BISG-Engine Torque Sharing for AC Compressor Engagement
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Solution Overview
Problem
The available torque from a belt-integrated starter generator (BISG) in vehicles may be insufficient to meet the torque demands of an air-conditioning (AC) compressor, leading to engine speed reduction and potential inefficiencies, especially when there is no demand for negative torque to decelerate the vehicle.
Innovation Solution
A controller mechanically couples the BISG and engine to the AC compressor shaft, and adjusts spark timing to compensate for torque shortfalls, ensuring efficient torque transfer and minimizing engine load by utilizing both BISG and engine torque when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the BISG is used to provide torque to the AC compressor, then the engine load is reduced, but the available torque from the BISG may be insufficient to meet the torque demands of the AC compressor
Solution Approach 1:
The patent combines the torque output from both the BISG and the engine to meet the AC compressor torque demand. When the BISG alone cannot satisfy the torque requirement, the system merges its output with engine torque through the belt drive system, ensuring both energy efficiency and reliable torque delivery.
Solution Approach 2:
The system dynamically adjusts the coupling between the BISG and engine based on real-time torque requirements. The controller monitors the AC compressor torque demand and dynamically engages or disengages the engine-BISG mechanical coupling, optimizing the balance between energy efficiency and torque availability.
2Reliability
If the engine is mechanically coupled to the AC compressor shaft to compensate for torque shortfall, then the torque demand is satisfied, but the engine speed may reduce leading to potential inefficiencies
Solution Approach 1:
The controller continuously monitors engine speed, torque demand, and BISG output, and adjusts the engine-BISG coupling and spark timing accordingly. This feedback mechanism ensures that engine speed is maintained within efficient operating ranges while still satisfying AC compressor torque demands.
Solution Approach 2:
The system changes engine operating parameters, specifically spark timing, to optimize performance under different coupling conditions. When the engine is coupled to the AC compressor, spark timing is adjusted to maintain engine efficiency and prevent excessive speed reduction.
3Reliability
If spark timing is retarded to compensate for torque shortfall, then the torque demand is met, but engine efficiency may be compromised
Solution Approach 1:
Instead of fully retarding spark timing to meet torque demands, the system uses partial spark timing adjustment combined with BISG torque contribution. This partial action approach meets the torque requirement while minimizing the negative impact on engine efficiency.
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 solution ensures reliable torque delivery to the AC compressor, maintaining engine efficiency and reducing load on the engine by dynamically managing torque distribution between the BISG and engine, thereby optimizing vehicle performance.
Implementation Method 1
belt-integrated starter generator (BISG)
Implementation Method 2
engine
Data Source
AI summary
A vehicle includes an air-conditioning (AC) compressor, an engine, a belt-integrated starter generator (BISG), and a controller. The controller, responsive to detecting a first AC compressor engagement condition, compares a first AC torque demand that is required to engage the AC compressor with an available torque from the BISG. The controller further, responsive to the available torque being insufficient to engage the AC compressor, engages the AC compressor using the available torque from the BISG and an engine torque from the engine to compensate a torque shortfall between the AC torque demand and the available torque by retarding spark timing and increasing air intake.