Self-contained compression brake control module for integrated rocker arm engine braking and methods

A lost motion exhaust rocker assembly for operating at least one exhaust valve of an internal combustion engine during a compression-release engine braking operation, the lost motion exhaust rocker assembly comprising a lost motion exhaust rocker arm, a slider screw assembly and a self-contained compression brake control module, both the slider screw assembly and self-contained compression brake control module mounted to the lost motion exhaust rocker arm and operatively coupled to the at least one exhaust valve through an exhaust valve bridge for controlling the lift and a phase angle of the at least one exhaust valve, the compression brake control module maintaining the at least one exhaust valve open during a compression stroke of the internal combustion engine when the internal combustion engine performs the compression-release engine braking operation,

• the compression brake control module comprising:
• a hollow casing including a single-piece body adapted to be mounted in the lost motion exhaust rocker arm, the casing defining an internal actuator cavity therewithin and including a hollow inner portion extending away from the internal actuator cavity;
• a hollow actuation piston disposed outside the casing and adapted to be in the lost motion exhaust rocker arm defining a variable volume hydraulic actuation piston cavity between the hollow casing and the actuation piston, the actuation piston reciprocating relative to the hollow inner portion of the hollow casing between an extended position and a collapsed position, the actuation piston engageable with the at least one exhaust valve in the extended position of the actuation piston;
• the actuation piston cavity and the internal actuator cavity in fluid communication through a connecting passage in the hollow casing;
• the hollow inner portion of the hollow casing extending into the actuation piston;
• the actuation piston 126 biased towards the extended position thereof by an actuation piston bias spring disposed in the actuation piston cavity;
• a reset check valve between the connecting passage and the actuation piston cavity, the reset check valve configured to hydraulically lock the actuation piston cavity when pressure of the hydraulic fluid within the actuation piston cavity exceeds the pressure of the hydraulic fluid in a supply port in the hollow casing, the reset check valve biased closed by a biasing spring;
• a compression brake actuator disposed in the internal actuator cavity to control the reset check valve, the compression brake actuator including a control piston exposed to atmospheric pressure, the control piston slidingly mounted within the internal actuator cavity to reciprocate between an extended position and a retracted position;
• and
• a control piston spring biasing the control piston toward the extended position in which the control piston is adapted to engage and open the reset check valve solely by the biasing force of the control piston spring so as to unlock the actuation piston cavity and fluidly connect the actuation piston cavity to the supply port.

A method of operating an exhaust rocker assembly for operating at least one exhaust valve of an internal combustion engine during a compression-release engine braking operation, the exhaust rocker assembly comprising an exhaust rocker arm formed with a control bore therewithin and a self-contained compression brake control module mounted to the exhaust rocker arm and operatively coupled to the at least one exhaust valve for controlling the lift and phase angle of the at least one exhaust valve, the compression brake control module provided to maintain the at least one exhaust valve open during a compression stroke of the internal combustion engine when the internal combustion engine performs the compression-release engine braking operation,

• the compression brake control module comprising:
• a hollow casing including a single-piece body mounted in the control bore, the casing defining an internal actuator cavity therewithin and including a hollow inner portion extending away from the internal actuator cavity;
• a hollow actuation piston disposed outside the casing and in the control bore so as to define a variable volume hydraulic actuation piston cavity between the hollow casing and the actuation piston, the actuation piston reciprocating relative to the hollow inner portion of the hollow casing within the control bore between an extended position and a collapsed position, the actuation piston configured to engage the at least one exhaust valve in the extended position of the actuation piston;
• the actuation piston cavity and the internal actuator cavity being in fluid communication through a connecting passage in the hollow casing;
• the hollow inner portion of the hollow casing extending into the actuation piston;
• a check valve between the connecting passage and the actuation piston cavity, the check valve configured to hydraulically lock the actuation piston cavity when the pressure of the hydraulic fluid within the actuation piston cavity exceeds the pressure of the hydraulic fluid in a supply port, the check valve biased closed by a biasing spring;
• a compression brake actuator disposed in the internal actuator cavity configured to control the check valve, the compression brake actuator including a control piston exposed to atmospheric pressure, the control piston slidingly mounted within the internal actuator cavity to reciprocate between an extended position and a retracted position;
• and
• a control piston spring biasing the control piston towards the extended position in which the control piston engages and opens the check valve solely by the biasing force of the control piston spring to unlock the actuation piston cavity and fluidly connect the actuation piston cavity to the supply port;
• the method comprises the steps of:
• biasing the reset check valve closed by the pressurized hydraulic fluid supplied from a compression brake fluid passageway to the compression brake control module to extend the hollow activation piston and hydraulically bias the reset check valve closed during a braking operation mode of the engine;
• and
• resetting the at least one exhaust valve by stopping the pressurized hydraulic fluid supplied to the compression brake control module to open the reset check valve and allow retraction of the hollow activation piston during a positive power operation mode of the engine.