Gearbox Open-Loop Control for Synchronization Delays
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Solution Overview
Problem
Existing gearbox control systems face challenges in synchronizing gear ratio changes, often resulting in delayed torque implementation and asynchronous engagement due to slip conditions during gear ratio transitions.
Innovation Solution
The implementation of an open-loop control method that determines a specified differential speed profile between the input shaft and the synchronous speed of the gear ratio to be engaged, using proportionally controllable shift elements, allowing for precise synchronization by influencing torque demand and control profiles based on various parameters such as slip time, load conditions, and temperature, ensuring smooth gear transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a predetermined amount of time is allocated before synchronous speed for gear changeover, then the gear ratio can be activated with sufficient time margin, but the gear ratio cannot be engaged at the suitable synchronous speed due to delay
Solution Approach 1:
The control device determines a torque demand profile in advance that anticipates the delayed implementation of torque influence. By calculating the required torque profile beforehand (including a lead time component), the system ensures that when the torque is actually applied after the predetermined time margin, the gear changeover occurs at the correct synchronous speed.
Solution Approach 2:
The system dynamically adjusts the torque demand profile based on actual implementation delays. The control device continuously monitors whether the actual torque influence occurs earlier or later than expected and modifies subsequent torque demands to compensate, maintaining synchronization accuracy despite variable implementation times.
2Ease of operation
If the torque demand is influenced to achieve smooth gear transitions, then the gear changeover becomes smoother, but the complexity of the control system increases
Solution Approach 1:
The control device influences torque demand by modifying control parameters such as torque magnitude and timing profile. By adjusting these parameters dynamically during the gear changeover process, the system achieves smooth transitions without requiring complex mechanical modifications to the gearbox itself.
Data Source
AI summary
A gearbox (100) includes an input shaft (105) and a first and a second proportionally controllable shift element (A to F). The shift elements (A to F) are configured to control, by way of an open-loop system, engagement or disengagement of a gear ratio in the gearbox (100). A method (200) for the open-loop control of the gearbox (100) includes: determining a specified differential speed profile that is a profile of a difference between a rotational speed of the input shaft (105) and a synchronous speed of a gear ratio to be engaged; and determining a torque demand of a drive source connected to the input shaft (105) or determining a control profile for the one of the first and second shift elements (A to F) to be engaged in the gear ratio on the basis of the specified differential speed profile.