Rocker Arm Assemblies for Engine Braking

Abstract

A rocker arm assembly is rotatable about a rocker shaft and includes a first portion and a second portion. The first portion is configured to receive a valve lift profile. The second portion is configured to operatively engage with one or more valves. The rocker arm assembly also includes an actuator assembly switchable between a first state and a second state, and a plunger assembly provided within a plunger bore and having a plunger axis angled to a longitudinal axis of the actuator assembly.

1 . A rocker arm assembly, the rocker arm assembly rotatable about a rocker shaft and comprising:
 a first portion configured to receive a valve lift profile; and   a second portion configured to operatively engage with one or more valves based on the valve lift profile, the second portion comprising:
 an actuator assembly switchable between a first state and a second state, the actuator assembly comprising a valve mechanism actuated by a control member; and 
 a plunger assembly comprising:
 an elongated member having a first end and a second end opposite the first end; 
 a plunger pad slidably disposed at the first end of the elongated member; and 
 a lash adjustment mechanism associated with the second end of the elongated member, 
 
 wherein a longitudinal axis of the actuator assembly is angled to a plunger axis of the plunger assembly, 
 wherein the control member of the actuator assembly is hydraulically actuated to act on the valve mechanism, and 
 wherein, based on an actuation of the actuator assembly, the plunger pad is selectively extendable relative to the elongated member along the plunger axis between a retracted position and an extended position. 
   
     
     
         2 . The rocker arm assembly of  claim 1 , wherein the plunger assembly further comprises:
 a collar secured to the plunger pad; and   a plunger biasing member disposed between the first end of the elongated member and the collar, wherein the plunger biasing member is configured to bias the plunger pad toward the retracted position.   
     
     
         3 . The rocker arm assembly of  claim 2 , wherein, corresponding to the second state of the actuator assembly, an extending force based on hydraulic pressure acts to overcome a force associated with the plunger biasing member such that the plunger pad extends to the extended position. 
     
     
         4 . The rocker arm assembly of  claim 2 , wherein the plunger biasing member comprises a spring. 
     
     
         5 . The rocker arm assembly of  claim 1 , wherein an inner surface of the plunger pad comprises a detent, and the elongated member of the plunger assembly further comprises a locking assembly provided proximal to the first end and configured to engage with the detent. 
     
     
         6 . The rocker arm assembly of  claim 5 , wherein, corresponding to the second state of the actuator assembly, an extending force based on hydraulic pressure acts to overcome a detent force associated with the locking assembly engaging with the detent such that the plunger pad extends to the extended position. 
     
     
         7 . The rocker arm assembly of  claim 5 , wherein the detent comprises a groove, and wherein the locking assembly comprises a protruding feature and a lock biasing member, the lock biasing member configured to bias the protruding feature toward the groove. 
     
     
         8 . The rocker arm assembly of  claim 7 , wherein the lock biasing member is disposed along a lock axis angled to the plunger axis. 
     
     
         9 . The rocker arm assembly of  claim 1 , wherein the lash adjustment mechanism is accessible via an upper surface of the rocker arm assembly to facilitate lash adjustment of the plunger assembly. 
     
     
         10 . The rocker arm assembly of  claim 9 , wherein the lash adjustment mechanism extends above the upper surface of the rocker arm assembly. 
     
     
         11 . The rocker arm assembly of  claim 1 , wherein the longitudinal axis of the actuator assembly is oriented perpendicular to the plunger axis. 
     
     
         12 . The rocker arm assembly of  claim 1 , the second portion further comprising a lost motion assembly configured to absorb at least a portion of the valve lift profile. 
     
     
         13 . The rocker arm assembly of  claim 12 , wherein the lost motion assembly comprises:
 a lost motion shaft movable within a bore provided along a longitudinal axis of the lost motion assembly; and   a lost motion biasing member configured to bias the lost motion shaft toward the one or more valves.   
     
     
         14 . The rocker arm assembly of  claim 13 , wherein the longitudinal axis of the lost motion assembly is disposed parallel to the plunger axis of the plunger assembly. 
     
     
         15 . The rocker arm assembly of  claim 1 , wherein the first portion of the rocker arm assembly comprises a roller configured to engage with a cam to receive at least a portion of the valve lift profile. 
     
     
         16 . The rocker arm assembly of  claim 1 , wherein, corresponding to the first state of the actuator assembly, the valve mechanism is held open by the control member so that the plunger pad retracts to the retracted position. 
     
     
         17 . The rocker arm assembly of  claim 1 , wherein the valve mechanism comprises a check valve biased against a hydraulic channel opening by a check valve biasing member. 
     
     
         18 . The rocker arm assembly of  claim 17 , wherein the control member comprises a control pin biased against the check valve by a control biasing member, the control member movable along the longitudinal axis of the actuator assembly. 
     
     
         19 . A method of assembling a rocker arm assembly, comprising:
 providing a plunger assembly proximal to a valve-engaging portion of the rocker arm assembly, the plunger assembly comprising an elongated member, a plunger pad slidably disposed at a first end of the elongated member, and a lash adjustment mechanism associated with a second end of the elongated member disposed opposite the first end;   providing a hydraulic actuator assembly connected in fluid communication with the plunger assembly such that a longitudinal axis of the hydraulic actuator assembly is angled to a plunger axis of the plunger assembly; and   configuring the second end of the elongated member to be accessible via an upper surface of the rocker arm assembly to facilitate lash adjustment of the plunger assembly.   
     
     
         20 . A valvetrain system comprising:
 a cam provided with a valve lift profile;   one or more valves;   a rocker shaft; and   a rocker arm assembly rotatable about the rocker shaft, the rocker arm assembly comprising:
 a first portion configured to receive the valve lift profile; and 
 a second portion configured to operatively engage with one or more of the valves based on the valve lift profile, the second portion comprising:
 an actuator assembly switchable between a first state and a second state, the actuator assembly comprising a valve mechanism actuated by a control member; and 
 a plunger assembly comprising:
 an elongated member having a first end and a second end opposite the first end; 
 a plunger pad slidably disposed at the first end of the elongated member; and 
 a lash adjustment mechanism associated with the second end of the elongated member, 
 
 
 wherein a longitudinal axis of the actuator assembly is angled to a plunger axis of the plunger assembly, 
 wherein the control member of the actuator assembly is hydraulically actuated to act on the valve mechanism, and 
 wherein, based on an actuation of the actuator assembly, the plunger pad is selectively extendable relative to the elongated member along the plunger axis between a retracted position and an extended position.