Hybrid Vehicle Reverse Torque Control via Dynamic Correction
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Solution Overview
Problem
In hybrid vehicles, the comfort and travel distance during backward running are compromised due to stepwise lowering of reverse drive torque when the internal combustion engine is actuated, leading to torque level differences and insufficient torque, especially when the battery state of charge (SOC) is low.
Innovation Solution
A control device is implemented to set reverse drive torque by combining a base torque common to both engine-off and engine-on backward running states, with a correction torque added based on the running state during engine-off backward running, ensuring the torque remains within the maximum capable by the engine-on state, thereby maintaining consistent drive torque and avoiding torque level differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the internal combustion engine is actuated during backward running to charge the battery, then the state of charge (SOC) is improved, but the reverse drive torque decreases due to application of forward rotation torque
Solution Approach 1:
The patent implements dynamic control of the motor's reverse rotation torque based on real-time detection of vehicle running state, accelerator opening, and battery SOC. The control device adjusts the motor torque output dynamically to compensate for the torque reduction caused by engine actuation, ensuring that the reverse drive torque remains sufficient while allowing the engine to charge the battery.
2Stability of the object's composition
If the reverse drive torque is uniformly suppressed to be low to avoid torque level difference, then the torque smoothness is improved, but the sufficient torque cannot be ensured especially when SOC is low
Solution Approach 1:
The patent changes the torque control parameters dynamically based on multiple conditions including vehicle running state (EV or HV mode), accelerator opening degree, and battery SOC level. The control device uses different torque setting strategies for different operating conditions, allowing high reverse drive torque when needed (low SOC, high accelerator opening) while maintaining smooth torque transitions during normal operation.
3Stability of the object's composition
If the base torque is set within the range not higher than maximum torque during engine-on backward running, then the torque level difference is reduced, but the correction torque must be added to ensure sufficient torque during engine-off backward running
Solution Approach 1:
The patent performs preliminary action by setting the base torque within the acceptable range before engine actuation occurs. The control device pre-calculates and applies correction torque based on predicted engine actuation timing and expected torque reduction, ensuring that the total reverse drive torque (base torque + correction torque) remains sufficient while preventing excessive torque level differences when the engine starts.
Data Source
AI summary
A maximum output line during HV backward running accompanying actuation of an engine is on a side of lower torque than a maximum output line in EV backward running in an engine stop state. Reverse drive torque during EV backward running is set in accordance with the sum of base torque suppressed within a range not higher than maximum output torque during HV backward running and correction torque added at the time when a reverse drive torque request from a driver is great in accordance with a running state.