Hybrid Vehicle Torque Control for Emissions and Drive Response
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Solution Overview
Problem
Existing hybrid vehicle control systems face challenges in limiting engine emission deterioration while maintaining drive force responsivity during sudden changes in accelerator position.
Innovation Solution
A control method for hybrid vehicles that calculates a target engine torque through a gradual change process, adjusting the constant K based on air-fuel ratio differences, and utilizes motor torque control to maintain drive force responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a gradual change process is applied to limit torque changes, then emission deterioration is limited, but drive force responsivity decreases
Solution Approach 1:
The control system segments the torque control into two independent parts: engine torque (subject to gradual change for emission control) and motor torque (fully responsive for drive force). This allows each component to optimize its control strategy independently, resolving the contradiction between emission control and responsivity.
Solution Approach 2:
The motor acts as an intermediary that compensates for the delayed engine torque response. When engine torque changes gradually, the motor provides immediate torque supplementation to maintain overall drive force responsivity, effectively mediating between the slow engine response and the driver's immediate needs.
2Stability of the object's composition
If the constant K is increased to limit torque change, then air-fuel ratio stability improves, but drive force response becomes slower
Solution Approach 1:
The constant K is made dynamic rather than fixed. It is adjusted in real-time based on the air-fuel ratio detection results: increased when air-fuel ratio deviation is large (to stabilize composition) and decreased when deviation is small (to allow faster response). This dynamic adjustment resolves the contradiction between stability and response time.
Solution Approach 2:
The system implements feedback control by continuously monitoring the air-fuel ratio and using this information to adjust the constant K. The feedback loop ensures that the gradual change process adapts to actual engine conditions, maintaining air-fuel ratio stability while minimizing unnecessary response delays.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A control device for a hybrid vehicle calculates a required drive force (TP*) based on an accelerator position (ACC). The control device also calculates a required torque (TEF*) of the engine (11) based on the required drive force (TP*). The control device further calculates a target torque (TE*) for the engine (11) by subjecting the required torque (TEF*) to a gradual change process for lessening a change in a value and performs an engine control such that an engine torque becomes equal to the target torque (TE*). The control device also performs a torque control on the motor (12, 13) such that a drive force of the hybrid vehicle becomes equal to the required drive force (TP*) in a state in which the engine torque is equal to the target torque (TE*).