Fluid Accumulator Assembly for Automatic Transmission Shock Damping
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Solution Overview
Problem
Automatic transmissions, particularly those with solenoid-controlled fluid circuits, face issues with pressure and volume changes that can damage components like planetary gears due to the lack of effective shock damping mechanisms.
Innovation Solution
A fluid accumulator assembly comprising a piston and a closed-and-ground compression spring, which acts as a 'moveable wall' within the fluid circuit to absorb and mitigate pressure and volume changes by sliding within a piston cylinder, maintaining stable fluid pressure and protecting transmission components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional accumulator design is used in solenoid-controlled fluid circuits, then the fluid circuit can handle pressure changes, but the pressure fluctuations can still damage transmission components like planetary gears
Solution Approach 1:
The patent applies beforehand cushioning by pre-installing the accumulator with a piston and compression spring into the fluid circuit before pressure fluctuations occur. The compression spring is pre-compressed to a predetermined force that will counteract incoming pressure waves from solenoid actuation, cushioning the impact before it reaches vulnerable components like planetary gears.
Solution Approach 2:
The accumulator assembly acts as an intermediary element between the solenoid-controlled fluid circuit and the transmission components. The piston and spring mechanism mediates the pressure transmission, absorbing and dampening pressure fluctuations before they propagate through the fluid circuit to damage-sensitive components.
2Reliability
If the piston and spring assembly is made larger to better absorb pressure fluctuations, then shock damping improves, but the accumulator cannot fit within the constrained valve body space
Solution Approach 1:
The patent applies nesting by placing the piston inside a cylinder and the compression spring inside the piston's hollow interior chamber. This nested arrangement allows the accumulator components to be compactly organized, fitting a functional assembly with multiple moving parts into a small volume that can be accommodated within the valve body's constrained space.
Solution Approach 2:
The invention utilizes the vertical dimension by orienting the piston and spring assembly vertically within the accumulator cylinder, allowing the spring to compress along the length of the piston rather than requiring lateral space. This dimensional arrangement maximizes the shock-absorbing capability within the limited horizontal footprint available in the valve body.
3Volume of moving object
If a small spring is used to fit within the compact piston, then the accumulator fits in the valve body, but the spring must be extremely stiff to provide sufficient damping force
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the spring's physical parameters - specifically the wire diameter, coil diameter, and number of active coils - to achieve the optimal spring constant. The spring is designed with a predetermined spring constant that provides sufficient damping force despite the small size, balancing the conflicting requirements of compact dimensions and adequate shock absorption capability.
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 fluid accumulator effectively reduces pressure fluctuations, preventing damage to transmission components by accommodating pressure waves and maintaining stable fluid pressure, ensuring consistent operation across varying conditions.
Implementation Method 1
a compression spring sized and configured to fit within an inner diameter of a piston... placing the large-bore piston into the accumulator piston cylinder
Implementation Method 2
a compression spring sized and configured to fit within an inner diameter of a piston... having a spring constant in the range of approximately 190 pounds/inch to approximately 210 pounds/inch
Implementation Method 3
a piston sized and configured for sliding receipt in the bore... in fluid communication with a solenoid-controlled fluid circuit of the transmission
Data Source
AI summary
A fluid accumulator assembly used with 2002 to 2005 model years of ZF Getriebe's GmbH ZF-6HP19, ZF-6HP26, ZF-6HP32 automatic transmissions, and model years up to 2011 of Ford's 6R60 automatic transmissions. The fluid accumulator assembly includes a piston that can be received into a bore that is in fluid communication with a solenoid-controlled fluid circuit of the transmission. The fluid accumulator assembly also includes a compression spring sized and configured to fit within the piston, and used to provide an urging force to the piston.