Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
  • F01L1/181—Centre pivot rocking arms
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/02—Valve drive
  • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/20—Adjusting or compensating clearance
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/20—Adjusting or compensating clearance
  • F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/0005—Deactivating valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
  • F01L2001/186—Split rocking arms, e.g. rocker arms having two articulated parts and means for varying the relative position of these parts or for selectively connecting the parts to move in unison
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L2305/00—Valve arrangements comprising rollers

Definitions

• the present invention relates to valve trains for internal combustion engines.
• the present invention relates to a split rocker arm arrangement for use in a valve train for internal combustion engines comprising a lash adjustment screw having a cam at one end which, when rotated, changes the angular orientation of two parts of a split rocker arm.
• the present invention provides an arrangement that allows the amount of transverse motion of the latch pin within the receiving latch pin bore to be controlled such that it ensures deactivating mechanism function and as well significantly reduces the noise generated by the impact in part of moving parts thereby reducing valve train NVH (noise, vibration, and harshness) and as well improving engine valve durability.
• NVH noise, vibration, and harshness
• the present invention is directed to an improved split rocker arm having a valve deactivation device for a valve train which provides for adjustment of mechanical lash.
• the first section and the second section of the split rocker arm comprise an adjustment system that includes a cam positioned between said sections, said cam which, when rotated, changes the angular orientation of said first section and said second section of said split rocker arm, thereby controlling the lateral clearance between the latch pin in said first section and a receiving latch pin hole in said second section to permit free movement of the latch pin which, when engaged, opens and engine valve in response to the valvetrain camshaft, and which, when disengaged, permits one section of the rocker arm to rotate in response to the valvetrain camshaft without opening the engine valve.
• the system of the invention locates the cam follower section relative to the valve actuator section such that the latch pin is free to move in and out of the receiving latch pin bore without contacting it while at the same time limiting the amount of transverse movement of the latch pin within the receiving latch pin bore.
• the opening and closing ramp portions of the cam profile are followed, ensuring proper engine valve motion, and thereby reducing the amplitude of the sound of impact of the engine valve against the valve seat, and to a lesser degree, the latch pin against the receiving latch pin bore, thereby improving valve train NVH (noise, vibration and harshness) and improving engine valve durability.
• the present invention reduces manufactured cost in that the rocker arm assemblies may be either manually or robotically adjusted to provide a specified amount of lateral clearance, or mechanical lash, between the latch pin and the receiving latch pin bore.
• the range of variation of mechanical lash is more economically controlled to a tighter tolerance thereby reducing NVH and wear and in addition may optionally be adjusted during the service life of the engine.
• FIG. 1 is a perspective view of a rocker arm assembly that includes a valve deactivation device in accordance with the present invention.
• FIG.2 is a rear perspective view of a rocker arm assembly of FIG. 1.
• FlG. 3 is a side view of the rocker arm assembly of FIG. 2.
• FTG. 4 is a sectional view taken along line 4-4 of FIG. 3 illustrating the valve deactivation device in accordance with the present invention in a valve activated condition.
• FlG. 5 is a detail view within circle 5 of FIG. 4 illustrating the eccentricity of the lash adjustment screw cam and the clearance, or mechanical lash, between the cam follower and valve actuator sections of the rocker arm.
• FlG. 6 is a perspective view of the lash adjustment screw illustrating the eccentricity of the cam portion relative to the threaded portion.
• FIG. 7 is an end view of the lash adjustment screw illustrating the eccentricity of the cam portion relative to the threaded portion.
• cam follower and valve actuator sections of a valve deactivating rocker arm assembly are mounted on a rocker shaft for free rotation about the shaft.
• the invention is devised to locate the cam follower section relative to the valve actuator section such that the latch pin of the rocker arm deactivating mechanism in one section is free to move in and out of the receiving latch pin bore in the other section without contacting the receiving latch pin bore.
• This construction allows the amount of transverse motion of the latch pin within the receiving latch pin bore to be controlled such that the opening and closing ramp portions of the cam profile are followed, ensuring proper engine valve motion.
• the invention significantly reduces the amplitude of the sound of impact of the engine valve against the valve seat, and to a lesser degree, the latch pin against the receiving latch pin bore, thereby reducing valve train NVH (noise, vibration and harshness) and improving engine valve durability.
• a lash adjustment pin preferably a threaded pin, screw having a cam at one end is provided which, when rotated, changes the angular orientation of two sections of the valve deactivating rocker arm assembly. It is necessary to control their rotational orientation to each other to ensure free movement of a latch pin which, when engaged, couples the two parts to open an engine valve in response to the valvetrain camshaft, and when disengaged, permits one part of the rocker arm to rotate in response to the valvetrain camshaft, but without opening the engine valve. Control of the two parts' rotational orientation to each other is essential to controlling lash within the valvetrain system to ensure consistent valvetrain operation.
• rocker arm assembly 10 includes a cam follower section 12 having a valve actuator section 14 journaled therein, a cam follower section retaining clip 16, a spring retaining clip 18, and a lost motion spring 20.
• Cam follower section 12 includes a tubular cam follower body portion 30 having an arm portion 32 and a deactivation device, or deactivation portion 34 extending therefrom.
• Arm portion 32 includes a cam spring pin 36 extending therefrom, a bifurcated end 38 having a roller 40 rotatably coupled thereto via a roller axle 42.
• Roller axle 42 is interposed through both the bifurcated end 38 and the roller 40.
• Valve actuator section 14 includes a tubular valve body portion 44 having an arm portion 46 extending therefrom.
• Arm portion 46 includes a proximal end 48 attached to valve body portion 44 and a distal end 50 having a valve contacting portion 52 attached thereto. Arm portion 46 further includes a lash adjustment screw 22 extending therefrom, a latch pin aperture 120 (FIGS. 4 and 5) formed therein, and a latch pin sliding surface 58 (FIG. 2).
• Cam follower body portion 30 is a hollow elongated cylinder that includes a first annular end 60, a second annular end 62 (FIG. 2), a generally cylindrical cam follower section inner surface (not shown), and a cylindrical cam follower section outer surface 66.
• deactivation portion 34 including a latch pin 72 is at least partially housed within body 68 and positioned so as to be in engagement with a return spring 74.
• Deactivation portion 44 includes a return spring 74 and a cap 76 secured to end 70.
• Cap 76 closes off body 68 and provides a surface for return spring 74 to react against.
• end 70 may be provided with mounting shoulders for return spring 74 to act against, thereby eliminating the need for cap 76.
• valve body portion 44 is a hollow elongated cylinder that includes a first annular end 80 (FIG. 2), a second annular end 82 (FIG. 1), a generally cylindrical valve actuation section inside surface 84, and a generally cylindrical valve actuation section outside surface 86.
• Valve body portion 44 also includes a pair of annular retaining grooves 88 formed in valve actuation section outside surface 86, adjacent the first annular end 80 and the second annular end 82, respectively.
• Valve contacting portion 52 includes a surface which slideably contacts the tip of a valve (not shown) for operation thereof.
• lost motion spring 20 is mounted on second annular end 82 of valve body portion 44.
• tost motion spring 20 includes a curved body 98 that defines an arcuate section. Curved body 98 has an open section 100 flanked by lash adjustment screw end 102 and a cam pin end 104.
• the lost motion spring may comprise a helical form (not shown) whereby lost motion spring hook 102 attaches to surface 28 (FIG. 6) of lash adjustment screw 22 and lost motion spring hook 104 attaches to a pin that would be coaxial with pin 36 but located on the other side of the cam follower section.
• lost motion spring 20 is superposed around second annular end 82 (FIG. 2). Lash adjustment screw end 102 of lost motion spring 20 is coupled to surface 28 of lash adjustment screw 22 and cam pin end 104 is coupled to cam spring pin 36. Lost motion spring 20 selectively biases cam spring pin 36 away from surface 28 of lash adjustment screw 22.
• lost motion spring 20 is a partial coil spring with at least a portion thereof curved about valve actuation section outside surface 86.
• lost motion spring 40 extends less than 360" about valve actuation section outside surface 86.
• the cam follower section retaining clip 16 is inserted into a retaining groove 88, limiting lateral clearance between valve actuator section 14 and cam follower section 12.
• the spring retaining clip 18 is inserted into retaining groove 88 to retain lost motion spring 20 on valve body portion 44.
• latch pin 72 is positioned within tubular body
• Latch pin 72 is moveable between an activated position (FIGS. 4 and 5) and a deactivated position (not shown).
• cam follower section 12 rotates about the axis of valve body portion 44 and valve actuation section 14 does not rotate. Since valve actuation section 14 does not rotate, the valve is not operated and is effectively shut down. With relative rotation of cam follower section 12 about valve actuation section 14, lost motion spring 20 is deflected, thereby storing energy and inducing a relative torsion between valve actuation section 14 and cam follower section 12. This torsion urges roller 40 to generally stay in contact with the camshaft.
• valve actuation section 14 When latch pin 72 contacts latch pin sliding surface 58, valve actuation section 14 will not rotate and lost motion spring 20 urges cam follower section 12 to rotate as the camshaft rotates. As cam follower section 12 rotates and valve actuation section 14 does not rotate latch pin 72 in contact with latch pin sliding surface 58, it follows a generally circular arc. As the camshaft rotates further, latch pin 72 will align with and engage cylindrical pin surface 120, thereby placing rocker arm assembly 10 in an activated condition. Thus, latch pin 72 is selectively guided into engagement with said cylindrical pin surface 120 within arm portion 46 by the relative rotation of cam follower section 12 and valve actuation section 14.
• a lash adjustment screw 22 which has a cam 24 and a feature 54 by which the pin can be rotated using a tool to adjust the lateral clearance or mechanical lash (FIG. 5) between the latch pin 72 and the cylindrical pin surface 120 within arm portion 46.
• the lash adjustment screw 22 is installed into a mating threaded hole in valve actuator section 14 wherein the cam end 24 of the lash adjustment screw 22 engages a stop feature 64 of the cam follower section 12.
• cam 24 is such that the rotational orientation of the valve actuator and cam follower sections is varied and in turn varies the lateral clearance or mechanical lash between the cam follower section latch pin 72 and the cylindrical pin surface 120 within arm portion 46.
• the lash adjustment screw 22 is rotated until a previously specified mechanical lash is obtained.
• a jam nut 56 is tightened on a portion of the threads 26 of the lash adjustment screw 22 to prevent rotation of the lash adjustment screw 22.
• the lash adjustment screw 22 provides the valve actuator section feature 28 upon which the lost motion spring 20 is mounted.
• valvelrain component design may be used to control the rotational orientation of the cam 24 to adjust the mechanical lash of the deactivating rocker arm assembly 10.
• the cam could be mounted on a shaft which, following adjustment, is secured from rotating by welding or bonding or mechanical means.
• the cam could be shouldered within a recess within one rocker arm section and, following adjustment, is secured from rotating by welding or bonding or mechanical means.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Valve Device For Special Equipments (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39938669

Family Applications (1)

Country Status (5)

Families Citing this family (10)

Family Cites Families (5)

• 2007
  • 2007-05-02 US US11/743,212 patent/US20080271693A1/en not_active Abandoned
• 2008
  • 2008-05-01 WO PCT/US2008/062152 patent/WO2008137503A1/en active Application Filing
  • 2008-05-01 EP EP08769258A patent/EP2142765A1/de not_active Withdrawn
  • 2008-05-01 KR KR1020087016655A patent/KR20100024331A/ko not_active Application Discontinuation
  • 2008-05-01 JP JP2010506628A patent/JP2010526238A/ja active Pending

Non-Patent Citations (1)

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