Hybrid Vehicle Clutch Control for Shift-Down Response
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Solution Overview
Problem
Hybrid vehicles face challenges in reducing clutch heat generation and improving acceleration response when starting the engine while performing a shift-down transmission action, as concurrent engine starting and shift-down actions increase clutch slipping and heat, but delaying the shift-down action post-engine start compromises vehicle responsiveness.
Innovation Solution
A control apparatus for hybrid vehicles that maintains the hydraulic pressure of the releasing side clutch at a predetermined lowest stand-by value during engine starting in a slipping state, then reduces it after the clutch is fully engaged, allowing for faster shift-down actions and reduced clutch slipping, thereby minimizing heat generation and enhancing acceleration response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is started concurrently with the shift-down action, then the vehicle response to acceleration requirement is improved, but the clutch heat generation is increased
Solution Approach 1:
The releasing side clutch is pre-positioned in a fully released state before the shift-down action begins. This preliminary preparation allows the clutch to be ready for immediate engagement after engine start, enabling the shift-down to execute quickly without delaying for clutch preparation, thus maintaining fast vehicle response while controlling heat generation through optimized engagement timing
Solution Approach 2:
The hydraulic pressure of the releasing side clutch is dynamically controlled: held at a stand-by value during engine start, then reduced to enable the shift-down action. This parameter change optimizes the clutch engagement characteristics to balance between preventing excessive slipping (reducing heat) and enabling quick shift execution (maintaining response speed)
2Temperature
If the shift-down action is delayed until after engine starting, then the clutch heat generation is reduced, but the vehicle response to acceleration requirement is deteriorated
Solution Approach 1:
The releasing side clutch is pre-positioned in a fully released state before the shift-down action begins. This preliminary preparation allows the clutch to be ready for immediate engagement after engine start, enabling the shift-down to execute quickly without delaying for clutch preparation, thus maintaining fast vehicle response while controlling heat generation through optimized engagement timing
Solution Approach 2:
The shift-down action is implemented continuously without interruption by preparing the releasing side clutch in advance. The clutch remains in the released state during engine start, then transitions smoothly to enable the shift-down, ensuring the acceleration process continues without time loss while managing heat through controlled engagement
3Ease of operation
If the clutch is placed in a slipping state for engine starting, then the engine can be started, but the amount of clutch slipping is increased when shift-down is performed concurrently
Solution Approach 1:
The releasing side clutch is pre-positioned in a fully released state before the shift-down action begins. This preliminary preparation allows the clutch to be ready for immediate engagement after engine start, enabling the shift-down to execute quickly without delaying for clutch preparation, thus maintaining fast vehicle response while controlling heat generation through optimized engagement timing
Solution Approach 2:
The shift-down action is executed rapidly immediately after engine start by quickly reducing the hydraulic pressure of the releasing side clutch. This rushed execution minimizes the duration of clutch slipping, reducing energy loss while still achieving the desired gear change and maintaining acceptable vehicle response
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 approach reduces clutch heat generation and improves the hybrid vehicle's acceleration response by minimizing clutch slipping during engine start and enabling quicker shift-down actions post-engine engagement, addressing the trade-off between heat reduction and responsiveness.
Implementation Method 1
the control apparatus holds a hydraulic pressure of a releasing side clutch of the transmission at a predetermined lowest stand-by value preventing a slipping action of the releasing side clutch
Implementation Method 2
the clutch is placed in a slipping state, as a result of the shift-down action, to increase an operating speed of the engine
Data Source
AI summary
Control apparatus for hybrid vehicles are described which reduce the heat generated by a clutch and improve the response of the hybrid vehicle when an operator requests a high degree of acceleration while starting the engine and the transmission is required to perform a shift-down. In one embodiment, when the engine is required to start while the transmission is required to perform a shift-down action, the control apparatus holds a hydraulic pressure of a releasing side clutch of the transmission at a predetermined lowest stand-by value preventing a slipping action of the releasing side clutch, while a clutch K0 between the motor and engine is placed in a slipping state, and reduces the hydraulic pressure of the releasing side clutch from the lowest stand-by value in the slipping state of the clutch K0 after the clutch K0 is placed in the fully engaged state.