Hydrodynamic Coupling Torque Control in Turbocompound Engines
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Solution Overview
Problem
Current transmission systems between the power turbine and crankshaft in turbocompound combustion engines face challenges in controlling torque transmission, leading to uncertain engine performance, noise, and emissions, especially during cold starts and auxiliary braking.
Innovation Solution
A method that continuously monitors engine load, temperature, and NVH parameters to adjust the torque transmitting ability of the hydrodynamic coupling, including braking the power turbine side to control rotational speed and fluid levels, optimizing torque transmission and reducing noise and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydrodynamic coupling is left partially filled with fluid during cold starts, then the power turbine inertia provides resistance to crankshaft rotation, but this causes uncertain engine performance and difficulty in controlling engine start-up
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the fluid level in the hydrodynamic coupling during engine operation. During cold starts, the control system modifies the filling level to optimize torque transmission characteristics, enabling reliable engine start-up while maintaining controllability. This involves changing the physical state parameter (fluid level) to adapt to different operating conditions.
2Power
If the hydrodynamic coupling transmits torque during auxiliary braking, then braking performance is improved, but torque variability and control difficulty increase
Solution Approach 1:
The patent implements feedback control by continuously monitoring engine parameters and braking conditions, then adjusting the hydrodynamic coupling torque transmission accordingly. The control system receives feedback about engine speed, load, and braking demands, and modifies the coupling characteristics in real-time to optimize braking performance while maintaining controllability. This closed-loop control resolves the contradiction between maximizing braking power and maintaining ease of operation.
3Productivity
If the hydrodynamic coupling operates with variable torque transmission, then engine performance and emissions are improved, but the complexity of the transmission system increases
Solution Approach 1:
The patent applies universality by designing the hydrodynamic coupling to perform multiple functions: torque transmission during normal operation, auxiliary braking, cold start assistance, and emissions control. By making the coupling multi-functional through variable fluid level control and adaptive torque characteristics, the system achieves improved engine performance across different operating conditions without adding separate dedicated systems for each function, thereby limiting the increase in overall 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
Enhances engine control and performance by optimizing torque transmission, reducing noise and emissions, and improving auxiliary braking efficiency, particularly during cold starts and low engine loads.
Implementation Method 1
Said transmission driven by the power turbine and connected to the crankshaft comprises a hydrodynamic coupling. The hydrodynamic coupling is used in order to avoid transmission of damaging irregular rotation to the power turbine and gearing on the power turbine side of the hydrodynamic coupling.
Implementation Method 2
if one or several of parameters a to c has passed a predetermined value for each of said parameters in one first direction, then braking a power turbine side of said hydrodynamic coupling
Implementation Method 3
Pressure force from the exhaust gases is transmitted to a crank shaft of the engine via a transmission to be used for vehicle propulsion.
Implementation Method 4
A turbocompound combustion engine, such as disclosed in for example U.S. Pat. No. 5,884,482, is equipped with a turbocharger turbine arranged for receiving exhaust gas from said combustion engine.
Data Source
AI summary
A device and method are provided for automatically adjusting torque transmitting ability of a hydrodynamic coupling in a transmission arranged between a power turbine and a crank shaft in a turbocompound combustion engine. The method includes continuously registering a value for one or several of:a. engine load parameter for the combustion engine and/or,b. temperature in the combustion engine and/or,c. parameters for indicating NVH in the transmission;If parameters a to c have passed a predetermined value for each of the parameters, then braking a power turbine side of the hydrodynamic coupling and continuously adjusting said torque transmitting ability of the hydrodynamic coupling in dependence of the development of the parameters a to c. Increased control of the transmission and engine performance, especially lower noise and exhaust emissions, and accelerated heating of the engine during cold starts, but also better auxiliary braking, can be provided.