Variable Cut-off Frequency Sensor Voltage Control

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Solution Overview

Problem

Conventional methods for estimating the element temperature of oxygen sensors are prone to inaccuracies, leading to potential failures in maintaining the active temperature range, which affects the accuracy of oxygen content detection.

Innovation Solution

An applied voltage control device that adjusts the cut-off frequency of AC voltage applied to the sensor, allowing for precise estimation of element temperature by improving the detection accuracy of sensor impedance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed cut-off frequency is used for AC voltage applied to the sensor, then the device complexity is reduced, but the measurement precision of sensor impedance deteriorates

Engineering Contradiction:

Improvevoltage control deviceVSAvoidsensor impedance detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies the dynamics principle by making the cut-off frequency of the AC voltage variable rather than fixed. The control device adjusts the cut-off frequency dynamically based on the detected sensor impedance characteristics, allowing optimal measurement precision across different temperature conditions while maintaining manageable device complexity through automated control.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by varying the cut-off frequency parameter of the AC voltage according to the sensor's impedance characteristics. This allows the measurement system to adapt to changing temperature conditions and maintain high measurement precision without requiring overly complex device architecture.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the cut-off frequency is adjusted to improve temperature estimation accuracy, then the measurement precision improves, but the device complexity increases

Engineering Contradiction:

Improveelement temperature estimation accuracyVSAvoidvoltage control device

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs feedback control by detecting the sensor impedance, determining the appropriate cut-off frequency based on impedance characteristics, and adjusting the AC voltage accordingly. This closed-loop approach improves temperature estimation accuracy while keeping device complexity manageable through automated feedback-based adjustment rather than manual configuration.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control device dynamically adjusts the cut-off frequency based on real-time sensor impedance measurements, enabling accurate temperature estimation across varying operating conditions without requiring a statically complex device design.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If a temperature sensor is directly attached to the sensor element, then the measurement precision of element temperature is improved, but the sensor size increases and manufacturing cost increases

Engineering Contradiction:

Improveelement temperature detection accuracyVSAvoidsensor size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent applies the self-service principle by using the sensor element itself to provide temperature information through its impedance characteristics. Instead of requiring a separate temperature sensor, the system measures the sensor's own impedance, which varies with temperature, thereby eliminating the need for additional temperature sensing components and reducing overall sensor size.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent uses sensor impedance as an intermediary parameter to indirectly measure element temperature. Rather than directly measuring temperature with a separate sensor, the system measures impedance (which can be done with minimal additional components) and derives temperature from the impedance-temperature relationship, thus avoiding the need for bulky direct temperature sensors.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enhances the accuracy of element temperature estimation and subsequent temperature control, ensuring reliable oxygen content detection even at temperature extremes.

Implementation Method 1

a solid electrolyte layer which allows a direct current to flow therethrough by the application of a direct current voltage

Methodology Applied

Scientific EffectElectrical conduction through solid electrolyte: Conduction (electrical)

Implementation Method 2

feedback-controls energization to the heater so as to maintain the element temperature at an active temperature by heat generation of the heater

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

a filtering unit that sets a cut-off frequency of the AC voltage applied to the sensor variable

Methodology Applied

Scientific EffectElectrical filtering: Filter (electronic)

Data Source

PatentUS9797852B2Applied voltage control device for sensor

Publication Date: 2017.10.24 DENSO CORP

AI summary

An applied voltage control device is used for a sensor, in which a direct current corresponding to an oxygen amount flows when a DC voltage is applied to the sensor, and an alternating current corresponding to a sensor impedance flows when an AC voltage is applied to the sensor. The applied voltage control device includes: a filtering unit that sets a cutoff frequency of the AC voltage applied to the sensor variable.