Rocker arm providing cylinder deactivation
View Patent ↗A rocker arm assembly to provide either cylinder deactivation or reduced valve lift. The rocker arm assembly includes inner and outer portions that are rotatably connected to one another. In one state, the inner and outer portions are locked together to provide traditional valve lift. In a second state, the inner portion is allowed to rotate relative to the outer portion to deactivate the cylinder or provide reduced valve lift. Bearings on both the inner and outer portions provide rolling contact with corresponding cam shaft features. A hydraulic system provides transition between the first and second states.
1. A rocker arm apparatus, comprising:
first and second outer arms connected to move together, the first and second outer arms having respective first and second recesses formed therein, each recess having a closed end and an open end facing inwardly of the outer arms;
an inner arm located between the first and second outer arms, the inner arm having third and fourth recesses formed therein each having an open end facing outwardly of the inner arm, the inner arm being rotatable relative to the first and second outer arms between first and second positions, the open ends of the first and third recesses facing and being aligned with each other, and the open ends of the second and fourth recesses facing and being aligned with each other when the inner arm is in the first position;
first and second pistons located at least partially in the third and fourth recesses, respectively;
springs urging the first and second pistons outwardly towards the open ends of the third and fourth recesses, respectively, such that when the inner arm is in the first position the first and second pistons extend into the first and second recesses, respectively, thereby locking the inner arm against rotation relative to the first and second outer arms; and
first and second fluid flow paths formed in the first and second outer arms, respectively, to allow fluid under pressure to be applied to the first and second recesses, respectively, wherein when the first and second pistons extend into the first and second recesses, they are pushed out of the first and second recesses, by the fluid pressure and the inner arm can be rotated relative to the first and second outer arms.
2. The rocker arm apparatus of claim 1 , further comprising a first bearing attached to the inner arm to provide rolling contact with a lobe of a cam shaft.
3. The rocker arm apparatus of claim 2 , further comprising a second bearing attached to the first outer arm and a third bearing attached to the second outer arm.
4. The rocker arm apparatus of claim 1 , further comprising at least one valve abutment element located at the valve end of each of the first and second outer arms, each valve abutment having a curved surface for contacting an end of a valve stem.
5. The rocker arm apparatus of claim 1 , further comprising a lost motion spring coupled between the inner arm and the first and second outer arms.
6. The rocker arm apparatus of claim 5 , wherein the lost motion spring resists rotation of the inner arm out of the first position.
7. The rocker arm apparatus of claim 1 , further comprising a curved surface on an outer portion of the first outer arm for contacting an end of a valve stem.
8. The rocker arm apparatus of claim 1 , wherein the first and second outer arms are fixedly connected by a transverse arm to form a generally u-shaped structure.
9. The rocker arm apparatus of claim 8 , wherein the transverse arm is coupled to respective ends of the first and second outer arms.
10. The rocker arm apparatus of claim 9 , wherein the first and second outer arms and the transverse arm are integrally formed with one another.