Cushioned Stop for Camshaft Phaser Energy Absorption
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Solution Overview
Problem
Mechanical stops in electrically-controlled camshaft phasers can cause binding, which stresses the components and limits the range of angular displacement, leading to direct collisions that may damage the phaser.
Innovation Solution
Incorporating cushioned stops within the planetary gear assembly, which absorb rotational energy and spread the force over a longer arc of travel, reducing the likelihood of binding and increasing stiffness between the sprocket and camshaft plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical stops are used to limit the range of angular displacement, then the phase adjustment range is controlled, but binding occurs and component stress increases
Solution Approach 1:
The patent applies beforehand cushioning by positioning the cushioned stop to engage with the planetary gear stop before direct collision occurs. The cushioned stop absorbs rotational energy and spreads the force over a longer arc of travel, preventing binding and reducing component stress while maintaining reliable phase adjustment range control.
2Reliability
If mechanical stops are used to enforce angular limits, then the range of authority is maintained, but direct collisions may damage the phaser
Solution Approach 1:
The cushioned stop is positioned to engage beforehand with the planetary gear stop, absorbing rotational energy and spreading the force over a longer arc of travel. This prevents direct collisions between hard surfaces while maintaining reliable enforcement of angular limits, thereby eliminating the harmful effect of collision damage.
3Ease of operation
If cushioned stops are incorporated, then rotational energy is absorbed and binding is reduced, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the physical properties of the stop mechanism. The cushioned stop changes the force distribution parameters by spreading the stopping force over a longer arc of travel and absorbing rotational energy, thereby reducing binding and improving ease of operation without requiring a fundamentally complex new mechanism.
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
The cushioned stops effectively absorb rotational energy, reducing the stress on components and allowing for smoother phase adjustments between the camshaft and crankshaft, thereby preventing direct collisions and extending the lifespan of the phaser.
Implementation Method 1
a cushioned stop configured to transmit energy between the planetary gear assembly and a planetary gear stop attached to a sprocket or a camshaft plate
Implementation Method 2
the cushioned stop absorbs rotational energy when engaged with a planetary gear stop of the variable camshaft timing device
Data Source
AI summary
A variable camshaft timing device adjusts phase between a camshaft and a crankshaft and includes a first ring gear configured to connect to the camshaft and rotate about a center axis, having a plurality of radially-inwardly facing gear teeth; a second ring gear axially spaced from the first ring gear, configured to receive rotational input from the crankshaft and rotate about the center axis, having a plurality of radially-inwardly facing gear teeth; a planetary gear assembly including one or more planet gears that are configured for rotation by an electric motor and engage the first ring gear and the second ring gear through the planet gear(s); and a cushioned stop configured to transmit energy between the planetary gear assembly and a planetary gear stop attached to a sprocket or a camshaft plate.