Hybrid Vehicle Mode Transition via Hybrid-High to Prevent Drive Force Drop
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Solution Overview
Problem
Hybrid vehicles experience a long time delay in shifting from electric vehicle mode to hybrid-low mode, resulting in uncomfortable drive force transitions due to significant speed differences between clutch elements, leading to prolonged engine startup times.
Innovation Solution
A control system for hybrid vehicles that predicts mode changes from single-motor mode to hybrid mode via a second hybrid mode, using a controller to manage speed differences between engagement devices, allowing earlier engine startup by engaging the first clutch after synchronizing the second clutch, thereby reducing engagement shock and accelerating smoothly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the operating mode is shifted directly from single-motor mode to hybrid-low mode, then a larger drive force can be generated, but the speed difference between clutch elements is large causing prolonged engagement time and temporal drop in drive force
Solution Approach 1:
The patent divides the mode transition into two separate steps: first transitioning to hybrid-high mode, then to hybrid-low mode. This segmentation of the clutch engagement process allows the speed difference to be managed in smaller increments, reducing engagement time and preventing temporal drop in drive force while still achieving the ultimate goal of generating larger drive force in hybrid-low mode.
Solution Approach 2:
The patent introduces a preliminary intermediate state (hybrid-high mode) before reaching the final target state (hybrid-low mode). By first engaging the clutch in hybrid-high mode where the speed difference is smaller, the system prepares the transmission elements for subsequent engagement in hybrid-low mode, thereby reducing the overall engagement time and avoiding drive force drop.
2Object-affected harmful factors
If the clutch engagement is performed to synchronize speed difference, then engagement shock is reduced, but the engine startup time is prolonged
Solution Approach 1:
The patent segments the clutch engagement into two phases: first in hybrid-high mode where speed synchronization occurs with smaller speed difference, then in hybrid-low mode. This segmentation allows engagement shock to be reduced in the first phase while minimizing the time penalty in the second phase, thereby resolving the contradiction between shock reduction and startup time.
Solution Approach 2:
The patent introduces hybrid-high mode as an intermediary state between single-motor mode and hybrid-low mode. This intermediate mode serves as a mediator that allows the clutch elements to synchronize their speeds with a smaller speed difference, reducing engagement shock while limiting the impact on engine startup time through the subsequent direct transition to hybrid-low mode.
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
The system enables prompt drive force increase and reduces the plateau period of drive force during mode transitions, ensuring smooth acceleration by starting the engine earlier and minimizing temporal drops in drive force.
Implementation Method 1
a speed difference between the drive member and the driven member of each of the first engagement device and the second engagement device is controlled by the first motor
Data Source
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AI summary
A control system for a hybrid vehicle (Ve) configured to shift an operating mode from a single-motor mode to a hybrid-low mode without causing a temporal drop in a drive force. A controller (31) is configured to predict an execution of a mode change from the single-motor mode to the hybrid-low mode, and to execute the mode change from the single-motor mode to the hybrid-low mode via a hybrid-high mode if the execution of the mode change from the single-motor mode to the hybrid-low mode is predicted.