Variable-Pitch Stator Torque Converter Blade Flutter Control
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Solution Overview
Problem
Existing torque converters with fixed stators face challenges in optimizing torque converter tightness (K-factor) for varying operating conditions, as they cannot dynamically adjust to balance engine efficiency and power production, leading to compromises in performance and fuel economy.
Innovation Solution
A torque converter with a variable-pitch stator that includes a hub, blades, and an annular carrier, where the blades pivot between open and closed positions in response to fluid pressure, allowing the stator to adjust its pitch to change the fluid flow area and converter tightness, and a thrust disk or ball-ramp mechanism to prevent blade flutter and ensure smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed stator is used in the torque converter, then the structure is simple and reliable, but the torque converter cannot dynamically adjust tightness (K-factor) for varying operating conditions, leading to compromises in performance and fuel economy
Solution Approach 1:
The stator blades are designed to pivot between open and closed positions dynamically in response to fluid pressure changes. The carrier rotates relative to the hub to adjust blade pitch angles, transforming the static stator structure into a dynamic one that can adapt to varying operating conditions and optimize torque converter tightness
Solution Approach 2:
The blade pitch angle parameter is changed dynamically through carrier rotation. By altering the pitch angle of the stator blades, the fluid flow characteristics and torque converter tightness are adjusted to match different operating conditions, enabling optimization of both fuel economy and power production
2Adaptability or versatility
If variable-pitch blades are added to the stator, then torque converter tightness can be adjusted, but blade flutter may occur during operation
Solution Approach 1:
The thrust disk is positioned to engage with the carrier and prevent rotation, thereby preemptively counteracting the fluid forces that would cause blade flutter. This preliminary anti-action stabilizes the blades during operation while still allowing pitch adjustment when needed
Solution Approach 2:
The thrust disk acts as an intermediary between the fluid forces and the carrier. It absorbs and dissipates the forces that would cause flutter, mediating the interaction between the variable-pitch mechanism and the fluid flow to ensure stable operation
3Use of energy by moving object
If the stator blades are biased to the closed position, then fuel economy improves at lower speeds, but power production at higher speeds may be limited
Solution Approach 1:
The stator blade pitch is periodically adjusted based on operating conditions. At lower speeds, the biased closed position optimizes fuel economy, while at higher speeds, the blades pivot to more open positions to maximize power production, creating a periodic adaptation cycle that optimizes performance across the operating range
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
Enables dynamic adjustment of the torque converter's tightness based on operating conditions, improving fuel economy, reducing vibrations, and enhancing engine performance by allowing the engine to operate efficiently at lower speeds and produce more power at higher speeds, while minimizing blade flutter and transition time.
Implementation Method 1
The first and second faces are configured to frictionally engage to resist rotation of the carrier relative to the hub in response to axial movement of the turbine towards the impeller
Implementation Method 2
Each of the blades are biased to the closed position and are configured to pivot to the open position in response to fluid exiting the turbine overcoming the bias
Data Source
AI summary
A torque converter includes an impeller, a turbine, and a variable-pitch stator adjacent the turbine. The stator includes a hub and blades circumferentially arranged around the hub and pivotal between open and closed positions. The stator further includes an annular carrier connected to the blades and configured to rotate relative to the hub in response to pivoting of the blades, and a thrust disk engageable with the carrier to inhibit rotation of the carrier relative to the hub to maintain positions of the blades.