ROCKER SYSTEM WITH STOPPER ARRANGEMENT ON CAM SIDE

Abstract

A rocker arm assembly for actuating a valve. The rocker arm assembly including a rocker arm having a valve side and a cam side. The rocker arm being pivotable about a rocker shaft via actuation on the cam side. At least one roller assembly is attached to the rocker arm. A latch assembly is provided for selectively latching the at least one roller assembly to the rocker arm, wherein when the latch assembly is in a lost motion state the at least one roller assembly is free to pivot relative to the rocker arm and when the latch assembly is in an activated state the at least one roller assembly is pivotably coupled to the rocker arm.

Claims

1. A rocker arm assembly for actuating a valve, the rocker arm assembly comprising: a rocker arm having a valve side and a cam side, the rocker arm being pivotable about a rocker shaft via actuation on the cam side; a hydraulic lift assembly positioned on the valve side of the rocker arm, the hydraulic lift assembly comprising: a plunger movable between an actuated position and an unactuated position; and a check ball for selectively locking the plunger in the actuated position; at least one roller assembly attached to the rocker arm; and a latch assembly for selectively latching the at least one roller assembly to the rocker arm, wherein when the latch assembly is in a lost motion state the at least one roller assembly is free to pivot relative to the rocker arm and when the latch assembly is in an activated state the at least one roller assembly is pivotably coupled to the rocker arm.

2. The rocker arm assembly of claim 1, wherein the at least one roller assembly includes: a roller engageable with a cam, the roller configured to pivot about the rocker shaft; a spring for biasing the roller to a stopped position; and a stopper for stopping the roller at the stopped position.

3. The rocker arm assembly of claim 2, wherein the stopper is a single pin.

4. The rocker arm assembly of claim 2, wherein the stopper is at least one of threaded, welded or press-fitted to the rocker arm.

5. The rocker arm assembly of claim 2, wherein the stopper engages a seat formed in the rocker arm.

6. The rocker arm assembly of claim 1, wherein the rocker arm is Y-shaped with a first arm and a second arm.

7. The rocker arm assembly of claim 2, wherein one end of the spring is fixed to the rocker arm and another end of the spring engages a bracket holding the roller.

8. The rocker arm assembly of claim 7, wherein the bracket is pivotable about the rocker shaft.

9. A rocker arm assembly for actuating a valve, the rocker arm assembly comprising: a rocker arm having a valve side and a cam side, the rocker arm being pivotable about a rocker shaft via actuation of a first roller on the cam side; at least one roller assembly attached to the rocker arm; and a latch assembly for selectively latching the at least one roller assembly to the rocker arm, wherein when the latch assembly is in a lost motion state the at least one roller assembly is free to pivot relative to the rocker arm and when the latch assembly is in an activated state the at least one roller assembly is pivotably coupled to the rocker arm.

10. The rocker arm assembly of claim 9, wherein the at least one roller assembly includes: a roller engageable with a cam, the roller configured to pivot about the rocker shaft; a spring for biasing the roller to a stopped position; and a stopper for stopping the roller at the stopped position.

11. The rocker arm assembly of claim 10, wherein the stopper is a single pin.

12. The rocker arm assembly of claim 10, wherein the stopper is at least one of threaded, welded or press-fitted to the rocker arm.

13. The rocker arm assembly of claim 10, wherein the stopper engages a seat formed in the rocker arm.

14. The rocker arm assembly of claim 10, wherein one end of the spring is fixed to the rocker arm and another end of the spring engages a bracket holding the roller.

15. The rocker arm assembly of claim 14, wherein the bracket is pivotable about the rocker shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a perspective view of a rocker arm assembly;

[0020] FIG. 2 is section view of the rocker arm assembly of FIG. 1 taken along line 2-2, illustrating a hydraulic lift assembly (HLA) in a deactivated state;

[0021] FIG. 3 is an enlarged section view of the HLA of FIG. 2;

[0022] FIG. 4 is a section view of a latch assembly of the rocker arm assembly of FIG. 1 taken along line 4-4, illustrating the latch assembly in a lost motion state;

[0023] FIG. 5 is plot of valve lift vs. cam angle for the latch assembly in the lost motion state;

[0024] FIG. 6 is a section view of a latch assembly of the rocker arm assembly of FIG. 1 taken along line 4-4, illustrating the latch assembly in an activated state; and

[0025] FIG. 7 is plot of valve lift vs. cam angle for the latch assembly in an activated state.

DETAILED DESCRIPTION

[0026] The following presents a description of the disclosure; however, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Furthermore, the following examples may be provided alone or in combination with one or any combination of the examples discussed herein. Directional references such as left and right are for ease of reference to the figures.

[0027] Referring to FIG. 1, the rocker arm assembly 50 includes a rocker arm 60. In the embodiment illustrated, the rocker arm 60 is a Y-shaped rocker arm having a first arm 60a and a second arm 60b. It is contemplated that the rocker arm 60 could be a single rocker arm (not illustrated). A hydraulic lash adjuster (HLA) 100 is positioned on a valve side 62 of the rocker arm 60. The HLA 100 is positioned to selectively engage a distal end of a valve 80 (partially illustrated in FIGS. 2 and 3) when it is desired to adjust the lash of the valve 80. In the embodiment illustrated, the rocker arm 60 includes a rocker bore 66 for allowing the rocker arm 60 to pivot about a shaft (not shown) via actuation at a roller end 64 of the rocker arm 60 by a cam 70 (partially illustrated in FIG. 2). A first roller 65 is disposed at the roller end 64 for engaging the cam 70.

[0028] Referring to FIGS. 2 and 3, the rocker arm 60 includes a bore 68 that is dimensioned to receive the HLA 100. In general, the HLA 100 includes an upper piston 102 and a lower piston 104 that together define a first fluid cavity 110 therebetween. The lower piston 104 and a plunger 112 of the HLA 100 define a second fluid cavity 120 therebetween. When it is desired to extend the plunger 112 from the bore 68, fluid is supplied to the first fluid cavity 110. A check ball 122 in the HLA 100 opens due to the force of the fluid flowing into the first fluid cavity 110 and allows the fluid to flow into and fill the second fluid cavity 120. As the first fluid cavity 110 and second fluid cavity 120 are filled, the plunger 112 extends from the bore 68 of the rocker arm 60 a predetermined distance to an extended position.

[0029] When the plunger 112 experiences a sudden force, e.g., from a spring (not shown) on the valve 80, the sudden application of force to the distal end of the plunger 112 causes the plunger 112 to move slightly toward the lower piston 104. This movement results in a sudden increase in pressure in the second fluid cavity 120 that causes the check ball 122 to seat against the lower piston 104 and to close an opening 105 extending through the lower piston 104. With the opening 105 is closed, pressurized fluid is locked into the second fluid cavity 120 and the entire HLA 100 acts as a solid component so that the force from the rocker arm assembly 50 may be transferred through the HLA 100 to the valve 80 to move the valve 80 to the desired position.

[0030] Once the resistance from the valve 80 is remove, e.g., when the rocker arm assembly 50 pivots to a position that does not apply a force to the valve 80, the resistance force from the spring (not shown) on the valve 80 is removed and the pressure in the second fluid cavity 120 is released. The fluid in the second fluid cavity 120 leaks into the surrounding environment as the plunger 112 returns to a retracted position.

[0031] The rocker arm assembly 50 includes a latch assembly 150 for selectively latching or connecting a roller assembly 200 to the rocker arm 60. Referring to FIG. 4, the latch assembly 150, in general, includes a plug 152 that is movable in a bore 67 of the rocker arm 60 and a bore 202 of the roller assembly 200. In the embodiment illustrated in FIG. 4, the plug 152 moves within sleeves 67a, 202a in the rocker arm 60 and roller assembly 200, respectively. When in the deactivated position (shown in FIG. 4), the roller assembly 200 is unlatched from the rocker arm 60 such that pivoting of the rocker arm 60 about the rocker shaft (not shown) is independent or separate from the movement of the roller assembly 200 about the rocker shaft (not shown). In other words, the movement of the roller assembly 200 in the direction of arrow C is not coupled to the movement of the rocker arm 60 in the direction of arrow B. This uncoupling is also referred to as lost motion because the motion of the rocker arm 60 is not transmitted to the roller assembly 200, i.e., the motion of the rocker arm 60 is lost.

[0032] Referring to FIG. 5, when the latch assembly 150 is deactivated, i.e., the roller assembly 200 is uncoupled from the rocker arm 60. In this position, the valve lift of the valve 80 follows the solid line in FIG. 5.

[0033] Referring to FIG. 6, when the latch assembly 150 is activated, the plug 152 is partially within the bore 67 of the rocker arm 60 and the bore 202 of the roller assembly 200. In this position, the roller assembly 200 is coupled to the rocker arm 60 such that they move as a unitary body about rocker shaft (not shown). In other words, movement of the roller assembly 200 in the direction of arrow D is coupled to the movement of the rocker arm 60 in the direction of arrow E. Referring to FIG. 7, when the roller assembly 200 is latched to the rocker arm 60, the displacement of the valve 80 is controlled by the rocker arm 60 up to a transition point A. After the transition point A, the displacement of the valve 80 is controlled by the roller assembly 200.

[0034] Referring back to FIGS. 1 and 2, the roller assembly 200, in general, includes a second roller 204 that is disposed in a bracket 206 that is pivotally about the rocker shaft (not shown). A stopper or pin 208 extends through the bracket 206 and is configured to engage a seat 69 formed in the rocker arm 60. Retaining pins 212 (FIG. 2) may be provided for retaining the stopper 208 in the bracket 206.

[0035] A spring 214 is disposed in the bracket 206 for biasing the bracket 206 such that the stopper 208 engages the seat 69. In the embodiment illustrated, one end of the spring 214 engages a plate 216 attached to the rocker arm 60 and an opposite end of the spring 214 engages the bracket 206. Bolts 218 may be provided for securing the plate 216 to mounting arms 71 of the rocker arm 60.

[0036] During operation, when the latch assembly 150 is in the activated position (FIG. 6), the force applied by the spring on the valve 80 is resisted by the cam 70 via the latch assembly 150 because the latch assembly 150 makes the roller assembly 200 and the rocker arm 60 function as a single unitary body. The stopper 208 and the seat 69 on the rocker arm 60 are positioned such that in this position the plug 152 aligns with the bores 67, 202 in the rocker arm 60 and the roller assembly 200, respectively. When the latch assembly 150 moves to the deactivated position (FIG. 4), the spring 214 maintains pressure on the HLA 100. By maintaining this force, the high pressure created in the second fluid cavity 120 of the HLA 100 remains so that the latch applied by the HLA 100 may be applied for sequential cycles.

[0037] The stopper pin 208 is position so that movement of the roller assembly 200 stops at the same position the roller assembly 200 would stop if the latch assembly 150 was activated. When the latch assembly 150 is activated, the rocker arm 60 and the roller assembly 200 (acting as a single unified body) applies pressure to the HLA 100. When the latch assembly 150 is deactivated, the spring 214 maintains pressure on the HLA 100. By maintaining pressure on the HLA 100 the high pressure created in the second fluid cavity 120 of the HLA 100 remains so that the latch applied by the HLA 100 may be applied for sequential cycles.

[0038] The stopper 208, thereby provides an apparatus that hinders total leak down of the HLA 100. By hindering total leak down, the stopper 208 may allow the HLA 100 to be used for sequential cycles

[0039] It is contemplated that the stopper 208 may be a separate part that is added to the rocker arm 60, e.g., by threading, press fitting, welding, etc., or the stopper 208 may be a part integral with the rocker arm, e.g., attached during molding of the rocker arm or machined into a body of the rocker arm. In the embodiment illustrate, the stopper 208 is an elongated pin. It is contemplated that the stopper 208 may have other shapes such as tabs or protrusions that extend from the bracket 206 so long as they are positioned and dimensioned to engage the seat 69 of the rocker arm 60.

[0040] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.