ROCKER ARM FOR AN INTERNAL COMBUSTION ENGINE

• US 20200131946A1
• Filed: 03/27/2017
• Published: 04/30/2020
• Est. Priority Date: 03/27/2017
• Status: Active Grant

• Current Assignee: Volvo Truck Corporation (Volvo AB)
• Original Assignee: Volvo Truck Corporation (Volvo AB)
• Inventors: Persson, Per
• Granted Patent: US 11,002,157 B2
• Time in Patent Office: Days
• CPC Class Codes: F01L 1/18 Rocking arms or levers
• CPC Class Codes: F01L 1/181 Centre pivot rocking arms
• CPC Class Codes: F01L 1/24 by fluid means, e.g. hydraulically
• CPC Class Codes: F01L 1/2411 by means of a hydraulic adjusting device located between the valve stem and rocker arm
• CPC Class Codes: F01L 1/267 with means for varying the timing or the lift of the valves
• CPC Class Codes: F01L 13/06 for braking
• CPC Class Codes: F01L 13/065 Compression release engine retarders of the "Jacobs Manufacturing" type
• CPC Class Codes: F01L 2820/043 Pressure
• CPC Class Codes: F02D 13/0203 Variable control of intake and exhaust valves
• CPC Class Codes: F02D 2200/024 Fluid pressure of lubricating oil or working fluid

Abstract

The present invention relates to a rocker arm (16) for an internal combustion engine (12). The rocker arm (16) comprises a cavity (41) with a cavity wall (42) at least partially accommodating a lash adjustment piston (44) for hydraulic lash adjustment. The rocker arm (16) further comprises a lash stop surface (46). At least a portion of the lash adjustment piston (44) is adapted to abut the lash stop surface (46) during at least one operating condition of the rocker arm (16). The cavity (41) comprises a lash adjustment chamber (50) at least partially delimited by the lash adjustment piston (44). The rocker arm (16) further comprising a control fluid conduit (52) and a valve assembly (54) located between the lash adjustment chamber (50) and the control fluid conduit (52), as seen in an intended direction of flow from the control fluid conduit (52) to the lash adjustment chamber (50).

Claims

1. A rocker arm (16) for an internal combustion engine (12), said rocker arm (16) comprising a cavity (41) with a cavity wall (42) at least partially accommodating a lash adjustment piston (44) for hydraulic lash adjustment, said rocker arm (16) further comprising a lash stop surface (46), at least a portion of said lash adjustment piston (44) being adapted to abut said lash stop surface (46) during at least one operating condition of said rocker arm (16), said cavity (41) comprising a lash adjustment chamber (50) at least partially delimited by said lash adjustment piston (44), said rocker arm (16) further comprising a control fluid conduit (52) and a valve assembly (54) located between said lash adjustment chamber (50) and said control fluid conduit (52), as seen in an intended direction of flow from said control fluid conduit (52) to said lash adjustment chamber (50), said valve assembly (54) being such that:

for a first fluid pressure range (Δ

P₁) wherein a fluid pressure in said control fluid conduit (52) is equal to or lower than a first predetermined threshold pressure level (P₁), said lash adjustment piston (44) can move relative to said cavity wall (42) in at least a direction towards said lash stop surface (46);

for a second fluid pressure range (Δ

P₂) from and including a low second predetermined threshold pressure level (P_L2) to and including a high second predetermined threshold pressure level (P_H2), said low second predetermined threshold pressure level (P_L2) being greater said first predetermined threshold pressure level (P₁), said lash adjustment piston (44) is prevented from moving relative to said cavity wall (42) in at least a direction towards said lash stop surface (46), and

for a third fluid pressure range (Δ

P₃) wherein the fluid pressure in said control fluid conduit (52) exceeds a third predetermined threshold level (P₃), said third predetermined threshold level (P₃) being greater than said high second predetermined threshold pressure level (P_H2), said lash adjustment piston (44) can move relative to said cavity wall (42) in at least a direction towards said lash stop surface (46).

2. The rocker arm (16) according to claim 1, wherein said valve assembly (54) is such that:

for said first fluid pressure range (Δ

P₁), said valve assembly (54) prevents fluid to flow from said control fluid conduit (52) to said lash adjustment chamber (50).

3. The rocker arm (16) according to claim 1, wherein said valve assembly (54) is such that:

for said first fluid pressure range (Δ

P₁), said valve assembly (54) allows fluid to flow from said lash adjustment chamber (50) to a drain channel (56).

4. The rocker arm (16) according to claim 1, wherein said valve assembly (54) is such that:

for said second fluid pressure range (Δ

P₂), said valve assembly (54) prevents fluid from flowing from said lash adjustment chamber (50).

5. The rocker arm (16) according to claim 1, wherein said valve assembly (54) is such that:

for said third fluid pressure range (Δ

P₃), said valve assembly (54) allows fluid to flow from said lash adjustment chamber (50) to said control fluid conduit (52).

6. The rocker arm (16) according to claim 1, wherein said valve assembly (54) is such that:

for said third fluid pressure range (Δ

P₃), said valve assembly (54) allows fluid to flow from said lash adjustment chamber (50) to a drain channel (56) but prevents fluid to flow from said control fluid conduit (52) to said lash adjustment chamber (50).

7. The rocker arm (16) according to claim 1, wherein said valve assembly (54) comprises a check valve (62) and a spool (64), said spool (64) having a spool inlet opening (66) and a spool outlet opening (68), said check valve (62) being adapted to assume an open check valve position relative to said spool (64), in which said spool inlet opening (66) is in fluid communication with said spool outlet opening (68), and a closed check valve position relative to said spool (64), in which said spool inlet opening (66) is fluidly disconnected from said spool outlet opening (68).

8. The rocker arm (16) according to claim 7, wherein said check valve (62) comprises a check valve member (70), said spool (64) comprising a check valve member seat (72) and a check valve biasing means (74) adapted to bias said check valve member (70) towards said check valve member seat (72).

9. The rocker arm (16) according to claim 7, wherein said rocker arm (16) comprises a spool cavity (76) with a spool cavity wall (78), said spool (64) being accommodated in said spool cavity (76) and being moveable relative to said spool cavity wall (78), said spool (64) being adapted to assume a closed spool condition, in which fluid communication between said control fluid conduit (52) and said lash adjustment chamber (50) via said spool inlet opening (66) and a spool outlet opening (68) is prevented.

10. The rocker arm (16) according to claim 9, wherein when said spool (64) assumes said closed spool condition, fluid is allowed to flow from said lash adjustment chamber (50) to a drain channel (56).

11. The rocker arm (16) according to claim 9, wherein said rocker arm (16) comprises a spool biasing assembly (86) adapted to bias said spool towards said closed spool condition.

12. The rocker arm (16) according to claim 9, wherein said spool (64) is adapted to assume said closed spool condition for said first fluid pressure range (Δ

P₁).

13. The rocker arm (16) according to claim 9, wherein said spool (64) is adapted to assume a first open spool condition, in which fluid communication between said control fluid conduit (52) and said lash adjustment chamber (50) via said spool inlet opening (66) and said spool outlet opening (68) is enabled when said check valve (62) assumes said open check valve position relative to said spool (64).

14. The rocker arm (16) according to claim 13, wherein when said spool (64) assumes said first open spool condition, fluid is prevented from flowing from said lash adjustment chamber (50) to a drain channel (56).

15. The rocker arm (16) according to claim 13, wherein said spool (64) is adapted to assume said first open spool condition for said second fluid pressure range (Δ

P₂).

16. The rocker arm (16) according to claim 13, wherein said spool (64) is adapted to assume a second open spool condition, in which fluid communication between said control fluid conduit (52) and said lash adjustment chamber (50) is allowed irrespective of the position of the check valve (62) relative to said spool (64).

17. The rocker arm (16) according to claim 16, wherein said spool (64) is adapted to assume said second open spool condition for said third fluid pressure range (Δ

P₃).

18. The rocker arm (16) according to claim 16, wherein when said spool (64) assumes said second open spool condition, fluid may flow between said control fluid conduit (52) and said lash adjustment chamber (50) without passing through said spool (64).

19. The rocker arm (16) according to claim 16, wherein when said spool (64) assumes said second open spool condition, fluid is allowed to flow from said lash adjustment chamber (50) to a drain channel (56) but fluid is prevented from flowing from said control fluid conduit (52) to said lash adjustment chamber (50).

20. An inlet rocker arm (16) adapted to control at least one inlet valve for an internal combustion engine (12), said inlet rocker arm (16) being according to claim 1.

21. An exhaust rocker arm (18) adapted to control at least one exhaust valve for an internal combustion engine (12), said exhaust rocker arm (18) being according to claim 1.

22. A rocker arm assembly (14) for an internal combustion engine (12), said rocker arm assembly (14) comprising an inlet rocker arm (16) according to claim 20 and an exhaust rocker arm (16) according to claim 20, the control fluid conduit (52) of said inlet rocker arm (16) and the control fluid conduit (52) of said exhaust rocker arm (18) being in fluid communication with each other.

23. The rocker arm assembly (14) according to claim 22, wherein said low second predetermined threshold pressure level (Pe_L2) associated with said exhaust rocker arm (18) is higher than said low second predetermined threshold pressure level (Pi_L2), preferably higher than said high second predetermined threshold pressure level (Pi_H2), associated with said inlet rocker arm (16).

24. The rocker arm assembly (14) according to claim 23, wherein said first predetermined threshold level (Pe₁) associated with said exhaust rocker arm (18) is equal to or greater than said high second predetermined threshold pressure level (Pi_H2) associated with said inlet rocker arm (16).

25. An internal combustion engine (12) comprising a rocker arm (16) and/or an inlet rocker arm (16), an exhaust rocker arm (18), a rocker arm assembly (14) according to claim 1.

26. A vehicle (10) comprising a rocker arm (16) and/or an inlet rocker arm (16), an exhaust rocker arm (18), a rocker arm assembly (14), and/or an internal combustion engine (12) according to claim 1.

27. A method for controlling a lash in a rocker arm for an internal combustion engine (12), said rocker arm comprising a cavity (41) with a cavity wall (42) at least partially accommodating a lash adjustment piston (44) for hydraulic lash adjustment, said rocker arm further comprising a lash stop surface (46), at least a portion of said lash adjustment piston (44) being adapted to abut said lash stop surface (46) during at least one operating condition of said rocker arm, said cavity (41) comprising a lash adjustment chamber (50) at least partially delimited by said lash adjustment piston (44), said rocker arm further comprising a control fluid conduit (52) and a valve assembly (54) located between said lash adjustment chamber (50) and said control fluid conduit (52), as seen in an intended direction of flow from said control fluid conduit (52) to said lash adjustment chamber (50), said method comprising:

feeding fluid at a first fluid pressure range (Δ

P₁) to said control fluid conduit (52) such that the fluid pressure in said control fluid conduit (52) is equal to or lower than a first predetermined threshold pressure level (P₁), such that said lash adjustment piston (44) can move relative to said cavity wall (42) in at least a direction towards said lash stop surface (46);

feeding fluid at a second fluid pressure range (Δ

P₂) to said control fluid conduit (52) such the fluid pressure in said control fluid conduit (52) is from and including a low second predetermined threshold pressure level (P_L2) to and including a high second predetermined threshold pressure level (P_H2), said low second predetermined threshold pressure level (P_L2) being greater said first predetermined threshold pressure level (P₁), such that said lash adjustment piston (44) is prevented from moving relative to said cavity wall (42) in at least a direction towards said lash stop surface (46), and

feeding fluid at a third fluid pressure range (Δ

P₃) to said control fluid conduit (52) such that the fluid pressure in said control fluid conduit (52) exceeds a third predetermined threshold level (P₃), said third predetermined threshold level (P₃) being greater than said high second predetermined threshold pressure level (P_H2), such that said lash adjustment piston (44) can move relative to said cavity wall (42) in at least a direction towards said lash stop surface (46).