Thermostat Valve Temperature Estimation via Position Feedback

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Solution Overview

Problem

Current cooling systems for motor vehicle drive motors often rely on a single temperature sensor, which limits precise control of the cooling circuit and is costly due to the use of multiple sensors, leading to inadequate temperature measurement at various points within the system.

Innovation Solution

A controlled thermostat system that uses a wax-filled valve mechanism and electrical resistance to regulate coolant temperature, with a processing unit managing temperature setpoints and voltage application to optimize coolant flow and heating, allowing for precise temperature control without the need for multiple sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple temperature sensors are used to measure temperature at different points in the cooling circuit, then temperature measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The thermostat valve body performs self-diagnosis by monitoring its own opening degree via the position sensor and correlating this with temperature measurements from the single sensor. The control unit calculates the relationship between valve opening and temperature to determine actual coolant temperature without requiring additional sensors at multiple points.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The single temperature sensor serves multiple functions: it measures coolant temperature for cooling control, provides data for determining thermostat valve opening characteristics, and enables the system to infer temperature conditions throughout the cooling circuit through the control unit's calculations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Device complexity

If a single temperature sensor is used to reduce device complexity and cost, then device complexity is reduced, but temperature measurement precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidtemperature measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The position sensor provides feedback on the thermostat valve opening degree to the control unit. This feedback is combined with temperature sensor data to calculate the relationship between valve position and temperature, enabling the system to accurately determine coolant temperature and thermal state throughout the circuit using only one temperature sensor.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention replaces the mechanical approach of using multiple temperature sensors with an electronic/control-based solution. The control unit uses mathematical relationships and the position sensor to substitute for the physical presence of multiple temperature measurement devices.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If the thermostat opens fully to cool the engine, then temperature control is achieved, but energy loss increases due to reduced engine efficiency

Engineering Contradiction:
Improvecoolant temperatureVSAvoidenergy loss
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The thermostat valve opening degree is dynamically adjusted based on real-time temperature measurements and engine operating conditions. The control unit continuously modulates the valve position to maintain optimal temperature, preventing both overheating and excessive cooling that would waste energy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the thermostat valve opening parameter dynamically based on temperature feedback and engine load conditions. By adjusting this parameter continuously rather than using fixed open/closed positions, the system optimizes the balance between cooling effectiveness and energy efficiency.

Inventive Principle:
Principle #35Parameter changes

4Loss of energy

If the thermostat remains closed to maintain engine temperature, then energy efficiency is improved, but temperature regulation precision deteriorates

Engineering Contradiction:
Improveenergy efficiencyVSAvoidtemperature regulation precision
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The temperature sensor continuously monitors coolant temperature and provides feedback to the control unit. This feedback enables the control unit to make precise adjustments to the thermostat valve opening, ensuring the engine maintains optimal temperature without excessive cooling, thereby balancing energy efficiency with temperature regulation precision.

Inventive Principle:
Principle #23Feedback

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 enables efficient and precise temperature regulation of the coolant, improving the overall control of the cooling system by continuously monitoring and adjusting the thermostat's operation based on engine load and speed, thus enhancing engine performance and reducing energy consumption.

Implementation Method 1

a wax-filled valve mechanism

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

electrical resistance to regulate coolant temperature

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3094842B1Method for controlling a heatable thermostatic valve
Publication Date: 2021.02.03 RENAULT SA
  • EP3094842B1 patent drawingFigure 1~2b
  • EP3094842B1 patent drawingFigure 3~4b
  • EP3094842B1 patent drawingFigure 5

AI summary

The invention relates to a method for estimating the temperature (TE) of a cooling liquid flowing in a cooling circuit of a driving engine (2) of a motor vehicle, which includes the following steps: a) measuring the temperature (Ts) of the cooling liquid flowing in a first pipe of the cooling circuit; b) acquiring at least one piece of information representing an operating parameter of the engine (2); and c) estimating the temperature (TE) of the cooling liquid flowing in a second pipe of the cooling circuit, which is separate from said first pipe, in accordance with the temperature (Ts) measured in step a) and the information acquired in step b). The invention also describes a cooling system of the engine.