Automatic Transmission Shift Element With Fast-Fill Valve Sealing
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Solution Overview
Problem
Existing automatic transmission systems face challenges in achieving short shift times and high transmission efficiency due to high flow requirements and complex configurations, which lead to increased power consumption and installation costs, as well as reliability issues with locking devices and manufacturing inaccuracies.
Innovation Solution
A hydraulically actuatable shift element with a clutch piston, fast fill piston, and valve device, featuring a fast fill pressure chamber and clutch pressure chamber, where the valve device includes a sealing body and control body with pressure surfaces that allow for efficient rapid filling and secure sealing, reducing the need for high flow rates and simplifying the configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional clutch system is used to eliminate clearance during engagement, then the shift time can be reduced, but the flow requirement of the transmission pump increases significantly
Solution Approach 1:
The patent divides the single clutch system into two independent clutches: a first clutch for eliminating clearance and a second clutch for torque transmission. This segmentation allows the first clutch to have a smaller hydraulic pressure surface area, thereby reducing the flow requirement while still achieving rapid clearance elimination and short shift times.
Solution Approach 2:
The first clutch is designed to perform only the partial function of eliminating clearance without needing to transmit the full torque. By applying excessive action only where needed (clearance elimination), the system achieves rapid engagement without requiring the large flow rates that would be needed if a single clutch had to perform both functions.
2Reliability
If a locking device is added to prevent radial displacement of the valve spool, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent extracts the locking function from a separate locking device and integrates it into the valve spool structure itself through the tapered bore design. The radial displacement of the valve spool against the tapered surface inherently provides the locking action, eliminating the need for additional locking components while maintaining reliability.
Solution Approach 2:
The valve spool and locking mechanism are merged into a single integrated component. The tapered bore and valve spool work together as a unified system where the valve spool's radial movement against the tapered surface simultaneously achieves both positioning and locking functions, reducing device complexity.
3Manufacturing precision
If the valve spool is allowed to move radially during operation, then the manufacturing precision requirements are reduced, but the reliability decreases due to potential malpositioning
Solution Approach 1:
The patent introduces controlled dynamics by allowing the valve spool to move radially during operation against the tapered bore surface. This dynamic adjustment capability compensates for manufacturing tolerances and wear, maintaining reliable sealing and positioning without requiring extremely tight clearance fits, thus balancing manufacturing precision requirements with operational reliability.
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 solution reduces the flow requirement of the transmission pump, decreases power consumption, and enhances transmission efficiency while maintaining reliable and spontaneous gear changes, thereby improving the overall performance and reducing costs.
Implementation Method 1
a clutch piston (101) having a first hydraulic pressure surface (A11), onto which pressure can be applied, and a clutch pressure chamber (117), in which the clutch piston (101) is arranged axially displaceably
Implementation Method 2
multiple friction bodies (104), wherein a force on the fast fill piston (102) is generatable by a device (126), in order to reduce the clearance
Data Source
AI summary
A hydraulically actuatable shift element (100) includes a clutch piston (101), a fast fill piston (102), a fast fill valve (103), a fast fill pressure chamber (126), and a clutch pressure chamber (117). The fast fill valve (103) includes a sealing body (132) and a control body (131). Before the actuation of the shift element (100), the sealing body (132) is in a first switching position, in which the fast fill pressure chamber (126) is connected to a pressurized oil source (108) and, after the actuation of the shift element (100) in a second switching position, seals off the fast fill pressure chamber (126) with respect to the rest of the hydraulic system. The control body (131) has a first pressure surface (A18) and a second pressure surface (A19), wherein, in the first switching position, only the first pressure surface (A18) is pressurizable from the pressurized oil source (108). The fast fill valve (103) is configured such that, in the second switching position or between the first switching position and the second switching position of the control body (131), the second pressure surface (A19), in addition to the first pressure surface (A18), is pressurizable.