US20160146074A1 - Engine brake lash adjuster device and method - Google Patents
Engine brake lash adjuster device and method Download PDFInfo
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- US20160146074A1 US20160146074A1 US14/898,026 US201414898026A US2016146074A1 US 20160146074 A1 US20160146074 A1 US 20160146074A1 US 201414898026 A US201414898026 A US 201414898026A US 2016146074 A1 US2016146074 A1 US 2016146074A1
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- Prior art keywords
- rocker arm
- engine
- lash
- valve
- cylinder
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Classifications
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- 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
- F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking
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- 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
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- 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
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- 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
- F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
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- 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
- F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking
- F01L13/065—Compression release engine retarders of the "Jacobs Manufacturing" type
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- F01L9/04—
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- 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
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
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- F01L2009/0403—
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- 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
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
- F01L9/21—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by solenoids
- F01L2009/2103—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by solenoids comprising one coil
Definitions
- This disclosure relates to an exhaust valve actuation mechanism in an internal combustion engine and an engine brake lash adjuster device associated with the exhaust valve actuation mechanism.
- Engine brakes or engine compression brakes take advantage of the compression and expansion of gases in an engine cylinder to induce a resistance to movement of a piston in the engine cylinder by opening and closing valves associated with the piston at appropriate times.
- conventional systems use various unique components and require certain precise tolerances.
- FIG. 1 is a view of an engine brake lash adjuster device in accordance with an exemplary embodiment of the present disclosure.
- FIG. 2 is a view of the engine brake lash adjuster device of FIG. 1 in a position to actuate an exhaust valve.
- FIG. 3 is a view of the engine brake lash adjuster device of FIG. 1 with a compression brake actuated.
- a compression brake includes a rocker arm pivotable about a rocker arm shaft to selectively force an exhaust valve to an open condition.
- the rocker arm has a lower position, an upper position, and a plurality of positions intermediate the lower and upper positions.
- the brake further includes a lash member coupled to the rocker arm.
- the lash member is configurable to define a plurality of positions relative to the rocker arm.
- the lash member has a first position that forces opening of the valve when the rocker arm is at the lower position.
- the brake also includes a lost motion cylinder at least partially defined within the rocker arm. The cylinder is biased towards a position of greatest internal displacement volume.
- the lost motion cylinder has a first operational mode wherein the lost motion cylinder permits compression thereof such that the ability of the rocker arm to open an exhaust valve is a function of the position of the lash member.
- the lost motion cylinder has a second operational mode wherein the lost motion cylinder retards compression thereof such that the ability of the rocker arm to open an exhaust valve is independent of the position of the lash member.
- a compression brake mechanism including: a rocker arm operable to selectively engage an engine valve; a lash member having a plurality of settings that define lash between rocker arm movement and engine valve movement; and a lost motion mechanism disposed between the lash member and the engine valve; the lost motion mechanism having a first operational mode and a second operational mode, the first operational mode providing an ability to open an engine valve as a function of the lash member setting, the second operational mode providing an ability to open an engine valve independent of the lash member setting.
- a method of operating an exhaust valve on an internal combustion engine including: providing a lost motion cylinder at least partially within a rocker arm operable to open the exhaust valve; providing a lash member to define a maximum travel of a piston of the cylinder that defines a first internal volume of the cylinder; providing a seal valve within the rocker arm to selectively seal and open the internal volume of the cylinder; closing the seal valve when the internal volume of the cylinder is a second internal volume that is greater than a the first volume defined by the lash member thereby sealing fluid within the cylinder; rotating the rocker arm with the seal valve closed to force open the exhaust valve; and opening the seal valve to release fluid from the cylinder; and rotating the rocker arm with the seal valve open such that the cylinder assumes the first internal volume to force open the exhaust valve.
- a method of adjusting lash between an exhaust valve and a rocker arm on an operating internal combustion engine including: providing a rocker arm having a first lash member defining a first lash amount between the rocker arm and the exhaust valve, the first lash amount defining a first point during downward travel of the rocker arm at which the exhaust valve is opened; providing a lash variance member defining a second lash amount between the rocker arm and the exhaust valve that is smaller than the first lash amount, the second last amount defining a second point in the downward travel of the rocker arm at which the exhaust valve is opened, the second point being higher than the first point; and toggling between the first and second lash amounts within a cycle of the engine.
- Engine 10 includes an engine brake or engine compression brake, which provides the ability to retard movement of a crankshaft (note shown) of engine 10 when actuated.
- Engine compression brakes provide a valuable capability in a variety of situations where a friction brake, such as might be found in conjunction with a vehicle wheel, could easily overheat or rapidly wear out. Such situations include high loads and steep hills. While engine compression brakes provide a valuable capability, they are expensive and complex, requiring additional components and precise component tolerances.
- the engine brake of the present disclosure includes an exhaust valve actuation mechanism with a lash adjuster device or mechanism that provides the ability to reduce the number of components associated with an engine compression brake and the ability to reduce the tolerances of certain components associated with the engine compression brake disclosed in U.S. Pat. No. 6,253,730, the entire contents of which are hereby incorporated by reference.
- Engine 10 includes a rocker arm assembly 12 having a rocker arm body 14 , an exhaust valve 16 moved by the action of rocker arm assembly 12 , a control shaft 18 that extends through rocker arm body 14 , a rotatable camshaft 20 , and an engine body 22 .
- the function of rocker arm assembly 12 is to control or actuate exhaust valve 16 .
- rocker arm assembly 12 is part of an exhaust valve actuation mechanism.
- Rocker arm assembly 12 includes a reset valve 24 , a lash adjuster device 26 , a compression brake or engine brake hydraulic cylinder or piston 28 , and a bearing 30 .
- Reset valve 24 includes a reset pin 32 , a detent pin 34 , and a reset member or ball 36 , each of which is positioned at least partially within a reset valve cavity 38 formed in rocker arm body 14 .
- Reset valve cavity 38 includes a reset valve seat 86 that provides a mating surface for reset ball 36 when reset valve 24 is actuated.
- Reset valve 24 may also include a bias spring 40 and a bias spring cup 42 positioned between bias spring 40 and reset ball 36 . Bias spring 40 and bias spring cup 42 bias reset ball 36 toward a proximate end of reset in 32 , contacting reset pin 32 during normal or non-compression braking operation of engine 10 .
- Reset valve 24 functions to cause the opening and closing of exhaust valve 16 at a time that is independent of the position of lash adjuster device 26 , explained further hereinbelow.
- Lash adjuster device 26 includes a distal end 84 and a threaded exterior surface 74 .
- Engine brake piston 28 is positioned in a body cavity 44 formed in rocker arm body 14 and having a body cavity longitudinal axis 46 .
- Engine brake piston 28 includes a portion 48 having a spherical shape on which is positioned a piston shoe 50 having a mating spherical shape and a shoe contact surface 52 , which contacts a proximate end 54 of exhaust valve 16 .
- Shoe contact surface 52 may be a planar surface and proximate end 54 mates with the planar surface of shoe contact surface 52 .
- Engine brake piston 28 includes an interior surface 56 that forms a piston cavity 58 .
- Interior surface 56 includes an interior distal surface 70 that extends in a direction that is at an angle to body cavity longitudinal axis 46 that may be 90 degrees.
- a piston bias spring 80 is positioned between rocker arm body 14 and interior distal surface 70 and functions to bias engine brake piston 28 toward piston shoe 50 and thus biases piston shoe 50 into contact with exhaust valve 16 , which is biased into the position shown in FIG. 1 by an exhaust valve spring (not shown).
- Lash adjuster device 26 extends along body cavity longitudinal axis 46 through a threaded passage 60 formed in rocker arm body 14 into body cavity 44 and then into piston cavity 58 . Lash adjuster device 26 is adjustable along body cavity longitudinal axis 46 and is secured in position with a jam nut or locking nut 62 .
- lash adjuster device 28 functions to actuate exhaust valve 16 during normal operation of engine 10 .
- Bearing 30 is positioned on rocker arm body 14 and contacts camshaft 20 . During operation of engine 10 , camshaft 20 rotates, causing pivotal oscillating motion of rocker arm assembly 12 about control shaft 18 .
- Control shaft 18 includes a control shaft oil passage 64 , which connects with a first rocker arm oil passage 66 formed in rocker arm body 14 that fluidly connects to reset valve cavity 38 .
- Rocker arm body 14 further includes a second rocker arm oil passage 68 that extends between reset valve cavity 38 and body cavity 44 , fluidly connecting reset valve cavity 38 to body cavity 44 .
- An engine oil pump (not shown) that provides oil pressure for various engine functions, such as lubrication, also provides pressure to the oil that flows into control shaft oil passage 64 , which then flows into first rocker arm body oil passage 66 .
- control shaft oil passage 64 and first rocker arm body oil passage 66 provides lubrication to the various components fluidly connected to control shaft oil passage 64 and rocker arm body oil passage 66 .
- These passages provide a control function to certain components of rocker arm assembly during engine compression braking, described further hereinbelow.
- lash adjuster device 26 The longitudinal position of lash adjuster device 26 is set daring assembly of engine 10 , and because of the ability to identify the distance exhaust valve 16 needs to open empirically, setting the lash is easily accomplished through an automated process.
- rocker arm assembly 12 With rocker arm assembly 12 in the position shown in FIG. 1 , and with jam nut 62 in a position to permit movement of lash adjuster device 26 , lash adjuster device 26 is driven or moved longitudinally downward toward interior distal surface 70 of engine brake piston 28 .
- the drive torque to move lash adjuster device 26 increases non-linearly, which indicates that lash adjuster device 26 has contacted interior distal surface 70 of engine brake piston 28 .
- lash adjuster device 26 is moved longitudinally away from interior distal surface 70 of engine brake piston 28 by a predetermined amount. Once movement of lash adjuster device 26 by the predetermined amount has been accomplished, jam nut 62 is secured against a jam nut contact surface 72 of rocker arm body 14 to lock lash adjuster device 26 in a fixed position.
- lash adjuster device 26 includes exterior threaded surface 74 that mates with a similar thread formed in threaded passage 60 of rocker arm body 14 , and longitudinal movement of lash adjuster device 26 is accomplished by rotating lash adjuster device 26 about body cavity longitudinal axis 46 , which moves lash adjuster device 26 longitudinally along body cavity longitudinal axis 46 .
- the ability to set the position of lash adjuster device 26 which determines when exhaust valve 16 is actuated, reduces the tolerances that would otherwise be required in the fabrication of rocker arm body 14 .
- Camshaft 20 includes a cam profile 76 that causes oscillating pivotal motion of rocker arm assembly 12 about control shaft 18 .
- cam profile 76 of camshaft 20 is shown as having only one lift event per revolution of camshaft 20 . It should be understood that camshaft 20 can have any number of lift events to achieve various performance conditions, which includes control of exhaust emissions.
- Reset pin 32 includes a recess, undercut, or engaging feature 78 , that is engaged by detent pin 34 during normal operation of engine 10 .
- detent pin 34 The position of detent pin 34 is maintained by a bias spring mechanism (not shown), until a solenoid or other actuation mechanism (not shown) moves detent pin 34 to a position where detent pin 34 disengages from reset pin 32 , which permits reset pin 32 to move toward a contact pad 80 formed on engine body 22 , as shown in FIG. 3 , which permits reset valve 24 to close, described further hereinbelow.
- rocker arm assembly 12 rotates in a counterclockwise direction through contact of bearing 30 with cam profile 76 , as shown in FIG. 2 , engine brake piston 28 compresses piston bias spring 82 until interior distal surface 72 of engine brake piston 28 contacts lash adjuster device 26 .
- This actuation of exhaust valve 16 is sometimes called lost motion. Further counterclockwise motion of rocker arm assembly 12 moves exhaust valve 16 , causing exhaust valve 16 to open, which permits exhaust gases to escape from engine body 22 in a known manner.
- Cam profile 76 of camshaft 20 is configured to provide for rapid movement of lash adjuster device 26 toward interior distal surface 70 of engine brake piston 28 until distal end 84 of lash adjuster device 26 approaches interior distal surface 70 of engine brake piston 28 , at which point cam profile 76 provides a decreased velocity of lash adjuster device 26 to minimize the impact of lash adjuster device 26 with interior distal surface 70 of engine brake piston 28 . By reducing the impact, the life and reliability of lash adjuster device 26 and engine brake piston 28 are extended.
- detent pin 34 When the engine brake function is engaged, as shown in FIG. 3 , detent pin 34 is moved to disengage from engaging feature 78 , permitting reset pin 32 to move longitudinally toward contact pad 80 of engine body 22 . Oil pressure present in rocker arm oil passage 66 and reset valve cavity 38 forces reset pin 32 longitudinally toward contact pad 80 , which permits reset valve ball 36 to move toward and contact reset valve seat 86 by the action of bias spring 40 , trapping oil in second rocker arm oil passage 68 and in body cavity 44 .
- engine brake piston 28 With oil trapped in second rocker arm oil passage 68 and body cavity 44 , engine brake piston 28 is unable to move as rocker arm assembly 12 moves in a counterclockwise direction, because engine brake piston 28 is unable to compress the trapped oil, and thus movement of rocker arm assembly 12 causes engine brake piston 28 to move exhaust valve 16 sooner than would otherwise happen by contact of lash adjuster device 26 with interior distal surface 70 of engine brake piston 28 .
- detent pin 34 is moved along its axis to engage with recess 78 reset pin 32 as reset pin 32 moves toward reset ball 36 through contact with contact pad 80 .
- lash adjuster device 26 in combination with reset valve 24 permits the ability o combine functions in rocker arm assembly 12 to provide movement of exhaust valve 16 during operation of engine 10 as well as a different timing of the motion of exhaust valve 16 during engine braking events.
- cost and complexity of engine 10 is reduced significantly while providing an engine compression brake for engine 10 .
Abstract
A compression brake device and method are provided that include a lash member coupled to a rocker arm. The lash member has a first position that forces opening of the valve when the rocker arm is at the lower position. The brake also includes a lost motion cylinder at least partially defined within the rocker arm. The cylinder is biased towards a position of greatest internal displacement volume. The lost motion cylinder has a first operational mode wherein the lost motion cylinder permits compression thereof such that the ability of the rocker arm to open an exhaust valve is a function of the position of the lash member. The lost motion cylinder has a second operational mode wherein the lost motion cylinder retards compression thereof such that the ability of the rocker arm to open an exhaust valve is independent of the position of the lash member.
Description
- The present application claims priority to U.S. provisional patent application, Ser. No. 61/859,598, filed Jul. 29, 2013, the disclosure of which is expressly incorporated by reference.
- This disclosure relates to an exhaust valve actuation mechanism in an internal combustion engine and an engine brake lash adjuster device associated with the exhaust valve actuation mechanism.
- Engine brakes or engine compression brakes take advantage of the compression and expansion of gases in an engine cylinder to induce a resistance to movement of a piston in the engine cylinder by opening and closing valves associated with the piston at appropriate times. In order for engine brakes to function properly, conventional systems use various unique components and require certain precise tolerances.
- Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings.
-
FIG. 1 is a view of an engine brake lash adjuster device in accordance with an exemplary embodiment of the present disclosure. -
FIG. 2 is a view of the engine brake lash adjuster device ofFIG. 1 in a position to actuate an exhaust valve. -
FIG. 3 is a view of the engine brake lash adjuster device ofFIG. 1 with a compression brake actuated. - According to one embodiment, a compression brake is provided. The brake includes a rocker arm pivotable about a rocker arm shaft to selectively force an exhaust valve to an open condition. The rocker arm has a lower position, an upper position, and a plurality of positions intermediate the lower and upper positions. The brake further includes a lash member coupled to the rocker arm. The lash member is configurable to define a plurality of positions relative to the rocker arm. The lash member has a first position that forces opening of the valve when the rocker arm is at the lower position. The brake also includes a lost motion cylinder at least partially defined within the rocker arm. The cylinder is biased towards a position of greatest internal displacement volume. The lost motion cylinder has a first operational mode wherein the lost motion cylinder permits compression thereof such that the ability of the rocker arm to open an exhaust valve is a function of the position of the lash member. The lost motion cylinder has a second operational mode wherein the lost motion cylinder retards compression thereof such that the ability of the rocker arm to open an exhaust valve is independent of the position of the lash member.
- In another embodiment, a compression brake mechanism is provided including: a rocker arm operable to selectively engage an engine valve; a lash member having a plurality of settings that define lash between rocker arm movement and engine valve movement; and a lost motion mechanism disposed between the lash member and the engine valve; the lost motion mechanism having a first operational mode and a second operational mode, the first operational mode providing an ability to open an engine valve as a function of the lash member setting, the second operational mode providing an ability to open an engine valve independent of the lash member setting.
- In another embodiment, a method of operating an exhaust valve on an internal combustion engine is provided including: providing a lost motion cylinder at least partially within a rocker arm operable to open the exhaust valve; providing a lash member to define a maximum travel of a piston of the cylinder that defines a first internal volume of the cylinder; providing a seal valve within the rocker arm to selectively seal and open the internal volume of the cylinder; closing the seal valve when the internal volume of the cylinder is a second internal volume that is greater than a the first volume defined by the lash member thereby sealing fluid within the cylinder; rotating the rocker arm with the seal valve closed to force open the exhaust valve; and opening the seal valve to release fluid from the cylinder; and rotating the rocker arm with the seal valve open such that the cylinder assumes the first internal volume to force open the exhaust valve.
- In yet another embodiment, a method of adjusting lash between an exhaust valve and a rocker arm on an operating internal combustion engine including: providing a rocker arm having a first lash member defining a first lash amount between the rocker arm and the exhaust valve, the first lash amount defining a first point during downward travel of the rocker arm at which the exhaust valve is opened; providing a lash variance member defining a second lash amount between the rocker arm and the exhaust valve that is smaller than the first lash amount, the second last amount defining a second point in the downward travel of the rocker arm at which the exhaust valve is opened, the second point being higher than the first point; and toggling between the first and second lash amounts within a cycle of the engine.
- Referring to
FIG. 1 , a portion of an internal combustion engine is shown and generally indicated at 10.Engine 10 includes an engine brake or engine compression brake, which provides the ability to retard movement of a crankshaft (note shown) ofengine 10 when actuated. Engine compression brakes provide a valuable capability in a variety of situations where a friction brake, such as might be found in conjunction with a vehicle wheel, could easily overheat or rapidly wear out. Such situations include high loads and steep hills. While engine compression brakes provide a valuable capability, they are expensive and complex, requiring additional components and precise component tolerances. The engine brake of the present disclosure includes an exhaust valve actuation mechanism with a lash adjuster device or mechanism that provides the ability to reduce the number of components associated with an engine compression brake and the ability to reduce the tolerances of certain components associated with the engine compression brake disclosed in U.S. Pat. No. 6,253,730, the entire contents of which are hereby incorporated by reference. -
Engine 10 includes arocker arm assembly 12 having arocker arm body 14, anexhaust valve 16 moved by the action ofrocker arm assembly 12, acontrol shaft 18 that extends throughrocker arm body 14, arotatable camshaft 20, and anengine body 22. The function ofrocker arm assembly 12 is to control or actuateexhaust valve 16. Thus,rocker arm assembly 12 is part of an exhaust valve actuation mechanism. Rockerarm assembly 12 includes areset valve 24, alash adjuster device 26, a compression brake or engine brake hydraulic cylinder orpiston 28, and abearing 30.Reset valve 24 includes areset pin 32, adetent pin 34, and a reset member orball 36, each of which is positioned at least partially within areset valve cavity 38 formed inrocker arm body 14.Reset valve cavity 38 includes areset valve seat 86 that provides a mating surface forreset ball 36 whenreset valve 24 is actuated.Reset valve 24 may also include abias spring 40 and abias spring cup 42 positioned betweenbias spring 40 and resetball 36. Biasspring 40 andbias spring cup 42 bias resetball 36 toward a proximate end of reset in 32, contactingreset pin 32 during normal or non-compression braking operation ofengine 10. Because this contact prevents resetball 36 from contactingreset valve seat 86, fluid is able to flow pastreset ball 36 towardengine brake piston 28. Resetvalve 24 functions to cause the opening and closing ofexhaust valve 16 at a time that is independent of the position oflash adjuster device 26, explained further hereinbelow.Lash adjuster device 26 includes adistal end 84 and a threadedexterior surface 74.Engine brake piston 28 is positioned in abody cavity 44 formed inrocker arm body 14 and having a body cavitylongitudinal axis 46.Engine brake piston 28 includes aportion 48 having a spherical shape on which is positioned apiston shoe 50 having a mating spherical shape and ashoe contact surface 52, which contacts aproximate end 54 ofexhaust valve 16.Shoe contact surface 52 may be a planar surface andproximate end 54 mates with the planar surface ofshoe contact surface 52.Engine brake piston 28 includes aninterior surface 56 that forms apiston cavity 58.Interior surface 56 includes an interiordistal surface 70 that extends in a direction that is at an angle to body cavitylongitudinal axis 46 that may be 90 degrees. Apiston bias spring 80 is positioned betweenrocker arm body 14 and interiordistal surface 70 and functions to biasengine brake piston 28 towardpiston shoe 50 and thus biasespiston shoe 50 into contact withexhaust valve 16, which is biased into the position shown inFIG. 1 by an exhaust valve spring (not shown).Lash adjuster device 26 extends along body cavitylongitudinal axis 46 through a threadedpassage 60 formed inrocker arm body 14 intobody cavity 44 and then intopiston cavity 58.Lash adjuster device 26 is adjustable along body cavitylongitudinal axis 46 and is secured in position with a jam nut orlocking nut 62. As described further hereinbelow, lashadjuster device 28 functions to actuateexhaust valve 16 during normal operation ofengine 10. Bearing 30 is positioned onrocker arm body 14 and contacts camshaft 20. During operation ofengine 10,camshaft 20 rotates, causing pivotal oscillating motion ofrocker arm assembly 12 aboutcontrol shaft 18. -
Control shaft 18 includes a controlshaft oil passage 64, which connects with a first rockerarm oil passage 66 formed inrocker arm body 14 that fluidly connects toreset valve cavity 38.Rocker arm body 14 further includes a second rockerarm oil passage 68 that extends betweenreset valve cavity 38 andbody cavity 44, fluidly connectingreset valve cavity 38 tobody cavity 44. An engine oil pump (not shown) that provides oil pressure for various engine functions, such as lubrication, also provides pressure to the oil that flows into controlshaft oil passage 64, which then flows into first rocker armbody oil passage 66. Under normal engine operating conditions, the oil in controlshaft oil passage 64 and first rocker armbody oil passage 66 provides lubrication to the various components fluidly connected to controlshaft oil passage 64 and rocker armbody oil passage 66. These passages provide a control function to certain components of rocker arm assembly during engine compression braking, described further hereinbelow. - The longitudinal position of
lash adjuster device 26 is set daring assembly ofengine 10, and because of the ability to identify thedistance exhaust valve 16 needs to open empirically, setting the lash is easily accomplished through an automated process. Withrocker arm assembly 12 in the position shown inFIG. 1 , and withjam nut 62 in a position to permit movement oflash adjuster device 26,lash adjuster device 26 is driven or moved longitudinally downward toward interiordistal surface 70 ofengine brake piston 28. Once lashadjuster device 26 contacts interiordistal surface 70 ofengine brake piston 28, the drive torque to movelash adjuster device 26 increases non-linearly, which indicates thatlash adjuster device 26 has contacted interiordistal surface 70 ofengine brake piston 28. Once an automated assembly mechanism (not shown) detects the contact betweenlash adjuster device 26 and interiordistal surface 70,lash adjuster device 26 is moved longitudinally away from interiordistal surface 70 ofengine brake piston 28 by a predetermined amount. Once movement oflash adjuster device 26 by the predetermined amount has been accomplished,jam nut 62 is secured against a jamnut contact surface 72 ofrocker arm body 14 to locklash adjuster device 26 in a fixed position. In the exemplary embodiment, lashadjuster device 26 includes exterior threadedsurface 74 that mates with a similar thread formed in threadedpassage 60 ofrocker arm body 14, and longitudinal movement oflash adjuster device 26 is accomplished by rotating lashadjuster device 26 about body cavitylongitudinal axis 46, which moves lashadjuster device 26 longitudinally along body cavitylongitudinal axis 46. The ability to set the position oflash adjuster device 26, which determines whenexhaust valve 16 is actuated, reduces the tolerances that would otherwise be required in the fabrication ofrocker arm body 14. - During normal operation of
engine 10, ascamshaft 20 rotates,camshaft 20 contactsrocker assembly bearing 30.Camshaft 20 includes acam profile 76 that causes oscillating pivotal motion ofrocker arm assembly 12 aboutcontrol shaft 18. In the exemplary embodiment,cam profile 76 ofcamshaft 20 is shown as having only one lift event per revolution ofcamshaft 20. It should be understood thatcamshaft 20 can have any number of lift events to achieve various performance conditions, which includes control of exhaust emissions.Reset pin 32 includes a recess, undercut, or engagingfeature 78, that is engaged bydetent pin 34 during normal operation ofengine 10. The position ofdetent pin 34 is maintained by a bias spring mechanism (not shown), until a solenoid or other actuation mechanism (not shown) movesdetent pin 34 to a position wheredetent pin 34 disengages fromreset pin 32, which permitsreset pin 32 to move toward acontact pad 80 formed onengine body 22, as shown inFIG. 3 , which permitsreset valve 24 to close, described further hereinbelow. - As
rocker arm assembly 12 rotates in a counterclockwise direction through contact of bearing 30 withcam profile 76, as shown inFIG. 2 ,engine brake piston 28 compressespiston bias spring 82 until interiordistal surface 72 ofengine brake piston 28 contacts lashadjuster device 26. This actuation ofexhaust valve 16 is sometimes called lost motion. Further counterclockwise motion ofrocker arm assembly 12 movesexhaust valve 16, causingexhaust valve 16 to open, which permits exhaust gases to escape fromengine body 22 in a known manner.Cam profile 76 ofcamshaft 20 is configured to provide for rapid movement oflash adjuster device 26 toward interiordistal surface 70 ofengine brake piston 28 untildistal end 84 oflash adjuster device 26 approaches interiordistal surface 70 ofengine brake piston 28, at whichpoint cam profile 76 provides a decreased velocity oflash adjuster device 26 to minimize the impact oflash adjuster device 26 with interiordistal surface 70 ofengine brake piston 28. By reducing the impact, the life and reliability oflash adjuster device 26 andengine brake piston 28 are extended. - When the engine brake function is engaged, as shown in
FIG. 3 ,detent pin 34 is moved to disengage from engagingfeature 78, permittingreset pin 32 to move longitudinally towardcontact pad 80 ofengine body 22. Oil pressure present in rockerarm oil passage 66 and resetvalve cavity 38 forces resetpin 32 longitudinally towardcontact pad 80, which permitsreset valve ball 36 to move toward and contact resetvalve seat 86 by the action ofbias spring 40, trapping oil in second rockerarm oil passage 68 and inbody cavity 44. With oil trapped in second rockerarm oil passage 68 andbody cavity 44,engine brake piston 28 is unable to move asrocker arm assembly 12 moves in a counterclockwise direction, becauseengine brake piston 28 is unable to compress the trapped oil, and thus movement ofrocker arm assembly 12 causesengine brake piston 28 to moveexhaust valve 16 sooner than would otherwise happen by contact oflash adjuster device 26 with interiordistal surface 70 ofengine brake piston 28. To disengage the give compression brake,detent pin 34 is moved along its axis to engage withrecess 78reset pin 32 asreset pin 32 moves towardreset ball 36 through contact withcontact pad 80. Asreset pin 32 moves offreset valve seat 86, oil compressed by engine brake piston is able to flow frombody cavity 44 into second rockerarm oil passage 68, and then through reset valve cavity into first rockerarm oil passage 66, and then into controlshaft oil passage 64, permittingengine brake piston 28 to move toward lashadjuster 26, restoring normal, or non-braking operation, ofrocker arm assembly 12. - Thus, lash
adjuster device 26 in combination withreset valve 24 permits the ability o combine functions inrocker arm assembly 12 to provide movement ofexhaust valve 16 during operation ofengine 10 as well as a different timing of the motion ofexhaust valve 16 during engine braking events. By combining two functions inrocker arm assembly 12, cost and complexity ofengine 10 is reduced significantly while providing an engine compression brake forengine 10. - While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.
Claims (25)
1. A compression brake including:
a rocker arm pivotable about a rocker arm shaft to selectively force an exhaust valve to an open condition, the rocker arm having a lower position, an upper position, and a plurality of positions intermediate the lower and upper positions;
a lash member coupled to the rocker arm, the lash member being configurable to define a plurality of positions relative to the rocker arm, the lash member having a first position that forces opening of the valve when the rocker arm is at the lower position, and
a lost motion cylinder at least partially defined within the rocker arm, the cylinder biased towards a position of greatest internal displacement volume, the lost motion cylinder having a first operational mode wherein the lost motion cylinder permits compression thereof such that the ability of the rocker arm to open an exhaust valve is a function of the position of the lash member, the lost motion cylinder having a second operational mode wherein the lost motion cylinder retards compression thereof such that the ability of the rocker arm to open an exhaust valve is independent of the position of the lash member.
2. The engine of claim 1 , wherein the second operational mode of the lost motion cylinder is an engine compression braking mode and the first operational mode of the lost motion cylinder is a non-engine compression braking mode.
3. The engine of claim 1 , further including a seal valve within the rocker arm that, when closed, places the lost motion cylinder into the second operational mode.
4. The engine of claim 3 , wherein the seal valve is biased towards a closed position.
5. The engine of claim 3 , wherein the seal valve includes an actuator that abuts a portion of an engine when the rocker arm is in the lower position to place the seal valve in the open position and to place the lost motion cylinder in the second operational mode.
6. The engine of claim 3 , further including a lock that holds the seal valve in the open position.
7. The engine of claim 6 , further including a solenoid that selectively releases the lock.
8. A compression brake mechanism including:
a rocker arm operable to selectively engage an engine valve;
a lash member having a plurality of settings that define lash between rocker arm movement and engine valve movement; and
a lost motion mechanism disposed between the lash member and the engine valve; the lost motion mechanism having a first operational mode and a second operational mode, the first operational mode providing an ability to open an engine valve as a function of the lash member setting, the second operational mode providing an ability to open an engine valve independent of the lash member setting.
9. The brake mechanism of claim 8 , further comprising an engine valve upon which the lash member acts, wherein the engine valve is an exhaust valve and the second operational mode provides engine compression braking.
10. The brake mechanism of claim 8 , further including at least one seal valve within the rocker arm, the at least one seal valve being operable such that the second operational mode of the lost motion mechanism traps fluid within a portion of the rocker arm.
11. The brake mechanism of claim 10 , wherein the trapping of fluid prevents loss of motion by the lost motion mechanism.
12. The brake mechanism of claim 10 , further including a lock operable to hold the lost motion mechanism in the first operational mode.
13. The brake mechanism of claim 12 , wherein the seal valve is biased to a closed position corresponding to the second operational mode, and releasing the hold provided by the lock permits the biasing of the seal valve to assume the closed position.
14. The brake mechanism of claim 13 , further including a reset pin that is selectively locked by the lock, the reset pin having a first portion extending outside of the rocker arm, force applied to the first portion urging opening of the seal valve.
15. The brake mechanism of claim 8 , wherein the lost motion mechanism includes a cylinder, the first operational mode permitting egress of fluid from the cylinder, the second operational mode preventing egress of fluid from the cylinder.
16. The brake mechanism of claim 15 , wherein the lash member provides a limit on the travel of the cylinder.
17. The brake mechanism of claim 15 , wherein the lash member provides a limit on the minimum interior volume of the cylinder.
18. The brake mechanism of claim 8 , wherein the brake is operational on a 4-stroke engine, wherein the lost motion mechanism is in the first operational mode during an exhaust stroke and the lost motion mechanism, when in the second operational mode, releases fluid compressed during a compression stroke.
19. The brake mechanism of claim 8 , wherein the brake mechanism is part of an internal combustion engine.
20. A method of operating an exhaust valve on an internal combustion engine including:
providing a lost motion cylinder at least partially within a rocker arm operable to open the exhaust valve;
providing a lash member to define a maximum travel of a piston of the cylinder that defines a first internal volume of the cylinder;
providing a seal valve within the rocker arm to selectively seal and open the internal volume of the cylinder;
closing the seal valve when the internal volume of the cylinder is a second internal volume that is greater than a the first volume defined by the lash member thereby sealing fluid within the cylinder;
rotating the rocker arm with the seal valve closed to force open the exhaust valve;
opening the seal valve to release fluid from the cylinder; and
rotating the rocker arm with the seal valve open such that the cylinder assumes the first internal volume to force open the exhaust valve.
21. The method of claim 20 , wherein rotating the rocker arm with the seal valve closed causes opening of the exhaust valve.
22. A method of adjusting lash between an exhaust valve and a rocker arm on an operating internal combustion engine including:
providing a rocker arm having a first lash member defining a first lash amount between the rocker arm and the exhaust valve, the first lash amount defining a first point during downward travel of the rocker arm at which the exhaust valve is opened;
providing a lash variance member defining a second lash amount between the rocker arm and the exhaust valve that is smaller than the first lash amount, the second last amount defining a second point in the downward travel of the rocker arm at which the exhaust valve is opened, the second point being higher than the first point; and
toggling between the first and second lash amounts within a cycle of the engine.
23. The method of claim 22 , wherein the lash variance member includes a hydraulic piston.
24. The method of claim 23 , wherein the hydraulic piston includes a displacement, the displacement being limited by the first lash member to define a first displacement.
25. The method of claim 23 , wherein the second lash amount is defined by a second displacement of the hydraulic piston that is greater than the first displacement.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US14/898,026 US20160146074A1 (en) | 2013-07-29 | 2014-06-26 | Engine brake lash adjuster device and method |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201361859598P | 2013-07-29 | 2013-07-29 | |
US14/898,026 US20160146074A1 (en) | 2013-07-29 | 2014-06-26 | Engine brake lash adjuster device and method |
PCT/US2014/044347 WO2015017057A1 (en) | 2013-07-29 | 2014-06-26 | Engine brake lash adjuster device and method |
Publications (1)
Publication Number | Publication Date |
---|---|
US20160146074A1 true US20160146074A1 (en) | 2016-05-26 |
Family
ID=52432318
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/898,026 Abandoned US20160146074A1 (en) | 2013-07-29 | 2014-06-26 | Engine brake lash adjuster device and method |
Country Status (4)
Country | Link |
---|---|
US (1) | US20160146074A1 (en) |
CN (1) | CN105683515A (en) |
DE (1) | DE112014003482T5 (en) |
WO (1) | WO2015017057A1 (en) |
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US20170175597A1 (en) * | 2014-02-14 | 2017-06-22 | Eaton Srl | Rocker arm assembly for engine braking |
US10132206B1 (en) | 2017-05-19 | 2018-11-20 | Caterpillar Inc. | Common rocker arm for hydraulic lash adjuster and non-hydraulic lash adjuster |
US10823018B1 (en) | 2019-06-25 | 2020-11-03 | Schaeffler Technologies AG & Co. KG | Valve train arrangement including engine brake system and lost-motion hydraulic lash adjuster |
CN111902615A (en) * | 2018-03-26 | 2020-11-06 | 雅各布斯车辆系统公司 | System and method for IEGR using secondary intake valve motion and lost motion reset |
US11022008B2 (en) * | 2017-08-24 | 2021-06-01 | Eaton Intelligent Power Limited | Ball engine brake mechanism |
US11060427B2 (en) | 2019-06-24 | 2021-07-13 | Schaeffler Technologies AG & Co. KG | Valve train including engine braking system |
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US11401839B2 (en) * | 2018-07-13 | 2022-08-02 | Eaton Intelligent Power Limited | Rocker based bleeder engine brake |
CN115324681A (en) * | 2022-09-02 | 2022-11-11 | 一汽解放汽车有限公司 | Valve driving rocker arm |
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Also Published As
Publication number | Publication date |
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WO2015017057A1 (en) | 2015-02-05 |
CN105683515A (en) | 2016-06-15 |
DE112014003482T5 (en) | 2016-04-07 |
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