Hybrid Vehicle Torque Modulation During Upshifts
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Solution Overview
Problem
In hybrid electric vehicles, the inertia torque transmitted during transmission shifts can cause driveline disturbances due to the combination of engine and electric motor, and existing torque modulation methods like engine spark retard may result in engine misfire or insufficient torque reduction at higher speeds.
Innovation Solution
A method and controller system that reduce the rate of engine air intake prior to or during transmission upshifts when the transmission input torque exceeds a threshold, using a combination of slow-path and fast-path torque modulation to minimize driveline disturbances, with the controller coordinating clutch pressures and engine operation to achieve a target speed ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If engine spark retard is used for torque modulation, then transmission input torque is reduced, but engine misfire may occur
Solution Approach 1:
The patent introduces an intermediary control mechanism that coordinates between the engine controller and transmission controller. The transmission controller detects shift events and communicates with the engine controller to implement coordinated torque modulation, using the transmission control as an intermediary to prevent engine misfire while achieving torque reduction
Solution Approach 2:
The patent changes the control parameters by implementing coordinated control of engine spark timing and transmission clutch pressure. Instead of solely retarding spark, the system modifies both engine parameters (spark timing) and transmission parameters (clutch pressure) simultaneously to achieve torque modulation without causing misfire
2Force
If electric machine is used for torque modulation at higher speeds, then torque reduction is achieved, but the electric machine may not have enough torque capacity
Solution Approach 1:
The patent merges the torque modulation capabilities of the engine and electric machine into a coordinated control system. By combining both torque sources and implementing joint control during shift events, the system achieves effective torque reduction even when the electric machine alone lacks sufficient torque capacity at higher speeds
Solution Approach 2:
The patent implements dynamic control that adapts to varying operating conditions. The coordinated control system dynamically adjusts the contribution of each torque source (engine and electric machine) based on real-time conditions, allowing effective torque modulation across different speed ranges where neither source alone would be sufficient
3Stability of the object's composition
If transmission input torque is reduced during upshift, then driveline disturbances are minimized, but vehicle performance may be impacted
Solution Approach 1:
The patent applies preliminary action by implementing torque modulation before and during the initial engagement of the oncoming shift element. The coordinated control of engine and transmission begins prior to complete clutch engagement, preemptively reducing torque to minimize driveline disturbance while maintaining vehicle performance
Solution Approach 2:
The patent applies preliminary anti-action by implementing torque reduction in anticipation of the shift event. The coordinated control system detects upcoming shifts and pre-adjusts torque from both engine and electric machine to counteract the inertial effects that would otherwise cause driveline disturbance during the transition
Data Source
AI summary
In response to a transmission upshift command and a transmission element speed being greater than a threshold, a controller may reduce a rate of engine air intake prior to initial engagement of an oncoming shift element, at least until a target speed ratio is achieved. This reduction may reduce a transmission input torque such that upshift driveline disturbances are reduced.