Automated Manual Transmission Neutral Hold by Fluid Pressure
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Solution Overview
Problem
Existing automated manual transmissions in heavy-duty vehicles require mechanical engagement means to maintain gear positions, which increases manufacturing costs and can lead to actuator overheating due to prolonged engagement of gear combinations without a neutral position.
Innovation Solution
An automated manual transmission that maintains the neutral position of the shift rod solely through fluid pressure, eliminating the need for mechanical engagement means, using a transmission control unit and actuator to balance fluid pressures and control valve duty cycles to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical engagement means are used to maintain gear positions, then the shift rod can be maintained in predetermined positions without fluid pressure, but manufacturing costs increase and device complexity increases
Solution Approach 1:
The patent removes mechanical engagement means (such as detents or springs) from the transmission system. Instead, the neutral position is maintained solely by fluid pressure from the actuator, eliminating unnecessary mechanical components while preserving the functionality of maintaining gear positions.
Solution Approach 2:
The patent replaces mechanical engagement means with a hydraulic/pneumatic system. The actuator uses fluid pressure to maintain the shift rod in the neutral position, substituting mechanical components with a fluid-based system that reduces complexity and manufacturing costs.
2Duration of action of stationary object
If mechanical engagement means are used to maintain gear positions, then gear combinations can be engaged for prolonged periods, but actuator overheating occurs due to prolonged engagement without neutral position
Solution Approach 1:
The patent enables periodic engagement and disengagement of the neutral position. The actuator can maintain the neutral position temporarily during gear shifts, then disengage to allow gear combinations to engage. This periodic action prevents continuous operation that would cause overheating, while still providing the necessary neutral position functionality.
Solution Approach 2:
By removing mechanical engagement means, the system allows the actuator to disengage completely during gear engagement periods. This eliminates the need for the actuator to maintain continuous pressure, reducing thermal load and preventing overheating while enabling prolonged gear engagement.
3Ease of manufacture
If mechanical engagement means are eliminated, then manufacturing costs are reduced, but the neutral position must be maintained by continuous fluid pressure
Solution Approach 1:
The system uses periodic action where the actuator maintains fluid pressure only temporarily during gear shift operations to establish the neutral position. Once the shift is complete, the actuator can disengage, allowing gear combinations to engage without continuous fluid pressure. This reduces energy consumption compared to continuous pressure maintenance while still eliminating mechanical engagement means.
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 manufacturing costs and prevents actuator overheating by maintaining the neutral position through fluid pressure alone, allowing for efficient gear shifting without mechanical synchronizers and ensuring robust transmission performance.
Implementation Method 1
an actuator for moving the shift rod between the first position, the second position and the neutral position by applying a fluid pressure acting on the shift rod
Implementation Method 2
a mechanical engagement means is provided. The mechanical engagement means maintains the shift rod in the predetermined position without having to apply fluid pressure acting on the shift rod by means of the actuator
Data Source
AI summary
An automated manual transmission, comprising:a transmission control unit,a shift rod movable between a predetermined first position in which it engages a first gear combination of the transmission, a predetermined second position in which it engages a second gear combination of the transmission, and a predetermined neutral position in which it does not engage any gear,an actuator for moving the shift rod between the first position, the second position and the neutral position by applying a fluid pressure acting on the shift rod in response to signals from the transmission control unit,mechanical engagement means for maintaining the first and second positions of the shift rod without applying any fluid pressure by means of the actuator,wherein the transmission is adapted to maintain the neutral position of the shift rod solely by applying fluid pressure acting on the shift rod.