Hybrid Axle Torque Control During Catalyst Light-Off
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Solution Overview
Problem
Hybrid vehicles face challenges in maintaining engine torque within a desired range during catalyst light-off, leading to increased emissions when the catalytic converter is not effective, and there is a need to diagnose torque constraints effectively.
Innovation Solution
A system for hybrid vehicles that includes a control module to calculate and manage primary and secondary axle torques based on driver requests, battery state, vehicle speed, and motor limits, while diagnosing torque constraints to ensure optimal engine operation and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the vehicle operates in EV mode during catalyst light-off, then emissions are reduced and fuel economy improves, but the engine torque cannot be maintained within the desired range for effective catalytic converter operation
Solution Approach 1:
The system dynamically adjusts torque distribution between the primary engine-driven axle and secondary electric motor-driven axles based on real-time catalyst temperature and vehicle operating conditions. The control module continuously monitors catalyst light-off status and modifies torque commands to maintain engine torque within the desired range while maximizing EV mode utilization, thereby resolving the contradiction between emission reduction and catalyst effectiveness.
Solution Approach 2:
The system changes operational parameters by adjusting the torque split between engine and electric motors based on catalyst temperature thresholds and light-off progress. When catalyst temperature approaches light-off conditions, the system modifies engine torque parameters to stay within optimal ranges, while compensating with electric motor torque to meet driver demand, thus maintaining both emission benefits and catalyst effectiveness.
2Reliability
If the engine torque is maintained within a desired range during catalyst light-off, then catalytic converter effectiveness is ensured, but the vehicle cannot fully utilize EV mode and electric axles for emission reduction
Solution Approach 1:
The system segments the drivetrain into primary engine-driven axles and secondary electric motor-driven axles, allowing independent torque control. This segmentation enables the engine to operate within the optimal torque range for catalyst light-off while electric motors provide additional propulsion, thus maintaining catalyst effectiveness while still achieving emission reductions through partial EV mode utilization.
Solution Approach 2:
The control system provides multi-functionality by simultaneously managing catalyst light-off requirements and emission reduction goals through intelligent torque distribution. The system can operate in hybrid mode where the engine maintains optimal torque for catalyst effectiveness while electric motors contribute to propulsion, achieving both catalyst light-off effectiveness and reduced emissions compared to full engine operation.
3Productivity
If the secondary torque target is calculated based on optimal engine torque and driver torque request, then the system can balance engine performance and driver demand, but torque constraints may limit the electric motor's ability to fully satisfy driver torque requests
Solution Approach 1:
The control module implements feedback by continuously monitoring driver torque requests, actual engine torque output, and vehicle operating conditions. Based on this feedback, the system dynamically adjusts the secondary torque target to balance engine efficiency requirements with driver demand fulfillment, compensating for torque constraints through real-time control adjustments.
Solution Approach 2:
The system applies partial action by using the electric motor to supplement rather than fully replace engine torque. When torque constraints prevent the electric motor from fully satisfying driver requests, the system provides partial electric torque assistance while maintaining engine operation within efficient ranges, achieving a compromise that balances productivity and ease of operation.
Data Source
AI summary
A system for determining a secondary axle torque of a hybrid vehicle is disclosed. The hybrid vehicle includes a primary axle driven by an engine and a secondary axle driven by an electric motor. The system includes one or more sensors configured to detect a driver torque request, and a control module in communication with the one or more sensors. The control module is configured to receive data from the one or more sensors indicative of the driver torque request, calculate a primary torque target for the primary axle based on an optimal engine torque, calculate a secondary torque target for the secondary axle based on the calculated primary torque target and the driver torque request, and generate a secondary torque command to drive the secondary axle based on the calculated secondary torque target and the driver torque request. Other example systems and methods are also disclosed.