Insertion Sensors for Fluid Condition Monitoring
Over the past five years Sentelligence™ has developed a flexible patent pending platform technology that can be applied to a wide range of uses for fluid condition and quality monitoring for automotive, mining, power generation, and industrial applications. The primary technology is a universal optical platform that measures the spectral or optical responses of the fluid and correlates these to specific properties. The sensor components are solid state and are selected to perform in the rigorous conditions encountered under normal extremes of temperature and vibration.
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The sensors are fully programmable. The electronics include a boot loader which enables sensors to be reprogrammed, reset and recalibrated, as required. In the case of the condition monitoring versions of the sensor they can be set up to handle various monitoring scenarios related to fluid condition, mechanical and operational performance. Note that these are defined for a diesel engine sensor, such as the one shown in Figure 1. However, similar or comparable scenarios can be defined for other forms of combustion engine oils (gasoline and natural gas), liquid fuels, and transmission and hydraulics fluids.
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Figure 1: Sentelligence Oil Condition Sensor for non-transparent media (such as soot-laden oils)
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The primary optical function monitored is light/energy absorption in the visible and near infrared regions of the electromagnetic spectrum. Extensions can include light scattering and optical emission, including fluorescence. All of these forms of measurement are capable of providing useful diagnostics for the characterization of specific fault conditions and/or the presence of undesirable materials.
Example specifications of the Sentelligence fluid condition monitoring sensors include:
- Insertion-style sensors designed for dynamic flow monitoring
- Example soot formation monitoring, with programmable reporting with typical accuracy of between 0.25 and 0.5% soot (relative) over the range of 0.25% to 10% soot content
- The measurement of degradation, aging and contamination in engine oils, fuels, hydraulic fluids and coolants
- Inferential measurement of properties used for fluid condition, such as oxidation/ acid number (engine oils, excluding diesel, transmission oils and fuels) and viscosity/TBN (for diesel engine oils)
- Designed for operation over a wide temperature range: -40°C to 130°C, non-operational to 200°C
- Communications via CAN-Bus, with J1939 protocol – sensor powered via bus (voltage range 6VDC to 40VDC, overload protection to 200VDC)
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A generalized layout of the Sentelligence optoelectronic insertion sensor is provided in Figure 2. This provides a functionalized schematic for the sensors, where the optical interface and the optoelectronics are customized for individual applications. The customization is based on the wavelengths selected and the geometry/dimensions of the interface. In terms of a standard configuration, multiple wavelengths can be independently monitored by the coupling of the source to a cooresponding set of optical detectors.
The standard sensors are configured for on-line/in-line applications with dynamic flow conditions. The sensors are ideally located within a flowing stream of fluid where the sensing head is frequently refreshed by fresh fluid. A typical assembly for implementation is provided in Figure 3. A good practical location for such an arrangement is just after a fluid filtration point. This provides a good constant flow of representative fluid. |
Figure 2: Generic format of insertion-style sensor for opaque and transparent media (as defined by optical coupling method) |
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The company name, Sentelligence, is derived from the terms defining the functionality and fundamental principles of the sensors – that is “intelligent sensing”. All sensors have onboard data handling functions that provide full sensor control, data acquisition, data pre- and post processing, communications, and fault and condition diagnostics.
Figure 3: Example implementation of an insertion-style sensor
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For this type of measurement the sensor monitors specific signals and trends. For example; in the oil condition monitor the sensor keeps track of events such as oil changes and top-offs and can also track deviations in the trends (see Figure 4). Deviations from normal performance are highly diagnostic and can be correlated to a number of performance related parameters.
Figure 4: An example smart sensor output where trends and change in trend direction are used as diagnostics
The Sentelligence sensors are designed for low-cost high volume production. They have the potential to address numerous areas of application some not covered in this document. End users and OEMs interested in other areas of application should contact Sentelligence for a system evaluation. |
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