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Characterization of Engine Variable Cam Phaser Fluid Dynamics and Phaser's Ability to Reject System Disturbances
Technical Paper
2004-01-1389
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Vane type cam phasers have been widely used in internal combustion engines to vary valve timing to achieve purposes such as low emissions, greater torque, and higher horsepower. One of the primary concerns in using a vane phaser is its position holding ability when disturbances are present. Disturbances include cam torque oscillation, cam pulley speed fluctuation, oil pressure fluctuation, and engine acceleration or deceleration. Cam torque disturbance is the biggest contributor to phaser position error. This paper will first present the generic schematic of a variable cam phasing system and its challenges, followed by the characterization of the fluid dynamics of the vane phaser, with an emphasis on the effects of pressure, leakage, and oil aeration on the vane phaser fluid dynamics and its ability to reject cam torque disturbance. Finally, numerical evaluations of the vane phaser's ability to reject cam torque disturbance and sensitivity to various system parameters will be presented.
- ϕ
- Fractional air content by volume
- χ
- Fractional air by volume that is undissolved
- γ
- Polytropic index
- β
- Effective oil bulk modulus
- β0
- A reference oil bulk modulus
- θ
- Rotor angular displacement relative to its equilibrium position
- θ0
- Bias spring pre-compressed angle
- θd
- Desired cam position relative to cam pulley
- θS
- Phaser moving authority or stroke
- ωh
- Hydraulic natural frequency
- ζ
- Damping ratio
- A
- Effective pressure area
- I
- Cam load inertia
- L
- Leakage coefficient
- L1
- Flow coefficient in flow path from advancing chamber to vent via OCV
- L2
- Flow coefficient in flow path from supply to advancing chamber via OCV
- L3
- Flow coefficient in flow path from supply to retarding chamber via OCV
- L4
- Flow coefficient in flow path from retarding chamber to vent via OCV
- L5
- Leakage coefficient in leak path from supply to advancing chamber
- L6
- Leakage coefficient in leak path from supply to retarding chamber
- L7
- Leakage coefficient in leak path from advancing chamber to vent
- L8
- Leakage coefficient in leak path from advancing chamber to retarding chamber
- L9
- Leakage coefficient in leak path from retarding chamber to vent
- K
- Phaser bias spring rate
- N
- Number of oil chambers of same type
- P
- Oil pressure
- Pa0
- Static oil pressure in advancing chamber
- Pa
- Oil pressure change from Pa0 in advancing chamber
- Pabs
- Absolute oil pressure
- Patmos
- Absolute atmosphere pressure
- Pm0
- Differential oil pressure across the load at equilibrium condition
- Pm
- Oil pressure change from Pm0
- Pr0
- Static oil pressure in retarding chamber
- Pr
- Oil pressure change from Pr0 in retarding chamber
- Ps
- Supply oil pressure
- Psat
- Air saturate pressure
- ql
- Oil leakage
- r0
- Force to torque gain, or distance from force centroid to centerline
- s
- Laplace transform operator
- t
- Time
- T
- Temperature
- Tabs
- Absolute temperature
- Tf
- Friction torque
- Vt
- Total volume of oil chambers
- x
- Oil control valve spool displacement
- xS
- Oil Control Valve (OCV) spool stroke
- x1
- OCV spool displacement to shut off flow from retarding chamber to vent
- x2
- OCV spool displacement to shut off flow from supply to advancing chamber
- x3
- OCV spool displacement to open flow from supply to retarding chamber
- x4
- OCV spool displacement to open flow from advancing chamber to vent
- dB
- Decibel
- FTP
- Federal test procedure
- lpm
- Liter per minute
- OCV
- Oil control valve
- PCM
- Powertrain control module
- PD
- Proportional and derivative
- PI
- Proportional and integral
- PID
- Proportional, integral and derivative
- PWM
- Pulse width modulated
- VCP
- Variable cam phasing
NOTATIONS
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Citation
Zheng, L. and Plenzler, J., "Characterization of Engine Variable Cam Phaser Fluid Dynamics and Phaser's Ability to Reject System Disturbances," SAE Technical Paper 2004-01-1389, 2004, https://doi.org/10.4271/2004-01-1389.Also In
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