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

Abstract

An exhaust rocker assembly for operating an exhaust valve of an engine during a compression-release engine braking operation. The exhaust rocker assembly comprises an exhaust rocker arm and a self-contained compression brake control module (CBCM) mounted to the exhaust rocker arm and operatively coupled to the exhaust valve for controlling a lift and a phase angle thereof. The CBCM includes a casing, an actuation piston disposed outside the casing so as to define an actuation piston cavity, a reset check valve provided between the casing and the actuation piston, and a compression brake actuator disposed in the casing. The actuation piston reciprocates relative to the casing. The compression brake actuator includes a control piston. The control piston engages the check valve when deactivated so as to unlock the actuation piston cavity and disengages from the check valve when activated so as to lock the actuation piston cavity.

We claim: 
     
         1 . 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 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 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 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 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;   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.   
     
     
         2 . The exhaust rocker assembly as defined in  claim 1 , wherein the supply port is formed within the casing and is fluidly connected to a compression brake fluid passageway in the exhaust rocker arm, and wherein the supply port is configured to provide pressurized hydraulic fluid to the actuation piston cavity through the connecting passage. 
     
     
         3 . The exhaust rocker assembly as defined in  claim 1 , wherein the exhaust rocker arm is formed with a control bore therewithin, wherein the hollow actuation piston is disposed within the control bore to define the variable volume hydraulic actuation piston cavity, and wherein the actuation piston reciprocates in the control bore. 
     
     
         4 . The exhaust rocker assembly as defined in  claim 3 , wherein the single-piece body has a partially threaded outer cylindrical surface configured to engage the control bore in the exhaust rocker arm. 
     
     
         5 . The exhaust rocker assembly of  claim 3 , wherein the actuation piston includes an outer seal and a smooth outer surface to engage, seal against, and reciprocate within the control bore. 
     
     
         6 . The exhaust rocker assembly as defined in  claim 1 , wherein the hollow inner portion separates the internal actuator cavity from the actuation piston cavity, and wherein the connecting passage is formed in the hollow inner portion of the hollow casing. 
     
     
         7 . The exhaust rocker assembly as defined in  claim 1 , wherein the control piston has a bottom face exposed to the hydraulic fluid and a top face exposed to atmospheric pressure. 
     
     
         8 . The exhaust rocker assembly as defined in  claim 7 , wherein the actuator cavity is closed with an end cap having a vent port. 
     
     
         9 . The exhaust rocker assembly of  claim 1 , wherein the actuation piston has a retaining ring mounted thereto and disposed within the actuation piston. 
     
     
         10 . The exhaust rocker assembly of  claim 1 , wherein the control piston is in the extended position when a bottom face of the control piston engages a control piston seat of the control piston, and wherein the control piston is in the retracted position when a top face of the control piston engages an end cap closing the internal actuator cavity of the casing. 
     
     
         11 . The exhaust rocker assembly of  claim 1 , wherein the compression brake control module further comprises a control piston spring disposed within the casing between the control piston and the end cap to bias the control piston toward the extended position in which the control piston engages and opens the 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. 
     
     
         12 . The compression brake module of  claim 1 , wherein the casing further includes a groove formed on an inner peripheral surface of the actuation piston and a retaining ring arranged within the groove, wherein the casing includes an inner stopping surface, and wherein the retaining ring is configured to stop movement of the actuation piston relative to the casing such that the actuation piston is in the extended position when the retaining ring engages the inner stopping surface. 
     
     
         13 . The exhaust rocker assembly of  claim 1 , wherein the exhaust rocker arm is a dedicated engine brake rocker arm adapted to be pivotally mounted about an engine brake rocker shaft and configured to open the at least one exhaust valve only through a valve bridge pin extending through an exhaust valve bridge. 
     
     
         14 . The exhaust rocker assembly of  claim 1 , wherein the exhaust rocker arm is a lost motion exhaust rocker arm adapted to be pivotally mounted about an engine rocker shaft and provided to open the at least one exhaust valve through an exhaust valve bridge. 
     
     
         15 . The exhaust rocker assembly of  claim 1 , wherein the actuation piston includes an inner end face, and an outer end face provided to engage the at least one exhaust valve in the extended position of the actuation piston. 
     
     
         16 . 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.   
     
     
         17 . The exhaust rocker assembly of  claim 16 , wherein the slider screw assembly is centered above the valve bridge. 
     
     
         18 . The exhaust rocker assembly of  claim 16 , wherein both the slider screw assembly and self-contained compression brake control module are mounted to a first distal end of the lost motion exhaust rocker arm. 
     
     
         19 . 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.