Hybrid Vehicle Shift Control for Torque Fluctuation
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Solution Overview
Problem
Hybrid vehicles experience shock and unintended driving force drops during mode shifting and gear shifting due to conflicting requirements of reducing torque fluctuations and improving response time, which existing solutions either shorten engine start/stop times but cause uncomfortable feel or perform shifts in parallel to enhance response time but increase shock.
Innovation Solution
A control system that selectively performs mode shifts and gear shifts based on vehicle information such as speed and engine load, allowing sequential or parallel execution depending on predetermined speed and load conditions to prioritize shock reduction or response time, ensuring smooth transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the second clutch is disengaged during mode shift or gear shift, then the time interval for starting or stopping the engine and performing the gear shift is shortened, but torque fluctuations are transmitted to the driving wheels causing uncomfortable feel
Solution Approach 1:
The control device determines in advance whether to engage the second clutch during mode shift or gear shift based on vehicle speed and acceleration requests. By pre-judging the necessity of clutch engagement before the shift operation, the system can prepare the appropriate configuration (clutch engaged or disengaged) to minimize both time loss and torque fluctuations, resolving the contradiction between speed and comfort.
2Object-affected harmful factors
If the second clutch is controlled to continuously transmit driving torque during mode shifts or gear shifts, then shock and unintended driving force reduction are reduced, but the time interval to complete both mode shift and gear shift is extended
Solution Approach 1:
The engagement state of the second clutch is dynamically adjusted based on real-time vehicle conditions (speed, acceleration request, mode shift status, gear shift status). Rather than maintaining a fixed state, the clutch engagement is optimized moment-by-moment to balance shock reduction and response time, allowing the system to adaptively resolve the contradiction between comfort and speed.
3Speed
If the accelerator pedal is pressed causing a request to shift gears simultaneously with mode shift, then the vehicle response to driver input is improved, but conflicting sequence controls extend the overall time interval
Solution Approach 1:
The control device merges the control of mode shift and gear shift operations by determining the engagement state of the second clutch based on both operations simultaneously. This integrated control approach allows the system to coordinate both shifts in a unified manner, reducing the overall time interval compared to sequential execution while maintaining responsive vehicle behavior to accelerator input.
4Adaptability or versatility
If the first clutch is engaged or disengaged and the engine is started or stopped during mode shift, then the mode transition is achieved, but torque fluctuations occur that require disengaging the second clutch, extending the process time
Solution Approach 1:
The control device determines in advance whether the second clutch should be engaged during mode shift operations involving engine start/stop. By pre-judging the necessity of clutch engagement based on the specific mode transition requirements, the system can minimize the process time while ensuring smooth torque transmission, resolving the contradiction between transition capability and operation speed.
Data Source
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AI summary
A drive state shift control apparatus for a hybrid vehicle and a control method for a hybrid vehicle smoothly perform a shift in drive state in accordance with an operating state by a mode shift and a gear shift. When an accelerator operation causes a mode shift request and a gear shift request at substantially the same time, vehicle information including at least one of the vehicle speed and the engine load is used to determine the sequence of the shifts based on the competing interests of shock control and responsiveness.