Compression-release engine brake system for lost motion rocker arm assembly and method of operation thereof

摘要

A compression-release brake system comprises an exhaust rocker arm, an actuation piston slidable in a piston bore in the exhaust rocker arm so as to press an exhaust valve, a supply conduit formed within the exhaust rocker arm, and an exhaust valve reset device mounted to the exhaust rocker arm. The actuation piston defines an actuation piston cavity within the actuation piston bore between the piston bore and the actuation piston. The exhaust valve reset device includes a reset check valve disposed between the supply conduit and the actuation piston cavity to hydraulically lock the actuation piston cavity by closing the reset check valve when a pressure of the hydraulic fluid within the actuation piston cavity exceeds the pressure of the hydraulic fluid in the supply conduit. The reset check valve is biased closed by the pressure of the hydraulic fluid within the actuation piston cavity during the brake-on mode.

主权项

1. A compression-release brake system for operating at least one exhaust valve of an internal combustion engine, said compression-release brake system operating in a brake-on mode during a compression-release engine braking operation and a brake-off mode during a positive power operation, said compression-release brake system maintaining said at least one exhaust valve open during a portion of a compression stroke of the engine when performing the compression-release engine braking operation, said compression-release brake system comprising:
an exhaust rocker assembly for operating said at least one exhaust valve, said exhaust rocker assembly including an exhaust rocker arm mounted about a rocker shaft and selectively pivotable to open said at least one exhaust valve; an actuation piston moveable between retracted and extended positions and slidably disposed in an actuation piston bore formed in said exhaust rocker arm, said actuation piston operatively coupled to said at least one exhaust valve when in the extended position thereof; said actuation piston defining an actuation piston cavity within said actuation piston bore between said actuation piston bore and said actuation piston; a supply conduit formed within said exhaust rocker arm, said supply conduit configured to supply pressurized hydraulic fluid to said actuation piston cavity to displace said actuation piston to the extended position when there is a gap between said actuation piston and said at least one exhaust valve; and an exhaust valve reset device mounted to said exhaust rocker arm and including a reset check valve disposed between said supply conduit and said actuation piston cavity to hydraulically lock said actuation piston cavity by closing said reset check valve when a pressure of the hydraulic fluid within said actuation piston cavity exceeds the pressure of the hydraulic fluid in said supply conduit; said reset check valve biased closed by the pressure of the hydraulic fluid within said actuation piston cavity when operating in the brake-on mode during the compression stroke of the internal combustion engine; said reset check valve biased open by the pressure of the hydraulic fluid within said actuation piston cavity when operating in the brake-on mode during an expansion stroke of the internal combustion engine.