Hybrid IVT Shift Control Using Electric Machine Torque Compensation
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Solution Overview
Problem
Conventional shifting in infinitely variable transmissions of hybrid vehicles is performed at standard shift points, which may not adequately address transient changes in rotational speed, leading to inefficiencies.
Innovation Solution
Incorporating hysteresis in shifts by providing supplemental or oppositional rotational energy using an electric machine to inhibit or induce shifts, compensating for transient changes in engine shaft rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shifts are performed at standard shift points without considering transient changes, then the transmission operates efficiently under steady-state conditions, but shift control becomes inadequate during transient changes in rotational speed
Solution Approach 1:
The patent applies dynamics by making the shift control system adaptive to changing operating conditions. The controller dynamically adjusts shift points based on real-time detection of transient changes in rotational speed, transitioning from fixed standard shift points to variable shift points that respond to actual system conditions. This allows the transmission to maintain optimal performance during both steady-state and transient operations.
Solution Approach 2:
The patent implements feedback by continuously monitoring rotational speed and detecting transient changes. The controller uses this feedback information to determine when to inhibit or induce shifts, creating a closed-loop control system that adapts to changing conditions. The feedback mechanism enables the system to distinguish between normal operational variations and transient changes requiring shift intervention.
2Stability of the object's composition
If shifts are inhibited during transient changes, then rotational speed stability is improved, but shift frequency increases due to repeated transient fluctuations
Solution Approach 1:
The patent applies preliminary action by detecting transient changes before they fully manifest and proactively inhibiting shifts during these transient periods. The controller anticipates rotational speed fluctuations and prevents shifts during the transient phase, thereby maintaining stability. Once the transient change subsides and steady-state conditions are restored, normal shifting resumes, preventing excessive shift frequency.
3Measurement precision
If the electric machine is used to provide supplemental rotational energy, then shift control precision is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary anti-action by using the electric machine to counteract transient changes in rotational speed that would otherwise trigger unnecessary shifts. The electric machine provides supplemental or opposing rotational energy to maintain speed stability during transients, preventing precision loss. This targeted intervention occurs only during transient periods rather than continuously, minimizing energy consumption while maintaining control precision when needed.
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
Enhances shift control by stabilizing rotational speed, reducing shift frequency, and improving energy management in hybrid vehicles.
Implementation Method 1
an electric machine configured to provide supplemental rotational energy in addition to rotational energy provided by the internal combustion engine
Data Source
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AI summary
Controlling a shift point on a vehicle includes determining whether a commanded torque and/or a commanded speed associated with a transient change in the rotational speed of an engine shaft of an internal combustion engine, are within a standard shift region for a proposed shift between a first gear ratio and a second gear ratio during a present sampling interval, and further determining whether an electric machine configured to provide supplemental rotational energy in addition to rotational energy provided by the internal combustion engine is operating at substantially zero speed during the present sampling interval. If so, the shift is inhibited for at least the next sampling interval to compensate for the transient change by providing compensating-rotational-energy to the engine shaft by using the electric machine to provide additional rotational energy to, or absorb excess rotational energy from, the rotational energy being provided by the internal combustion engine.