Electric Cam Phaser with Fixed Sun Planetary Gear
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Solution Overview
Problem
Existing electric cam phasers for internal combustion engines require continuous power to maintain the phase angle between the camshaft and crankshaft, leading to inefficiencies in fuel consumption due to the use of brushless DC motors.
Innovation Solution
A planetary gear assembly with a sun gear driven by an electric motor, connected to a phaser sprocket and a planetary gear carrier, allows for dynamic adjustment of the camshaft's phase angle relative to the crankshaft using an epicyclic gear structure and a worm gear, reducing power consumption by enabling adjustable angular positions without constant power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brushless DC motor is used to maintain camshaft position, then the cam phase position can be maintained, but continuous power consumption occurs
Solution Approach 1:
The electric motor operates periodically rather than continuously. The controller activates the motor only when cam phase adjustment is needed based on sensor feedback, allowing the motor to remain stationary and consume no power during normal operation, thus resolving the contradiction between maintaining position reliability and reducing continuous power consumption
Solution Approach 2:
The system uses sensor feedback to autonomously determine when motor activation is required. The sensor continuously monitors cam phase position and automatically triggers motor correction only when deviation occurs, eliminating the need for continuous power consumption while maintaining accurate cam phase positioning
2Adaptability or versatility
If a magnetic clutch with helical spline mechanism is used, then cam phase adjustment is achieved, but continuous power is required to maintain position
Solution Approach 1:
The patent replaces the magnetic clutch with helical spline mechanism with a planetary gear assembly driven by an electric motor. This mechanical substitution allows for precise cam phase adjustment through gear ratios while eliminating the need for continuous power to maintain position, as the mechanical gear structure holds position without active power input
Solution Approach 2:
The electric motor in the planetary gear system operates only periodically when phase adjustment is needed, rather than continuously. The motor activates briefly to reposition the cam phase and then remains stationary, eliminating continuous power requirements while maintaining full adjustability through the planetary gear mechanism
3Adaptability or versatility
If the sun gear is made adjustable, then cam phase position can be varied, but the structure becomes more complex
Solution Approach 1:
The sun gear serves multiple functions: it acts as both a structural support element for the planetary gears and as the adjustable component for cam phase control. This multi-functionality reduces overall device complexity by combining positioning and structural roles in a single component, allowing cam phase variability without proportionally increasing structural complexity
Solution Approach 2:
The planetary gear assembly acts as an intermediary mechanism between the electric motor and the camshaft. This intermediary provides mechanical advantage through gear ratios, allowing precise cam phase adjustment with minimal motor movement, thus achieving high adaptability while managing structural complexity through efficient mechanical transmission
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution dynamically adjusts the camshaft's phase angle with reduced power consumption, enhancing fuel efficiency by allowing for precise control of valve timing without continuous power consumption, thus improving engine performance.
Implementation Method 1
A planetary gear assembly can include a ring gear, a planetary gear carrier, and a sun gear. The carrier can support at least one rotatable planetary gear operably engageable with the ring gear and the sun gear. The sun gear can drive the at least one rotatable planetary gear in rotation for relative movement of the carrier.
Implementation Method 2
The electric cam phaser can include an electric motor driven worm gear connected to adjust the angular position of the sun gear.
Implementation Method 3
The sun gear can be fixed for maintaining a cam phase position of the camshaft relative to the crankshaft and can be driven with an electric motor to provide an adjustable angular position for varying the cam phase position.
Data Source
AI summary
A cam phaser (30, 130, 230) dynamically adjusts a rotational relationship of a camshaft (32) of an internal combustion engine with respect to an engine crankshaft operably connected with a phaser sprocket (42, 142, 242). The cam phaser (30, 130, 230) can include a planetary gear assembly having a ring gear (34, 134, 234) driven by the phaser sprocket (42, 142, 242), a planetary gear carrier (36, 136, 236) connected to the camshaft (32), a sun gear (38, 138, 238), and at least one rotatable planetary gear (40, 140, 240). The cam phaser (30, 130, 230) can include a sprocket housing (44, 144, 244) connected with the phaser sprocket (42, 142, 242) and operable for connection with the ring gear (34, 134, 234), a cover plate (46, 146, 246) secured to the carrier (36, 136, 236), and a adapter (48) connected between the sun gear (38, 138, 238) and an electric motor (47) for changing an angular position of the sun gear (38, 138, 238) and adjustably varying a cam phase position of the camshaft (32) relative to the crankshaft.