Pressure Detection Device Base Voltage Adjustment Circuit
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Solution Overview
Problem
The existing pressure detection devices for combustion pressure in engines face issues with reliability due to variations in the magnitude and repetition period of the detection signal, leading to erroneous failure diagnoses caused by the sinking phenomenon, where the base voltage is displaced from the reference voltage, resulting in inaccurate pressure detection.
Innovation Solution
A pressure detection device is designed with an integrator circuit and a base voltage adjustment circuit using a transistor pair to maintain a constant base voltage, ensuring the base voltage remains equal to the reference voltage, even with variations in the detection signal, and incorporating a computation amplifier circuit operated with a single power supply to reduce component count and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an integrator circuit is used to convert the detection signal into a voltage waveform, then the pressure detection function is achieved, but the base voltage is displaced from the reference voltage due to the sinking phenomenon, causing erroneous failure diagnoses
Solution Approach 1:
A base voltage adjustment circuit is introduced as an intermediary component between the integrator circuit and the reference voltage source. This circuit actively compensates for the sinking phenomenon by adjusting the base voltage to match the reference voltage, thereby preventing erroneous failure diagnoses while maintaining accurate pressure detection functionality
Solution Approach 2:
The base voltage adjustment circuit implements a feedback mechanism where the base voltage is continuously monitored and adjusted based on its deviation from the reference voltage. This feedback control ensures that the base voltage remains stable and equal to the reference voltage, eliminating the sinking phenomenon and improving failure diagnosis reliability
2Adaptability or versatility
If the magnitude and repetition period of the detection signal vary, then the detection signal adapts to different combustion conditions, but the base voltage is displaced from the reference voltage, causing the output signal to enter the failure diagnosis region
Solution Approach 1:
The base voltage adjustment circuit uses feedback control to continuously monitor and adjust the base voltage, ensuring it remains equal to the reference voltage regardless of variations in detection signal magnitude and repetition period. This feedback mechanism prevents the output signal from entering the failure diagnosis region while maintaining adaptability to different combustion conditions
3Reliability
If multiple circuits (integrator, amplifier, base voltage adjustment) are used to stabilize the output signal, then pressure detection reliability is improved, but the device complexity increases
Solution Approach 1:
The base voltage adjustment circuit is designed to be integrated with the existing integrator and amplifier circuits, sharing common components such as the reference voltage source and power supply. This merging approach minimizes the increase in device complexity while achieving the desired reliability improvement through coordinated circuit operation
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 configuration stabilizes the output signal, preventing erroneous failure diagnoses and enabling accurate and reliable pressure detection, while also reducing the risk of temperature-induced variations in base voltage.
Implementation Method 1
uses a piezoelectric element or the like as a sensor to detect a combustion pressure within a combustion chamber
Data Source
Figure 1~2
Figure 3~4(c)
Figure 5~6(c)
AI summary
A pressure detection device (10) comprises a pressure detection element (21) which receives pressure so as to output a detection signal corresponding to the pressure and a processing circuit (30) which processes and outputs the detection signal output from the pressure detection element. A processing circuit (30) is adopted which includes at least one or more amplifier circuits which amplify an output signal (Vout21) from an integrator circuit and a base voltage adjustment circuit (40) which is connected between a supply portion of a reference voltage (Vr) fed to the amplifier circuit and an input terminal of at least one of the amplifier circuits and which adjusts the magnitude of a base voltage (Vb22) that is a potential when a detection signal (Qi) in an output signal (Vout22) output from the amplifier circuit is not present.