Switching roller finger follower for bleeder braking

Abstract

A switching rocker arm assembly includes an inner arm, an outer arm pivotably secured to the inner arm, and a camshaft having a first lobe to contact one of the outer arm and the inner arm to perform a normal valve motion, and a second lobe to contact the other of the outer arm and the inner arm to perform at least one of: a full cycle bleeder brake exhaust valve motion, a partial cycle bleeder brake exhaust valve motion, an additional engine brake intake valve motion, and a compression relief braking exhaust valve motion.

What is claimed is: 
     
         1 . A switching rocker arm assembly comprising:
 an inner arm;   an outer arm pivotably secured to the inner arm; and   a camshaft having a first lobe to contact one of the outer arm and the inner arm to perform a normal valve motion, and a second lobe to contact the other of the outer arm and the inner arm to perform at least one of:
 a full cycle bleeder brake exhaust valve motion; 
 a partial cycle bleeder brake exhaust valve motion; 
 an additional engine brake intake valve motion; and 
 compression relief braking exhaust valve motion. 
   
     
     
         2 . The assembly of  claim 1 , further comprising a latching mechanism configured to selectively latch the inner arm to the outer arm. 
     
     
         3 . The assembly of  claim 1 , wherein when the inner arm is latched to the outer arm, the second lobe is configured to impart motion to the other of the outer arm and the inner arm to perform at least one of the following: (i) hold open an exhaust valve to perform the full cycle bleeder brake exhaust valve motion, (ii) hold open an exhaust valve to perform the partial cycle bleeder brake exhaust motion, and/or (ii) open an intake valve after a normal intake valve opening to perform an additional intake valve opening. 
     
     
         4 . The assembly of  claim 3 , wherein when the inner arm is not latched to the outer arm, the other of the inner arm and the outer arm undergoes lost motion when the second lobe imparts motion thereto such that the motion is not imparted to exhaust valve. 
     
     
         5 . The assembly of  claim 2 , further comprising a biasing mechanism mounted around a spring retainer and including a first end engaged with the outer arm and a second end engaged with the inner arm. 
     
     
         6 . The assembly of  claim 5 , further comprising:
 a pair of outer rollers rotatably coupled to the outer arm, wherein the first lobe comprises a pair of first lobes configured to selectively engage the pair of outer rollers to impart motion to the outer arm; and   an inner roller rotatably coupled to the inner arm, wherein the second lobe is configured to selectively engage the inner roller to impart motion to the inner arm.   
     
     
         7 . The assembly of  claim 1 , further comprising a deactivating hydraulic lash adjuster, the outer arm configured to pivot about the deactivating hydraulic lash adjuster. 
     
     
         8 . The assembly of  claim 1 , wherein the full cycle bleeder brake exhaust valve motion holds an exhaust valve open throughout intake, compression, and expansion cycles of an engine,
 wherein the partial cycle bleeder brake exhaust valve motion holds the exhaust valve open throughout the compression and expansion cycles of the engine,   wherein the additional engine brake intake valve motion adds a small intake lift opposite a normal intake event, and   wherein the compression relief braking exhaust valve motion includes at least one compression relief event and at least one brake gas recirculation event.   
     
     
         9 . The assembly of  claim 1 , wherein the second lobe is an enlarged base circle having a first radius larger than a second radius of a base circle of the first lobe, wherein the enlarged base circle is configured to contact the other of the outer arm and the inner arm to perform the full cycle bleeder brake exhaust valve motion. 
     
     
         10 . The assembly of  claim 1 , wherein the second lobe has a lengthened lobe with a first radius larger than a second radius of a base circle of the first lobe, wherein the lengthened lobe is configured to contact the other of the outer arm and the inner arm to perform the partial cycle bleeder brake exhaust valve motion. 
     
     
         11 . A valvetrain assembly configured to perform an engine braking operation, the valvetrain assembly comprising:
 a first switching rocker arm assembly having a first outer arm pivotably secured to a first inner arm; and   a camshaft having a first lobe to contact one of the first outer arm and the first inner arm to perform a normal valve motion, and a second lobe to contact the other of the first outer arm and the first inner arm to perform at least one of (i) a full cycle bleeder brake exhaust valve motion, (ii) a partial cycle bleeder brake exhaust valve motion, (iii) an additional engine brake intake valve motion, and (iv) compression relief braking exhaust valve motion.   
     
     
         12 . The valvetrain assembly of  claim 11 , further comprising:
 a second switching rocker arm assembly having a second outer arm pivotably secured to a second inner arm; and   the camshaft having a third lobe to contact one of the second outer arm and the second inner arm to perform a normal valve motion, and a fourth lobe to contact the other of the second outer arm and the second inner arm to perform the additional engine brake intake valve motion,   wherein the second lobe contacting the other of the first outer arm and the first inner arm performs at least one of (i) the full cycle bleeder brake exhaust valve motion, and (ii) the partial cycle bleeder brake exhaust valve motion.   
     
     
         13 . The valvetrain assembly of  claim 12 , wherein the second lobe is an enlarged base circle having a first radius larger than a second radius of a base circle of the first lobe, wherein the enlarged base circle is configured to contact the other of the first outer arm and the first inner arm to perform the full cycle bleeder brake exhaust valve motion. 
     
     
         14 . The valvetrain assembly of  claim 12 , wherein the second lobe has a lengthened lobe with a first radius larger than a second radius of a base circle of the first lobe, wherein the lengthened lobe is configured to contact the other of the first outer arm and the first inner arm to perform the partial cycle bleeder brake exhaust valve motion. 
     
     
         15 . The valvetrain assembly of  claim 12 , wherein the fourth lobe has a smaller lobe with a first radius smaller than a second radius of the first lobe, wherein the smaller lobe is configured to contact the other of the second outer arm and the second inner arm to perform the additional engine brake intake valve motion. 
     
     
         16 . The valvetrain assembly of  claim 12 , wherein the first switching rocker arm assembly includes a first latching mechanism configured to selectively latch the first inner arm to the first outer arm; and
 wherein the second switching rocker arm assembly includes a second latching mechanism configured to selectively latch the second inner arm to the second outer arm.   
     
     
         17 . The valvetrain assembly of  claim 16 , wherein when the first inner arm is latched to the first outer arm, the second lobe is configured to impart motion to the other of the first outer arm and the first inner arm to perform at least one of the following: (i) hold open an exhaust valve to perform the full cycle bleeder brake exhaust valve motion, and (ii) hold open an exhaust valve to perform the partial cycle bleeder brake exhaust motion, and
 wherein when the second inner arm is latched to the second outer arm, the fourth lobe is configured to impart motion to the other of the second outer arm and the second inner arm to open an intake valve after a normal intake valve opening to perform the additional engine brake intake valve motion.   
     
     
         18 . The valvetrain assembly of  claim 17 , wherein when the first inner arm is not latched to the first outer arm, the other of the first outer arm and the first inner arm undergoes lost motion when the second lobe imparts motion thereto such that the motion is not imparted to the exhaust valve, and
 wherein when the second inner arm is not latched to the second outer arm, the other of the second outer arm and the second inner arm undergoes lost motion when the fourth lobe imparts motion thereto such that the motion is not imparted to the intake valve.   
     
     
         19 . The valvetrain assembly of  claim 18 , further comprising:
 a first pair of outer rollers rotatably coupled to the first outer arm, wherein the first lobe comprises a pair of first lobes configured to selectively engage the first pair of outer rollers to impart motion to the first outer arm;   a first inner roller rotatably coupled to the first inner arm, wherein the second lobe is configured to selectively engage the first inner roller to impart motion to the first inner arm;   a second pair of outer rollers rotatably coupled to the second outer arm, wherein the third lobe comprises a pair of third lobes configured to selectively engage the pair of second outer rollers to impart motion to the second outer arm; and   a second inner roller rotatably coupled to the second inner arm, wherein the fourth lobe is configured to selectively engage the second inner roller to impart motion to the second inner arm.   
     
     
         20 . A method of operating a valvetrain assembly comprising a first switching rocker arm assembly having a first outer arm pivotably secured to a first inner arm, and a camshaft having a first lobe to contact one of the first outer arm and the first inner arm, and a second lobe to contact the other of the first outer arm and the first inner arm, the method comprising:
 operating in a normal mode where the first inner arm is unlatched from the first outer arm such that (i) when the first lobe contacts the one of the first outer arm and the first inner arm, motion is imparted to an exhaust valve to perform a normal exhaust valve opening, and (ii) when the second lobe contacts the other of the first outer arm and the first inner arm, the other of the first outer arm and the first inner arm undergoes lost motion such that motion is not imparted to the exhaust valve; and   operating in an engine brake mode where the first inner arm is latched to the first outer arm such that (i) when the first lobe contacts the one of the first outer arm and the first inner arm, motion is imparted to the exhaust valve to perform the normal exhaust valve opening, and (ii) when the second lobe contacts the other of the first outer arm and the first inner arm, the other of the first outer arm and the first inner arm imparts motion to the exhaust valve to perform at least one of (a) a full cycle bleeder brake exhaust valve motion, and (b) a partial cycle bleeder brake exhaust valve motion.