Vehicle System Controller Power Compensation for Engine Speed Stability
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Solution Overview
Problem
Existing internal combustion engines with advanced vehicle system controllers experience intrusive engine speed changes due to accessory loads like the air conditioner compressor, leading to inefficient fuel economy and driver discomfort, especially at higher altitudes where the engine frequently runs at wide open throttle.
Innovation Solution
The engine speed flare-ups are mitigated by reducing driver demanded wheel power when the engine is at wide open throttle, using electronic throttle control to determine this condition and applying the reduction smoothly through software filtering, ensuring the reduction is transparent to the driver and only occurs when necessary to maintain battery charge balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the VSC increases engine speed to compensate for A/C compressor power consumption, then the total power demand is met, but intrusive engine speed fluctuations occur causing driver discomfort
Solution Approach 1:
The patent extracts the A/C compressor power consumption from the engine power calculation by introducing a separate electric load compensation mechanism. The VSC calculates engine power demand excluding A/C compressor power when the clutch is engaged, and this power deficit is compensated by reducing the driver demanded wheel power rather than increasing engine speed, thereby preventing intrusive speed fluctuations while maintaining total power balance
Solution Approach 2:
The patent changes the control parameter from engine speed adjustment to driver demanded wheel power adjustment. Instead of modifying engine speed to compensate for A/C compressor power consumption, the system modifies the driver demanded wheel power parameter in the power balance equation, which indirectly compensates for the accessory load without causing intrusive engine speed fluctuations
2Power
If the VSC adjusts throttle position to compensate for A/C cycling, then power balance is maintained, but engine speed fluctuations still occur at wide open throttle conditions
Solution Approach 1:
The patent applies preliminary action by detecting A/C clutch engagement status in advance and proactively adjusting the driver demanded wheel power before engine speed fluctuations can occur. The VSC continuously monitors clutch position and pre-calculates the power compensation needed, applying the adjustment to driver demanded wheel power ahead of time, thereby preventing intrusive engine speed changes before they happen
Solution Approach 2:
The patent introduces driver demanded wheel power as an intermediary variable between A/C compressor power consumption and engine operation. Instead of directly linking A/C clutch engagement to engine speed or throttle position, the system uses driver demanded wheel power as a mediator in the power balance calculation, which indirectly compensates for accessory loads while decoupling the direct cause-effect relationship that causes intrusive speed fluctuations
3Use of energy by moving object
If the VSC independently schedules engine speed and load operating point, then fuel economy is maximized, but intrusive engine speed changes occur due to accessory loads
Solution Approach 1:
The patent segments the power demand calculation into separate components: driver wheel power demand, accessory loads (excluding A/C compressor), and A/C compressor power compensation. By segmenting the A/C compressor power as a separate compensable item in the power balance equation, the system can independently manage this specific load without disrupting the overall fuel economy optimization strategy, thereby preventing intrusive engine speed changes while maintaining efficient operation
Data Source
AI summary
An internal combustion engine includes an advanced vehicle system controller (VSC) that calculates a total power demand to meet a driver wheel power demand plus any accessory loads and independently schedules an engine speed and load operating point to meet the total power demand. A reduction in available engine brake power that is not associated with a driver input, and would ordinarily cause the VSC to respond by raising engine speed, is detected. The driver wheel power demand is reduced to compensate for the reduction in available engine brake power such that the VSC does not need to raise engine speed to meet the driver wheel power demand. A magnitude of the reduction may be determined according to a calibration map to allow a trade off to be made between driveability and noise, vibration, and harshness.