Torque Transmission Unit Freewheel Layout to Prevent Converter Cavitation
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Solution Overview
Problem
Existing torque transmission units for hybrid vehicles face challenges in efficiently transmitting torque between internal combustion engines and electric machines, leading to unnecessary losses and wear due to cavitation effects in hydrodynamic converters.
Innovation Solution
The torque transmission unit incorporates a hydrodynamic converter with a lock-up clutch and a freewheel mechanism that operates in two states to prevent torque transmission from the electric machine to the hydrodynamic converter, thereby minimizing losses and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the hydrodynamic converter is used to transmit torque from the internal combustion engine to the output, then torque transmission is achieved with torque multiplication capability, but unnecessary losses and wear occur due to cavitation effects when the turbine wheel pumps against the impeller
Solution Approach 1:
The patent extracts the turbine wheel from the torque transmission path when it would otherwise pump against the impeller causing cavitation. The freewheel mechanism allows the turbine wheel to be decoupled from the impeller, preventing harmful reverse torque transmission while maintaining the hydrodynamic converter's torque multiplication capability during normal operation.
Solution Approach 2:
The freewheel acts as an intermediary mechanism between the turbine wheel and the impeller. It selectively engages to allow torque transmission in the forward direction while disengaging to prevent reverse torque transmission that would cause cavitation, thus mediating the interaction between these two components.
2Adaptability or versatility
If the turbine wheel is allowed to rotate freely relative to the impeller, then the electric machine can independently drive the output, but unnecessary bearing wear occurs and torque transmission efficiency decreases
Solution Approach 1:
The freewheel mechanism provides self-service by automatically engaging and disengaging based on the relative rotation directions of the impeller and turbine wheel. When the turbine wheel rotates in the opposite direction to the impeller, the freewheel automatically locks to prevent reverse rotation, protecting bearings without requiring external control systems.
3Loss of energy
If the freewheel is designed to completely prevent torque transmission from the second input side, then cavitation losses are minimized, but the electric machine's contribution to output torque is reduced
Solution Approach 1:
The freewheel implements partial action by selectively blocking only the harmful reverse torque transmission from the turbine wheel to the impeller, while allowing full torque transmission in the forward direction. This partial blocking action prevents cavitation losses without unnecessarily restricting the electric machine's ability to contribute torque to the output.
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 ensures reliable transmission of torque from the internal combustion engine to the output, reduces unnecessary losses, minimizes wear on the converter, and maintains high efficiency across all operating states.
Implementation Method 1
a hydrodynamic converter (65)... to transmit the first torque from the first input side to the output side when the lock-up clutch is open
Implementation Method 2
wear of the converter is minimized because, when the turbine wheel pumps against the impeller, in which the turbine wheel acts as a pump and the impeller acts as a turbine, the impeller and/or the turbine wheel is unnecessarily worn due to cavitation effects that may occur in a converter fluid of the hydrodynamic converter
Data Source
AI summary
A torque transmission unit includes a first input side, a second input side, an output side, a hydrodynamic converter and a lock-up clutch. The first input side is configured to receive a first torque, and the second input side is configured to receive a second torque. The torque transmission unit has a freewheel. The freewheel is arranged downstream of the hydrodynamic converter, and the second input side is arranged downstream of the freewheel in a torque flow of the first torque from the first input side to the output side. The freewheel is designed to, in a first freewheel operating state, connect, in a torque-locking manner, the hydrodynamic converter to the output side for the transmission of the first torque from the first input side to the output side when the lock-up clutch is open. The freewheel is designed to, in a second freewheel operating state, decouple the hydrodynamic converter from the output side, to at least partially prevent a transmission of the second torque from the second input side into the hydrodynamic converter.