Estimating Disconnect Clutch Torque Without Sensors
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Solution Overview
Problem
Determining clutch torque during engine start in hybrid vehicles is challenging due to the difficulty in measuring it accurately, especially when the clutch is slipping, and existing methods require costly torque sensors.
Innovation Solution
A system and method that estimate clutch torque using a controller configured to control motor torque based on the difference between measured and predicted powertrain states, employing an adaptive gain to drive the error toward zero, and utilizing a powertrain dynamics model to predict motor and turbine speeds, allowing for smooth engine starts without the need for a torque sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque sensors are used to measure clutch torque accurately, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical torque sensor measurement system with an estimation system using a powertrain dynamics model. The controller estimates clutch torque by processing signals from existing sensors (motor speed, engine speed, turbine speed) through mathematical models, eliminating the need for direct mechanical torque measurement devices on the clutch.
Solution Approach 2:
The patent introduces a powertrain dynamics model as an intermediary between the measurable parameters (speeds) and the unmeasurable parameter (clutch torque). This model acts as a mediator that translates easily measurable quantities into estimates of the difficult-to-measure clutch torque without requiring direct contact with the clutch mechanism.
2Reliability
If clutch torque is measured directly during engine start, then reliability is improved, but ease of operation deteriorates due to clutch slipping conditions
Solution Approach 1:
The patent performs preliminary estimation of clutch torque using the powertrain dynamics model before the clutch fully engages and before slipping conditions complicate direct measurement. The controller continuously calculates estimated clutch torque based on current powertrain states, preparing accurate torque information in advance of when it would be needed for control decisions.
Solution Approach 2:
The patent implements a feedback mechanism where the estimated clutch torque is fed back to the controller to adjust motor torque commands. The controller uses the estimated clutch torque information to modify motor torque in real-time, creating a closed-loop control system that adapts to changing clutch engagement conditions and maintains reliable torque determination throughout the slipping phase.
3Object-generated harmful factors
If motor torque is controlled based on estimated clutch torque, then smooth engine start is achieved, but device complexity increases due to adaptive gain calculation
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the adaptive gain based on current powertrain operating conditions. The gain is not fixed but varies with engine speed, motor speed, and clutch engagement state, allowing the control system to adapt to changing dynamics during engine start and smoothly transition through different operating phases.
Solution Approach 2:
The patent changes control parameters dynamically during engine start. The adaptive gain parameter is modified based on the difference between measured and predicted powertrain states, and motor torque commands are adjusted as functions of estimated clutch torque and varying gain values, enabling smooth control adaptation throughout the engine starting process.
Data Source
AI summary
A system and method for estimating disconnect clutch torque during engine start with the motor in vehicles having an engine selectively coupled to the motor and transmission may be configured to control motor torque based on a clutch torque estimated from a difference in a measured powertrain state and a predicted powertrain state using motor torque as an input. The powertrain states may include, for example, motor speed, turbine speed, engine speed and clutch torque. An adaptive gain may be used to drive the difference between measured and estimated clutch torque toward zero.