or ranges of cruise conditions results in overuse of fuel. These low operating conditions do not need optimal engine output.

Likewise, in diesel systems, there are situations where the amount fuel being used is in excess of that necessary to power an engine. It is desirable to reduce fuel consumption.

SUMMARY

The methods disclosed herein overcome the above disadvantages and improves the art by way of systems and methods to reduce fuel consumption and improve engine efficiencies.

A diesel engine system can comprise a selectively actuated cylinder deactivation mechanism configured to lift and lower a valve and to deactivate actuation of the valve. A rocker arm in the system can comprise a rotatable arm comprising a recess and a controllable latch movable between a latched condition to catch in the recess of the rotatable arm and an unlatched condition configured to collapse the controllable latch from the recesses. A cam lobe in the system can be configured to rotate among a base circle position and a lift position to reciprocate the rocker arm between a valve closed position and valve open position. A cylinder deactivation controller in the system can be configured to run a failsafe subroutine to restrict command signals to move the controllable latch between the latched condition and the unlatched condition to a time period between when the cam lobe has begun to move the rocker arm to the valve open position and when the cam lobe has returned to base circle to reciprocate the rocker arm to the valve closed position.

A method of controlling a cylinder deactivation mechanism can comprise executing a valve lift event configured to lift a valve via a rocker arm, wherein the rocker arm is configured with a controllable latch in a latched condition, wherein the controllable latch is configured with an edge that is clamped in a recess in the rocker arm during the valve lift event, a clamp force supplied in part by pressure from the valve lift event. A deactivation signal can be sent to select the unlatched condition to collapse the controllable latch from the recess while the controllable latch is configured in the valve lift event with the edge clamped in recess. A subsequent valve lift event can be have actuation deactivated by collapsing the controllable latch from the recess once the valve lift event is complete and the clamp force is removed.

A method of controlling a cylinder deactivation mechanism comprises executing a valve lift event configured to lift a valve via a pushrod and rocker arm combination. The pushrod is coupled via a sleeve with a controllable latch in a latched condition. The controllable latch is configured with edges that are clamped in recesses of the sleeve during the valve lift event. A clamp force is supplied in part by pressure from the pushrod. A deactivation signal is sent to select the unlatched condition to collapse the latch from the recesses while the controllable latch is configured with edges that are clamped in recesses of the sleeve. A step of deactivating actuation of the valve is done by collapsing the latch from the recess once the valve lift event is complete and the clamp force supplied in part by pressure from the pushrod diminishes.

Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claimed invention.

