Bidet Water Heating With Dual Sensor Failure Detection

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing toilet devices face challenges in reliably detecting failures of temperature sensors over time due to aging deterioration, which can lead to the discharge of high-temperature water, posing a risk to users.

Innovation Solution

The toilet device incorporates a dual temperature sensor system with a first sensor downstream of an instantaneous heat exchanger and a second sensor further downstream, along with a control unit that compares temperature readings to detect sensor failures, and includes a human body detection sensor to initiate failure diagnosis before use, and corrects for temperature loss along the flow path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single temperature sensor is used to detect water temperature, then the device structure is simple, but the sensor may fail due to aging deterioration and accurate temperature measurement cannot be ensured

Engineering Contradiction:
Improvetemperature sensor systemVSAvoidtemperature sensor failure detection
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the temperature detection function into multiple independent temperature sensors (first temperature sensor and second temperature sensor) positioned at different locations in the flow path. This segmentation allows the system to compare readings from multiple sensors to detect failures, resolving the contradiction between simple structure and reliable failure detection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control unit continuously monitors temperature readings from both sensors and compares them to detect discrepancies. When a failure is detected through this feedback mechanism, the system can alert the user or switch to using the functioning sensor, thereby maintaining reliable temperature measurement despite sensor aging.

Inventive Principle:
Principle #23Feedback

2Length of stationary object

If temperature sensors are positioned close together, then the structure is compact, but temperature difference due to flow path length cannot be properly accounted for

Engineering Contradiction:
Improveflow path lengthVSAvoidtemperature measurement accuracy
Core Design Contradiction:
Length of stationary objectVSMeasurement precision

Solution Approach 1:

The patent accounts for the temperature change that occurs over the flow path length by introducing a correction value that corresponds to the distance between sensors. The control unit uses this correction value to adjust the temperature reading from the upstream sensor, enabling accurate temperature measurement despite the spatial separation between sensors.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the instantaneous heat exchanger operates continuously, then water is always available for discharge, but energy consumption increases

Engineering Contradiction:
Improvewater discharge availabilityVSAvoidheat exchanger energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic failure diagnosis by the control unit, which operates the instantaneous heat exchanger and temperature sensors at scheduled intervals to check for sensor failures. This periodic operation allows the system to maintain water discharge availability while reducing continuous energy consumption compared to constant monitoring operations.

Inventive Principle:
Principle #19Periodic action

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 approach enhances the reliability of detecting temperature sensor failures, preventing the discharge of high-temperature water by accurately determining sensor malfunctions and ensuring user safety.

Implementation Method 1

an instantaneous heat exchanger that is provided in the flow path and warms water supplied from the water supply source

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a first temperature sensor that is provided downstream of the instantaneous heat exchanger in the flow path and detects a temperature of water

Methodology Applied
Scientific EffectTemperature detection: Thermistor

Implementation Method 3

an electromagnetic valve that is provided in the flow path and configured to control supply of water from the water supply source (WS) to the nozzle

Methodology Applied
Scientific EffectElectromagnetic actuation: Electromagnet

Data Source

PatentEP4124697B1Toilet device
Publication Date: 2025.11.12 TOTO LTD
  • EP4124697B1 patent drawingFigure 1
  • EP4124697B1 patent drawingFigure 2
  • EP4124697B1 patent drawingFigure 3

AI summary

An object is to provide a toilet device (500) capable of more reliably detecting a failure of a temperature sensor. A toilet device (500) includes: a nozzle (30) that discharges water toward a private part of a human body; a flow path (40) connecting a water supply source (WS) and the nozzle (30); an instantaneous heat exchanger (50) that is provided in the flow path (40) and warms water supplied from the water supply source (WS); a first temperature sensor (60) that is provided downstream of the instantaneous heat exchanger (50) in the flow path (40) and detects a temperature of water; a second temperature sensor (65) that is provided downstream of the first temperature sensor (60) in the flow path (40) and detects a temperature of water; and a control unit (70) that determines whether the first temperature sensor (60) or the second temperature sensor (65) has failed, characterized in that when a difference between a first temperature detected by the first temperature sensor (60) and a second temperature detected by the second temperature sensor (65) is equal to or larger than a predetermined value, the control unit (70) determines that the first temperature sensor (60) or the second temperature sensor (65) has failed.