Intake Air Temperature Sensor IC Integration
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Solution Overview
Problem
Existing intake air temperature sensors face challenges due to the difficulty in integrating a reference resistor into an integrated circuit, leading to increased size and errors in resistance value measurement, especially at high temperatures.
Innovation Solution
An intake air temperature sensor with a temperature sensing element and a resistive element integrated into the circuit, using a writable memory to store resistance values and correct signals, eliminating the need for a reference resistor and switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference resistor and change-over switch are used to correct resistance value fluctuations, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the reference resistor function from the external circuit and integrates it into the IC as a resistive element. The correction capability is taken out from the mechanical switch-based change-over circuit and transferred to a digital correction method using ADC and memory, simplifying the overall device structure while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical change-over switch with an electronic/digital system consisting of ADC, memory, and processing circuitry. The switch-based mechanical selection of reference resistors is substituted with digital storage and computational correction, eliminating mechanical wear and reducing circuit complexity.
2Volume of moving object
If a reference resistor is integrated into the IC, then device size is reduced, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent implements feedback by measuring the actual resistance value of the integrated resistive element using the ADC and storing it in memory. This measured value is then used to correct the thermistor resistance measurements, compensating for manufacturing variations and ensuring accurate temperature readings despite integration challenges.
Solution Approach 2:
The patent changes the approach from requiring high manufacturing precision during fabrication to using post-fabrication parameter measurement and digital correction. The actual resistance value parameter of the resistive element is measured and stored, then used to adjust calculations, transforming a manufacturing precision problem into a digital correction problem.
3Measurement precision
If switch turning-on resistance is reduced to maintain accuracy at high temperatures, then measurement precision is improved, but device size increases
Solution Approach 1:
The patent eliminates the mechanical switch entirely and replaces it with an electronic ADC-based measurement system. The change-over function that previously required a physical switch with specific resistance characteristics is now performed digitally through software control of the ADC channels, removing the constraint of switch turning-on resistance at high temperatures.
Solution Approach 2:
The patent extracts the switching function from the physical domain and transfers it to the digital domain. The channel selection and reference resistor selection that previously required mechanical switching is now achieved through digital multiplexing and software control, eliminating the need for low-turning-on-resistance switches.
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 results in a compact and highly accurate intake air temperature sensor by correcting resistive element fluctuations, reducing the need for a reference resistor and switch, thereby enhancing measurement precision and reducing size.
Implementation Method 1
a temperature sensing element 2 whose resistance value varies with the intake temperature
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An object of the present invention is to provide a compact and highly accurate intake air temperature sensor by integrating a fixed resistor, connected in series to a temperature sensing element, into an integrated circuit and dispensing with a reference resistor or a changeover switch for connecting the fixed resistor to this reference resistor. The intake air temperature sensor has a temperature sensing element 2 whose resistance value varies with the intake temperature; an integrated circuit 1 electrically connected to the temperature sensing element 2; a resistive element 3 connected in series to the temperature sensing element 2; a writable memory 7 that stores correction information corresponding to the resistance value of the resistive element 3; and a correction processing unit 6 that corrects errors based on the resistance value of the resistive element 3, which are included in output signals of the temperature sensing element 2, on the basis of the correction information stored in the writable memory 7.