Transmission Brake Support Layout for Stable Snap Ring Retention
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Solution Overview
Problem
In automatic transmissions, the supporting portions between multi-plate brake devices face challenges in maintaining rigidity due to layout restrictions, leading to potential deformation and instability in supporting snap rings, especially when using lightweight materials like magnesium alloys.
Innovation Solution
The design incorporates a piston retainer with an abutting portion that has a thicker radial thickness on the lower side to push back the supporting portion, increasing the contact area and preventing deformation, while the snap ring is supported by a protruding portion from the transmission case, enhancing stability and reducing tilt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the supporting portion is made thick to increase rigidity, then the supporting portion can resist deformation, but the layout restrictions between two multi-plate brake devices prevent increasing thickness
Solution Approach 1:
The abutting portion is designed with non-uniform radial thickness, featuring a thick portion at the lower side and a thin portion at the upper side. This local variation in thickness provides enhanced rigidity precisely where deformation is most likely to occur (lower side) while maintaining space efficiency in areas where less support is needed (upper side), thereby resolving the contradiction between strength and volume constraints.
2Volume of moving object
If the supporting portion is made thin to reduce space occupation, then the layout between brake devices is optimized, but the supporting portion deforms under piston pressure
Solution Approach 1:
The abutting portion features a thick portion at the lower side where the snap ring is most vulnerable to deformation under piston pressure. This localized thickness enhancement provides the necessary structural stability and deformation resistance precisely where needed, while keeping other areas thinner to optimize space occupation, thus resolving the contradiction between volume efficiency and stability.
3Reliability
If the supporting portion is made thick to prevent deformation, then the snap ring is stably supported, but the overall device size increases
Solution Approach 1:
Rather than uniformly thickening the supporting portion throughout, the invention applies thickness selectively - creating a thick portion at the lower side where snap ring stability is critical and a thin portion at the upper side where less support is required. This localized approach ensures reliable snap ring support while minimizing the overall device size and maintaining layout efficiency.
Data Source
AI summary
A first multi-plate brake device and a second multi-plate brake device are arranged side by side in a direction of a rotating axis X along an inner peripheral surface of a transmission case. In the second multi-plate brake device, the snap ring is supported by a supporting portion which is formed on the first multi-plate brake device side of the snap ring and protrudes from the inner peripheral surface of the transmission case radially inward to the rotating axis X. The piston retainer of the first multi-plate brake device includes an abutting portion that protrudes to the second multi-plate brake device side and abuts the supporting portion from the opposite side of the snap ring of the second multi-plate brake device. The abutting portion includes a thick portion whose radial thickness on a lower side in a vertical direction is increased as compared to on an upper side in the vertical direction based on a state of mounting the automatic transmission on a vehicle.