Hydraulic lash adjustment-compatible engine braking system with guided bridge arrangement

A method of configuring an added-motion engine braking system to enable automatic hydraulic lash adjustment, the method comprising:

• constraining a motion of a valve bridge to be parallel to a valve opening direction, the valve bridge configured to selectively act on a main exhaust valve and a brake valve based on an exhaust rocker arm assembly acting on the valve bridge;
• configuring a hydraulic lash adjuster (HLA) disposed on the exhaust rocker arm assembly to selectively extend so as to automatically compensate for lash between the exhaust rocker arm assembly and the valve bridge;
• configuring, in a base circle position of the exhaust rocker arm assembly in which the main exhaust valve and the brake valve are closed, the valve bridge to be in contact with the main exhaust valve and to provide at least one gap along the valve opening direction between the valve bridge and the brake valve such that the valve bridge first opens the main exhaust valve relative to the brake valve in response to the exhaust rocker arm assembly acting on the valve bridge;
• and
• configuring an engine braking rocker arm assembly to selectively act on the brake valve in an engine brake mode, the engine braking rocker arm assembly provided separately from the exhaust rocker arm assembly.

A valvetrain system of an engine selectively operating in an engine brake mode and a drive mode, the valvetrain system comprising:

• an exhaust camshaft including a main exhaust cam and a braking cam;
• an exhaust rocker arm assembly operatively coupled to the main exhaust cam;
• a main exhaust valve and a brake valve;
• a valve bridge configured to selectively act on the main exhaust valve and the brake valve based on the exhaust rocker arm assembly acting on the valve bridge, a motion of the valve bridge constrained to be parallel to a valve opening direction;
• a hydraulic lash adjuster (HLA) disposed on the exhaust rocker arm assembly, the HLA configured to selectively extend so as to automatically compensate for lash between the exhaust rocker arm assembly and the valve bridge;
• and
• an engine braking rocker arm assembly provided separately from the exhaust rocker arm assembly so as to be operatively coupled to the braking cam, the engine braking rocker arm assembly configured to selectively act on the brake valve in the engine brake mode,
• wherein, in a base circle position of the exhaust rocker arm assembly in which the main exhaust valve and the brake valve are closed, the valve bridge is configured to be in contact with the main exhaust valve and to provide at least one gap along the valve opening direction between the valve bridge and the brake valve such that the valve bridge first opens the main exhaust valve compared to the brake valve when the exhaust rocker arm assembly acts on the valve bridge.