Rocker based bleeder engine brake

Patent metadata

Field	Value
Publication number	US-11401839-B2
Application number	US-202117146784-A
Country	US
Kind code	B2
Filing date	Jan 12, 2021
Priority date	Jul 13, 2018
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

An exhaust valve rocker arm assembly operable in an engine braking mode includes a rocker arm configured to rotate about a rocker shaft defining a pressurized fluid supply conduit, the rocker arm having a fluid supply passage defined therein. An engine brake capsule is disposed in the rocker arm and in fluid communication with the fluid supply passage. The engine brake capsule is configured to selectively move from a retracted position to an extended position where the engine brake capsule engages and partially opens an exhaust valve to perform a bleeder brake operation. A reset pin assembly is configured to selectively drain fluid from the engine brake capsule.

First claim

What is claimed is:

1. An exhaust valve rocker arm assembly operable in an engine braking mode, the exhaust valve rocker arm assembly comprising:
a rocker arm configured to rotate about a rocker shaft defining a pressurized fluid supply conduit, the rocker arm having a fluid supply passage defined therein;
an engine brake capsule disposed in the rocker arm and in fluid communication with the fluid supply passage, the engine brake capsule configured to selectively move from a retracted position to an extended position where the engine brake capsule engages and partially opens an exhaust valve to perform a bleeder brake operation;
a transverse bore formed in the rocker arm and extending transversely across a body of the rocker arm;
a reset pin assembly configured to selectively drain fluid from and reset the engine brake capsule, the reset pin assembly including a reset pin slidingly disposed within the transverse bore; and
a fixed shoulder formed on a fixed rocker housing, the fixed shoulder configured to be selectively engaged by the reset pin assembly when the rocker arm rotates downward toward the exhaust valve during a main exhaust event, to thereby actuate the reset pin assembly and facilitate draining the fluid from the engine brake capsule.

2. The exhaust valve rocker arm assembly of claim 1 , wherein the engine brake capsule is disposed in a capsule bore formed within the rocker arm, wherein the transverse bore extends along an axis generally perpendicular to an axis of extension of the capsule bore.

3. The exhaust valve rocker arm assembly of claim 2 , wherein the reset pin assembly further includes a biasing mechanism configured to bias the reset pin into a closed position such that the reset pin acts as a spool valve and blocks a fluid outlet conduit formed in the rocker arm.

4. The exhaust valve rocker arm assembly of claim 1 , wherein the reset pin is arranged entirely outside of the fluid supply passage that extends between the fluid supply conduit and the engine brake capsule.

5. The exhaust valve rocker arm assembly of claim 1 , wherein the rocker arm further includes a fluid outlet conduit in fluid communication with the engine brake capsule, the fluid outlet conduit configured to drain the fluid from the engine brake capsule via the reset pin assembly.

6. The exhaust valve rocker arm assembly of claim 1 , wherein the engine brake capsule includes a plunger slidingly disposed within the rocker arm.

7. The exhaust valve rocker arm assembly of claim 1 , wherein the engine brake capsule includes a check ball assembly comprising a check ball, a first biasing mechanism configured to bias the check ball into a sealing position to seal the fluid supply passage, and a second biasing mechanism configured to bias a plunger into a retracted position within a bore defined in the rocker arm.

8. The exhaust valve rocker arm assembly of claim 1 , wherein the rocker arm further includes an outlet conduit having a first end fluidly coupled to the engine brake capsule, and an opposite second end configured to drain the fluid from the rocker arm, wherein the outlet conduit is a straight passage between the first and second ends.

9. The exhaust valve rocker arm assembly of claim 1 , further comprising a controller configured to generate a backpressure inside an exhaust manifold to reopen the exhaust valve.

10. The exhaust valve rocker arm assembly of claim 9 , wherein the controller is configured to generate the backpressure by closing at least one of a butterfly valve and a variable geometry turbocharger.

11. A valvetrain assembly comprising:
a rocker housing including a fixed shoulder fixed to the rocker housing;
a rocker shaft received within the rocker housing;
a rocker arm assembly configured to rotate about the rocker shaft; and
a pushrod configured to selectively engage and rotate the rocker arm assembly about the rocker shaft to engage and open an exhaust valve,
wherein the rocker arm assembly comprises:
a rocker arm having a fluid supply passage defined therein;
an engine brake capsule disposed in the rocker arm and in fluid communication with the fluid supply passage, the engine brake capsule configured to selectively move from a retracted position to an extended position where the engine brake capsule engages and partially opens the exhaust valve to perform a bleeder brake operation; and
a reset pin assembly configured to selectively engage the fixed shoulder when the rocker arm rotates downward toward the exhaust valve during a main exhaust event to thereby drain fluid from and reset the engine brake capsule.

12. The valvetrain assembly of claim 11 , further comprising:
a camshaft having a lift profile configured to engage and cause upward movement of the pushrod; and
a hydraulic lash adjuster lifter implemented between the camshaft and the pushrod.

13. The valvetrain assembly of claim 11 , wherein the rocker arm further includes a fluid outlet conduit in fluid communication with the engine brake capsule, the fluid outlet conduit configured to drain the fluid from the engine brake capsule via the reset pin assembly.

14. The valvetrain assembly of claim 11 , wherein the reset pin assembly comprises:
a reset pin slidingly disposed within a transverse bore formed in the rocker arm; and
a biasing mechanism configured to bias the reset pin into a closed position such that the reset pin acts as a spool valve and blocks a fluid outlet conduit formed in the rocker arm.

15. The valvetrain assembly of claim 11 , wherein the engine brake capsule comprises:
a plunger slidingly disposed within the rocker arm; and
a check ball assembly having a check ball, a first biasing mechanism configured to bias the check ball into a sealing position to seal the fluid supply passage, and a second biasing mechanism configured to bias a plunger into a retracted position within a bore defined in the rocker arm.

16. A method of operating a valvetrain assembly having an exhaust rocker arm assembly comprising a rocker arm configured to rotate about a rocker shaft defining a pressurized fluid supply conduit, the rocker arm having a fluid supply passage defined therein, an engine brake capsule disposed in the rocker arm and in fluid communication with the fluid supply passage, the engine brake capsule configured to selectively move from a retracted position to an extended position where the engine brake capsule engages and partially opens an exhaust valve to perform a bleeder brake operation, and a reset pin assembly configured to selectively drain fluid from the engine brake capsule, the method comprising:
activating an engine braking mode by closing one of a butterfly valve and a variable geometry turbocharger to generate backpressure inside an exhaust manifold;
opening the exhaust valve with the generated backpressure along with in-cylinder pressure to momentarily create lash;
supplying pressurized fluid via the fluid supply conduit and the fluid supply passage to the engine brake capsule to thereby expand the engine brake capsule into the extended position to compensate for the lash and hold the exhaust valve open;
maintaining the exhaust valve partially open for a predetermined time via the engine brake capsule in the extended position; and
when the rocker arm rocks downward toward the exhaust valve in response to a camshaft lift profile, engaging the reset pin assembly with a fixed shoulder of a fixed rocker housing to thereby drain fluid from the engine brake capsule and reset the engine brake capsule to the retracted position.

17. The method of claim 16 , wherein said ma

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Sarati Venkata

Classifications

• F01L1/146

  Push-rods · CPC title

• F01L2001/054

  Camshafts in cylinder block · CPC title

• F01L2001/256

  between cam and push rod · CPC title

• F01L1/2411

  by means of a hydraulic adjusting device located between the valve stem and rocker arm · CPC title

• F01N2260/14

  for modifying or adapting flow area or back-pressure · CPC title