Rocker arm assembly for engine braking

1. An exhaust valve rocker arm assembly operable in a combustion engine mode and an engine braking mode, the exhaust valve rocker arm assembly comprising:

a rocker shaft that defines a pressurized oil supply conduit;

a rocker arm configured to receive the rocker shaft and configured to rotate around the rocker shaft, the rocker arm including a rocker arm oil supply passage defined in the rocker arm;

a valve bridge configured to engage a first exhaust valve and a second exhaust valve;

a hydraulic lash adjuster assembly, disposed on the rocker arm, including a first plunger body movable between a first position and a second position, wherein, in the first position, the first plunger body is configured to extend rigidly and cooperatively engage with the valve bridge; and

a check valve, disposed on the rocker arm, including an actuator configured to selectively release pressure in the hydraulic lash adjuster assembly;

wherein the exhaust valve rocker arm assembly is configured such that, in the engine braking mode, pressurized oil is communicated through the pressurized oil supply conduit, through the rocker arm oil supply passage, and against the actuator such that the first plunger body occupies the first position and acts on the valve bridge during rotation of the rocker arm to a first angle opening the first exhaust valve a predetermined distance while the second exhaust valve remains closed.

2. The assembly of claim 1 , wherein the hydraulic lash adjuster assembly is at least partially received by a first bore defined on the rocker arm.

3. The assembly of claim 1 , wherein the hydraulic lash adjuster assembly further includes a second plunger body that is at least partially received by the first plunger body, and

wherein the second plunger body defines a valve seat.

4. The assembly of claim 3 , wherein the check valve is disposed between the first and second plunger bodies,

wherein the check valve further includes a check ball configured to selectively seat against the valve seat on the second plunger body.

5. The assembly of claim 4 , wherein the actuator further includes a needle including a longitudinal pin portion and a disk portion, and

wherein the exhaust valve rocker arm assembly is configured such that, in the engine braking mode, pressurized oil acts against the disk portion moving the longitudinal pin portion a distance away from the check ball.

6. The assembly of claim 5 , wherein the disk portion of the actuator is configured to be received in a second bore defined in the rocker arm, and

wherein the first and second bores are collinear.

7. The assembly of claim 1 , configured such that rotation of the rocker arm to a second predetermined angle disconnects the rocker arm oil supply passage from the pressurized oil supply conduit.

8. The assembly of claim 7 , wherein the rocker shaft further defines a vent oil conduit, and

wherein the exhaust valve rocker arm assembly is configured such that rotation of the rocker arm to a third predetermined angle connects the rocker arm oil supply passage to the vent oil conduit releasing the oil pressure from the actuator.

9. The assembly of claim 1 , further comprising:

a spigot, disposed on the rocker arm,

wherein the assembly is configured such that, in the engine braking mode, subsequent to an opening of the first valve the predetermined distance, further rotation of the rocker arm causes the spigot to move the valve bridge and open the second valve while further opening the first valve.

10. The assembly of claim 9 , wherein the spigot is configured to slidably translate along a passage defined in the rocker arm prior to moving the valve bridge.

11. An exhaust valve rocker arm assembly operable in a combustion engine mode and an engine braking mode, the exhaust valve rocker arm assembly comprising:

a rocker shaft that defines a pressurized oil supply conduit;

a rocker arm configured to receive the rocker shaft and configured to rotate around the rocker shaft, the rocker arm including a rocker arm oil supply passage defined therein;

a valve bridge configured to engage a first exhaust valve and a second exhaust valve;

a first plunger body movable between a first position and a second position, wherein, in the first position, the first plunger body is configured to extend rigidly and cooperatively engage with the valve bridge; and

an actuator, configured to selectively release pressure acting against the first plunger body;

wherein the exhaust valve rocker arm assembly is configured such that, in the engine braking mode, pressurized oil is communicated through the pressurized oil supply conduit, through the rocker arm oil supply passage, and against the actuator such that the first plunger body occupies the first position and acts on the valve bridge during rotation of the rocker arm to a first angle opening the first exhaust valve a predetermined distance while the second exhaust valve remains closed.

12. The assembly of claim 11 , configured such that rotation of the rocker arm to a second predetermined angle disconnects the rocker arm oil supply passage from the pressurized oil supply circuit.

13. The assembly of claim 11 , wherein the rocker shaft further defines a vent oil conduit, and

wherein the exhaust valve rocker arm assembly is configured such that rotation of the rocker arm to a third predetermined angle connects the rocker arm oil supply passage to the vent oil conduit releasing the oil pressure from the actuator.

14. The assembly of claim 11 , further comprising: a spigot disposed on the rocker arm,

wherein, in the engine braking mode, subsequent to the opening of the first valve the predetermined distance, further rotation of the rocker arm causes the spigot to move the valve bridge and open the second valve while further opening the first valve.

15. The assembly of claim 11 , further comprising:

a second plunger body configured to be at least partially received by the first plunger body,

wherein the second plunger body defines a valve seat.

16. The assembly of claim 15 , wherein a check valve is disposed between the first and second plunger bodies,

wherein the check valve further includes a check ball configured to selectively seat against the valve seat on the second plunger body.

17. The assembly of claim 16 , wherein the actuator further includes a needle including a longitudinal pin portion and a disk portion,

wherein the exhaust valve rocker arm assembly is configured such that, in the engine braking mode, pressurized oil acts against the disk portion moving the longitudinal pin portion a distance away from the check ball.

18. The assembly of claim 17 wherein the disk portion of the actuator is configured to be received in a second bore defined in the rocker arm,

wherein the first and second bores are collinear.

19. An exhaust valve rocker arm assembly operable in a combustion engine mode and an engine braking mode, the exhaust valve rocker arm assembly comprising:

a rocker shaft that defines a pressurized oil supply conduit and a vent oil conduit;

a rocker arm configured to receive the rocker shaft and configured to rotate around the rocker shaft, the rocker arm including a rocker arm oil supply passage defined in the rocker arm;

a valve bridge configured to engage a first exhaust valve and a second exhaust valve;

a first plunger body movable between a first position and a second position, wherein in the first position, the first plunger body is configured to rigidly extend and cooperatively engage with the valve bridge;

a check valve, disposed on the rocker arm, including an actuator configured to selectively release pressure acting on the first plunger body; and

wherein the exhaust valve rocker arm assembly is configured such that, in the engine braking mode, the rocker arm is configured to rotate to (i) a first predetermined angle wherein pressurized oil is communicated through the pressurized oil supply conduit, through the rocker arm oil supply passage, and against the actuator such that the first plunger d occupies the first position and acts on the valve bridge opening the first exhaust valve a predetermined distance while the second valve remains closed, (ii) a second predetermined angle wherein rocker arm oil supply passage disconnects from the pressurized oil conduit, (iii) a third predetermined angle wherein the rocker arm oil supply passage connects with the vent oil conduit releasing oil pressure from the actuator.

20. The assembly of claim 19 , further comprising:

a spigot disposed on the rocker arm,

wherein the assembly is configured such that, in the engine braking mode, subsequent to the opening of the first exhaust valve the predetermined distance, further rotation of the rocker arm causes the spigot to move the valve bridge and open the second exhaust valve while further opening the first exhaust valve.

21. The assembly of claim 1 , wherein the valve bridge is configured to engage the first exhaust valve at a spherical elephant foot and the second exhaust valve at a cylindrical elephant foot.