Automatic Transmission Piston Servo Pin Support
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Solution Overview
Problem
Automatic transmission pistons with servo pins experience wear and binding due to high loads and excentric loading, leading to damage and reduced effectiveness, with existing solutions only addressing damage after it occurs rather than preventing it.
Innovation Solution
A hydraulic piston assembly with an extended length servo pin supported on both ends, one end in the servo pin bore and the other in a cover support bore, maintaining proper alignment and reducing wear, along with a kit and method for replacing the existing servo pin without modifying the transmission housing or piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a servo pin is used to support the piston, then the piston can be guided in the piston bore, but the servo pin experiences wear and scoring due to high loads and excentric loading
Solution Approach 1:
A bushing is introduced as an intermediary component between the servo pin and the piston bore. The bushing absorbs the wear and scoring that would otherwise occur on the servo pin, serving as a sacrificial element that protects the more critical servo pin while still providing the necessary guidance function.
Solution Approach 2:
The bushing acts as a pre-positioned protective layer that cushions the servo pin from direct contact with the piston bore walls. This beforehand cushioning prevents the harmful wear and scoring effects from occurring on the servo pin during normal operation.
2Manufacturing precision
If the servo pin is extended to provide support, then the piston alignment is improved, but the device complexity increases
Solution Approach 1:
The support function is segmented into two separate components: the extended servo pin provides structural support and alignment, while the bushing provides the sliding interface. This segmentation allows each component to be optimized for its specific function while maintaining overall simplicity.
Solution Approach 2:
The extended servo pin serves multiple functions: it provides structural support for the piston, maintains proper alignment through its extended length, and works in conjunction with the bushing to reduce wear. The bushing itself serves as both a wear surface and a guiding element.
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 prevents wear and binding, ensuring the piston moves freely and reliably applies or releases the band clutch, reducing the risk of damage and extending the lifespan of transmission components.
Implementation Method 1
high loads or excentric loading on the piston may create wear and scoring in the pin bore or on the pin itself, which can restrict the motion of the piston
Implementation Method 2
the servo pin is coupled to the piston and extends along a central longitudinal axis, the first end of the servo pin extending from the hydraulic fluid release side of the piston to be slidably received in the servo pin bore
Data Source
AI summary
In an automotive automatic transmission, a force applying piston mounted on a servo pin is supported at both sides of the piston. A first end of the servo pin is conventionally supported in a servo pin bore. A second, extended end is supported in a specially configured support bore formed in the assembly cover. Excentric loading and excessive wear of the servo pin and servo pin bore, which can result in damage to the piston, is reduced or eliminated thereby.