Concentric Camshaft Electric Phasing
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Solution Overview
Problem
Camshaft phasers in internal combustion engines experience excessive oscillation and noise due to oil leakage and air accumulation during engine start-up, leading to potential damage, as hydraulic fluid pressure is insufficient to maintain proper phasing.
Innovation Solution
A concentric camshaft assembly with electric motors and a harmonic drive system, which includes a wave generator and flexible gear, allows for precise phasing control of camshafts without relying on hydraulic pressure, using electric motors to offset the camshafts and maintain phasing independently of oil pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic phasers are used for camshaft phasing, then phasing control is achieved during normal operation, but excessive oscillation and noise occur during engine start-up due to oil leakage and insufficient hydraulic pressure
Solution Approach 1:
The patent extracts the problematic hydraulic fluid system from the phasing mechanism during start-up conditions. By using an electric motor to drive the camshaft independently of the hydraulic system during engine start-up, the harmful effects of oil leakage and air accumulation are eliminated, preventing oscillation and noise while maintaining reliable phasing control.
Solution Approach 2:
The electric motor performs preliminary action by establishing proper camshaft phasing before the hydraulic system becomes operational. The electric motor drives the camshaft to the correct phase position during engine start-up, and then the hydraulic system takes over for normal operation, ensuring smooth transition and preventing start-up oscillation.
2Ease of operation
If hydraulic fluid is used to maintain phasing, then phasing control is maintained during normal operation, but oil loss through leakage occurs and air accumulation causes oscillation
Solution Approach 1:
The patent replaces the hydraulic fluid-based phasing system with an electric motor-driven system. This substitution eliminates the need for hydraulic fluid, preventing oil leakage and air accumulation issues while maintaining automatic phasing control through electronic actuation of the camshaft position.
3Area of stationary object
If concentric camshaft assembly is used, then space requirements are reduced, but complex phasing control of both camshafts is required
Solution Approach 1:
The electric motor serves multiple functions: it directly drives the outer camshaft and also provides phasing control for the inner camshaft through the harmonic drive mechanism. This multi-functionality simplifies the overall control system compared to using separate hydraulic phasers for each camshaft, reducing device complexity while maintaining the space-saving concentric configuration.
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 provides stable and controlled camshaft phasing, reducing noise and potential damage, and allows for dynamic phasing adjustments based on engine conditions, independent of oil pressure, with faster response times and reduced space requirements compared to hydraulic systems.
Implementation Method 1
a flexible gear radially disposed about the wave generator and including a radially inner circumference in contact with the wave generator, and a radially outer circumference with a plurality of drive teeth. The electric motor is arranged to rotate the wave generator, with respect to the flexible gear, about an axis of rotation for the wave generator: to change respective radial distances of a plurality of points on the outer circumference of the flexible gear
Implementation Method 2
an electric motor arranged to rotate the wave generator, with respect to the flexible gear, about an axis of rotation for the wave generator
Implementation Method 3
an input gear non-rotatably connected to the first camshaft and arranged to rotate at a first speed, with respect to an axis of rotation for the first and second camshafts, in response to receiving rotational torque from a crankshaft of an engine
Data Source
AI summary
A concentric cam shaft assembly, including: a first camshaft; a second camshaft including at least a portion disposed radially within the first camshaft; and at least one phasing assembly including first and second electric motors and a first input gear arranged to rotate at a first speed in response to receiving rotational torque from a crankshaft of an engine. The rotational torque is arranged to rotate the first and second camshafts. The first electric motor is arranged to circumferentially off-set the first camshaft with respect to the first input gear. The second electric motor is arranged to circumferentially off-set the second camshaft with respect to the first input gear.