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
  • F01L1/02—Valve drive
• • 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
  • F01L1/024—Belt drive

Definitions

• Camshaft phase shifting devices are used in internal combustion engines to vary valve timing to improve fuel consumption and to improve exhaust gas quality. It is possible with current camshaft shifters to time the operation of the valves for maximum comfort and/or for maximum torque and the highest performance. Camshaft phase shifting devices used today are driven by a crankshaft though a synchronous belt or chain drive.
• the use of positive/synchronous engagement drive systems i.e. toothed belt drives and chain drives
• the cost, however, associated with positive engagement drive systems is higher than that of the non- positive engagement drive systems such as flat belt or V-belt drive systems, known as non-synchronous belts.
• camshaft phasing device that is suitable for being driven by a simple non-positive/non-synchronous belt drive for packaging and cost savings, and yet is adjustable to achieve and maintain desired valve timing, while being electronically controlled for simplicity and high precision.
• the present disclosure relates to a camshaft phase device for an internal combustion engine, and in particular, relates to a non-synchronous, belt driven camshaft phase device.
• the belt driven camshaft phase device comprises a non-synchronous belt and an epiclyclic gear train operatively connected to an input shaft and an output shaft.
• the input shaft is connected to the crankshaft via the non-synchronous belt and the output shaft is connected to a camshaft.
• the camshaft phase device further includes sensors and a controller, through which the positions of the input and output shafts and the positions of the camshaft and crankshaft are detected and tracked. Should the desired relationship in positions between the crankshaft and camshaft become unsynchronized as determined by an error signal exceeding a tolerance band, correction or compensation is applied to the output shaft through the gear train.
• the camshaft phase device of the present disclosure includes an adequate slew rate to achieve real-time compensation for mismatches in relative angular positions between the camshaft and crankshaft resulting from the operation of the non-synchronous belt drive system.
• Figure 1 is a schematic view of a non-synchronous, belt-driven drive system and schematically illustrates internal components of an internal combustion engine, associated pulleys thereof and a non-synchronous belt;
• FIG. 2 is a schematic view of a camshaft phase shift device constructed in accordance with and embodying the present disclosure
• Figure 3 illustrates a cross sectional view of the input shaft, an output shaft and the phase shift device
• Figure 4 illustrates an exploded view of a phase shift device constructed in accordance with and embodying the present disclosure
• Figure 5 illustrates another exploded view of components of the phase shift device of Figure 4
• Figure 6 illustrates a cross sectional view of a phase shift device constructed in accordance with and embodying the present disclosure
• Figure 7 is a schematic view of a torque based control structure of the camshaft phase shift device that controls the desired angular position of the output shaft of with respect to the input shaft.
• Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale. DETAILED DESCRIPTION The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure.
• a drive system for an internal combustion engine E is schematically shown as 10 ( Figure 1).
• the drive system comprises a crankshaft 12 and crankshaft pulley 14; an air-conditioning compressor 16 and compressor pulley 18; a power steering pump 20 and pump pulley 22; a water pump 24 and pump pulley 26; an alternator 28 and alternator pulley 30; tensioner 32 and tension pulley 34; input shafts 36 and associated pulleys 38 and a non-synchronous belt 40.
• the non-synchronous belt 40 operatively connects associated pulleys 14, 18, 22, 26, 30, 34 and 38 wherein the crankshaft 12, via its pulley 14, drives the non- synchronous belt 40.
• the input shaft 36 couples with the input pulley 38 at an end of the input shaft 36.
• An output shaft 42 couples with a camshaft 44 at an end of the output shaft 42.
• an electro-mechanic phase shift device of the present disclosure is shown located at the end of a camshaft 44 of the internal combustion engine E.
• the phase shift device 46 comprises an epicyclic gear train generally shown as 48; a motor generally shown as 50; sensors 51 and associated target wheels 47, 49 in operative connection with the input shaft 36 and the output shaft 42 and an engine control unit ECU.
• the epicyclic gear train 48 co-axially aligns around the input shaft 36 and the output shaft 42.
• the epicyclic gear train 48 comprises a first branch in the form of an input sun gear 52, a second branch in the form of an output sun gear 54, and a control branch in the form a carrier 56.
• the gear train 48 also comprises a first planet gear 58 and a second planet gear 60.
• the first planet gear 58 may comprise a set of first planet gears
• the second planet gear 60 may comprise a set of second planet gears.
• the sets of first planet gears and second planet gears 60 are equally spaced within the carrier 56.
• the input sun gear 52 meshes with the first set of planet gears 58
• the output sun gear 54 meshes with the second set of planet gears 60.
• Each planet gear 58 in the first planet gear set couples to, and thus rotates as a unit with, a corresponding planet gear 60 in the second planet gear set.
• Planet gears 58, 60 together form a planetary gear pair to rotate about a common axis at the same angular velocity.
• the planetary gear pairs are supported by a set of planet shafts 62 ( Figure 2), through bearings 64.
• the carrier 56 is supported in a housing 66 though bearings 68.
• planet gears 58, 60 are substantially identically formed and are integrated as a single gear 70.
• the single gear 70 has a first gear end 72 and a second gear end 74 correlating to planet gears 58, 60, respectively.
• Figure 6 illustrates a cross sectional view of a set of single gears 70 positioned 180 degrees apart.
• the input shaft 36 connects to input pulley 38 at one end and to the input sun gear 52 at the other end.
• the input shaft 36 is supported in the housing 66 though bearings 64.
• the output shaft 42 connects to the output sun gear 54 at one end and couples to camshaft 44 at the other end.
• the output shaft 42 is supported in the housing 66 through bearings 64.
• the first and second sun gears 52, 54 may be integrally formed, respectively, from the input shaft 36 and output shaft 42.
• the motor 50 includes a rotor 76 and a stator 78.
• the rotor 76 fits over the carrier 56 to establish a firm mechanical connection, so that the carrier 56 rotates with the rotor 76 as a unit.
• the stator 78 mounts to the housing 66.
• the input shaft 36 and output shaft 42 may extend beyond the input sun gear 52 and the output sun gear 54 with one piloted on the other through bearing 80 ⁇ Figure 2).
• Input shaft 36 is allowed to rotate with respect to the output shaft 42 when phase shift between the two shafts 36, 42 is desirable.
• an angular position limiting device generally shown as 82 (Figs. 1 , 4-6) is employed to provide mechanical stops in both rotating directions.
• the limiting device 82 rotatably couples the input sun gear 52 with the output sun gear 54.
• the limiting device 82 in an embodiment, comprises a slot 84 positioned on a face 86 of the input sun gear 52 and comprises an extension 88 protruding from another face 90 of the output sun gear 54 such that the extension 88 slidably engages with the slot 84.
• the extension 88 comprises pins protruding from the output sun gear 54.
• the input shaft 36 drives the output shaft 42 through the gear train 48.
• Sensors 51 monitor the angular velocities and positions of the input shaft 36 and output shaft 42 via target wheels 47, 49. The sensors 51 then communicate the shaft information to the engine control unit ECU.
• the effective creep rate defined as a percentage pitch line velocity loss with respect to pitch line velocity of the crankshaft pulley 14, is denoted below as "f.
• the ratio of pitch diameter of the input shaft pulley 38 to the pitch diameter of the crankshaft pulley 14 is denoted below as “ ⁇ ”.
• the ratio " ⁇ " of the angular velocity of the crankshaft 12 to the angular velocity of the input shaft 36 is characterized as
• the pulley diametric ratio of the input shaft 36 to the crankshaft 12 is set as
• the angular speed of the carrier 56 is set in accordance with the angular speed of the input shaft 36 or the output shaft 42 to closely maintain the following relationship ⁇ c _ 2 -24 C ⁇ !,c_ _ ⁇ -2i b or (3) ⁇ 'S, l ⁇ -2i h ⁇ s 2 ⁇ - ⁇ ' h where
• ⁇ / P - ⁇ , /V P2 number of teeth for the first and second planet gear ends 72, 74, respectively.
• ⁇ angular speed ratio of the crankshaft 12 to the input shaft 36, and is related to the creep rate though the following equation,
• a controller operatively connects to the engine control unit ECU and the motor 50.
• the controller is configured to receive engine operating signals generated by the engine control unit ECU and to receive signals from position sensors 51 coupled to the input shaft 36 and to the output shaft 42 and in response thereto generates and sends a command signal to the motor 50 to command the motor 50 to control the planetary gear train 48 through the carrier 56 to adjust the phase shift angle between the camshaft 12 and the crankshaft 44.
• Figure 4 shows another control structure for achieving the desired angular position of the output shaft 42.
• Figure 4 shows a torque-based control structure, generally shown as 92, suitable for use with the camshaft phasing device 46 of the present disclosure for achieving the desired angular position of the output shaft 42 with respect to the position of the crankshaft 12.
• the main control variable is the camshaft angle which is defined as the angular position of the camshaft 44 with respect to the position of the crankshaft 12.
• the control torque based control structure 92 comprises a controller 94 operatively connected to the engine E and the engine control unit 96 (ECU). Based on information the controller 94 receives from the engine control unit 96, the controller 94 generates a torque command signal 98, such as a voltage signal.
• the received information includes, but is not limited to: a camshaft phase shift set point (reference); the actual camshaft phase shift angle measured from angular position sensor signals; a camshaft torque load and a camshaft angular
• the actual camshaft phase shift angle is compared to a reference value to generate a differential (error) signal.
• the differential or error signal is then fed to a proportional-integral-derivative (PID) compensator 100 of the controller 94 to generate a feed back torque signal 102.
• PID proportional-integral-derivative
• This feed back torque signal 102 can be used to generate the torque command signal 98 to command the motor 50 to control to adjust the camshaft phase angle such that the error signal to the input of the PID compensator 100 or lead/lag compensator is reduced to an acceptable level. In doing so, the desired cam phase shift is achieved.
• the compensator 100 may comprise a proportional-and-derivative compensator (PD), a lead/lag compensator or a lead compensator.
• the control system may experience disturbances as the camshaft torque varies as a function of the cam phase angle during valve lift events.
• the controller 94 may further include a feed forward branch or block 104 for processing and computing the anticipated torque disturbances.
• the resulting feed forward torque signal 106 generated from the anticipated torque disturbance is fed forward to, and combined with, the output signal of the PID compensator 100 (or lead/lag compensator), forming the torque command signal 98.
• the anticipated torque disturbance also referred to as feed forward torque
• 7 " rq _ s tatic and ruction- ⁇ static is calculated from the frictionless static equilibrium condition of the three-branch gear drive.
• 7 rq fricllo ⁇ is the component required to overcome the frictional torque for current camshaft torque load.
• the sign of Taction is determined by the relative speed between the carrier 56 and the input shaft 36 (or the output shaft 42).
• the feed forward torque is calculated as
• T cam is the camshaft torque load, which is a function of the phase angle of the camshaft.
• the cam phase angle can be expressed by an analytical equation or as a look-up table.
• the function sgn(v) represents the sign of the relative speed v between the carrier 56 and the input shaft 36.
• the function f(T cam ) represents the magnitude of frictional torque Taction- During operation, T f iw d can be determined in dynamometer test as a function of engine torque and speed. The calibrated test data can then be stored in on-board memory devices (not shown) for real-time access.
• control structure 92 automatically controls the motor speed ⁇ c such that the speed relationship set forth by equation (3) is maintained.
• controller 94 adjusts the motor speed ⁇ c to cause the cam phase angle change over a small period of time to achieve the desired cam phase angle at the end of the shifting event.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve Device For Special Equipments (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)
• Retarders (AREA)

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• 2008
  • 2008-10-09 KR KR1020107007616A patent/KR20100100754A/ko not_active Application Discontinuation
  • 2008-10-09 JP JP2010529016A patent/JP2010540844A/ja active Pending
  • 2008-10-09 WO PCT/US2008/079274 patent/WO2009049001A1/en active Application Filing
  • 2008-10-09 EP EP08837604A patent/EP2222940B1/de not_active Not-in-force
  • 2008-10-09 US US12/681,449 patent/US20100218738A1/en not_active Abandoned
  • 2008-10-09 CN CN200880110953A patent/CN101821484A/zh active Pending
  • 2008-10-09 AT AT08837604T patent/ATE510109T1/de not_active IP Right Cessation

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