Piezoelectric Sensor for Non-Invasive Hydraulic Pressure Diagnostics
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Solution Overview
Problem
Existing high-pressure hydraulic systems face challenges in accurately detecting pressure signals within the control chamber of fuel injectors due to high pressures and small spaces, limiting the effectiveness of existing sensors in diagnosing the operation of complex systems like diesel engines.
Innovation Solution
A piezoelectric sensor arrangement with a diaphragm and elastic element, integrated into the hydraulic system, which detects pressure variations through deformations of a reaction surface, providing an electrical signal indicative of fluid pressure without direct contact, allowing for non-invasive diagnostics and resistance to high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is placed close to the injector control chamber to directly detect pressure signals, then measurement precision is improved, but the sensor must withstand very high pressures (thousands of bars) in small spaces, increasing device complexity and limiting sensor element size
Solution Approach 1:
The patent introduces an intermediary chamber connected to the control chamber via a calibrated orifice. This intermediary chamber acts as a buffer that translates the high-pressure control chamber signals into measurable pressure variations that the sensor can detect without direct exposure to the extreme pressure environment, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces direct mechanical pressure sensing in the high-pressure control chamber with an electrical sensing system in a low-pressure intermediary chamber. The pressure signal is transmitted through the calibrated orifice and converted to electrical signals by the piezoelectric sensor, eliminating the need for the sensor to directly withstand thousands of bars of pressure
2Measurement precision
If a piezoelectric sensor is used to detect pressure variations during injector needle opening and closing, then measurement precision is improved, but the sensor is limited by the small size of the control chamber and high pressures, reducing its ability to withstand loads and deformations
Solution Approach 1:
The calibrated orifice serves as an intermediary that decouples the sensor from the high-pressure control chamber environment. The orifice creates a controlled pressure drop that allows the sensor to measure pressure variations indirectly in a lower-pressure zone, protecting the sensor from direct exposure to extreme loads while maintaining measurement precision
Solution Approach 2:
The patent segments the pressure detection system into two distinct zones: the high-pressure control chamber where the actual injector operation occurs, and the low-pressure intermediary chamber where the sensor is located. This segmentation allows the sensor to operate in a protected environment while still detecting the pressure variations generated by the injector needle movement
3Ease of operation
If the sensor is placed in a low-pressure region and loaded by axial force from the control valve rod, then the sensor can detect pressure changes, but the sensor cannot directly detect control chamber pressure due to the pressure drop across the valve seat and orifice
Solution Approach 1:
The calibrated orifice is introduced as an intermediary element that creates a controlled pressure transition zone. This orifice allows the sensor to be positioned in a low-pressure region for ease of installation while still enabling accurate detection of control chamber pressure variations through the calibrated pressure drop relationship
Solution Approach 2:
The patent replaces direct mechanical coupling of the sensor to the control chamber with an electrical sensing system positioned in a low-pressure region. The pressure signal is transmitted through the calibrated orifice and converted to electrical signals, allowing the sensor to operate in a more accessible low-pressure environment while maintaining measurement capability
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
Enables cost-effective, non-invasive monitoring of hydraulic system operations, providing accurate diagnostic parameters for injector performance by effectively measuring pressure in high-pressure environments within small spaces, enhancing the reliability of hydraulic system diagnostics.
Implementation Method 1
A piezoelectric sensor arrangement with a diaphragm and elastic element, integrated into the hydraulic system, which detects pressure variations through deformations of a reaction surface, providing an electrical signal indicative of fluid pressure
Data Source
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AI summary
A high pressure hydraulic system comprising: - a hydraulic chamber (34) containing pressurized fluid, - a wall (50) which encloses at least one part of the hydraulic chamber (34) and comprising an integral diaphragm (120), - a piezoelectric sensor (70) isolated from the pressurized fluid contained in the hydraulic chamber (34) by the diaphragm (120), and - an elastic element (102) arranged to apply an elastic force to the piezoelectric sensor (70), between the piezoelectric sensor (70) and the diaphragm (120), wherein a deformation of the diaphragm (120) produced by a change in the pressure of the fluid contained in the hydraulic chamber (34) causes a change in the elastic force that the elastic element (102) applies to the piezoelectric sensor (70).