Hybrid Transmission Shift Control for Anticipated Deceleration
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Solution Overview
Problem
Hybrid transmissions in prior art face issues where gears can no longer be shifted during strong deceleration, leading to potential stalling of the internal combustion engine and a seized drive train due to form-locking shift elements being overloaded, without a clutch to disengage the engine from the power flow.
Innovation Solution
A method that monitors the surroundings of a vehicle to anticipate deceleration situations and proactively decides between electrodynamic and output-assisted gear shifts to transition the hybrid transmission into a shift condition, ensuring the engine is not stalled and the drive train is not overloaded, allowing gear changes to occur without interrupting tractive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If form-locking shift elements are used to engage gears in the powershift transmission, then gear engagement is reliable and tractive force is maintained during shifting, but during strong deceleration the shift elements become overloaded and cannot be relieved of load, causing the engine to stall or the drive train to seize
Solution Approach 1:
The control unit anticipates deceleration situations by monitoring vehicle surroundings and proactively switches the transmission to shift condition before the deceleration occurs. This preliminary action relieves the form-locking shift elements of load in advance, preventing overload and seizure during the actual deceleration event
Solution Approach 2:
The electric machine acts as an intermediary between the engine and the powershift transmission. During anticipated deceleration, the electric machine absorbs or provides torque to relieve load from the form-locking shift elements, enabling safe gear changes without engine stalling or drive train seizure
2Reliability
If the transmission is switched to shift condition to enable gear changes during deceleration, then gear changes can occur without engine stalling, but the switching process may be noticeable and disrupt vehicle operation
Solution Approach 1:
The transmission is switched to shift condition in advance of the actual deceleration event, based on predicted driving situations. This timing allows the gear change to be completed before the driver experiences deceleration, making the transition imperceptible and maintaining smooth vehicle operation
Solution Approach 2:
The control unit continuously monitors vehicle surroundings and driving conditions to predict deceleration events. This feedback loop enables optimal timing of the transmission switch, ensuring gear changes occur at the most appropriate moment without disrupting vehicle operation or being noticed by the driver
Data Source
AI summary
A method for operating a hybrid transmission includes monitoring the surroundings of a motor vehicle and, based on the data ascertained within the scope of the monitoring, determining a probability of occurrence of a driving situation to be anticipated, which, upon occurring, results in a deceleration of the motor vehicle. Based on the determined probability of occurrence, it is decided whether to carry out an electrodynamic gear shift or an output-assisted gear shift in order to transfer the hybrid transmission out of an operating condition, in which a gear is engaged, into a shift condition.