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US20030029402A1 - Variable valve timing system for an internal combustion engine - Google Patents

Variable valve timing system for an internal combustion engine Download PDF

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Publication number
US20030029402A1
US20030029402A1 US09/924,041 US92404101A US2003029402A1 US 20030029402 A1 US20030029402 A1 US 20030029402A1 US 92404101 A US92404101 A US 92404101A US 2003029402 A1 US2003029402 A1 US 2003029402A1
Authority
US
United States
Prior art keywords
rocker arm
displacement system
cam
valve stem
sliding block
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US09/924,041
Other languages
English (en)
Inventor
Daniel Pomerleau
Gary Knutson
Dusty Keashly
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP
Original Assignee
ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP filed Critical ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP
Priority to US09/924,041 priority Critical patent/US20030029402A1/en
Priority to PCT/CA2002/001231 priority patent/WO2003014536A1/fr
Assigned to ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP. reassignment ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KEASHLY, DUSTY, POMERLEAU, DANIEL GUY, KNUTSON, GARY
Publication of US20030029402A1 publication Critical patent/US20030029402A1/en
Abandoned legal-status Critical Current

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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
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
    • F01L13/0042—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction with cams being profiled in axial and radial direction

Definitions

  • the invention describes a rocker arm displacement system for variable valve timing in internal combustion engines. More specifically, the system provides a rocker arm displacement system including a rocker arm having a pivot, a cam-contacting portion and a valve stem contacting portion and a linear displacement system for linear displacement of the cam-contacting portion with respect to a variable profile cam.
  • lift and duration of valve opening also affects breathability. At high speed, higher lift quickens air intake and exhaust, However, at lower speed such lift will generate counter effects like deteriorating the fuel and air mixing process resulting in a decrease in output or even misfire. Therefore the lift and duration should also be variable according to engine speed.
  • a single cam profile is used with the result that engineers choose a single timing sequence (or cam profile) which is usually a compromise based on the desired general characteristics of the vehicle. For example, a van may adopt less overlapping for the benefits of low speed output whereas a racing engine may adopt considerable overlapping for high-speed power.
  • An ordinary sedan may adopt valve timing optimised for mid-range rpm so that both the low speed drivability and high-speed output will not be sacrificed to a significant extent.
  • lift and duration is determined for a limited rpm range. In other words, the valve timing is optimized for a limited speed range.
  • Variable valve timing provides a solution to the above problems by enabling the adjustment of valve timing as rpm changes with the result that power and torque are optimized across a wide rpm band.
  • VTEC Value Timing Electronic Control
  • the VTEC system does not allow a continuous change of timing but does provide two (or three) distinct phases of performance.
  • the cam-changing system of the VTEC engine is mechanically complex.
  • Another system is the Toyota VVTL-I which provides both variable camphasing and lift and duration. This system does not provide continuous variation of lift and duration but instead utilizes a 2-stage variable lift design.
  • variable timing systems have been proposed, there remain several problems with respect to the implementation of the technology to its theoretical potential. That is, the current state-of-the-art as implemented by Hyundai, Toyota and other major engine manufacturers provides variable valve timing systems which are mechanically complex and which do not provide true continuously variable timing with respect to lift, duration and phasing. Furthermore, variable valve timing systems which propose continuously variable lift and duration have been unsuccessful as a result of cam follower failure.
  • variable valve timing systems which provide the ability to adjust lift, duration and degreeing with a relatively simple mechanical system which does not require the complex mechanical interplay of many mechanical components.
  • a system which provides for a fine cam follower/cam interface and which can survive the high compressive loads at this interface.
  • variable valve timing system which can be retrofit to existing vehicles by replacing a rocker arm/fixed cam system with a linear displaceable rocker arm/variable profile cam system or factory installed into new engines.
  • systems which will significantly reduce fuel consumption and emissions particularly during idling without affecting vehicle performance.
  • a rocker arm displacement system for linear displacement of a rocker arm having a cam contacting portion with respect to a rotating, variable-profile cam comprising a linear displacement system operatively connected to a rocker arm.
  • a rocker arm displacement system comprising:
  • a rocker arm having a pivot, a cam contacting portion and a valve stem contacting portion
  • the cam-contacting device has improved thermal dissipation properties including a coefficient of thermal expansion less than 3 ⁇ 10 ⁇ 6 /degree Celsius.
  • the cam contacting system is a ball bearing and a bearing race and support and the coefficient of thermal expansion of the ball bearing is less than the coefficient of thermal expansion of the bearing race and support.
  • the cam contacting system is ceramic selected from any one of silicon nitride (including CERALLOY 147-31E, 147-31N, 147-1E, or 147-1) or silicon carbide.
  • the cam contacting devices is selected from any one of a radiused wheel, a ball bearing or a semi-spherical surface and wherein the cam contacting surface is selected from any one of CERALLOY 147-31E, 147-31N, 147-1E, or 147-1.
  • the valve stem contacting portion may also be selected from these materials.
  • the linear displacement system includes a sliding block operatively connected to a linear displacement cylinder and the sliding block pivotally retains the rocker arm.
  • a lash adjustment system is provided within the sliding block, rocker arm or valve stem.
  • the lash adjustment system is hydraulic and includes a piston within the sliding block for setting the range of motion of the rocker arm within the sliding block.
  • the rocker arm is pivotally connected to the valve stem.
  • the invention provides a rocker arm displacement system comprising:
  • a rocker arm having a pivot, a cam contacting system and a valve stem contacting system, the cam contacting system a silicon nitride ball bearing rotatably retained within the rocker arm;
  • a sliding block operatively connected to a linear displacement cylinder for linear displacement of the cam contacting portion with respect to the variable profile cam wherein the sliding block pivotally retains the rocker arm and wherein the sliding block includes a hydraulic lash adjustment system.
  • the invention provides a method of retrofitting an internal combustion engine with a rocker arm displacement system as in claim 1, the internal combustion engine having a valve cover, valve stems, a rocker arm assembly and a camshaft comprising the steps of:
  • the invention provides an internal combustion engine characterized by a rocker arm displacement system for linear displacement of a rocker arm with respect to a camshaft.
  • FIGS. 1A, 1B and 1 C are schematic drawings of the geometric design of three embodiments of a rocker arm displacement system showing the relative positions of the valve stem/spring, pivot and cams with respect to a rocker arm;
  • FIGS. 2A and 2B are forward and rear perspective views of a rocker arm displacement system for a variable valve timing system for an overhead cam engine in accordance with one embodiment of the invention
  • FIG. 2C is a partial cross-sectional view of a rocker arm displacement system for a variable valve timing system for an overhead cam engine in accordance with one embodiment of the invention showing details of a linear displacement cylinder;
  • FIGS. 3A and 3B are forward and end perspective views of a rocker arm displacement system for a variable valve timing system for an overhead cam engine in accordance with another embodiment of the invention.
  • FIG. 3C is a partial cross-sectional view of a rocker arm displacement system for a variable valve timing system for an overhead cam engine in accordance with another embodiment of the invention showing details of a linear displacement cylinder and sliding block;
  • FIG. 4 is a schematic diagram of a further embodiment of a rocker arm displacement system for variable valve timing system for an overhead cam engine in accordance with a further embodiment of the invention.
  • the system generally includes a rocker arm (R) in operative connection with a valve stem (V)/spring (Vs), a cam contacting device (CCD) contacting a variable profile cam shaft (C) and a linear displacement system (LDS) for linear displacement of the rocker arm with respect to the cam shaft.
  • R rocker arm
  • V valve stem
  • Vs spring
  • CCD cam contacting device
  • LDS linear displacement system
  • FIGS. 1A, 1B and 1 C Different embodiments of the system are schematically illustrated in FIGS. 1A, 1B and 1 C wherein options for the geometric layout of the rocker arm (R), camshaft (C), valve stem (V) /spring (Vs, with ⁇ showing the direction of spring force) are shown with respect to a rocker arm pivot (P).
  • FIG. 1A shows a rocker arm having a centrally located pivot with both the valve stem/spring and camshaft on the same side of the rocker arm.
  • FIG. 1B shows a rocker arm with the pivot at one end with a centrally positioned camshaft and with the valve stem/spring on the opposite side and end of the rocker arm.
  • FIG. 1C shows an embodiment with the pivot at one end with a centrally positioned valve stem/spring and with the camshaft on the opposite side and end of the rocker arm.
  • FIGS. 2A, 2B and 2 C show perspective and cross-sectional views of the embodiment of FIG. 1A.
  • the camshaft includes variable profile lobes 20 on a rotating camshaft C.
  • Rocker arms R for each cam are mounted on a rocker shaft 22 at the rocker arm pivot and include cam followers or cam-contacting devices 24 biased against each respective variable profile lobes by valve springs Vs acting on the opposite end of the rocker arm.
  • a linear displacement system (LDS) is operatively connected to the rocker shaft and includes a hydraulic cylinder 26 for linear displacement of the rocker shaft 22 and, hence, linear displacement of the cam followers 24 with respect to the variable profile lobes 20 .
  • LDS linear displacement system
  • the cam followers 24 are spherical ball bearings rotatably retained within bearing races within the rocker arm.
  • the spherical bearing provides a fine contact point with respect to the cam lobe thereby permitting continuous setting of the valve timing between the end limits of the cam 20 .
  • valve stem contacting device such as valve stem bearing 28 rotatably retained within a tip ball retainer 30 (as shown in FIG. 2 b ).
  • valve stem bearing may be rotatably retained within the rocker arm (not shown).
  • the rocker arm will preferably include a hydraulic lash adjustment system 32 enabling adjustment of the clearance between the rocker arm and valve stem.
  • valve stem end of the rocker arm is displaced with respect to the valve stem when actuated by the LDS.
  • actuation cylinder 26 may be positively positioned at a full range of positions across the width of the cam as may be determined by an appropriate control algorithm, such as one where the linear position of the rocker arms is proportional to engine rpm.
  • FIGS. 3A, 3B and 3 C a second embodiment of the system corresponding to that shown schematically in FIG. 1B is described.
  • the pivot is located at one end of the rocker arm with the cam followers located in the middle of the rocker arm and valve stem/spring located at the opposite end.
  • the linear displacement system includes a sliding block 40 which pivotally retains the rocker arm.
  • the sliding block permits pivotal up and down motion of the rocker arm but prevents side-to-side motion of the rocker arm within the sliding block.
  • the sliding block is retained within a retaining system 42 allowing linear displacement of the sliding block under the control of the linear displacement cylinder 26 .
  • the sliding block may also contain a lash adjustment system 32 a permitting adjustment of the clearance between the valve stem and rocker arm.
  • the lash adjustment system may be hydraulically controlled wherein the sliding block includes hydraulic pistons 32 b (as shown in cutaway in FIG. 3C) for setting the range of motion of the rocker arm.
  • the valve stem includes a valve stem contacting device such as a valve stem bearing 28 rotatably retained within a tip ball retainer 30 (as shown in FIG. 3B).
  • a valve stem contacting device such as a valve stem bearing 28 rotatably retained within a tip ball retainer 30 (as shown in FIG. 3B).
  • the rocker arm is pivoted about a second axis P 2 orthogonal to the main pivot axis P of the rocker arm. That is, the rocker arm does not include a tip bearing or roller but rather is pivotally connected to the valve stem and is pivotally connected to the LDS thereby allowing rotational movement of the rocker arm with respect to the valve stem.
  • the cam-contacting device may be embodied in different forms including a ball bearing, a roller, a tapered wheel and a half sphere as described in applicant's copending applications.
  • the cam-contacting device will preferably provide a fine contact point between the cam-contacting device and cam so as to provide for continuous variability of the cam profile between the different ends of the cam.
  • the cam-contacting device is preferably a ceramic material such as silicon nitride, which provides improved thermal properties between the cam contacting device and the cam to accommodate the high contact stresses.
  • the valve stem contacting system may be embodied in different forms to achieve the result of valve actuation while permitting linear or pivotal movement of the rocker arm with respect to the valve stem.
  • the valve stem contacting system may include a bearing system or other contact system located on either the rocker arm or valve stem or between the rocker arm and valve stem.
  • the bearing system may be a ball bearing or roller bearing.
  • Other contact systems may include flat or curved surfaces engageable with one another and linearly displaceable with respect to one another.
  • the valve stem contacting system preferably utilizes a ceramic material such as silicon nitride, which provides improved thermal properties between the rocker arm and the valve stem to accommodate the high contact stresses.
  • the rocker arm may also be pivotally connected to the valve stem.
  • the linear displacement system may be actuated by a hydraulic cylinder as described above or other linear motion systems as are known in the art including electromechanical systems.
  • the rocker arm displacement system as described is readily retrofit to existing overhead cam engines.
  • the following general procedure would be followed.
  • the valve cover would be removed to expose the existing rocker arm and camshaft assembly.
  • the existing fixed profile camshaft would be removed and replaced with a variable profile camshaft.
  • the existing rocker arm assembly would similarly be removed. Any required modification to the valve stem tips would be completed for the particular design of the valve stem contacting system.
  • a new rocker arm displacement assembly would be installed between the camshaft and valve stems, likely requiring the addition of an adaptive plate to permit linear movement of the new rocker arm assembly. Modification to the valve cover will likely be required for the linear displacement system to extend through the valve cover, if required.
  • a specifically designed valve cover assembly may be utilized to accommodate the linear displacement system.
  • the linear displacement system would be connected to an appropriate control system such as an electro-hydraulic, electromechanical or electrical system.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
  • Valve Device For Special Equipments (AREA)
US09/924,041 2001-08-07 2001-08-07 Variable valve timing system for an internal combustion engine Abandoned US20030029402A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US09/924,041 US20030029402A1 (en) 2001-08-07 2001-08-07 Variable valve timing system for an internal combustion engine
PCT/CA2002/001231 WO2003014536A1 (fr) 2001-08-07 2002-08-07 Systeme de reglage de soupapes variable pour moteur a combustion interne

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US09/924,041 US20030029402A1 (en) 2001-08-07 2001-08-07 Variable valve timing system for an internal combustion engine

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US20030029402A1 true US20030029402A1 (en) 2003-02-13

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US (1) US20030029402A1 (fr)
WO (1) WO2003014536A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060027194A1 (en) * 2004-08-03 2006-02-09 Stefan Battlogg Positive-guidance apparatus for conversion of a rotary movement of a drive to a reciprocating movement of a part
US20090178637A1 (en) * 2008-01-16 2009-07-16 Gm Global Technology Operations, Inc. Sliding-pivot locking mechanism for an overhead cam with multiple rocker arms
US20120312263A1 (en) * 2011-05-26 2012-12-13 Arrieta Francisco A Variable Geometry Cam Shafts For Multiple-Cylinder Internal Combustion Engines
CN114689231A (zh) * 2022-03-30 2022-07-01 安徽华菱汽车有限公司 一种凸轮轴接触应力测试方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3986484A (en) * 1974-11-18 1976-10-19 Dyer Glenn L Camshaft for controlling variably opening valves
US5329895A (en) * 1992-09-30 1994-07-19 Mazda Motor Corporation System for controlling valve shift timing of an engine
US5445117A (en) * 1994-01-31 1995-08-29 Mendler; Charles Adjustable valve system for a multi-valve internal combustion engine

Family Cites Families (10)

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US3730150A (en) * 1971-10-20 1973-05-01 S Codner Method and apparatus for control of valve operation
JPS5926768B2 (ja) * 1976-07-27 1984-06-30 トヨタ自動車株式会社 内燃機関のバルブ駆動装置
JPS55148912A (en) * 1979-05-10 1980-11-19 Nissan Motor Co Ltd Valve lifter for internal combustion engine
JPH0674811B2 (ja) * 1987-03-12 1994-09-21 日本特殊陶業株式会社 摺動部品の製造法
US4887564A (en) * 1989-04-10 1989-12-19 Edwards James R Valve actuation system for desmodromic internal combustion engines
US5809842A (en) * 1995-06-26 1998-09-22 Sumitomo Electric Industries, Ltd. Ceramic sliding component
US6032630A (en) * 1997-11-17 2000-03-07 Ntn Corporation Valve lifter
CA2257437A1 (fr) * 1999-01-12 2000-07-12 Daniel G. Pomerleau Amelioration a un systeme de calage de distribution variable pour moteur a combustion interne
FR2799792B1 (fr) * 1999-10-15 2002-04-12 Jean Louis Rico Moteur thermique a distribution variable
CA2315595A1 (fr) 2000-08-08 2002-02-08 Daniel G. Pomerleau Ameliorations a des systemes de distribution a programme variable

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3986484A (en) * 1974-11-18 1976-10-19 Dyer Glenn L Camshaft for controlling variably opening valves
US5329895A (en) * 1992-09-30 1994-07-19 Mazda Motor Corporation System for controlling valve shift timing of an engine
US5445117A (en) * 1994-01-31 1995-08-29 Mendler; Charles Adjustable valve system for a multi-valve internal combustion engine

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060027194A1 (en) * 2004-08-03 2006-02-09 Stefan Battlogg Positive-guidance apparatus for conversion of a rotary movement of a drive to a reciprocating movement of a part
US7421988B2 (en) * 2004-08-03 2008-09-09 Stefan Battlogg Positive-guidance apparatus for conversion of a rotary movement of a drive to a reciprocating movement of a part
US20090178637A1 (en) * 2008-01-16 2009-07-16 Gm Global Technology Operations, Inc. Sliding-pivot locking mechanism for an overhead cam with multiple rocker arms
WO2009091768A3 (fr) * 2008-01-16 2009-10-01 Gm Global Technology Operations, Inc. Mécanisme de blocage de pivot glissant pour cames en tête avec culbuteurs multiples
US7845324B2 (en) 2008-01-16 2010-12-07 Gm Global Technology Operations, Inc. Sliding-pivot locking mechanism for an overhead cam with multiple rocker arms
CN101910570B (zh) * 2008-01-16 2013-05-01 通用汽车环球科技运作公司 用于顶置凸轮的具有多个摇臂的滑动枢转锁定机构
US20120312263A1 (en) * 2011-05-26 2012-12-13 Arrieta Francisco A Variable Geometry Cam Shafts For Multiple-Cylinder Internal Combustion Engines
CN114689231A (zh) * 2022-03-30 2022-07-01 安徽华菱汽车有限公司 一种凸轮轴接触应力测试方法

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Publication number Publication date
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Owner name: ABSOLUTE ZERO EMISSION TECHNOLOGIES CORP., CANADA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:POMERLEAU, DANIEL GUY;KNUTSON, GARY;KEASHLY, DUSTY;REEL/FRAME:013342/0840;SIGNING DATES FROM 20020725 TO 20020726

STCB Information on status: application discontinuation

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