BACKGROUND

The present invention relates to operation of an internal combustion engine system, and more particularly, but not exclusively, relates to a switching tappet and a roller finger follower for compression release braking of an internal combustion engine.

Various engine braking systems have been developed to provide compression release braking of an internal combustion engine. One form of an engine braking system is a compression release engine brake. When the compression release engine brake is activated, it opens exhaust valves in the cylinders after the compression cycle, releasing the compressed air trapped in the cylinders, and slowing the vehicle. However, a compression release engine brake is sensitive and often hard to implement, maintain, or install properly. Moreover, compression release engine brakes are expensive.

However, further contributions in this area of technology are needed to provide improved compression release braking and control for certain types of valvetrains. Further contributions are needed to provide improved compression release for a lower cost.

SUMMARY

Certain embodiments of the present application includes unique systems, methods and apparatus for operation of an internal combustion engine using an engine braking system for compression release braking. In a unique system, a switching tappet includes an inner tappet and an outer tappet that are selectively controlled to cooperate with inner and outer cam lobes for exhaust release (braking) during the exhaust stoke and compression release during the compression stroke. In another unique system, a roller finger follower is selectively controlled to cooperate with inner and outer cam lobes for exhaust release (braking) during the exhaust stoke and compression release during the compression stroke. Other embodiments include unique apparatus, devices, systems, and methods involving the control of an internal combustion engine system via an engine braking system to meet one or more of an engine braking request and a vehicle or engine speed request. Either of these embodiments can also be used for a compression release event. The compression release event can be changed to a compression brake event with a camshaft phaser to move the exhaust brake event to a power stroke rather than the compression stroke. Moreover, a default position of either valvetrain is to provide compression release event. No system response is required during cranking or starting of the engine. These systems are capable of compression braking when the exhaust event is positioned during the exhaust stroke to release gas and as a compression release when positioned on the compression stroke. When the gas release occurs on the power stroke there is a braking function. When the gas release occurs on the compression stroke there is a lower power starting situation.

This summary is provided to introduce a selection of concepts that are further described below in the illustrative embodiments. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

