Als je olie op het juiste moment wil kunnen vervangen, dan zul je op heel wat variabelen moeten monitoren. Doe je dat niet, kan je niet anders dan gewoon termijnen aanhouden waar noodzakelijkerwijs een redelijke marge in verwerkt is. Dat de termijnen in de loop der jaren verruimd zijn heeft voornamelijk te maken met betere smeermiddelen en de betere passing van onderdelen nu tov vroeger. Vroeger moest een motor ook de eerste 1000 km ingereden worden met inloopolie, die vervolgens vervangen moest worden door de echte motorolie. Dat hoeft niet meer. Ook gebruiken de meeste motoren tegenwoordig in de eerste 10 jaar nauwelijks meer olie door die betere passing. Dat betekent omgekeerd dat er veel minder vervuiling in de motor terecht komt. Ook zijn de oliefilters tegenwoordig een stuk beter. Maar wil je het goed doen, moet je monitoren. Ofwel op de variabelen die de levensduur beïnvloeden (temperatuur, aantal koude starts, conditie van de aanzuiglucht, etc), ofwel op veranderende variabelen in de olie zelf (geleidbaarheid, capacitiviteit, optische eigenschappen). Daar zijn diverse technische oplossingen voor, kun je hier meer over lezen:
General Motors Corporation GM Oil-Life™ System
The General Motors (GM) Oil-Life System, first introduced commercially in the 1998 Oldsmobiles, determines when to change the oil and filter based on several operating conditions. The technology does not actually monitor any single quality or physical property of the oil. Instead, the Oil-Life System monitors engine revolutions, operating temperature, and other factors that affect the length of oil change intervals.
The sensor is based on GM’s determination that nearly all driving conditions can be grouped into one of four categories: easy freeway driving; high-temperature, high-load service; city driving; or extreme short-term, cold-start driving. GM discovered that oil degradation in the first three categories was largely a function of the oil temperature. During extreme short-trip driving (the fourth category), the principle cause of oil degradation is water condensation and contaminants in the oil - the lower the oil temperature, the greater the contamination.
The software automatically adjusts the oil change interval based on engine characteristics, driving habits and climate. When the system notifies the owner that it is time for an oil change, the owner can go to the nearest GM dealer and a technician will change the oil and filter, properly recycle the oil, then reset the vehicle’s oil life system.
If the owner prefers to change his/her oil, the GM owner’s manual provides instructions on resetting the timer. Because the Oil-Life System does not actually sense oil condition, it is important for the engine computer to know when an oil change takes place. Therefore, the Oil Life System must be reset each time to ensure accurate and proper performance.
It is now available on all light-duty North American GM cars except for some models of Buick Park Avenue and Le Sabre, Pontiac Bonneville and Sunfire/Sunbird, Chevrolet Tracker, Cavalier and Malibu, S10/Sonoma trucks, Astro/Safari Vans, and the Pontiac Vibe.
DaimlerChrysler Corporation Flexible Service System
DaimlerChrysler’s version of the oil monitor is called ASSYST in Europe and the Flexible Service System (FSS) in the United States. Like GM’s sensor, the FFS uses a computerized system to track multiple engine operating conditions. From research on oil quality through the span of an engine’s life, Daimler discovered that the breakdown in oil is determined by such factors as driving habits (frequent short trips vs. long trips), driving speed and failure to replenish low oil levels. Therefore, the FSS monitors time between oil changes, vehicle speed, coolant temperature, load signal, engine rpm, engine oil temperature and engine oil level. It uses this information to determine the remaining time and mileage before the next oil change and it displays the information in the vehicle’s instrument cluster.
In addition, Daimler discovered that oil degradation is correlated directly with its ability to conduct electric current. Therefore, Daimler has fitted V-6 and V-8 engines with a digital oil quality dielectric sensor, that is mounted above the oil pan along with an analog oil level sensor. This sensor measures changes in capacitance, which effectively is a proxy for the amount and type of contaminants and oil degradation products present in the oil. An increase in dielectric constant (less resistance to electrical flow) indicates oil contamination and degradation.
Daimler-Benz (Mercedes-Benz) has been incorporating the sensor into its vehicles since 1998.
Delphi Corporation INTELLEK® Oil Condition Sensor
The INTELLEK Oil Condition Sensor uses both a computer algorithm as well as a sensing element that directly measures various oil properties. The algorithm takes into account important factors affecting the rate of oil deterioration like temperature, driving severity, oil level and oil type. It measures the temperature every 10 seconds to verify whether it reaches a specific normal operating temperature before the engine shuts off. It also records the number of times the engine turns on and off.
A proprietary capacitive sensing element is the core technology. It tracks the oil’s conductivity, detects water and glycol contamination, oil temperature, and determines the oil level. According to Delphi, the oil’s conductivity is important because it characterizes additive depletion and changes in viscosity and acid number.
The INTELLEK Oil Condition Sensor tracks the many different parameters using onboard software to indicate when the oil is nearing the end of its service life. It attaches to the oil pan or wherever there is a continuous flow of oil.
Continental Temic Microelectronic GmbH QLT Oil Condition Sensor
The QLT sensor was launched in 1996 to monitor engine oil quality, level and temperature. Two sensors simultaneously and continuously monitor diesel engine oils containing soot. The instrument also monitors nitric oxide and oxidation products in spark-ignited engines, as well as water and fuel contamination. Because these factors influence the oil’s electrical properties and permittivity (ability of a material to resist the formation of an electric field within it), an effective oil condition sensor is achieved, according to the manufacturer.
The QLT also has an integrated precision probe that allows it to measure critical temperatures and exact oil levels. It can track temperatures ranging from -40°C to 160°C. The oil level, up to 100 milliliters, is calculated by a second capacitor.
Voelker Sensors Inc. Oil Insyte
The Oil Insyte sensor uses a patented technology based on the electrical properties of an oil-insoluble polymeric bead matrix (see Automotive Sensor Technologies Explained below for more details). The Oil Insyte employs an in-line method for continuous oil condition monitoring with an LCD readout providing detailed information about oxidation, additive depletion, soot contamination and oil temperature. The technology does not require external calibration standards and reports oil condition independent of viscosity.
Voelker Sensors Inc. - Oil Insyte
According to the manufacturer, the sensor measures key indicators of oil degradation and allows the conventional analyses approach of oil monitoring (sampling and analysis) to be combined into a single more efficient analysis. No assumptions are required as to the condition of the engine or the initial baseline quality of the oil.
The Oil Insyte technology measures oxidation and additive depletion, and has the ability to examine the interdependence between the two. They claim difficulties encountered with sensors that measure only the electrical properties of oil (conductive additives masking the true condition of the oil) are overcome by using a differential technique where the conductivity of the bead matrix is measured relative to the conductivity of the oil. The true polar condition of the oil can then be determined.
The soot detection feature of the sensor determines the amount of undispersed agglomerated soot (vs. dispersed finely divided soot) present in the oil. Depending on the oil’s additive package, the same amount of undispersed soot can be present at 1 percent to 2 percent (for the base oil without dispersants) as a fully formulated motor oil with more than 7 percent soot.
Lubrigard Ltd. Lubrigard Oil Condition Monitoring Sensor
Lubrigard Ltd. - Lubrigard Oil Condition Monitoring Sensor
The Lubrigard sensor unit is designed to be fitted by the original equipment manufacturers (OEMs) to new cars and trucks to warn the operator of abnormal lubricant conditions. According to the manufacturer, it indicates when an oil or filter change is necessary or when the oil should be inspected or tested.
The sensor was designed to optimize oil drain intervals and to detect problems like coolant leaks, metallic wear debris and oil degradation by direct measurement. It is particularly useful for measuring high concentrations of soot in diesel engines’ crankcase oils.
The sensor’s technology is based on the dielectric loss factor, also known as Tan Delta. According to Lubrigard, this method is more sensitive to changes in contamination than other dielectric measurements. At the same time, it is tolerant of normal differences in operating temperatures and lubricant formulations. To compensate temperature variations, a temperature sensor communicates with the unit’s microcontroller. The technology monitors soot, water, coolant, oxidation and/or wear particles.
The sensor is designed so that it can be connected to the car’s onboard computer. Outputs and alarms are displayed in accordance with the auto maker’s preference. For example, a dashboard display could show a thermometer-type scale growing in size and changing color from green through amber to red as the oil degrades.
The Lubrigard sensor is readily mountable on any engine, gearbox or hydraulic system, and it will work in both gasoline and diesel engine oils.
Symyx Technologies Inc. Solid-State Oil Condition Sensor
Symyx Technologies developed a sensor that uses a solid-state micromechanical resonator and a special signal-processing algorithm to measure important physical properties of lubricants. This sensor can measure three independent physical properties: viscosity, density and dielectric constant. This is significant technology because the direct measurement of a lubricant’s physical properties can provide important information about changing lubricant and engine health.
The miniature sensor allows for innovative packaging and strategic placement of the sensor in an engine to provide in-situ oil analysis without negatively affecting the design parameters of an overall system. The extremely fast response time and signal processing of the sensor allows for real-time measurement of lubricant properties.
According to Symyx, its solid-state resonator technology will operate in various types of fluid environments that experience a broad range of temperature, pressure, shock, vibration and fluid flow.
Symyx is actively pursuing companies interested in using or licensing this technology to measure and monitor the quality and condition of lubricants and other fluids. Already, several Symyx licensees of the sensor are commercializing the technology for use in the industrial and consumer markets. It is also currently being used in Symyx’ laboratories to measure the physical properties of gases and liquids.
Bosch GmbH Multifunction Oil Condition Sensor
Bosch is developing a multifunctional oil sensor that will determine oil level and oil condition. The oil level information will allow the oil dipstick to be omitted from the automobile.
Monitoring the engine oil condition is primarily intended to optimize oil drain intervals. However, it also provides increased insight into the actual state of the engine, which enables the possible detection of approaching engine failures or change in lubricant quality. The oil condition sensor will constantly measure the oil’s viscosity, permittivity, conductivity and temperature. The measured viscosity and permittivity (or dielectric constant) are the primary values supporting the oil condition evaluation. Commonly, chemical oil deterioration is associated with an increase in viscosity, whereas mechanical wear (shear) and fuel dilution lead to a decrease in viscosity.
A novel microacoustic device determines the viscosity. This device utilizes the piezoelectric effect to electrically excite high-frequency mechanic (or acoustic) vibrations at a sensitive surface. When this sensitive surface comes into contact with the oil, the electrical device parameters, such as oscillation frequency and damping, are changed according to the oil’s mechanical properties, especially viscosity. Thus, the viscosity can be electrically detected by measuring these parameters. In contrast to conventional viscometers, which are commonly used in laboratory applications, the microacoustic sensor does not contain any moving parts. Furthermore, due to its small size, it can be easily incorporated into the multifunctional oil-level and condition sensor.
Bosch’s multifunctional oil sensor is suitable for spark-ignition and diesel engines.
Eaton Corporation Fluid Condition Monitor
Eaton has developed a unique fluid condition monitor (FCM) technology that can monitor multiple fluid properties. The Eaton FCM is an in-situ real-time sensor based on impedance spectroscopy - a technology that measures multiple electrical properties of a fluid. It uses very small alternating current (AC) signals, which do not permanently disturb the fluid or the electrodes used in the measurement. Eaton’s FCM technology is differentiated by two critical attributes: it measures surface properties of the fluid in addition to bulk properties, and it has more degrees of freedom to enable the independent tracking of multiple lubricant parameters.
Measuring bulk properties reveals information about the conductivity (concentration and charge of ions) and dielectric constant (size, shape, and polarizability of the base fluid and its additives). Measuring the surface properties provides a quantitative measure of the physical and chemical properties of a fluid at the fluid-to-metal interface. This is a powerful technique when it is correlated to the real and measured physiochemical property changes occurring in aging or stressed motor oils.
The current prototype sensors are oil pan-mounted and include temperature-sensing capability. A small electronic module is used for signal conditioning, data capture and analysis.
Volgens mij was BMW één van de eersten die op basis van olieeigenschappen de interval aangaf met lampjes op het dash. Ik meen me te herinneren dat zij met een optische sensor in het carter door de olie keken en op basis van de zwarting de interval aangaven. Auto's met variabele intervallen moeten altijd zo'n soort van monitoring hebben.
Voor transmissies zou je vergelijkbare systemen kunnen toepassen, al weet ik niet of er ook fabrikanten zijn die dergelijke systemen toepassen. Recent kwam hier wel een topic voorbij van iemand met een Punto met (semi)automaat waar op het dash een lampje was gaan branden dat de transmissie onderhoud nodig had. Maar op welke variabelen dat gebaseerd is zou ik niet weten.
