Engine Torque Control During Transmission Upshift Torque Holes
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Solution Overview
Problem
Existing vehicle control systems struggle to manage torque demand during transmission gearshifts, leading to unstable engine operation, poor driveability, and potential drivetrain issues like 'clonk', 'shunt', or 'shuffle', due to the transient nature of input variables and the non-linear torque output of transmissions during upshifts.
Innovation Solution
A control system that receives transmission speed and driver demand signals to determine a torque demand signal for the engine, using a predicted variance in the torque ratio of the transmission during gearshifts to tailor the torque demand and compensate for transmission losses, thereby maintaining a steady torque output and improving driveability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque demand is filtered heavily to smooth sharp changes and maintain driveability, then the driveability is improved, but the vehicle response becomes unresponsive
Solution Approach 1:
The system performs preliminary action by anticipating the torque hole that occurs during upshifts and applying compensatory torque demand increases before the actual torque drop occurs. This predictive compensation is implemented by detecting upshift conditions and modifying the torque demand signal in advance, allowing the engine to maintain steady output torque despite the transmission's non-linear torque ratio changes.
2Stability of the object's composition
If the engine torque is increased to compensate for transmission torque drop during upshift, then the torque output stability is improved, but a torque hole appears due to lag in actuator response
Solution Approach 1:
The system performs preliminary action by anticipating the torque hole that occurs during upshifts and applying compensatory torque demand increases before the actual torque drop occurs. This predictive compensation is implemented by detecting upshift conditions and modifying the torque demand signal in advance, allowing the engine to maintain steady output torque despite the transmission's non-linear torque ratio changes.
Solution Approach 2:
The system applies beforehand cushioning by preparing the engine torque output in advance to counteract the expected torque drop during upshifts. The control system calculates the anticipated torque hole and applies compensatory torque demand that cushions against the future torque deficiency, ensuring smooth torque delivery throughout the upshift event.
3Reliability
If the driveability filter removes torque compensation during upshift, then the driveability is maintained, but the torque output becomes unstable
Solution Approach 1:
The system uses an intermediary approach by introducing a dedicated upshift compensation mechanism that operates independently of the main driveability filter. This intermediary compensation path detects upshift conditions and applies torque adjustments that bypass the filter's torque-reducing effect, ensuring that compensation reaches the engine actuators without being removed by the driveability filter.
4Productivity
If the transmission torque ratio varies non-linearly during upshift, then the gearshift is completed, but the torque output drops causing drivetrain instability
Solution Approach 1:
The system applies feedback by continuously monitoring transmission output speed and comparing it against expected values during upshifts. This feedback information is used to detect actual upshift events and trigger appropriate torque compensation adjustments, creating a closed-loop control system that responds to real-time transmission behavior and corrects torque output deviations.
Data Source
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AI summary
A control system (32, 33) for a vehicle (10), the control system (32, 33) comprising one or more controllers, the control system (32, 33) being configured to: receive a transmission speed signal that is indicative of an output speed of a transmission (24) of the vehicle (10) as the transmission (24) performs a gearshift; receive a driver demand signal that is indicative of a driver demand for acceleration of the vehicle (10) during the gearshift; and determine a torque demand signal for an engine (20) of the vehicle (10) in accordance with the transmission speed signal and the driver demand signal.