Transmission Brake Hub Fluid Evacuation Design
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Solution Overview
Problem
Hydraulically-actuated automatic transmission brakes in motor vehicles experience high drag losses due to direct splining of separator plates to the transmission case, making it difficult to evacuate transmission fluid and increasing installation complexity and costs.
Innovation Solution
A brake hub assembly that eliminates the need for machining spline teeth in the transmission case by using a hub with cutouts for the brake piston and securing the brake hub to the pump support instead of the case, allowing the brake cylinder to rotate outside the clutch pack and facilitating oil evacuation, thereby reducing hydraulic drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If separator plates are splined directly to the transmission case, then the brake assembly is structurally stable, but hydraulic drag increases due to difficulty in evacuating transmission fluid
Solution Approach 1:
The patent extracts the splining function from the transmission case and relocates it to a dedicated hub component. The hub is secured to the transmission case while the separator plates are splined to the hub, allowing fluid to be evacuated from the clutch pack without the constraint of direct case splining.
Solution Approach 2:
The hub acts as an intermediary component between the transmission case and the separator plates. It provides the splining interface for the brake assembly while being secured to the case, mediating the connection in a way that facilitates fluid evacuation and reduces hydraulic drag.
2Ease of manufacture
If separator plates are splined directly to the transmission case, then the brake assembly is structurally stable, but installation complexity increases requiring final assembly instead of subassembly
Solution Approach 1:
The patent segments the brake assembly into modular components that can be assembled as a subassembly. The separator plates are splined to the hub in a modular configuration, allowing the entire brake assembly to be pre-assembled and installed as a unit rather than requiring complex final assembly operations.
3Ease of manufacture
If spline teeth are machined in the transmission case, then the brake assembly is securely attached, but manufacturing costs increase and scrap production increases
Solution Approach 1:
The patent extracts the expensive and wasteful machining operation from the transmission case and relocates the splining function to the hub component. This eliminates the need to machine spline teeth in the transmission case, reducing manufacturing costs and scrap production while maintaining secure attachment through the hub's splined connection.
Data Source
AI summary
A brake assembly includes first and second brakes, a gearset including first and second members, a hub held against rotation, the first brake selectively producing a connection between the hub and the first member, the second brake selectively producing a connection between the hub and the second member, and a support secured to a transmission case and the hub, the support formed with brake-apply circuits, each circuit corresponding to one of the brakes.