Torque Converter Stator Control for Idle Vibration Reduction
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Solution Overview
Problem
Conventional torque converters transmit torque pulses from fuel-efficient engines as noise and vibration due to their design, which is most effective at zero output speed, leading to undesirable vehicle motion when brakes are applied.
Innovation Solution
A controllable clutch assembly is integrated into the torque converter, allowing the stator to rotate with the turbine and apply an opposing torque, reducing output and vibration by selectively engaging or disengaging the stator-turbine coupling based on vehicle conditions, such as coasting, braking, or idling, using a multi-plate clutch pack and a controller for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the torque converter is designed to provide greatest torque increase at zero output speed, then torque multiplication capability is improved, but engine vibration and noise are transmitted to the vehicle suspension
Solution Approach 1:
The patent applies a controllable clutch assembly that dynamically changes the coupling state between stator and turbine based on operating conditions. During idle, the clutch engages to couple stator and turbine, preventing stator from reacting against the one-way clutch and applying load to the fixed member, thereby reducing torque output and vibration. During acceleration, the clutch disengages to enable relative rotation and torque multiplication, resolving the contradiction between vibration reduction and power transmission
Solution Approach 2:
The system changes the operational parameters of the stator-turbine interaction by controlling the clutch engagement state. When the clutch is engaged, the relative speed and torque reaction parameters are modified to reduce vibration during idle. When disengaged, the parameters return to normal for torque multiplication during acceleration, allowing adaptive optimization of both vibration and power transmission characteristics
2Power
If the stator is prevented from rotating to provide torque multiplication, then power transmission is improved, but the stator applies load to the fixed member causing vibration during idle
Solution Approach 1:
The controllable clutch assembly dynamically switches the stator's rotational constraint state. During idle conditions, the clutch engages to allow stator rotation with the turbine, preventing reaction against the fixed member and eliminating vibration. During acceleration, the clutch disengages to prevent stator rotation, enabling torque multiplication through the one-way clutch mechanism, thus dynamically optimizing both vibration reduction and power transmission
3Object-generated harmful factors
If a controllable clutch assembly is added to reduce vibration, then engine vibration and noise are reduced, but device complexity increases
Solution Approach 1:
The controllable clutch assembly serves multiple functions: it acts as a vibration reduction mechanism during idle by coupling stator and turbine, and simultaneously serves as a torque management device during acceleration by disengaging to enable torque multiplication. This multi-functionality justifies the added complexity by providing both vibration reduction and power transmission optimization in a single component
Solution Approach 2:
The clutch assembly acts as an intermediary between the stator and turbine, controlling their relative motion based on operating conditions. This intermediary component enables the system to switch between vibration reduction mode (clutch engaged) and torque multiplication mode (clutch disengaged), mediating the conflicting requirements of the torque converter system
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 solution significantly reduces engine vibration and torque fluctuations during idle, minimizing the need for braking and enhancing the overall transmission efficiency by internally managing torque reactions within the stator-turbine assembly.
Implementation Method 1
the controllable clutch assembly is a multi-plate clutch pack formed of intermeshed first and second friction discs
Implementation Method 2
an impeller, a stator and a turbine that cooperate using hydraulic fluid to transmit energy from an input (e.g., engine) to an output (e.g., transmission)
Implementation Method 3
a one-way clutch coupled to the stator and configured to couple to a fixed member
Data Source
AI summary
A torque converter for a vehicle includes an impeller, a turbine, a stator positioned between the impeller and the turbine, a one-way clutch coupled to the stator and configured to couple to a fixed member, and a controllable clutch assembly. The controllable clutch assembly is configured to selectively engage the stator and the turbine such that the stator is able to rotate with the turbine to facilitate preventing the stator from reacting against the one-way clutch and applying a load to the fixed member and thereby facilitating reducing an output of the torque converter and reducing engine vibration during idle, and disengage the stator from the turbine to enable relative rotation between the stator and turbine.