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
  • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
  • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
• • 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
  • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
  • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
  • F01L1/352—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using bevel or epicyclic gear
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
  • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation

Definitions

• the present invention is related generally to a camshaft adjustment mechanism for use in an internal combustion engine, and in particular, to a control structure for an electro-mechanical camshaft phase shifting device.
• Camshaft phase shifting devices are used more often in gasoline engines to vary valve timing for benefits of improving fuel consumption and exhaust gas quality.
• cam shaft phase shifting devices There are many types of cam shaft phase shifting devices. Hydraulic adjusters are commonly seen in many current applications. The major challenges for hydraulic adjusters includes improving slew rate in slow-speed operation, maintaining accurate camshaft angular position, and extending the operating temperature range.
• hydraulic adjusters are commonly seen in many current applications. The major challenges for hydraulic adjusters includes improving slew rate in slow-speed operation, maintaining accurate camshaft angular position, and extending the operating temperature range.
• an electro-mechanic camshaft phase shifting device eCPS
• the eCPS device includes a three-shaft gear unit and an electric machine. According to the demand from engine electronic control unit (ECU), the electric machine is operated in one of three available modes, the neutral operating mode, the motoring mode, and the generating mode, to achieve desired performance objectives.
• ECU engine electronic control unit
• the present invention discloses a control structure that provides a concrete means for an eCPS device to realize these operation modes.
• the disclosed control structure may additionally be applied to regulate the operation of other similar electro-mechanical camshaft phase shifting devices.
• the present disclosure provides a control structure for electro- mechanic camshaft phase shifting devices in general and a control structure for an electro-mechanic camshaft phase shifting device with a self-locking mechanism in particular.
• the camshaft phase shifting device includes a coaxially arranged three-shaft gear system, having an input shaft, an output shaft, and a control shaft for adjusting the phase angle between the input and output shafts.
• the control structure is a torque-based control structure.
• the dynamic response of the gear system and thus the desired phase angle of camshaft is controlled and adjusted by a controller (or compensator) which produces a torque command based on received signals.
• signals include, but are not limited to, cam shaft phase angle error signal (deviation of cam phase shift angle from the reference value), torque load, and/or angular position signal of the cam shaft, and relative speed signal between the input and output shafts.
• This torque command (a voltage signal for example) is then converted by an electric machine into an electromagnetic torque exerting on the control shaft of the camshaft phase shifting device.
• the torque command includes two parts, a feed forward part to compensate for the known disturbances in system torques and a feedback part to clear up unknown disturbances and to track reference change.
• the controller may include an on-and-off switch to turn off the torque command for energy savings when self- locking mechanism is determined active.
• Figure 1 illustrates a block diagram of a preferred control structure for controlling an electro-mechanical cam phase shifting device of the present invention
• Figure 2 is a sectional view of an electro-magnetic cam phase shifting device
• FIG. 3 is an input-output diagram for the control structure of Fig. 1 ;
• Figure 4 illustrates a block diagram of an alternate control structure for controlling an electro-mechanical cam phase shifting device of the present invention.
• 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. Description of the Preferred Embodiment
• FIG. 1 a preferred control structure for controlling an electro-mechanical cam phase shifting device is shown generally.
• the system shown in Figure 1 is comprised of an engine 10, an engine control unit (ECU) 20, a phase shifting device 30, and a controller (or compensator) 40.
• the phase shifting device 30 is a three-shaft, positive differential gear drive, having three co-axially arranged rotate-able shafts, as is depicted in Figure 2.
• the input shaft 16 is connected through sprocket 18 and a chain drive (not shown) to engine crank shaft.
• the output shaft 14 is connected to engine cam shaft 12.
• the control shaft 34 is coupled to the rotor of an electric machine 32.
• the phase shifting device has a built-in frictional self-locking mechanism, which enables the output shaft 14 to lock-up with the input shaft 16, and therefore to transmit torque between the two shafts with a 1 :1 speed ratio. Under this condition, there will be no phase shift between input shaft 16 and output shaft 14. Frictional locking between the input shaft 16 and the output shaft 14 can only be unlocked by applying an adequate toque to the control shaft 34. The required torque is generated by the electric machine 32 coupled to the shaft 34 in response to a torque command received by the electric machine. When the phase shifting device is unlocked, there may be a slight difference between the input and output shaft speeds. This allows the cam shaft connected to the output shaft 14 to shift in angular position with respect to the input shaft 16. -A-
• the controller (or compensator) 40 generates the torque command, which can be in the form of a voltage signal or any other suitable signal form, based on information received by the controller (or compensator) 40.
• the received information may include, but is not limited to, a cam shaft phase shift set point (reference), or an actual cam shaft phase shift measured and/or computed from one or more angular position sensor signals.
• the actual cam phase shift angle is compared to a reference value to generate a differential (error) signal.
• the differential or error signal is then communicated to a PID compensator 42 to generate a feedback torque (torque adjustment) command.
• This feedback torque command in turn is used to direct the electric machine for controlling and adjusting the cam phase angle to reduce the error signal to the input of the PID compensator 42. In doing so, the desired cam phase shift is archived.
• the PID compensator is primarily a proportional-and-derivative controller (PD).
• controller (or compensator) 40 may further include a feed-forward branch (or a unit) 44 for processing and computing the anticipated torque disturbances within the system. The resulting signal is fed forward to, and combined with, the output signal of the PID controller, forming the torque command signal.
• the anticipated torque disturbance also referred to as feedforward torque
• T ⁇ static and Trqjricthn- Trq_ s tatic is calculated from the frictionless static equilibrium condition of the three-shaft gear drive, while Trqjri cth n represents the component required to overcome the frictional torque for a current cam shaft torque load.
• the sign of Trqj ⁇ c t ion is determined by the relative speed between the control shaft 34 and the input shaft 16 (or the output shaft 14).
• T cam is the cam shaft torque load, which is a function of cam phase angle and which can be expressed by an analytical equation or by a look-up table.
• the value sgn(v) represents sign of relative speed v between the control shaft 34 and the input shaft 16, while the function f(T ca m) represent the magnitude of the frictional torque Trqj ⁇ ction-
• SRo is the base speed ratio of output shaft 14 to the input shaft 16, given by following equation
• N denotes the number of gear teeth with its subscripts si, S 2, PI , and P2 representing the first sun gear 31 coupled to the input shaft 16, the second sun gear 33 coupled to the output shaft 14, the first planet gear 35 engaging the first sun gear 31 , and the second planet gear 37 engaging the second sun gear 33, respectively.
• the first and second planet gears 35, 37 are integrally formed with, and carried on a common planet assembly 39 which is supported by, and rotates with, the control shaft 34.
• the phase shaft device features a self-locking mechanism, it is possible to turn the controller and the electric machine off for energy savings when the actual cam phase shift angle is in a close proximity to the desired value (a reference value or a set point). This is done, for example, by commanding a zero torque to the electric machine.
• Figure 3 illustrates an alternate implementation of the controller 40 in simulation, where a power-on logic and power switch are shown in separate blocks.
• the derivative portion of the PID compensator may be moved to the feedback path to reduce the effects of impulses (sudden changes) in reference input.
• Figure 4 shows the corresponding control structure for this optional configuration.
• the present disclosure can be embodied in-part the form of computer- implemented processes and apparatuses for practicing those processes.
• the present disclosure can also be embodied in-part the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD- ROMs, hard drives, or an other computer readable storage medium, wherein, when the computer program code is loaded into, and executed by, an electronic device such as a computer, micro-processor or logic circuit, the device becomes an apparatus for practicing the present disclosure.
• the present disclosure can also be embodied in-part the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes an apparatus for practicing the present disclosure.
• the computer program code segments configure the microprocessor to create specific logic circuits.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Valve Device For Special Equipments (AREA)
• Gear Transmission (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)

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• 2007
  • 2007-12-04 WO PCT/US2007/024822 patent/WO2008070066A2/en not_active Ceased
  • 2007-12-04 EP EP07862495A patent/EP2089613A2/de not_active Withdrawn
  • 2007-12-04 JP JP2009540255A patent/JP2010511839A/ja not_active Withdrawn
  • 2007-12-04 KR KR1020097012622A patent/KR20090096465A/ko not_active Ceased
  • 2007-12-04 US US12/517,920 patent/US20110011359A1/en not_active Abandoned

Patent Citations (1)

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