Hybrid Vehicle EHC Control Device for Leakage Prevention
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Solution Overview
Problem
Existing vehicle control devices with electrically heated catalysts (EHC) face challenges in preventing electric leakage, which can lead to wasted energy and potential electrical shocks, especially in hybrid vehicles where the internal combustion engine starts frequently from a cold state, resulting in increased dew formation and condensation-related issues.
Innovation Solution
A control device that includes an identifying device to assess the conductive characteristics and heat load conditions of the EHC before energization, a determining device to determine if an electric leakage avoidance request state is present, and an inhibiting device to prevent energization when such a state is detected, using a low voltage for detection to minimize risks and ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EHC is energized to promote heating of the catalyst, then exhaust gas purification effect is improved, but electric leakage occurs due to condensed water establishing conductive state
Solution Approach 1:
The control device performs preliminary detection of conductive characteristics and heat load conditions before energizing the EHC. By assessing these parameters in advance, the system determines whether an electric leakage avoidance request state is present, preventing energization when condensed water has created a conductive state that would cause electric leakage.
Solution Approach 2:
The control device acts as an intermediary between the energizing device and the EHC. It introduces a detection and determination layer that assesses conductive characteristics and heat load conditions, mediating the decision to energize based on whether electric leakage risks are present, thus preventing harmful electric leakage while allowing beneficial heating when safe.
2Temperature
If the EHC is energized when dew condensation is present, then catalyst heating is improved, but electric power is wasted due to electric leakage
Solution Approach 1:
The control device performs preliminary detection of conductive characteristics before energizing the EHC. By detecting abnormal conductive states caused by condensed water in advance, the system prevents wasteful energization that would result in electric leakage, while still allowing energization when conductive characteristics are normal and heating is beneficial.
3Reliability
If the EHC is energized in humid atmosphere, then catalyst activation is improved, but driver safety is compromised due to electrical shock risk
Solution Approach 1:
The control device performs preliminary detection of heat load conditions and conductive characteristics before energizing the EHC. By detecting abnormal conductive states in advance, the system prevents energization when condensed water has created pathways for electrical shock, while still enabling catalyst activation when conditions are safe.
Solution Approach 2:
The control device serves as a safety intermediary between the energizing system and the driver. It introduces detection and determination functions that assess whether energization would create electrical shock risks, mediating to prevent harmful shocks while allowing beneficial catalyst activation when safe.
4Reliability
If hardware measures are used to prevent electric leakage, then prevention capability is improved, but detection accuracy of abnormality is reduced
Solution Approach 1:
The control device replaces hardware-based prevention measures with a control-based detection system. Instead of relying on physical barriers or structural modifications to prevent electric leakage, the system uses electrical detection of conductive characteristics and heat load conditions to identify abnormal states, achieving both prevention and accurate detection through control logic rather than mechanical means.
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 electric leakage and associated failures while maintaining exhaust gas purification efficiency, ensuring safe operation and reducing the risk of electrical shocks by accurately determining and inhibiting energization during potential leakage conditions.
Implementation Method 1
an electrically heated catalyst (EHC) which is disposed in an exhaust passage of the internal combustion engine, purifies exhaust gases introduced into the exhaust passage
Implementation Method 2
heated by energization
Implementation Method 3
when the internal combustion engine is left unoperated for a long period, dew is likely to be formed as a result of condensation especially in an exhaust passage of the internal combustion engine
Data Source
AI summary
In a hybrid vehicle, an ECU executes drive control of an EHC. For the control, the ECU first executes low-voltage drive in which a drive voltage is reduced to 50 V when an energization request of the EHC is made. Then, based on a resistance value of the EHC, the ECU detects whether or not electric leakage is caused by dew formation of condensed water in the EHC. Consequently, if the electric leakage is detected, the energization of the EHC is inhibited. If electric leakage is not detected, the drive voltage Vd is increased to 200 V for normal drive to heat a catalyst by the EHC.