Development of a switching roller finger follower for cylinder deactivation in internal combustion engines

A rocker arm, comprising:

• an outer arm comprising a first side and a second side;
• an inner arm disposed between the first side and the second side of the outer arm;
• a pivot axle pivotally coupling the inner arm to the outer arm at a first end of the inner arm and a first end of the outer arm;
• a latch pin including a first position and a second position, the latch pin configured to:
• in the first position pivotally fix the inner arm to the outer arm at a second end of the inner arm and a second end of the outer arm;
• and
• in the second position, enable the inner arm to pivot independently of the outer arm;
• a first biasing member urging the latch pin into one of the first position and the second position, a hydraulic fluid passage hydraulically coupled to the latch pin;
• and
• two lost motion springs respectively secured to a mount on each of the first and second sides of the outer arm, each lost motion spring including coils with a trapezoidal cross-sectional shape arranged such that elongated sides of each coil rest against elongated sides of adjacent coils so as to stabilize the respective lost motion spring by holding each coil in an upright position, thereby preventing the coils from angling or passing over each other when subjected to torsional loading,
• wherein the latch pin is responsive to hydraulic pressure in the hydraulic fluid passage so as to selectively switch between the first position and the second position,
• wherein the inner arm comprises an inner arm sloped surface, and
• wherein the latch pin comprises a latch pin sloped surface.