Measurement sensor assembly and method for measuring the quality of a fluid
First Claim
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1. A measuring system for determining a property of an oil from a dielectric property of the oil, comprising:
- a first sensor for measuring an electric capacitance and a second sensor for measuring a temperature, wherein the first sensor is designed as a dielectric sensor which is immersed in the oil and has a stray-field capacitor which functions as the measuring capacitor, and the second sensor is designed as a temperature sensor which is immersed in the oil; and
a compensation device for correcting the measured value of the electric capacitance, taking into account a capacitance reference value measured on an auxiliary capacitor situated in proximity to the measuring capacitor, wherein the corrected measured value of the electric capacitance and the temperature measured by the second sensor are used to determine an ageing state of the oil,wherein the dielectric sensor includes the auxiliary capacitor and on introduction of the dielectric sensor into the oil, the auxiliary capacitor is not immersed in the oil until the measuring capacitor is fully immersed in the oil, wherein feeder lines of the measuring capacitor and the auxiliary capacitor are identical in design and are arranged in mutual symmetry.
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Abstract
The aim of the invention is to provide a simple and reliable method of measuring the quality of a fluid (2), in particular an oil or fat. This is achieved by a dielectric measurement in conjunction with a temperature measurement, which are carried out in situ by means of a measuring assembly and a sensor assembly (1) used with the latter, whereby the sensor assembly is submerged in the fluid. This permits information concerning the condition of the fluid, in particular concerning the age of the frying oil or fat, to be obtained in a rapid, low-cost manner.
27 Citations
32 Claims
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1. A measuring system for determining a property of an oil from a dielectric property of the oil, comprising:
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a first sensor for measuring an electric capacitance and a second sensor for measuring a temperature, wherein the first sensor is designed as a dielectric sensor which is immersed in the oil and has a stray-field capacitor which functions as the measuring capacitor, and the second sensor is designed as a temperature sensor which is immersed in the oil; and a compensation device for correcting the measured value of the electric capacitance, taking into account a capacitance reference value measured on an auxiliary capacitor situated in proximity to the measuring capacitor, wherein the corrected measured value of the electric capacitance and the temperature measured by the second sensor are used to determine an ageing state of the oil, wherein the dielectric sensor includes the auxiliary capacitor and on introduction of the dielectric sensor into the oil, the auxiliary capacitor is not immersed in the oil until the measuring capacitor is fully immersed in the oil, wherein feeder lines of the measuring capacitor and the auxiliary capacitor are identical in design and are arranged in mutual symmetry. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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2. A measuring system for determining a property of an oil from a dielectric property of the oil, comprising:
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a first sensor for measuring an electric capacitance and a second sensor for measuring a temperature, wherein the first sensor is designed as a dielectric sensor which is immersed in the oil and has a stray-field capacitor which functions as the measuring capacitor, and the second sensor is designed as a temperature sensor which is immersed in the oil; and a compensation device for correcting the measured value of the electric capacitance, taking into account a capacitance reference value measured on an auxiliary capacitor situated in proximity to the measuring capacitor, wherein the corrected measured value of the electric capacitance and the temperature measured by the second sensor are used to determine an ageing state of the oil, wherein the dielectric sensor includes the auxiliary capacitor and on introduction of the dielectric sensor into the oil, the auxiliary capacitor is not immersed in the oil until the measuring capacitor is fully immersed in the oil, wherein the auxiliary capacitor is composed of at least one spur line which ends upstream from the measuring capacitor and is designed and arranged like the feeder lines of the measuring capacitor. - View Dependent Claims (23, 24, 25, 26, 27)
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9. A measuring system for determining a property of an oil from a dielectric property of the oil, comprising:
a first sensor for measuring an electric capacitance and a second sensor for measuring a temperature, wherein the first sensor is designed as a dielectric sensor which is immersed in the oil and has a stray-field capacitor which functions as a measuring capacitor, and the second sensor is designed as a temperature sensor which is immersed in the oil, and wherein the first and second sensors are each connected to an analyzer device which assigns a value of the property to be determined to a measured temperature value and a measured electric capacitance value, wherein the property to be determined includes an ageing state of the oil, and wherein the value of the electric capacitance measured by the dielectric sensor is compared in a comparator device of the analyzer device with a stored reference value assigned to the measured temperature value, and a signal is output as a function of whether the reference value is reached or exceeded, wherein the dielectric sensor has an auxiliary capacitor and on introduction of the dielectric sensor into the oil, the auxiliary capacitor is not immersed in the oil until the measuring capacitor is fully immersed in the oil, and wherein feeder lines of the measuring capacitor and the auxiliary capacitor are identical in design and are arranged in mutual symmetry, wherein the auxiliary capacitor is composed of at least one spur line which ends upstream from the measuring capacitor and is designed and arranged like the feeder lines of the measuring capacitor, wherein the measuring capacitor is formed by a plurality of flat printed conductors in particular in the form of interdigital capacitor, and wherein the printed conductors are printed on an insulating substrate by thin-film or thick-film methods. - View Dependent Claims (28, 29, 30, 31, 32)
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10. A measuring device, comprising:
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a first sensor that measures a first property of an oil and outputs a first measured value; a second sensor that measures a second property of said oil and outputs a second measured value; an analyzer device connected to said first and second sensors, wherein said analyzer device compares said first and second measured values with stored reference values and outputs at least one signal based on differentials between said measured values and said stored reference values, wherein the at least one signal determines an ageing state of the oil; and a compensation device that takes calibrating measurements of said first and second properties, wherein said compensation device is an auxiliary capacitor disposed in proximity to said first sensor, and wherein said auxiliary capacitor includes at least one spur line ending upstream from feeder lines of a measuring capacitor of said first sensor and that is symmetrical with the feeder lines of said measuring capacitor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification