DE102018114210B4 - Process for evaluating fluids - Google Patents

Abstract

Method for determining the state of a fluid (7), wherein the fluid (7) consists partly of water or is miscible with water and is suitable for building up a reaction layer on the surface of a component (1a, b; 13), with a sensor (2) is provided which comprises at least one pair of electrodes (1a, b), the electrodes (1a, b) being insulated from one another and made of different materials, the electrodes (1a, b) protruding or being movable into the fluid, with the following steps: - Creation of a reaction surface on at least one partial surface of an electrode (1a, b) of the electrode pair; - Creation of an electrically conductive connection between the electrodes (1a, b), the electrodes (1a, b) being connected directly to the ammeter ( 4) are connected, and measure the electrical current flow between the electrodes (1a, b) over a predefinable period of time when the electrodes (1a, b) are at least partially wetted by the fluid (7), or measure the voltage between the electrodes (1a, b), the electrodes (1a, b) being connected directly via the voltage measuring device (5), over a predeterminable period of time when the electrodes (1a, b) are at least partially removed from the fluid (7 ) are wetted; - Assessment of the condition of the fluid (7) after the specified period of time on the basis of the measured current strength or the measured voltage, the condition of the fluid (7) being considered good if the measured current strength or voltage is less than a specifiable threshold value or lies within a specifiable value range.

Description

The invention relates to a method and a device for evaluating the condition of fluids. The fluid can be, for example, the cooling water in the cooling circuit of a motor vehicle or any other fluid.

The coolant in vehicles usually consists of a coolant based on water, as well as additives such as glycol (e.g. ethylene glycol) and additives. The addition of the additives is tailored to the materials used in the engine and the other components of the cooling system and is therefore usually dependent on the specifications of the engine manufacturer. Since the additives degrade over time or are subject to an aging and / or wear process, the coolant must be changed regularly.

In addition to the engine, a retarder, which uses the cooling liquid as the working medium, can also form a channel section in the cooling system. Furthermore, such cooling systems have at least one cooling fluid delivery device and a heat exchanger. The cooling circuit comprises several channel sections that usually consist of different materials, with the cooling liquid ideally covering all materials with a protective layer that is able to build up a reaction layer on the surface of the channel so that corrosion is reliably prevented.

To ensure that corrosion processes are reliably avoided, the change intervals must be observed. In general, therefore, there is a disposal of coolant, which could still have been used. This represents a serious disadvantage in terms of costs, in particular with regard to the need for professional disposal and / or the associated interruption of operations.

From the DE 195 33 628 A1 a switching arrangement for a motor vehicle cooling system with the usual features and components of a cooling system is known in which a sensor is provided by means of which a dielectric value measurement can be carried out so that the antifreeze concentration can be determined.

From the DE 10 2005 043 699 A1 A sensor unit is known which generates at least one piece of measurement information for determining a proportion of anti-corrosion agent in a fluid of a fluid system for a vehicle, with a resistance value or an impedance value of the immersed reference conductor and the reaction conductor for determining the proportion of anti-corrosion agent in the fluid of the fluid system being output as measurement information.

US 2014/0303 831 A1 also discloses a method for evaluating the condition of a vehicle coolant based on the temperature and conductivity of the liquid.

A method is known from WO 2016/146 624 A1 in which a voltage is applied between two electrodes and the current flowing is measured, the measured current being dependent on a corrosion protection layer, which allows conclusions to be drawn about the quality of the coolant.

Furthermore, from the EP 2 775 297 A1 a method with a detection sensor is known which detects a change in the concentration of a corrosion inhibitor, which inhibits the corrosion of a corrosion protection carrier material, when the corrosion protection performance deteriorates. An alternating voltage with a predetermined frequency is used for this purpose.

However, it has been shown that the measurement of properties or property changes are very complex and the measured values do not correlate reliably with the functionality of the fluid.

One of the objects of the present invention is therefore to propose a method and a device for evaluating the condition and / or the functionality of a fluid.

According to the invention, this object is achieved with a method according to claim 1 and a device according to claim 10. Further advantageous configurations and preferred solution variants are described in the dependent claims.

The invention is based on the knowledge that the ability of a fluid to build up a reaction layer on the surface of a component changes when the properties of the fluid change, which occurs, for example, when the coolant ages.

With the above in mind, it is an object of the present invention to propose a method and an apparatus by means of which the state of a fluid can be determined.

A method for determining the state of a fluid is proposed, the fluid partly consisting of water or with water is miscible and is suitable for building up a reaction layer on the surface of a component, a sensor being provided which comprises at least one pair of electrodes, the electrodes being insulated from one another and made of different materials. Furthermore, the electrodes protrude into the fluid or can be moved into the fluid.

• - Schaffung einer Reaktionsfläche an zumindest einer Teiloberfläche einer Elektrode des Elektrodenpaares;
• - herstellen einer elektrisch leitenden Verbindung zwischen den Elektroden, wobei die Elektroden direkt über das Strommessgerät verbunden sind, und messen des elektrischen Stromflusses zwischen den Elektroden über eine vorgebbare Zeitspanne, wenn die Elektroden zumindest teilweise von dem Fluid benetzt sind, oder messen der Spannung zwischen den Elektroden, wobei die Elektroden direkt über das Spannungsmessgerät (5) verbunden sind, über eine vorgebbare Zeitspanne, wenn die Elektroden zumindest teilweise von dem Fluid benetzt sind;
• - Beurteilung des Zustandes des Fluids nach der vorgegebenen Zeitspanne auf Basis der gemessenen Stromstärke oder der gemessenen Spannung, wobei der Zustand des Fluids als gut gilt, wenn die gemessene Stromstärke oder Spannung kleiner ist als ein vorgebbarer Schwellwert oder innerhalb eines vorgebbaren Wertebereichs liegt.

The process comprises the following steps:

• Creation of a reaction surface on at least one partial surface of one electrode of the electrode pair;
• - Establish an electrically conductive connection between the electrodes, the electrodes being connected directly via the ammeter, and measure the electrical current flow between the electrodes over a predeterminable period of time when the electrodes are at least partially wetted by the fluid, or measure the voltage between the Electrodes, the electrodes being connected directly to the voltmeter ( 5 ) are connected over a predefinable period of time when the electrodes are at least partially wetted by the fluid;
• - Assessment of the state of the fluid after the specified period of time on the basis of the measured current strength or the measured voltage, the state of the fluid being considered good if the measured current strength or voltage is less than a specifiable threshold value or lies within a specifiable value range.

For the purposes of the application, a reaction surface is considered to be any surface on which a reaction layer can build up that causes a change in the current flow so that when the electrodes are short-circuited, the measurable current flow is smaller than the current flow without a reaction layer.

Furthermore, to assess the condition of the fluid, the course of the current strength or the voltage can also be taken into account until the specified time span has elapsed.

In a further advantageous method, a short circuit between the electrodes can be produced to assess the state of the fluid, which short circuit is temporarily interrupted, a voltage measurement taking place during the time of the interruption. The short circuit accelerates or promotes the formation of reaction layers on the electrode surfaces. The measurement of the voltage can be used to assess the condition of the fluid.

Furthermore, the predefined time span can comprise several first time segments for voltage measurement and second time segments for current measurement. As a result of this alternating measurement of voltage and current, the voltage curve and the current curve can be used particularly advantageously for assessing the fluid.

The first time segment for the voltage measurement can be between 0.2s and 10s and the second time segment for the current measurement between 0.2s and 600s. However, the first time segment for the voltage measurement can preferably also be between 1 s and 2 s and the second time segment for the current measurement between 1 s and 10 s.

A measurement can also begin with a current measurement or a short circuit.

• - Anlegen einer Spannung zwischen den Elektroden;
• - Generierung einer Bruchfläche;
• - spanende Bearbeitung;
• - elektrochemisches Verfahren;
• - gezielte abrasive Bearbeitung;
• - gezielte Erzeugung von Kavitation an zumindest einer Elektrodenoberfläche in

einem Fluidstrom;To achieve the removal of an existing reaction layer on the electrodes, at least one of the following methods is used:

• - applying a voltage between the electrodes;
• - Generation of a fracture surface;
• - machining;
• - electrochemical process;
• - targeted abrasive machining;
• - targeted generation of cavitation on at least one electrode surface in

a fluid stream;

The voltage can be a DC or AC voltage that is applied between the electrodes. In a further embodiment, a direct or alternating voltage can also be applied between an auxiliary electrode and the electrodes.

Alternatively, abrasive processing can also be carried out using a movable cleaning body.

Furthermore, a device for determining the state of a fluid is proposed which is suitable for a method according to one of the methods described. This comprises a sensor consisting of a support element and at least one pair of electrodes, which are made of different materials and insulated from one another, the electrodes being connected directly via an ammeter or a voltage measuring device and the device comprising a processing body and means for abrasive processing of the electrodes enable.

The means can allow a movement of the electrode and / or the processing body, wherein the drive can be mechanical, electrical, hydraulic or pneumatic.

A fluid circuit can for example comprise a plurality of channel sections through which a fluid can flow, wherein the fluid circuit comprises a device according to one of Claims 10 or 11.

In one embodiment, the channel sections can be formed by components that are made of different materials, the sensor comprising at least one pair of electrodes, the electrodes being made of materials that match the materials used for different channel sections.

Further features of the method and device according to the invention and further advantages of the invention emerge from the following description with reference to the drawings.

The invention is explained in more detail below with the aid of sketches.

• 1 eine erfindungsgemäße Messanordnung
• 2a, b zeigt beispielhaft den Spannungsverlauf und den Stromverlauf
• 3 ist der Stromverlauf für ein Fluid dargestellt, welches unterschiedlich lang im Einsatz war
• 4 zeigt die Stromstärken nach 120s Messzeit, für ein alterndes Fluid
• 5 zeigt ein erstes Ausführungsbeispiel einer Messvorrichtung im Fluidstrom
• 6 zeigt ein zweites Ausführungsbeispiel einer Messvorrichtung im Fluidstrom

In these show:

• 1 a measuring arrangement according to the invention
• 2a, b shows an example of the voltage curve and the current curve
• 3 the current curve is shown for a fluid that has been in use for different lengths of time
• 4th shows the current intensities after a measurement time of 120s for an aging fluid
• 5 shows a first embodiment of a measuring device in the fluid flow
• 6th shows a second embodiment of a measuring device in the fluid flow

1 shows a measuring arrangement according to the invention to explain the measuring method by means of which the state of a fluid can be measured or determined. In the vessel shown as an example 8th is the fluid to be tested 7th . The fluid can be water or water with at least one additive. The fluid 7th must be suitable for building up a reaction layer on the surface of a component. The component here is the electrodes 1a , b, which consist of different materials and are electrically isolated from one another.

The desk 3 has two positions, with the switch in the first position 3 the electrodes 1 a, b via the current measuring unit 4th can be connected directly to one another so that a current measurement can be carried out and in the second position of the switch 3 a voltmeter can be switched between the electrodes so that a voltage can be measured.

If the sensor or the bare electrodes are immersed in the fluid, a reaction layer forms on the surfaces of the electrodes wetted with fluid 1a , b. The formation of the reaction layer depends on the composition of the fluid or its condition and the position of the switch 3 .

In the 2a , 2 B , 3 and 4th voltage and current curves are shown. The first measured value is always a value shortly after the bare electrodes have been immersed 1a , b was measured in the fluid. A bare electrode is to be understood as an electrode that has no reaction layer.

2a and 2 B show examples of the voltage curve and the current curve over approx. 60s. Here are in the diagram 2a the stress curve for several material pairings is shown. So here it was measured how the voltage changes if a reaction layer changes over time on at least one of the electrodes 1a , 1b builds up, whereby the reaction layer acts like an insulating layer.

In the diagram 2 B the same material pairings were used and the current was measured. Here, too, the structure of the reaction layer can be clearly seen with two material pairings.

In 3 the current curve for a fluid is shown, which was measured repeatedly at different times or after different periods of use. The reaction layer was removed before each new measurement. The course of the current strength clearly shows that the build-up of a new reaction layer takes different times. It can also be clearly seen that the fluid used loses its ability to build up a reaction layer with increasing age.

If the fluid is a cooling liquid, for example, it should be replaced as soon as it loses its ability to build up a reaction layer on the electrodes or to protect the inner walls of the channel sections in a cooling circuit by means of the reaction layer.

4th shows again clearly how the currents change after a measuring time of 120 seconds as the fluid ages. From a certain period of use, here after about 250 hours, the ability to build up a reaction layer decreases rapidly.

5 shows a first embodiment of a sensor 2 in the fluid flow 7th . The sensor is on a lifting device 9 attached so that the sensor 2 with the electrodes 1a , 1b in the channel section 13 can be moved up and down, the hub is denoted by 6.

Before each measurement, the sensor 2 against the machining body 10 moves through which the electrodes 1a , 1b cleaned or the reaction layer removed. This can be done, for example, by rotating the processing body 10 respectively. The lifting device 9 can be operated using compressed air.

6th shows a second embodiment of a measuring device in the fluid flow, here the removal of the reaction layer on the electrodes 1a , 1b by means of one, in the channel section 13 , freely movable processing body 10 he follows. The fluid flow is used here 7th as a drive for the movement of the processing body 10 .

The embodiments shown show only two possible constructions, other arrangements and kinematics also being conceivable.

Furthermore, two or more electrode pairs can be used 1a , 1b a sensor 2 form. Several material pairings that are used in a cooling circuit can be measured at the same time. If it is determined that a material is no longer adequately protected - a reaction layer no longer builds up - this is an indication to replace the coolant.

The use of the measurement method is not limited to the area of application described. For example, it is also possible to determine the condition of water from rivers and lakes (hydro), mine water (turbo mine application), etc., which can have very different corrosive effects. The different corrosiveness results from impurities, which are then to be understood as additives in the context of the invention.

Claims (14)

Method for determining the state of a fluid (7), wherein the fluid (7) consists partly of water or is miscible with water and is suitable for building up a reaction layer on the surface of a component (1a, b; 13), with a sensor (2) is provided which comprises at least one pair of electrodes (1a, b), the electrodes (1a, b) being insulated from one another and made of different materials, the electrodes (1a, b) protruding or being movable into the fluid, with the following steps: - Creation of a reaction surface on at least one partial surface of an electrode (1a, b) of the electrode pair; - Establishing an electrically conductive connection between the electrodes (1a, b), the electrodes (1a, b) being connected directly via the ammeter (4), and measuring the electrical current flow between the electrodes (1a, b) over a predeterminable time period when the electrodes (1a, b) are at least partially wetted by the fluid (7), or measure the voltage between the electrodes (1a, b), the electrodes (1a, b) being connected directly via the voltage measuring device (5) over a predeterminable period of time when the electrodes (1a, b) are at least partially wetted by the fluid (7); - Assessment of the condition of the fluid (7) after the predetermined period of time on the basis of the measured current strength or the measured voltage, the condition of the fluid (7) being considered good if the measured current strength or voltage is less than a predetermined threshold value or within a predefinable range of values. Procedure according to Claim 1 , characterized in that to assess the condition of the fluid (7), the course of the current strength or the voltage is also taken into account until the specified time period has elapsed. Procedure according to Claim 1 or 2 , characterized in that to assess the condition of the fluid (7) a short circuit between the electrodes (1a, b) is produced, which is temporarily interrupted, with a voltage measurement taking place during the time of the interruption. Procedure according to Claim 3 , characterized in that the predetermined time span comprises several first time segments for voltage measurement and second time segments for current measurement. Procedure according to Claim 4 , characterized in that the first time segment is between 0.2s and 10s and the second time segment between 0.2s and 600s. Procedure according to Claim 4 , characterized in that the first time segment is between 1s and 2s and the second time segment between 1s and 10s. Procedure according to Claim 1 , characterized in that at least one of the following methods is used to remove an existing reaction layer on the electrodes (1a, b): - applying a voltage between the electrodes; - Generation of a fracture surface; - machining; - electrochemical process; - targeted abrasive machining; targeted generation of cavitation on at least one electrode surface in a fluid flow; Procedure according to Claim 7 , characterized in that a DC or AC voltage is applied between the electrodes (1a, b). Procedure according to Claim 7 , characterized in that a DC or AC voltage is applied between an auxiliary electrode and the electrodes (1a, b). Procedure according to Claim 7 , characterized in that the abrasive machining is carried out by means of a movable cleaning body (10). Device for determining the state of a fluid (7) for a method according to one of the Claims 1 - 9 , comprising a sensor (2) consisting of a carrier element and at least one pair of electrodes (1a, b), which consists of different materials and is insulated from one another, characterized in that the electrodes (1a, b) are directly connected to a current measuring device (4) or a voltage measuring device (5) are connected, wherein the device comprises a processing body (10) and means (11) which enable an abrasive processing of the electrodes (1a, b). Device according to Claim 11 , characterized in that the means enable a movement of the electrode (1a, b) and / or of the processing body (10), wherein the drive can be mechanical, electrical, hydraulic or pneumatic. Fluid circuit comprising a plurality of channel sections through which a fluid (7) can flow, wherein the fluid circuit comprises a device according to one of the Claims 11 or 12 includes. Fluid circuit according to Claim 13 , characterized in that the channel sections (13) are formed by components which consist of different materials, the sensor (2) comprising at least one pair of electrodes (1a, b), the electrodes (1a, b) being made of materials which match the materials used in different duct sections.

Images