HEV Mode Release Control for Uphill Clutch Shock Reduction
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Solution Overview
Problem
Hybrid electric vehicles experience shocks or jerks when the engine clutch is forcibly disengaged on uphill roads, leading to reduced riding comfort and drivability due to the absence of a controlled HEV mode release strategy.
Innovation Solution
A method and apparatus for controlling the driving mode of a hybrid vehicle that determines the gradient of the road and the motor speed to release the HEV mode before forcibly disengaging the engine clutch, allowing for a normal clutch release sequence and preventing power transmission to the driving shaft, thereby reducing shocks and improving comfort and drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine clutch is forcibly disengaged on an uphill road when the accelerator pedal is engaged, then the vehicle can maintain power transmission, but shocks or jerks occur reducing riding comfort
Solution Approach 1:
The controller determines a release determination speed based on road gradient before forcing clutch disengagement. When motor speed reaches this predetermined threshold, the system proactively releases the HEV mode and disengages the engine clutch in a controlled manner, preventing the harmful shocks that would occur from abrupt forced disengagement at higher speeds.
Solution Approach 2:
The system dynamically determines a release determination speed parameter based on the road gradient. By adjusting this speed threshold according to the specific uphill condition, the controller optimizes the timing of HEV mode release to balance power transmission needs with riding comfort, avoiding both forced disengagement shocks and excessive mode maintenance.
2Power
If the HEV mode is maintained on an uphill road with accelerator engagement, then power transmission is ensured, but the engine clutch cannot be properly disengaged when motor speed decreases
Solution Approach 1:
The controller sets a release determination speed threshold before the clutch disengagement issue occurs. When motor speed reaches this predetermined value during uphill driving, the system proactively releases the HEV mode, ensuring the engine clutch can be properly disengaged before motor speed drops to the problematic low-speed range where disengagement becomes difficult.
Solution Approach 2:
The controller continuously monitors motor speed and road gradient conditions, using this feedback to dynamically determine when to release the HEV mode. This closed-loop control ensures the clutch disengagement timing is optimized based on real-time operating conditions, preventing the clutch from being stuck in an indeterminate state.
3Power
If the engine clutch is forcibly disengaged without HEV mode release, then power transmission continues, but normal clutch release sequence is bypassed causing shocks
Solution Approach 1:
The controller determines a release determination speed based on road gradient before forcing clutch disengagement. When motor speed reaches this predetermined threshold, the system proactively releases the HEV mode and disengages the engine clutch in a controlled manner, preventing the harmful shocks that would occur from abrupt forced disengagement at higher speeds.
Data Source
AI summary
An apparatus and a method for controlling a driving mode of an HEV are provided. The apparatus releases an HEV mode at an appropriate time before forcibly releasing an engine clutch even when an accelerator pedal is engaged while driving the vehicle on an uphill road in the HEV mode to reduce a shock caused when the engine clutch is forcibly disengaged and improve riding comfort and drivability. The method includes determining whether the vehicle is driven on an uphill road from gradient information of a current road while the vehicle is driven in a HEV mode and determining a clutch engagement impossible speed corresponding to the gradient of the current road when the vehicle is driven on the uphill road. The engine clutch is disengaged to release the HEV mode when the speed of the motor is equal to or less than the determined clutch engagement impossible speed.