Crankshaft Damper Feedback Coupling for Torsional Isolation
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Solution Overview
Problem
Existing crankshaft arrangements with torsional vibration dampers face challenges in effectively isolating the drive train from torsional non-uniformities, as conventional solutions either lead to excessive stress in elastomer materials or are costly due to the use of additional seismic masses, and systems with negative mechanical rigidity are complex and limited in their operating range.
Innovation Solution
Incorporating a feedback device with negative rigidity into the crankshaft arrangement, coupling the vibration damper ring to the secondary side of the elastomer coupling, which stabilizes the system and reduces torsional vibrations by using either spring or magnetic elements distributed uniformly around the circumference, allowing for adaptable and space-efficient design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rigidity of the elastomer coupling is reduced to lower the isolation frequency, then the drive train isolation is improved, but the static torsion angle increases and stresses in the elastomer material exceed the permissible limit
Solution Approach 1:
The feedback device acts as an intermediary element between the vibration damper ring and the secondary coupling, introducing a negative rigidity mechanism that mediates the force transmission. This allows the elastomer coupling to operate at lower rigidity for better isolation while the feedback device compensates for the increased static torsion angle, preventing excessive stresses in the elastomer material
Solution Approach 2:
The feedback device creates a closed-loop system where the torsional movements of the vibration damper ring are fed back to the secondary coupling through the negative rigidity mechanism. This feedback action dynamically adjusts the coupling characteristics, allowing the system to maintain stability and prevent excessive stress accumulation in the elastomer coupling while achieving improved isolation frequencies
2Reliability
If a tuned mass damper or adaptive rotational speed absorber is used to reduce torsional non-uniformities, then the vibration damping is improved, but the system costs increase due to additional seismic mass
Solution Approach 1:
The invention merges the torsional vibration damper function with the drive train coupling function into a single integrated system. The vibration damper ring is coupled to both the crankshaft (via primary coupling) and the secondary coupling (via feedback device), allowing the same component structure to perform both vibration damping and torque transmission functions, thereby eliminating the need for separate seismic mass components
Solution Approach 2:
The feedback device with negative rigidity serves multiple functions simultaneously: it provides the additional coupling path required for vibration damping, maintains the static torque transmission capability of the elastomer coupling, and enables the system to achieve both isolation and durability without requiring additional dedicated components for each function
3Reliability
If components with negative mechanical rigidity are used for vibration isolation, then the isolation performance is improved, but the hardware implementation becomes relatively complex and limited to a very limited operating range
Solution Approach 1:
The feedback device replaces complex mechanical negative rigidity hardware with a coupled system where the interaction between the vibration damper ring, elastomer coupling, and feedback mechanism collectively produces the negative rigidity effect. This substitution simplifies the hardware implementation by using standard mechanical components arranged in a feedback configuration rather than requiring specialized negative rigidity mechanisms
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 configuration significantly reduces torsional non-uniformities and improves drive train isolation, leading to lower component loading and enhanced frequency stability in generated alternating current, with reduced transmission wear and improved sine wave cleanliness.
Implementation Method 1
the vibration damper ring and the primary mass being coupled via a viscous fluid
Implementation Method 2
the primary mass being coupled via an elastomer coupling ring to a secondary coupling
Implementation Method 3
the torsional vibration damper being coupled to the secondary coupling via a feedback device... This additional coupling has a negative rigidity (stiffness), as a result of which the desired behavior is configured
Data Source
AI summary
A crankshaft arrangement for an internal combustion engine includes a crankshaft, a torsional vibration damper having a primary mass and a flywheel, wherein the primary mass is connected fixedly to the crankshaft, and the flywheel and the primary mass are coupled via a viscous fluid. The torsional vibration damper is attached to an output end of the crankshaft. The primary mass is coupled to a secondary coupling via an elastomer coupling ring. The torsional vibration damper is coupled to the secondary coupling via a feedback device. The feedback device has a negative stiffness.