Shift Rod Neutral Holding by Fluid Pressure in AMT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing automated manual transmissions require mechanical engagement means to maintain the neutral position of the shift rod, which increases manufacturing costs and can lead to actuator overheating due to prolonged engagement of gear combinations without a mechanical synchronizer.
Innovation Solution
The automated manual transmission maintains the neutral position solely through fluid pressure applied by the actuator, eliminating the need for mechanical engagement means and allowing for efficient gear shifting without a mechanical synchronizer, using a combination of hydraulic or pneumatic actuators and pulse width modulation (PWM) control to manage fluid pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical engagement means are used to maintain the neutral position of the shift rod, then the shift rod can be maintained in position without fluid pressure, but manufacturing costs increase and device complexity increases
Solution Approach 1:
The patent removes the mechanical engagement means (such as springs or detents) from the neutral position maintenance system. Instead, the neutral position is maintained solely by fluid pressure from the actuator, simplifying the device structure and reducing manufacturing costs while maintaining reliability through the hydraulic/pneumatic system alone.
2Use of energy by moving object
If mechanical engagement means are used to maintain gear combinations, then the actuator does not need to apply continuous fluid pressure, but the actuator can overheat due to prolonged engagement without mechanical synchronizer
Solution Approach 1:
The patent implements a control strategy where the actuator applies fluid pressure in a periodic or intermittent manner rather than continuously. The actuator engages the gear combination, maintains it for the necessary duration, then releases and re-engages as needed. This periodic action prevents continuous operation that would cause overheating, while still achieving reliable gear engagement and maintenance through controlled cycles of pressure application and release.
3Device complexity
If mechanical engagement means are eliminated and fluid pressure alone is used to maintain neutral position, then manufacturing costs are reduced and device complexity is reduced, but the actuator must maintain continuous fluid pressure
Solution Approach 1:
The control system manages fluid pressure application in a periodic manner, activating the actuator only when gear engagement or disengagement is required. During neutral position maintenance, the system uses controlled cycles of pressure application rather than continuous pressure, reducing energy consumption while maintaining the simplified structure without mechanical engagement means.
4Productivity
If the transmission is designed without mechanical synchronizer, then the neutral position is used temporarily for synchronization, but the actuator may overheat if engaged for too long
Solution Approach 1:
The patent employs periodic action by controlling the actuator to engage and disengage in controlled cycles during the gear shifting process. The actuator quickly engages the neutral position to allow synchronization, then disengages and re-engages to complete the shift. This periodic engagement pattern ensures the actuator operates only for the minimum necessary time, preventing overheating while maintaining high gear shifting speed and productivity.
Solution Approach 2:
The system rushes through the neutral position engagement phase by minimizing the duration the actuator remains engaged during synchronization. The control strategy quickly moves through the neutral state to complete the gear shift, reducing the time the actuator is under load and preventing heat buildup, thereby maintaining both speed and thermal management.
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 using fluid pressure alone, enabling robust and efficient gear shifting in unsynchronized transmissions, particularly suitable for heavy-duty vehicles.
Implementation Method 1
Each actuator comprises a piston arranged in a cylinder having one or more filling chambers connected to a hydraulic or pneumatic system by means of valves. To initiate a gear shift, the valves are controlled to selectively pressurize the filling chambers and thereby move the piston
Implementation Method 2
Each actuator comprises a piston arranged in a cylinder having one or more filling chambers connected to a hydraulic or pneumatic system by means of valves
Implementation Method 3
In order to ensure that the shift rod does not move once the desired position is reached, 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
Implementation Method 4
The valves are controlled to selectively pressurize the filling chambers and thereby move the piston, in turn acting on a shift rod connected to a shift fork used to engage a specific gear combination
Data Source
Figure 1~2
Figure 3
AI summary
An automated manual transmission (2), comprising: - a transmission control unit (10), - a shift rod (20) 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 (30) 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 (40) 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 by means of the actuator.