Hybrid Drive Train Shift Coordination for Engine Start
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Solution Overview
Problem
In hybrid vehicles, the frequent shifting between electric motor and internal combustion engine driving modes can lead to illogical and time-consuming sequences during gear shifts and engine starts, affecting driving comfort and dynamics, especially with automatic transmissions having many gears.
Innovation Solution
A method that coordinates drag starts or externally assisted starts of the internal combustion engine by checking if ongoing transmission shifts can be interrupted or completed, allowing for partial or full discontinuation of the shift process before initiating the engine start, thereby avoiding unnecessary shifts and reducing long sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gearshift is completed first and then the drag start or externally assisted start is carried out, then the transmission shift process is finished properly, but the time sequence is extended and driving comfort is reduced
Solution Approach 1:
The control unit checks whether a drag start or externally assisted start is required during the gearshift process and initiates the start sequence in advance. The separating element is actuated to connect the internal combustion engine to the drive-train before the gearshift is fully completed, overlapping the start sequence with the remaining shift phase to reduce total time sequence.
Solution Approach 2:
The control unit dynamically adjusts the gearshift process based on the detected start requirement. It can interrupt or modify the ongoing gearshift to accommodate the engine start sequence, making the system flexible rather than rigid in executing shift commands.
2Loss of time
If the internal combustion engine is started during a gear ratio change, then the time sequence is shortened, but illogical shifts may occur due to switching between electric motor and internal combustion engine driving modes
Solution Approach 1:
The control unit continuously monitors the driving mode (electric motor or internal combustion engine) and uses this feedback to determine whether to interrupt or complete the gearshift. It compares the current driving mode with the target driving mode to avoid illogical shifts that would reduce driving comfort.
Solution Approach 2:
The control unit acts as an intermediary between the transmission control and the engine start sequence. It coordinates the separating element actuation and gearshift timing, ensuring that transitions between driving modes are logical and plausible from the driver's perspective.
3Use of energy by moving object
If consecutive multiple shifts or nested shifts are carried out in vehicles with automatic transmissions having many gears, then the transmission can optimize fuel consumption and power, but the time sequence is extended and driving behavior is adversely affected
Solution Approach 1:
The control unit checks for drag start or externally assisted start requirements at the beginning of the gearshift process and initiates the start sequence in advance, before multiple consecutive shifts are executed. This prevents the accumulation of multiple shift sequences that would extend the total time.
Solution Approach 2:
The control unit prevents the initiation of multiple consecutive shifts by detecting the start requirement in advance and blocking further shift commands until the current start sequence is completed, avoiding the adverse effect of nested shifts.
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 method improves driving comfort and dynamics by minimizing illogical shifts and long sequences, ensuring smoother transitions between electric motor and internal combustion engine operations.
Implementation Method 1
the electric machine can act as an integrated starter-generator and start the internal combustion engine by operating as an electric motor
Implementation Method 2
the internal combustion engine can be drive-connected to the electric machine by way of a separator clutch
Data Source
AI summary
A method of operating a vehicle hybrid drive-train in which, depending on the operating situation, the engine and electric machine either operate individually or together. The engine and the electric machine can be coupled or separated by a clutch. The engine can be started by the electric machine or a separate starting device. To co-ordinate transmission shifts and required engine starts, during a transmission shifting process, if the engine needs to be started, then based on whether the shift is an upshift, a downshift, a traction shift or an overdrive shift and also depending on the type of engine start required, it is first determined whether the shift should be completed, at least partially completed or discontinued before carrying out the start and, based on this determination, measures for continuing, at least partially continuing or discontinuing the shift process are initiated.