Coolant Pump Motor Current Diagnosis for Vehicle
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Solution Overview
Problem
Current methods for diagnosing a lack of coolant in fuel cell vehicles, such as using water level sensors, pressure sensors, and flow sensors, are either inaccurate due to disturbances or require additional costly components, making them inefficient and difficult to install.
Innovation Solution
A method that involves monitoring the revolution per minute (RPM) and driving current of a coolant pump to determine coolant insufficiency by setting target RPM and current thresholds, averaging these values over preset times, and recording determinations to ensure accurate diagnosis with reduced hardware requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a water level sensor is mounted on the reservoir to measure the water level, then coolant level can be detected, but a package space for mounting the sensor cannot be ensured and the sensor fails when air bubbles are present in the coolant
Solution Approach 1:
The patent extracts the detection function from the traditional water level sensor mounted on the reservoir and relocates it to the coolant pump motor. By measuring the motor current instead of directly sensing coolant level, the system eliminates the need for separate sensor mounting space while maintaining detection capability.
Solution Approach 2:
The patent introduces motor current as an intermediary parameter to indirectly measure coolant level. Instead of directly detecting coolant level with a sensor, the system uses the relationship between motor current and pump load (which depends on coolant viscosity and flow) to infer coolant conditions, thereby avoiding direct sensor mounting issues.
2Measurement precision
If a pressure sensor is mounted on the coolant pipe to diagnose lack of coolant, then coolant level can be detected, but erroneous sensing values are frequently obtained due to temperature change, cooling loop changes, or vehicle vibration
Solution Approach 1:
The patent uses motor current as an intermediary measurement that is less sensitive to external disturbances like temperature changes and vibrations. By monitoring the current draw of the coolant pump motor, the system indirectly assesses coolant conditions without being directly exposed to the unstable environmental factors that affect pressure sensors.
Solution Approach 2:
The system uses the coolant pump's own motor current characteristics to diagnose coolant level, rather than relying on separate sensors that are vulnerable to external disturbances. The pump motor essentially serves its own diagnostic function by providing current information that reflects its loading conditions based on coolant properties.
3Measurement precision
If a flow sensor is installed on the coolant pipe to diagnose lack of coolant, then coolant flow can be measured, but installation cost increases and additional pipe placement is required making installation difficult
Solution Approach 1:
The patent makes the coolant pump motor serve multiple functions: it not only pumps coolant but also acts as a sensor for detecting coolant level and flow conditions. By monitoring the motor's electrical characteristics, the system eliminates the need for separate flow sensors and their associated installation requirements.
Solution Approach 2:
The patent extracts the flow measurement function from a dedicated flow sensor and integrates it into the coolant pump motor control system. By analyzing motor current characteristics, the system derives flow information without requiring a separate flow sensor installation, thereby simplifying the overall system architecture.
Data Source
AI summary
A method for diagnosing a lack of coolant includes: (a) determining whether a target revolution per minute (RPM) of a coolant pump is set to be constantly maintained for a first time, which is preset, or more, (b) calculating an actual average RPM and an actual average driving current of the coolant pump for a second time, which is preset to be shorter than the first time, when the target RPM is set to be constantly maintained for the first time, and (c) determining whether the coolant to be supplied to the coolant pump is insufficient, based on the actual average RPM and the actual average driving current.