Hybrid Vehicle Engine Start Threshold Control
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Solution Overview
Problem
Hybrid vehicles experience unnecessary warm-up of catalytic converters when operating in electric motor mode, leading to increased fuel consumption, as existing control systems fail to accurately assess the need for converter warm-up based on the vehicle's traveling distance and state of charge.
Innovation Solution
A hybrid vehicle system that includes a catalytic converter, a warming unit, a setting unit, an estimation unit, a comparison unit, and a control unit to determine if the vehicle can complete a set traveling distance in electric motor mode without engine operation, thereby preventing unnecessary warm-up of the catalytic converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started to warm up the catalytic converter when battery SOC is low, then the emission characteristics are maintained, but fuel consumption increases when the vehicle can travel in EV mode
Solution Approach 1:
The patent applies dynamics by making the engine start decision adaptive rather than fixed. The control device dynamically adjusts the engine start threshold based on the relationship between estimated EV traveling distance and set traveling distance. When the EV distance is sufficient to reach the destination, the engine start threshold is raised, allowing the vehicle to remain in EV mode and avoid unnecessary fuel consumption. When EV distance is insufficient, the threshold is lowered to ensure the engine starts for proper catalytic converter warm-up, maintaining emission standards.
Solution Approach 2:
The patent changes the parameter of engine start threshold based on battery SOC and traveling distance conditions. By modifying this control parameter dynamically, the system optimizes the balance between emission control (requiring engine operation for catalyst warm-up) and fuel efficiency (preferring EV mode when possible). This parameter adjustment allows the same catalytic converter to be protected under different operating conditions without unnecessary fuel consumption.
2Quantity of substance
If the engine is started for battery charging when SOC reaches lower limit, then the power storage device is recharged, but unnecessary warm-up of the catalytic converter occurs when EV mode is sufficient
Solution Approach 1:
The system dynamically adjusts the engine start decision based on real-time assessment of EV traveling distance versus set traveling distance. Instead of following a fixed SOC threshold for engine start, the control device evaluates whether the current battery charge level is sufficient to complete the journey in EV mode. This dynamic approach prevents unnecessary engine starts for catalytic converter warm-up when the vehicle can reach the destination on electric power alone, while still ensuring engine operation when battery charging is needed and EV distance is insufficient.
Solution Approach 2:
The patent modifies the engine start threshold parameter based on the comparison between estimated EV traveling distance and set traveling distance. When the EV distance exceeds the set distance, the effective SOC threshold for engine start is raised, allowing the battery to be discharged further before engine intervention. This parameter change optimizes the balance between battery charging needs and avoidance of unnecessary fuel consumption for catalytic converter warm-up.
3Reliability
If the catalytic converter is warmed up to ensure proper exhaust gas purification, then emission standards are met, but fuel consumption increases in hybrid vehicles with extended EV mode range
Solution Approach 1:
The patent implements a dynamic control strategy where the engine start decision is not fixed but adapts to the specific traveling conditions. The control device continuously estimates the EV traveling distance based on battery SOC and compares it with the set traveling distance. This dynamic assessment allows the system to maintain catalytic converter warm-up only when necessary (when EV distance is insufficient), rather than applying a static warm-up protocol that would cause unnecessary fuel consumption in vehicles with extended EV mode capability.
Solution Approach 2:
The system changes the effective engine start threshold parameter based on the ratio of estimated EV traveling distance to set traveling distance. When this ratio indicates sufficient EV range, the parameter adjustment prevents unnecessary engine starts for catalytic converter warm-up. When the ratio indicates insufficient EV range, the parameter ensures proper warm-up occurs. This parameter adaptation resolves the contradiction between maintaining exhaust gas purification standards and minimizing fuel consumption in hybrid vehicles with extended EV mode.
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 effectively prevents unnecessary warm-up of the catalytic converter, reducing fuel consumption by accurately assessing the vehicle's electric motor travel distance and adjusting the engine start threshold based on the state of charge and set traveling distance.
Implementation Method 1
a catalytic converter (8) purifying an exhaust gas discharged from the internal combustion engine (2)
Implementation Method 2
a warming-up unit (2, 8) for warming up the catalytic converter (8)
Data Source
AI summary
A hybrid vehicle is equipped with an engine and a motor generator (MG2) serving as a power source for driving the vehicle. A catalytic converter is provided in an exhaust pipe of the engine. An HV-ECU estimates a possible EV-running distance based on an SOC of a power storage device for comparison with a traveling distance (L) to a destination set by a navigation device. When the possible EV-running distance is longer than the traveling distance (L), the HV-ECU outputs a control signal (CTL2) instructing prohibition of warm-up of the catalytic converter, to an EG-ECU.