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1. WO2020221477 - TYPE II PAIRED HYDRAULICS ENGINE BRAKE

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[ EN ]

CLAIMS

What is claimed is:

1. A hydraulic system for a rocker arm assembly having an exhaust rocker arm configured to selectively open an engine valve, the system comprising:

a carrier assembly configured to couple to a cylinder head of an engine;

a brake plunger assembly disposed in the carrier assembly and configured to be actuated by a braking lobe of a camshaft; and

a slave plunger assembly disposed in the carrier assembly and configured to be selectively hydraulically coupled to the brake plunger assembly,

wherein when the brake plunger assembly and the slave plunger assembly are hydraulically coupled, the brake plunger assembly is configured to impart movement via hydraulic fluid and the slave plunger assembly to actuate the exhaust rocker arm and open the engine valve to perform an engine braking operation.

2. The hydraulic system of claim 1 , further comprising a spool valve fluidly coupled between the brake plunger assembly and the slave plunger assembly, the spool valve selectively movable between (i) a sealed position that hydraulically couples the brake plunger assembly and the slave plunger assembly into a pressurized activated position, and (ii) an unsealed position that vents the brake plunger assembly and the slave plunger assembly into a depressurized, deactivated position that does not perform the engine brake operation.

3. The hydraulic system of claim 2, wherein the brake plunger assembly includes a plunger slidingly disposed within a cavity defined by a housing.

4. The hydraulic system of claim 3, further comprising a biasing mechanism configured to bias the plunger out of the cavity toward the camshaft.

5. The hydraulic system of claim 2, wherein the slave plunger assembly includes a plunger slidingly disposed within a cavity defined by a housing.

6. The hydraulic system of claim 5, further comprising a biasing mechanism configured to bias the plunger into the cavity away from the exhaust rocker arm.

7. A hydraulic system for a rocker arm assembly of an engine, comprising: an exhaust rocker arm having a first end and a second end, the first end configured to cooperate with an engine valve;

a carrier assembly configured to couple to a cylinder head of the engine;

a brake plunger assembly disposed in the carrier assembly and configured to be actuated by a braking lobe of a camshaft; and

a slave plunger assembly disposed in the carrier assembly and configured to be selectively hydraulically coupled to the brake plunger assembly,

wherein when the brake plunger assembly and the slave plunger assembly are hydraulically coupled, the brake plunger assembly is configured to impart movement via hydraulic fluid and the slave plunger assembly to actuate the exhaust rocker arm and open the engine valve to perform an engine braking operation.

8. The hydraulic system of claim 7, further comprising a spool valve fluidly coupled between the brake plunger assembly and the slave plunger assembly, the spool valve selectively movable between (i) a sealed position that hydraulically couples the brake plunger assembly and the slave plunger assembly into a pressurized activated position, and (ii) an unsealed position that vents the brake plunger assembly and the slave plunger assembly into a depressurized, deactivated position that does not perform the engine brake operation.

9. The hydraulic system of claim 8, wherein the brake plunger assembly includes a plunger slidingly disposed within a cavity defined by a housing.

10. The hydraulic system of claim 9, further comprising a biasing mechanism configured to bias the plunger out of the cavity toward the camshaft.

1 1. The hydraulic system of claim 8, wherein the slave plunger assembly includes a plunger slidingly disposed within a cavity defined by a housing.

12. The hydraulic system of claim 1 1 , further comprising a biasing mechanism configured to bias the plunger into the cavity away from the exhaust rocker arm.

13. The hydraulic system of claim 7, wherein the exhaust rocker arm is a roller finger follower.

14. The hydraulic system of claim 7, further comprising a camshaft having a first lobe configured to engage the exhaust rocker arm to perform a drive mode operation, and the braking lobe configured to engage the brake plunger assembly to perform the engine braking operation.

15. The hydraulic system of claim 7, wherein the exhaust rocker arm second end is operably coupled to a deactivating pivot configured to selectively move between an activated position acting as a rigid body, and a deactivated position for absorbing downward motion of the exhaust rocker arm, wherein the deactivating pivot comprises: an outer body;

a plunger slidingly disposed within the outer body;

a latching mechanism; and

a ball pivot, wherein the exhaust rocker arm second end is configured to pivot about the ball pivot.

16. A method of operating a hydraulic system for a rocker arm assembly of an engine, the hydraulic system having a carrier assembly configured to couple to a cylinder head of the engine, a brake plunger assembly disposed in the carrier assembly and configured to be actuated by a braking lobe of a camshaft, and a slave plunger assembly disposed in the carrier assembly and configured to be selectively hydraulically coupled to the brake plunger assembly, the method comprising:

operating in a normal drive mode including hydraulically depressurizing the hydraulic system so the brake plunger assembly does not impart movement to the slave plunger assembly, wherein in the normal drive mode the camshaft rotates normal lift lobes into contact with an exhaust rocker arm to open the engine valve; and

operating in a brake mode including pressurizing the hydraulic system such that the camshaft rotates the brake lift lobe into contact with brake plunger assembly to impart movement to the slave plunger assembly to thereby contact the exhaust rocker arm and open the engine valve to perform an engine brake operation.

17. The method of claim 16, wherein pressurizing the hydraulic system comprises supplying high pressure fluid to a volume between the brake plunger assembly and the slave plunger assembly.

18. The method of claim 17, wherein supplying the high pressure fluid comprises supplying high pressure fluid to the volume via a spool valve.

19. The method of claim 17, wherein operating in the brake mode comprises: contacting, with the brake lift lobe, a brake plunger of the brake plunger assembly; and

transferring motion of the brake plunger to a slave plunger of the slave plunger assembly via the high pressure fluid in the volume between the brake plunger assembly and the slave plunger assembly.

20. The method of claim 16, wherein the exhaust rocker arm includes a first end and a second end, the method further comprising:

operating a deactivating pivot in an activated position acting as a rigid body such that when the normal lift lobes contact the exhaust rocker arm, the second end pivots about the deactivating pivot and the first end transfers motion to the engine valve;

selectively operating the deactivating pivot in a deactivated position for absorbing downward motion of the exhaust rocker arm;

providing the deactivating pivot with a hydraulic lash adjuster (HLA); and loading the HLA during the brake mode to prevent pump up.