Hybrid Vehicle Engine Stop Control via Battery Internal Resistance
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Solution Overview
Problem
Existing vehicle controlling systems face challenges in optimizing engine stop and start conditions, particularly in hybrid vehicles, as stopping the engine when the battery state of charge (SOC) is low can lead to decreased opportunities for engine shutdown, affecting fuel economy and engine restartability.
Innovation Solution
A vehicle controlling apparatus that includes an engine processor, electric motor, electric power storage, SOC detector, internal resistance detector, and resistance threshold setting unit, which determines whether to stop or start the engine based on the battery's internal resistance threshold set relative to its state of charge, ensuring sufficient power for engine restart and maximizing engine stop opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the engine stop condition is based only on SOC threshold, then the control logic is simple, but the engine stop opportunities are reduced when battery charge is low
Solution Approach 1:
The patent changes the control parameter from SOC alone to a combination of SOC and internal resistance. By introducing internal resistance as an additional parameter, the system can determine engine stop permission more accurately, allowing engine stops even when SOC is low if the internal resistance is within acceptable limits. This resolves the contradiction by expanding stop opportunities without significantly complicating the control logic.
2Loss of energy
If the engine stop is permitted when battery SOC is low, then fuel economy improves, but the engine restartability may be compromised
Solution Approach 1:
The patent implements feedback control by continuously monitoring both SOC and internal resistance, and using this information to dynamically adjust engine stop permission decisions. The control unit uses the internal resistance value as feedback to determine whether the battery can support an engine restart, allowing fuel-saving engine stops when conditions permit while preventing stops that would compromise restartability. This resolves the contradiction by providing reliable feedback-based decision making.
Solution Approach 2:
The patent treats the internal resistance measurement as a temporary, easily obtained indicator of battery capability. Rather than relying on SOC alone, which may not accurately reflect immediate battery performance, the system uses the readily measurable internal resistance as a quick assessment tool to determine if the battery can support engine restart, enabling more aggressive fuel-saving strategies without sacrificing reliability.
3Device complexity
If only SOC is used to determine engine stop permission, then the detection system is simple, but the accuracy of stop condition judgment is insufficient
Solution Approach 1:
The patent merges two detection parameters - SOC and internal resistance - into a unified engine stop permission determination system. By combining these two measurements, the system achieves more accurate judgment of whether the engine should be stopped, as internal resistance provides additional information about battery capability that SOC alone cannot provide. This resolves the contradiction by showing that adding one more parameter (internal resistance) significantly improves accuracy without proportionally increasing system complexity.
Data Source
AI summary
A vehicle controlling apparatus includes an engine processor, an electric motor, an electric power storage, an SOC detector, an internal resistance detector, and a resistance threshold setting unit. The engine processor is configured to stop an engine of a vehicle on the basis of a stop condition, and start the engine on the basis of a start condition. The engine processor is configured to prohibit a stop of the engine based on the stop condition based on determining that an internal resistance of the electric power storage detected by the internal resistance detector is equal to or greater than a resistance threshold set by the resistance threshold setting unit on the basis of a state of charge of the electric power storage, and permit the stop of the engine based on determining that the internal resistance is less than the resistance threshold.