P2 Hybrid Engine Clutch Pressure Learning for Kickdown Slip
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Solution Overview
Problem
In P2 type parallel hybrid vehicles, the engine clutch experiences slip during kickdown shifts due to abrupt changes in engine torque and load, leading to decreased acceleration and poor gear shifting sensations.
Innovation Solution
A method and system that determine a learning hydraulic value to suppress slip by capturing gear shift progress and engine torque data, storing a compensation value, and applying it to the engine clutch during subsequent kickdown shifts to prevent slip, using a controller that computes a final hydraulic pressure based on target pressure and compensation factors like engine torque and oil temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable hydraulic control is performed on the engine clutch, then energy efficiency is improved, but slip occurs during kickdown shift leading to decreased acceleration
Solution Approach 1:
The controller performs preliminary action by detecting kickdown shift conditions in advance and proactively increasing hydraulic pressure to the engine clutch before slip occurs. This predictive control prevents slip during acceleration while maintaining energy-efficient variable hydraulic control during normal operation.
Solution Approach 2:
The system dynamically adjusts hydraulic pressure based on real-time operating conditions. During kickdown shift, the controller increases pressure beyond normal variable control levels to prevent slip, while maintaining lower pressure during steady-state operation to improve energy efficiency. This dynamic adaptation resolves the contradiction between efficiency and acceleration performance.
2Speed
If hydraulic pressure is increased to prevent slip, then acceleration is improved, but energy consumption increases
Solution Approach 1:
The controller applies preliminary action by detecting kickdown shift conditions and preemptively increasing hydraulic pressure only when needed. This prevents slip before it occurs while avoiding continuous high-pressure application, thereby maintaining acceleration performance without excessive energy consumption during normal operation.
Solution Approach 2:
The system changes hydraulic pressure parameters dynamically based on operating conditions. During kickdown shift, pressure is increased to prevent slip and improve acceleration. During steady-state variable hydraulic control, pressure is maintained at lower levels for energy efficiency. This conditional parameter adjustment resolves the energy-acceleration trade-off.
3Measurement precision
If learning mode is activated to capture slip data, then control precision is improved, but system complexity increases
Solution Approach 1:
The learning mode implements feedback by capturing slip occurrence data and using it to refine future control decisions. The controller monitors kickdown shift conditions and slip events, storing this information to improve subsequent hydraulic pressure control. This feedback mechanism enhances control precision without requiring complex additional hardware.
Solution Approach 2:
The system performs self-service through automated learning and adaptation. The controller automatically captures slip data, analyzes patterns, and adjusts hydraulic pressure control without external intervention. This self-learning capability improves control precision while maintaining relatively simple system architecture by utilizing existing sensors and processing capabilities.
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
Effectively prevents slip and improves acceleration and drivability by applying the learned compensation value during subsequent kickdown shifts, enhancing gearshift quality.
Implementation Method 1
The engine clutch 30 allows or blocks the transfer of the motive power between the engine 10 and the motor 40 through an opening, slipping, closing, or lock-up operation by a hydraulic control actuator (HCA)
Data Source
AI summary
A method and system for controlling an engine clutch of a P2 type parallel hybrid vehicle includes steps of: determining whether or not a learning mode entry condition is satisfied, depending on whether or not a kickdown shift occurs during performance of variable hydraulic control of an engine clutch and based on the degree to which slip of the engine clutch occurs, deriving and storing a learning hydraulic value for suppressing the slip that is to occur when the kickdown shift occurs during the performance of the variable hydraulic control in such a manner that the slip does not occur, when a vehicle state satisfies a predetermined learning mode entry condition, and computing a final hydraulic pressure by adding a hydraulic compensation value to a target hydraulic pressure, when the same kickdown shift situation occurs, and controlling the engine clutch using the computed final hydraulic pressure.