Vehicle Torque Control Using Engine Speed Target Linearization
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Solution Overview
Problem
Existing vehicle systems experience erratic changes in engine speed due to the non-linear relationship between torque and engine speed, leading to rough operation and unwanted wear, despite limiting the rate of torque change.
Innovation Solution
Convert torque changes into corresponding engine speed target values, which are then converted back into torque requests to manage engine speed changes in a linear manner, using hysteresis thresholds to stabilize control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If torque requests are controlled to limit the rate of change of torque demand, then torque changes are smoothed, but engine speed still changes rapidly and unexpectedly due to the non-linear relationship between torque and engine speed
Solution Approach 1:
The patent changes the control parameter from direct torque demand to an intermediate parameter that accounts for the non-linear torque-speed relationship. By modifying how torque requests are processed through a non-linear compensation factor, the system achieves better engine speed stability without increasing overall system complexity
Solution Approach 2:
The patent introduces an intermediate calculation step that acts as a mediator between torque requests and engine speed changes. This intermediate parameter (involving engine speed raised to a power) smooths the non-linear relationship, preventing rapid engine speed variations while maintaining responsive torque control
2Speed
If torque requests are responded to immediately, then vehicle responsiveness is improved, but engine speed changes erratically causing rough operation and component wear
Solution Approach 1:
The patent applies preliminary action by pre-calculating the non-linear compensation factor based on current engine speed before processing torque requests. This preparation allows immediate response to torque demands while the pre-computed factor ensures smooth engine speed transitions, preventing rough operation and wear
Solution Approach 2:
The patent makes the control system dynamic by adjusting the torque request processing based on real-time engine speed conditions. The non-linear compensation factor changes dynamically with engine speed, allowing responsive control at all operating points while preventing harmful speed variations
Data Source
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AI summary
Techniques are disclosed herein that provide for controlling torque in a vehicle. In some embodiments, desired torque values are generated and are compared to an amount of torque currently being generated by an engine. If a different amount of torque is desired, an engine speed target is altered in a linear fashion, and then converted back to a torque request to be provided to an engine ECU for implementation. Techniques disclosed herein may cause changes in torque demand to be limited in such a way to cause predictable and smooth changes in engine speed, even when engine speed and torque do not have a linear relationship to each other.