DE102018114210A1 - Methods for evaluating fluids - Google Patents

Abstract

The invention relates to a method for determining the state of a fluid (7), which is suitable for building up a reaction layer on the surface of a component (1a, b; 13), a sensor (2) being provided which has 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) projecting into or being movable into the fluid. The invention is based on the finding that the ability of a fluid Building a reaction layer on the surface of a component changes when the properties of the fluid change, which occurs, for example, with the aging of the coolant.

Description

The invention relates to a method and a device for evaluating the state 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 additives is tailored to the materials used in the engine and the other components of the cooling system and is therefore generally dependent on the specifications of the engine manufacturers. Since the additives degrade over time or are subject to an aging and / or wear process, a regular change of the coolant is necessary.

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

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

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 frost protection concentration can be determined.

From the DE10 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, 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.

The US2014 / 0303831 further discloses a method for evaluating the condition of a vehicle coolant based on the temperature and conductivity of the liquid.

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 dependent thereon.

The invention is based on the finding 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 coolant ages.

Taking the above into account, it is an object of the present invention to propose a method and a device 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 consisting partly of water or being miscible with water and being 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, wherein the electrodes are insulated from each other and consist 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 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 über eine vorgebbare Zeitspanne, wenn die Elektro 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 an electrode of the pair of electrodes;
• - Establish an electrically conductive connection between the electrodes and measure the electrical current flow between the Electrodes over a predeterminable period of time if the electrodes are at least partially wetted by the fluid, or measure the voltage between the electrodes over a predeterminable period of time if the electrodes are at least partially wetted by the fluid;
• - Assessment of the state of the fluid after the predetermined period of time on the basis of the measured current or voltage, the state of the fluid being considered good if the measured current or voltage is less than a predeterminable threshold value or within a predeterminable value range.

Any surface on which a reaction layer can be built up which causes a change in the current flow is regarded as a reaction surface in the sense of the application, so that when the electrodes are short-circuited, the measurable current flow is smaller than the current flow without a reaction layer.

Furthermore, the course of the current strength or the voltage up to the expiry of the predetermined time period can also be taken into account for assessing the state of the fluid.

In a further advantageous method, a short circuit can be produced between the electrodes to assess the state of the fluid, which short-term interruption, a voltage measurement being carried out during the interruption. The short circuit accelerates or favors the formation of reaction layers on the electrode surfaces. The measurement of the voltage can be used to assess the state of the fluid.

Furthermore, the predetermined period of time can include several first time periods for voltage measurement and second time periods for current measurement. Through this alternating measurement of voltage and current, the voltage profile and the current profile can be used particularly advantageously for assessing the fluid.

The first time period for the voltage measurement can be between 0.2s and 10s and the second time period for the current measurement between 0.2s and 600s. Preferably, however, the first time period for the voltage measurement can also be between 1s and 2s and the second time period for the current measurement can be between 1s and 10s.

A measurement can also start 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;

In order 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 processing;
• - targeted generation of cavitation on at least one electrode surface in a fluid stream;

The voltage can be a direct or alternating 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 that is suitable for a method according to one of the described methods. This comprises a sensor, consisting of a carrier element and at least one pair of electrodes, which consists of different materials and is insulated from one another, the device comprising a processing body and means which enable abrasive processing of the electrodes.

The means can enable the electrode and / or the processing body to move, 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, the fluid circuit comprising a device according to one of claims 10 or 11.

In one embodiment, the channel sections can be formed by components which consist of different materials, the sensor comprising at least one pair of electrodes, the electrodes consisting of materials which correspond to the materials used for different channel sections.

Further features of the method and the device according to the invention as well as further advantages of the invention result 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 profile is shown for a fluid that was used for different lengths of time
• 4 shows the currents after 120s measuring time, for an aging fluid
• 5 shows a first embodiment of a measuring device in the fluid flow
• 6 shows a second embodiment of a measuring device in the fluid flow

1 shows a measuring arrangement according to the invention for explaining 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 7 , The fluid can be water or water with at least one additive. The fluid 7 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 insulated from each other.

The desk 3 has two positions, being in the first position of the switch 3 the electrodes 1 a, b via the current measuring unit 4 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, its state and the position of the switch 3 ,

In the 2a . 2 B . 3 and 4 voltage and current profiles are shown. The first measured value is always a value that appears shortly after the bare electrodes are 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 pairs is shown. Here we measured how the voltage changes if a reaction layer changes over time on at least one of the electrodes 1a . 1b builds up, wherein the reaction layer acts like an insulating layer.

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

In 3 the current profile for a fluid is shown, which was measured repeatedly at different times or after different times of use. The reaction layer was removed before each new measurement. It can be clearly seen from the course of the current intensity that the construction of a new reaction layer takes different lengths of time. Furthermore, it can 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 by means of the reaction layer in a cooling circuit.

4 shows clearly how the current changes after a measurement time of 120s as the fluid gets older. After a certain period of use, here after approx. 250 hours, the ability to build up a reaction layer rapidly decreases.

5 shows a first embodiment of a sensor 2 in the fluid flow 7 , 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 stroke is designated 6.

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

6 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, in the channel section 13 , freely movable processing body 10 he follows. The fluid flow serves here 7 as a drive for the movement of the machining body 10 ,

The versions shown only show two possible constructions, although other arrangements and kinematics are also conceivable.

Furthermore, two or more electrode pairs can be used 1a . 1b a sensor 2 form. In this way, several material pairs that are used in a cooling circuit can be measured simultaneously. If it is determined that a material is no longer adequately protected - there is no longer a reaction layer - this is an indication to replace the coolant.

The use of the measuring 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 here from impurities, which are then to be understood as additives in the sense of the invention.

LIST OF REFERENCE NUMBERS

1a, b

electrodes

2

sensor

3

counter

4

ammeter

5

voltmeter

6

stroke

7

fluid

8th

container

9

lifting device

10

treating body

11

drive

12

compressed air

13

channel section

14

elec. connection

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19533628 A1 [0005]
• DE 102005043699 A1 [0006]
• US 2014/0303831 [0007]

Claims (14)

Method for determining the state of a fluid (7), the fluid (7) consisting partly of water or being miscible with water and being suitable for building up a reaction layer on the surface of a component (1a, b; 13), 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) projecting into 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 pair of electrodes; - Establish an electrically conductive connection between the electrodes (1a, b) and measure 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) over a predefinable time period if the electrodes (1a, b) are at least partially wetted by the fluid (7); - Assessment of the state of the fluid (7) after the predetermined period of time on the basis of the measured current or the measured voltage, the state of the fluid (7) being considered good if the measured current or voltage is less than a predeterminable threshold value or within a specifiable range of values. Procedure according to Claim 1 , characterized in that for the assessment of the state of the fluid (7) the course of the current strength or the voltage is also taken into account up to the expiry of the predetermined time period. Procedure according to Claim 1 or 2 , characterized in that, in order to assess the state of the fluid (7), a short circuit is produced between the electrodes (1a, b) which is temporarily interrupted, a voltage measurement being carried out during the period of the interruption. Procedure according to Claim 3 , characterized in that the predetermined time span includes several first time sections for voltage measurement and second time sections for current measurement. Procedure according to Claim 4 , characterized in that the first time period between 0.2s and 10s and the second time period between 0.2s and 600s. Procedure according to Claim 4 , characterized in that the first period between 1s and 2s and the second period 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 processing; - targeted generation of cavitation on at least one electrode surface in a fluid stream; Procedure according to Claim 7 , characterized in that a direct or alternating voltage is applied between the electrodes (1a, b). Procedure according to Claim 7 , characterized in that a direct or alternating voltage is applied between an auxiliary electrode and the electrodes (1a, b). Procedure according to Claim 7 , characterized in that the abrasive processing takes place 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 device comprises a processing body (10) and means (11) which allow an abrasive processing of the electrodes (1a, b). Device after Claim 11 , characterized in that the means enable movement of the electrode (1a, b) and / or of the processing body (10), it being possible for the drive to take place mechanically, electrically, hydraulically or pneumatically. Fluid circuit comprising a plurality of channel sections through which a fluid (7) can flow, the fluid circuit being a device according to one of the Claims 10 or 11 includes. Fluid circuit after Claim 13 , characterized in that the channel sections (13) are formed by components which are made 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 for different duct sections.

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