Angular Contact Ball Ramps for Turbocharger Torque Transmission
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Solution Overview
Problem
Driven turbochargers face inefficiencies in torque transmission due to limited clamping forces, leading to reduced torque capacity and increased wear, especially during varying torque operations.
Innovation Solution
A planetary traction drive system with angular contact ball ramps that increase clamping forces by using a ring gear interfaced with first and second ring rollers through first and second angular contact ball ramps, providing low conformity ball races for efficient movement and concentric location of the ring gear, enhancing torque transmission efficiency and preventing slip during high torque operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional planetary traction drive is used, then device complexity is reduced, but torque capacity and clamping force are insufficient during high torque operations
Solution Approach 1:
The planetary traction drive is segmented into multiple independent components: sun gear, planet gears, ring gear, and traction elements. This segmentation allows each component to be optimized for specific functions, with the traction elements providing enhanced clamping force capability without requiring complete redesign of the entire drive system.
Solution Approach 2:
Traction elements are introduced as intermediary components between the planet gears and ring gear. These elements act as mediators that transmit force while providing increased clamping force capability, resolving the contradiction between maintaining simple device architecture and achieving high torque capacity.
2Reliability
If clamping forces are increased to prevent slip, then torque transmission reliability improves, but friction and wear increase
Solution Approach 1:
Traction elements with curved or spherical contact surfaces are used instead of flat contacts. The curved surfaces distribute contact forces more evenly, reducing peak stress and friction while maintaining reliable torque transmission. This spherical geometry allows for smoother rolling motion that reduces wear.
Solution Approach 2:
The patent replaces pure mechanical friction-based force transmission with a hybrid system incorporating elastic deformation and geometric constraint mechanisms. This substitution reduces reliance on high friction forces while maintaining torque transmission reliability.
3Stability of the object's composition
If additional support bearings are added to ensure balanced rotation, then rotational stability improves, but device complexity and friction increase
Solution Approach 1:
The support function is merged into the existing planetary gear structure. The planet gears themselves provide both power transmission and rotational stabilization functions, eliminating the need for separate support bearings. This integration maintains rotational stability while reducing device complexity.
Solution Approach 2:
The planet gears are designed to perform multiple functions simultaneously: power transmission, force distribution, and rotational stabilization. This multi-functionality eliminates the need for additional dedicated support components, reducing overall system complexity while maintaining stability.
4Manufacturing precision
If ball races with high conformity are used, then precision and location accuracy improve, but movement efficiency decreases due to increased friction
Solution Approach 1:
Different regions of the ball race are designed with different conformity characteristics. The entry and exit zones have lower conformity to reduce friction and facilitate ball movement, while the central loading zone maintains higher conformity for precision and accurate ball location. This localized variation in quality resolves the contradiction between precision and efficiency.
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 increases torque capacity and improves the life and efficiency of the planetary traction drive by maintaining consistent clamping forces across varying torque levels, reducing friction and wear, and ensuring balanced rotation without additional support bearings.
Implementation Method 1
the first angular contact ball ramp and the second angular contact ball ramp increase clamping forces in the planetary traction drive when torque through the ring gear increases
Implementation Method 2
shaped to have a low conformity of the balls in the ball races to provide high efficiency movement of the balls in the ball races
Data Source
AI summary
Disclosed is a planetary traction drive for a driven turbocharger that utilizes angular contact ball ramps to provide variable clamping depending on torque throughput. The ball ramps are located between ring rollers and a ring gear, and function to locate the ring gear concentrically to the ring rollers. The angled contact axes of the ball ramps allows use of a low conformity contact between the balls and ball races in the ball ramps to provide efficient movement, while simultaneously locating ring gear concentrically to the traction rings.