WO2021110286A1

WO2021110286A1 - Rocker arm, reaction bar and valvetrain

Info

Publication number: WO2021110286A1
Application number: PCT/EP2020/025554
Authority: WO
Inventors: Mark VAN WINGERDEN
Original assignee: Eaton Intelligent Power Limited
Priority date: 2019-12-02
Filing date: 2020-12-01
Publication date: 2021-06-10

Abstract

A rocker arm can comprise a body panel comprising a reaction opening, a valve end and a pivot end. The reaction opening can comprise a first reaction seat and a second reaction seat. A first pivot can be positioned in the first reaction seat about which the first reaction seat can selectively rotate. A second pivot can be positioned movably in the reaction opening and can be configured to selectively abut the second reaction seat about which the second pivot can selectively rotate. A reaction bar can be positioned in the reaction opening. The reaction bar can be configured to press the first pivot against the first reaction seat. The reaction bar can be positioned to selectively press the second pivot against the second reaction seat.

Description

ROCKER ARM, REACTION BAR AND VALVETRAIN

Field

[001] A rocker arm for use in a valvetrain is disclosed with alternative reaction bars and alternative reaction seats about which the rocker arm rotates on alternative pivots.

Background

[002] A rocker arm can be formed with a single pivot location to transfer a lift profile from a rotating cam to one or more valves. It is desired to switch lift profiles transferred by the rotating cam, but this can require an additional cam lobe, additional rocker arm, or other duplication.

SUMMARY

[003] Instead of, or in addition to, duplicating the cam lobes and rocker arms to add variable valve lift to a valvetrain, it is possible to include more than one pivot and reaction seat in a rocker arm. Switching the reaction seat from one to the other allows a valvetrain to switch from a first lift profile to a second lift profile. While an engine braking technique is described, it is possible to alternatively use the disclosed rocker arm and valvetrain to switch between a nominal lift profile and an extended lift profile, such as late valve closing or early valve opening, among others. Or, it is possible to alternatively use the disclosed rocker arms for a hold- open technique such as an internal exhaust gas recirculation technique or a negative valve overlap technique, among others.

[004] A rocker arm can comprise a body panel comprising a reaction opening, a valve end and a pivot end. The reaction opening can comprise a first reaction seat and a second reaction seat. A first pivot can be positioned in the first reaction seat about which the first reaction seat can selectively rotate. A second pivot can be positioned movably in the reaction opening and can be configured to selectively abut the second reaction seat about which the second pivot can selectively rotate. A reaction bar can be positioned in the reaction opening. The reaction bar can be configured to press the first pivot against the first reaction seat. The reaction bar can be positioned to selectively press the second pivot against the second reaction seat. [005] The first pivot can be a first ball. The second pivot can be a second ball and the reaction bar can be configured with a spring-biased cup and a latch configured to selectively press the second pivot against the second reaction seat. The reaction bar can comprise a latch bore in a first tower, and the latch can be configured to reciprocate in the latch bore to selectively engage the spring-biased cup.

[006] The reaction opening can be configured to rotate about the reaction bar. The second pivot can be a movable pin and the reaction bar can be configured with a movable latch to selectively press the second pivot against the second reaction seat.

[007] The reaction bar can comprise a first tower and a second tower. The first tower can comprise the movable latch in a latch bore. The second tower can comprise a compliant knob in a bore. The movable latch can be configured to move the second pivot to catch in the bore. The compliant knob can be configured to push the second pivot out of the bore when the movable latch retracts into the latch bore.

[008] A valvetrain can comprise the rocker arm. The valvetrain can comprise a push tube coupled to lift and lower against the reaction end. When a lift force is applied to the reaction end, the body panel can rotate against the first pivot. When the body panel has rotated against the first pivot, the reaction bar can be configured to press the second pivot against the second reaction seat.

[009] A valvetrain can comprise the rocker arm with the valvetrain comprising a push tube coupled to lift and lower against the reaction end. When a lift force is applied to the reaction end, the body panel can be configured to rotate against the first ball. When the body panel has rotated against the first ball, the movable latch can be configured to engage the spring-biased cup and to press the second ball against the second reaction seat. When the movable latch is engaged with the spring-biased cup, the body panel can be configured to transfer the lift force from rotation of the first ball in the first reaction seat to rotation of the second ball against the second reaction seat.

[010] A valvetrain can comprise the rocker arm and a push tube coupled to lift and lower against the reaction end. When a lift force is applied to the reaction end, the body panel can be configured to rotate against the first ball. Wen the body panel has rotated against the first ball, the movable latch can be configured to push the second pivot to catch in the bore. When the movable latch pushes the second pivot to catch in the bore, the body panel can be configured to transfer the lift force from rotation of the first ball in the first reaction seat to rotation of the second pivot against the second reaction seat. [011] Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[012] Figure 1 is a view of a rocker arm at base circle of a nominal lift profile.

[013] Figure 2 is a view of a rocker arm at a maximum lift of a nominal lift profile.

[014] Figure 3 is a view of a rocker arm at a maximum lift with a second pivot moved to engage. As an example, a decompression lift profile can begin.

[015] Figure 4 is a view of a rocker arm at base circle of the exemplary decompression lift profile and with the valve held open.

[016] Figure 5 includes examples of nominal lift profiles and a comparative decompression lift profile. [017] Figures 6A-6C include a first alternative reaction bar arranged with a first rocker arm to form a first valvetrain.

[018] Figures 7A-7C include a second alternative reaction bar arranged with a second rocker arm to form a second valvetrain.

DETAILED DESCRIPTION [019] Reference will now be made in detail to the examples which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[020] A rocker arm can be configured to switch between a first lift profile and a second lift profile. A first lift profile can be accomplished by rotating the rocker arm around a first pivot. A second lift profile can be accomplished by switching to a second pivot location as by engaging a second pivot. By way of a working example, the rocker arm can be configured so that the second pivot is engaged after the rocker arm has rotated around the first pivot. The second pivot can cause an affiliated valve to be held open until the rocker arm rotates back to a position where the second pivot can be disengaged.

[021] A rocker arm 10 can comprise a body panel 13 comprising a reaction opening 14, a valve end 12 and a pivot end 11. The body panel 13 can comprise a sheet material that is stamped. The sheet material can be formed with a knurl for engaging a valve stem of an engine valve 22 on the valve end 12 and another knurl can be formed to engage a push tube 21 against the reaction end 11. A rotating cam can ride directly or indirectly against the push tube 21 and a lash adjuster such as a hydraulic or mechanical lash adjuster can be included.

[022] The body panel 13 can have an upper edge 18 and a lower edge 17 with the reaction opening 14 in-between. The reaction opening 14 comprises a first reaction seat 15 and a second reaction seat 16 that can be formed as grooves, dents, apertures, or sockets, among others. An insert can alternatively form the first and second reaction seats 15, 16. The insert can be seated in or on the reaction opening 14 and can comprise a shim, cup, stake, or brace, among others.

[023] A first pivot 31 can be positioned in the first reaction seat 15 to selectively rotate. In Figure 1, the rocker arm is on base circle of a nominal (normal or baseline) lift profile. A cam input to the push tube 21 can lift the rocker arm 10 as in Figure 2, which transfers to valve 22 to open a cylinder on a corresponding engine cylinder. A maximum lift profile is shown in Figure 2. A second pivot 32 can be positioned movably in the reaction opening 14 and can be configured to selectively abut the second reaction seat 16 to rotate. In Figure 3, both the first and the second pivot 31 , 32 are engaged against the reaction opening 14. This can be the beginning of a decompression lift profile, which is done while the rocker arm is at the maximum lift. Now, when the cam input to the push tube 21 returns to base circle, the rocker arm 10 reacts against second reaction seat 16. When the cam input acts on push tube 21 , the lift profile and rocker arm 10 reaction is different from the nominal lift profile. The valve 22 is held open and a decompression event occurs on valve 22 while the second pivot 32 is engaged against the second reaction seat 16. A decompression engine braking function can be achieved, among other variable valve actuation techniques. [024] Figure 5 illustrates the differences in lift profiles another way. The nominal (normal or baseline) lift profiles, where the first pivot 31 is engaged against the first reaction seat 15 can be seen relative to a lifting and lowering piston. The intake and exhaust (drive) lift profiles are contrasted against the decompression lift profile. The decompression lift profile overlaps slightly with the exhaust (drive) lift profile because the two pivots 15, 16 are engaged for a portion of the rocker arm motion. When the second pivot 16 is engaged, the valve lift does not return to zero, meaning that valve does not close until the second pivot 16 disengages.

[025] Figures 1 -4 omit the actuation mechanisms in favor of the clarity in rocker arm motion against the first and second pivots 15, 16. Figures 6A-6C show a first actuation mechanism and Figures 7A-7C show another actuation mechanism.

In Figure 6A, the rocker arm 10 includes a reaction bar 40 positioned in the reaction opening 14. The reaction opening 14 is configured to rotate about the reaction bar 40. The reaction bar 40 is configured with a pivot location 47 to press the first pivot 31 against the first reaction seat 15, as shown in Figure 6B. The first pivot 31 can be a ball, a hollow or solid shaft or other structure about which a rotation force can be enacted. Figure 6B shows that reaction bar 40 comprises a first tower that is secured on a first side 44 to a portion of engine block or cylinder head 55 by a bolt or pin or other securement 41 through a riser 48. A body portion 46 protrudes through reaction opening 14 so that a second side 45 of first tower protrudes through or aligns flush with body panel 13. Body portion 46 includes the pivot location 47, such as a cup, groove, dent, aperture, socket or the like to position first ball 31 relative to first reaction seat 15.

[026] In Figure 6C, the reaction bar 40 is positioned to selectively press the second pivot 32 against the second reaction seat 16. First and second pivots 31 , 32 can be a ball or shaft or other structure configured to enable rotation or pivoting of the rocker arm 10. The reaction bar 40 is configured with a spring-biased cup 50 in a pocket 71 or body portion 45. A spring 60 can be seated against a spring seat 72 such as a groove, pin, or other guide. Spring 60 can bias the cup 50 in a direction that secures the second pivot 32 against the second latch seat 16. Flowever, the spring force of spring 60 can be light enough that the rocker arm motion, when the lift forces are applied and the latch is selectively unlatched, moves the cup 50 in the pocket 71. Cup 50 can be configured with a rotation surface 51 such as a groove, dent, socket or the like. A latch slot 52 can also be included as a rim, groove, notch or the like. A latch 82 comprising a latch nose 81 can be configured to engage with the latch slot 52. Then, when the latch is selectively engaged and when the rocker arm 10 receives lift forces, the cup cannot move in the pocket 71 as it is locked relative to the pocket and first tower. The rocker arm 10 reacts against second pivot 32 while the latch 82 and cup 50 selectively press the second pivot 32 against the second reaction seat 16.

[027] The latch 82 can comprise a variety of alternatives for actuation, with an actuator 100 and actuation line 101 generally shown. Actuator can comprise or be linked to an onboard controller such as an onboard computer programmed with corresponding stored programming for selecting the latch position as latched or unlatched. As one example, latch 82 can reciprocate in latch bore 73 when hydraulic pressure is applied via a supply line from an oil control valve. Or, an armature can be linked to the latch and the armature can be actuated by an electrical control pulse to a solenoid around the armature. Or, a mechanical switching device, such as a spring, can be linked to the latch and pushed and pulled. So, the reaction bar 40 can comprise a latch bore 73 in a first tower, and the latch 82 can be configured to reciprocate in the latch bore 73 to selectively engage the spring-biased cup 50. Numerous alternatives exist and are compatible with the latch 82 herein.

[028] Figures 7A-7C shown an alternative for the reaction opening 114 to be configured to rotate about the reaction bar 400. In Figure 7A, the rocker arm 102 is shown with a reaction bar 400 positioned in the reaction opening 114 to form another exemplary portion of a valvetrain. The reaction bar is 400 configured to press the first pivot 31 against the first reaction seat 161. At this cross-section, the reaction bar 400 is similarly positioned for the reaction opening 114 to rotate about the reaction bar 400. A body portion 46 of the first tower 401 can protrude through the reaction opening 114 with a pivot location 47 and other features similar to Figure 6B, incorporated herein from above. A pin, bolt or other securement 141 , 142 through riser 430 can secure the first side of first tower 401 to the cylinder head 55 of the engine block. A second side 450 of first tower can abut the second tower 402. A butt coupling or other arrangement can brace the first tower 401 against the second tower 402. Second tower 402 can be secured to the cylinder head 55 via second pins, bolts or securements 143, 144.

[029] Reaction bar 400 can be positioned to selectively press the second pivot 92 against the second reaction seat 116. In this example, the body panel 113 comprises a solid material that includes bore for the reaction opening 114. The body panel 113 rotates or pivots between the first and second towers 401 , 402 at this cross-section. The second side 450 of the first tower and inboard side 420 of the second tower 402 guide the body panel 113 when the rocker arm 102 moves.

[030] The second pivot 92 is a movable pin and the reaction bar 400 is configured with a movable latch 91 to selectively press the second pivot 92 against the second reaction seat 116. In this example, pressing the second pivot 92 against the second reaction seat 116 can additional comprise the second pivot 92 pressing against either the latch bore 491 or the knob bore 493. The second pivot 92 can be slide into the knob bore 493 or into the latch bore 491 , depending upon the control technique used for the latch 91. When a lift profile is applied to the rocker arm 102 in this latched condition, the rocker arm 102 is re-directed by the second pivot 92. The second pivot 92 cannot travel with the rocker 102 as it does when the latch 91 is unlatched. The actuator 100 can be similar to the above actuator with actuation line 101. Latch 91 can be moved backwards so that compliant knob 93 and compliant spring 94 push the second pivot 92 into the latch bore 491. Or, the latch 91 can be configured and controlled so that latch 91 pushes the second pivot 92 into knob bore 493 and overcomes compliant spring 94. Spring force of compliant spring 94 and counterforces to latch 91 can be chosen to balance the position of the second pivot 92 during the nominal lift profile.

[031] The reaction bar 400 comprising first tower 401 and a second tower 402 can comprise the movable latch 91 in a latch bore 491. The second tower 402 can comprise a compliant knob 93 in a knob bore 493. The movable latch 91 can be configured to move the second pivot 92 to catch in the latch bore 491. The compliant knob 93 can be configured to push the second pivot 92 out of the knob bore 493 when the movable latch 91 retracts into the latch bore 491. The latch 91 and the compliant knob 93 can be configured with chamfers or other edging to encourage the return of the second pivot 92 to the unlatched position. The chamfers or other edging can be selected to encourage the rocker arm 102 motion relative to the first and second towers 401 , 402.

[032] A valvetrain can comprise a rocker arm 10, 102. The valvetrain can comprise a push tube 21 coupled to lift and lower against the reaction end 11, 111. When a lift force is applied to the reaction end 11, 111 , the body panel 13, 113 can rotate against the first pivot 31. When the body panel 13, 113 has rotated against the first pivot 31 , the reaction bar 40, 400 can be configured to press the second pivot 32, 92 against the second reaction seat 16, 116.

[033] A valvetrain can comprise a rocker arm 10. A push tube 21 can be coupled to lift and lower a valve 22, with the push tube 21 coupled against the reaction end 11. When a lift force is applied to the reaction end 11 , the body panel 13 can rotate against the first ball 31. When the body panel 13, 113 has rotated against the first ball 31, the movable latch 82 can be configured to engage the spring-biased cup 50 and to press the second ball 32 against the second reaction seat 16. When the movable latch 82 is engaged with the spring-biased cup 50, the body panel 13 can be configured to transfer the lift force from the push tube 21 for rotation of the first ball 31 in the first reaction seat 15 to rotation of the second ball 32 against the second reaction seat 16.

[034] A valvetrain can comprise a rocker arm 102. A push tube 21 can be coupled to lift and lower a valve 22, with the push tube 21 coupled against the reaction end 111. When a lift force is applied to the reaction end 111 , the body panel 113 can rotate against the first ball 31. When the body panel 113 has rotated against the first ball 31, the movable latch 91 can be configured to push the second pivot 92 to catch in either the latch bore 491 or the knob bore 493. When the movable latch 91 pushes the second pivot 92 to catch in the latch bore 491 or the knob bore 493, the body panel 113 is configured to transfer the lift force from the push tube 21 so that the rocker arm rotation of the first ball 31 in the first reaction seat 115 transfers to rotation of the second pivot 92 against the second reaction seat 116.

[035] Other implementations will be apparent to those skilled in the art from consideration of the specification and practice of the examples disclosed herein.

Claims

WHAT IS CLAIMED IS:

1. A rocker arm, comprising: a body panel comprising a reaction opening, a valve end and a pivot end, the reaction opening comprising a first reaction seat and a second reaction seat; a first pivot positioned in the first reaction seat to selectively rotate; a second pivot positioned movably in the reaction opening and configured to selectively abut the second reaction seat to rotate; and a reaction bar positioned in the reaction opening, the reaction bar configured to press the first pivot against the first reaction seat, and the reaction bar positioned to selectively press the second pivot against the second reaction seat.

2. The rocker arm of claim 1 , wherein the first pivot is a first ball.

3. The rocker arm of claim 2, wherein the second pivot is a second ball and the reaction bar is configured with a spring-biased cup and a latch configured to selectively press the second pivot against the second reaction seat.

4. The rocker arm of claim 3, wherein the reaction bar comprises a latch bore in a first tower, and wherein the latch is configured to reciprocate in the latch bore to selectively engage the spring-biased cup.

5. The rocker arm of claim 1 , wherein the reaction opening is configured to rotate about the reaction bar.

6. The rocker arm of claim 2, wherein the second pivot is a movable pin and the reaction bar is configured with a movable latch to selectively press the second pivot against the second reaction seat.

7. The rocker arm of claim 6, wherein the reaction bar comprises a first tower and a second tower.

8. The rocker arm of claim 7, wherein the first tower comprises the movable latch in a latch bore, wherein the second tower comprises a compliant knob in a bore, and wherein the movable latch is configured to move the second pivot to catch in the bore.

9. The rocker arm of claim 7, wherein the compliant knob is configured to push the second pivot out of the bore when the movable latch retracts into the latch bore.

10. A valvetrain comprising the rocker arm of claim 1 , the valvetrain comprising a push tube coupled to lift and lower against the reaction end, and when a lift force is applied to the reaction end, the body panel rotates against the first pivot.

11. The valvetrain of claim 10, wherein, when the body panel has rotated against the first pivot, the reaction bar is configured to press the second pivot against the second reaction seat.

12. A valvetrain comprising the rocker arm of claim 4, the valvetrain comprising a push tube coupled to lift and lower against the reaction end, and when a lift force is applied to the reaction end, the body panel rotates against the first ball, and when the body panel has rotated against the first ball, the movable latch is configured to engage the spring-biased cup and to press the second ball against the second reaction seat.

13. The valvetrain of claim 12, wherein, when the movable latch is engaged with the spring-biased cup, the body panel is configured to transfer the lift force from rotation of the first ball in the first reaction seat to rotation of the second ball against the second reaction seat.

14. A valvetrain comprising the rocker arm of claim 8, the valvetrain comprising a push tube coupled to lift and lower against the reaction end, and when a lift force is applied to the reaction end, the body panel rotates against the first ball, and when the body panel has rotated against the first ball, the movable latch is configured to push the second pivot to catch in the bore.

15. The valvetrain of claim 14, wherein, when the movable latch pushes the second pivot to catch in the bore, the body panel is configured to transfer the lift force from rotation of the first ball in the first reaction seat to rotation of the second pivot against the second reaction seat.