Multi-area Piston Staged Actuation for Transmission Clutch Engagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current transmission systems with multiple gear ratios face challenges in efficiently engaging and disengaging clutches to transition between gear ratios, often requiring additional actuation components and experiencing unintended torque transfer due to lash or shaft compliance.
Innovation Solution
A dual-stage piston design with an annular piston body and auxiliary pistons is used, where the auxiliary pistons are actuated at a first pressure to engage the clutch pack in a first torque transfer configuration, and the piston body is actuated at a higher pressure to engage in a second torque transfer configuration, utilizing the clutch pack's separator springs for return and additional torque transfer without additional actuation components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-stage piston is used to engage the clutch pack, then the structure is simple, but unintended torque transfer occurs due to lash or shaft compliance during gear ratio transitions
Solution Approach 1:
The piston is segmented into two distinct stages: an auxiliary piston for initial clutch engagement and a main piston body for full engagement. This segmentation allows the auxiliary piston to take up lash and comply with shaft compliance first, preventing unintended torque transfer, while the main piston body completes the engagement. The segmented design resolves the contradiction by improving torque transfer efficiency through staged actuation while maintaining reasonable structural complexity.
2Reliability
If additional actuation components are added to prevent unintended torque transfer, then torque transfer efficiency improves, but device complexity increases
Solution Approach 1:
The auxiliary piston and main piston body are merged into a single integrated piston assembly that acts as one unified component. This merging eliminates the need for separate actuation components while achieving staged engagement through the dual-stage design. The auxiliary piston and main piston body work together in sequence, resolving the contradiction by improving torque transfer efficiency without increasing device complexity through additional actuation components.
Solution Approach 2:
The dual-stage piston design is self-actuating through fluid pressure applied to both the auxiliary piston and main piston body simultaneously. The staged engagement occurs automatically based on the different travel distances and pressure requirements of each stage, without requiring additional control valves or actuators. This self-service mechanism resolves the contradiction by improving torque transfer efficiency while avoiding additional actuation components.
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 design enhances torque transfer efficiency and reduces unintended torque transfer by staged actuation of the piston and auxiliary pistons, allowing for smooth gear ratio transitions without additional actuation components, improving the overall performance and reliability of transmission systems.
Implementation Method 1
increasing a fluid pressure in a bore chamber to a first pressure to actuate the auxiliary pistons. The method may further include increasing the fluid pressure in the bore chamber to a second pressure greater than the first pressure to actuate the piston body
Implementation Method 2
The clutches may comprise alternating friction plates and separator plates that are configured to selectively couple two rotating elements (shafts, gears, etc.)
Implementation Method 3
The transmission may further include a return spring adapted to bias the annular piston body in a direction away from the clutch pack
Data Source
AI summary
A transmission includes a case defining a bore and a piston disposed within the bore. The piston and the case define a fluid chamber in fluid communication with a fluid source. The piston includes an annular piston body defining a plurality of auxiliary bores angularly spaced along the annular piston body about a central axis of the annular piston body. The piston further includes a plurality of auxiliary pistons disposed within the auxiliary bores. The piston body and the auxiliary pistons have rear surfaces in communication with the fluid chamber. The transmission further includes a clutch pack disposed opposite the piston from the fluid chamber. The clutch pack includes at least one friction plate, at least one separator plate, and at least one separator spring. The transmission further includes a return spring adapted to bias the annular piston body in a direction away from the clutch pack.