Hybrid Torque Control for Shift Shock Reduction
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Solution Overview
Problem
Existing hybrid vehicle torque control strategies for automatic transmissions face challenges in reducing torque disturbances during shifting, particularly due to the slower response of engine torque, which can lead to undesirable shift shocks and inefficiencies, and may adversely impact fuel economy and emissions.
Innovation Solution
A controller coordinates engine and electric motor torque during upshifts by generating a reserve torque during the preparatory phase, prioritizing electric motor torque if sufficient, and adjusting engine torque through spark retardation to maintain driver demand torque, eliminating the need for additional torque sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If engine torque is increased to provide reserve torque for torque hole filling, then torque disturbances during shifting are reduced, but response time is slower due to system dynamics of fuel and airflow
Solution Approach 1:
The controller initiates engine torque increase in anticipation of the transmission upshift by opening the throttle and providing additional fuel before the shift event occurs. This preliminary action creates a torque reserve that can be quickly deployed during the torque phase to fill the torque hole and reduce disturbances.
Solution Approach 2:
The system changes engine operating parameters (throttle opening, fuel injection quantity, and spark timing) to rapidly adjust torque output. By opening the throttle more than required for driver demand and using spark retard to maintain desired torque, the engine can quickly provide the needed torque reserve during shifting.
2Object-affected harmful factors
If throttle is opened more than required and spark retard is used to create torque reserve, then torque hole filling is improved, but fuel economy and feedgas emissions are adversely impacted
Solution Approach 1:
The controller prepares the engine for torque hole filling by opening the throttle and providing additional fuel in advance of the shift event. This preliminary fueling creates the necessary torque reserve without requiring excessive fuel during the actual shift, thereby minimizing the impact on overall fuel economy.
Solution Approach 2:
The system temporarily adjusts fuel injection and spark timing parameters to create the torque reserve needed for smooth shifting. These parameter changes are precisely controlled and time-limited to only when needed for torque hole filling, minimizing the adverse impact on fuel economy and emissions during normal operation.
3Speed
If electric motor torque is increased to provide reserve torque, then torque response speed is improved, but available torque may be insufficient under certain conditions
Solution Approach 1:
The system combines both the electric motor and engine as torque sources to provide the reserve torque needed for torque hole filling. The controller coordinates torque contributions from both sources, allowing the electric motor to provide rapid response when available and the engine to supplement when additional torque is needed, thereby achieving both fast response and sufficient torque availability.
Solution Approach 2:
The dual-powertrain system serves multiple functions: the electric motor provides rapid torque response for immediate torque hole filling needs, while the engine provides sustained torque capacity and can supplement when the motor alone is insufficient. This multi-functional arrangement ensures torque availability across various operating conditions.
4Measurement precision
If additional torque sensors are used for closed-loop control, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The controller uses existing sensor data (such as clutch torque, transmission input torque, and vehicle operating parameters) to estimate and control torque during shifting events. By utilizing information already available from the vehicle's existing sensor suite and applying control algorithms, the system achieves effective torque control without requiring additional dedicated torque sensors.
Solution Approach 2:
The system implements control strategies that use feedback from existing sensors to monitor and adjust torque delivery during shifting. The controller continuously monitors clutch engagement states, transmission parameters, and powertrain operating conditions to dynamically adjust torque distribution, achieving precise control through software-based feedback rather than additional hardware sensors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces torque disturbances, improves powertrain efficiency, and minimizes shift shocks while optimizing fuel economy and reducing emissions by synchronized control of engine and motor torque.
Implementation Method 1
an electric machine selectively coupled to the engine by a first clutch, an automatic step-ratio transmission selectively coupled to the electric machine by a second clutch
Implementation Method 2
An engine torque increase may be initiated in anticipation of a transmission upshift by opening a throttle and providing additional fuel
Implementation Method 3
retards spark to reduce engine torque during the preparatory phase only if the combined engine and electric machine torque exceeds driver demand torque after reducing electric machine torque to a minimum torque threshold
Data Source
AI summary
A vehicle includes a motor between an engine and transmission and a controller configured to control motor and engine torque during an upshift to generate a reserve torque during a preparatory phase applied to the transmission during a torque phase. The controller increases engine torque for the reserve torque, and decreases motor torque such that combined engine and motor torque satisfy driver demanded torque without retarding spark when available motor torque is insufficient to provide the reserve torque. A method for controlling a vehicle having a motor connected between an engine and a transmission includes increasing engine torque for reserve torque to be applied during a torque phase of an upshift responsive to available motor torque being insufficient to satisfy the reserve torque, and reducing engine torque by retarding spark only if combined engine torque and motor torque exceeds driver demand torque after reducing motor torque to a minimum threshold.