Flexible Coupling Isolates Torsional Vibrations in Turbocharged Diesel Work Machines
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Solution Overview
Problem
Existing turbo compounding systems for work machines face inefficiencies due to the amplification of torsional vibrations from diesel engines through gear trains, leading to reduced power transmission efficiency and potential power turbine failure, necessitating the use of viscous dampers which are inherently inefficient.
Innovation Solution
A flexible coupling using an elastomeric element connects the internal combustion engine's rotary power output to a power distribution device, isolating torsional vibrations and providing a high-efficiency mechanical connection to a power turbine, while allowing for the placement of an exhaust aftertreatment device upstream of the power turbine to reduce pumping losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gear train is used to connect the power turbine to the engine crankshaft, then the power turbine can be isolated from torsional vibrations, but the mechanical efficiency of power transmission is significantly reduced
Solution Approach 1:
A flexible coupling acts as an intermediary element between the engine crankshaft and the power turbine, providing vibration isolation while maintaining high mechanical efficiency. The flexible coupling's elastomeric element dampens torsional vibrations without the significant energy losses associated with gear trains, thus serving as an effective mediator that resolves the contradiction between reliability and energy loss.
2Reliability
If a viscous damper is used between the gear train and crankshaft, then torsional vibrations are damped and the power turbine is isolated, but the mechanical coupling efficiency drops to 80-93%
Solution Approach 1:
The flexible coupling serves as a superior intermediary that replaces the viscous damper in the power transmission path. While the viscous damper provides vibration damping, it introduces significant energy losses (80-93% efficiency). The flexible coupling achieves vibration isolation through its elastomeric element while maintaining much higher mechanical efficiency, thus resolving the contradiction between damping capability and energy loss.
3Loss of energy
If a direct connection is maintained between the power turbine and engine, then mechanical efficiency is maximized, but the power turbine is subjected to amplified torsional vibrations leading to failure
Solution Approach 1:
The flexible coupling is introduced as a mediator between the engine crankshaft and the power turbine. This intermediary element provides the necessary vibration isolation to protect the power turbine from amplified torsional vibrations, while simultaneously maintaining high mechanical efficiency close to direct connection. This resolves the contradiction between maximizing mechanical efficiency and ensuring power turbine durability.
4Loss of energy
If exhaust aftertreatment device is placed upstream of the power turbine, then pumping losses are reduced, but the system complexity increases
Solution Approach 1:
The exhaust aftertreatment device is positioned upstream of the power turbine in the exhaust flow path. This preliminary placement allows the aftertreatment device to process exhaust gases before they reach the power turbine, reducing pumping losses by optimizing exhaust flow. The flexible coupling enables this configuration by providing vibration isolation that protects the power turbine from vibrations generated by the aftertreatment device and engine, thus managing the increased system complexity.
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 effectively isolates the power turbine from torsional vibrations, enhancing its durability and achieving a significant increase in mechanical efficiency by eliminating previous constraints and reducing pumping losses, thereby optimizing power transmission and system efficiency.
Implementation Method 1
A flexible coupling using an elastomeric element connects the internal combustion engine's rotary power output to a power distribution device, isolating torsional vibrations
Implementation Method 2
at least one turbo machinery device is provided to receive the products of combustion from the IC engine, the turbo machinery device including at least one power turbine
Data Source
Figure 1
AI summary
A work machine (10) having an internal combustion engine (18) such as a diesel is connected to a transmission by a flexible coupling (46). The engine (18) may have a turbocharger to increase its output. A power turbine (58) is connected to receive exhaust products from the turbocharger turbine (28) via an exhaust aftertreatment device. The power turbine (58) is connected to either the transmission downstream of the flexible coupling (46) or to an external load. In either case, the power turbine (58) in the form of a centripetal turbine is isolated from the torsional vibrations of the IC engine (18).