DE102015200203A1 - Measuring arrangement for detecting foreign particles in a medium - Google Patents

Abstract

A measuring arrangement (1) for detecting foreign particles (4) in a medium (2) and / or for detecting a change in the medium should be improved in such a way that non-ferromagnetic particles in the medium and other changes in the medium can be detected in a simple manner , This is achieved by a voltage or current source (5), an anode (6) and a cathode (7) which form a closed circuit with the voltage or current source (5) and a current or voltmeter in the circuit (8), wherein the medium flows in a measuring channel between the anode (6) and the cathode (7) and flows through a current of the voltage or current source (5), wherein the current or voltmeter (8) for detecting the Foreign particles (4) is carried out in the medium and / or for detecting the change of the medium.

Description

The invention relates to a measuring arrangement according to the preamble of claim 1. Furthermore, the invention relates to a method for detecting foreign particles in a medium and / or a change in a composition of the medium.

In machine systems, for example a vehicle transmission, permanent wear of the individual components occurs in the operating state. The wear generates chips and abrasion, which can drive as a foreign body in a cooling-lubricating circuit and can lead to further damage and failures. In particular, valves can become clogged. For example, there are numerous intermeshing gear arrangements in a transmission. These arrangements are regularly lubricated via the oil circuit. In operation, however, the gears rub against each other. As a result, micro metal shavings are created that drift in the oil circuit. In the oil circuit located metal chips could be on the tooth flanks of the gears, so that they would run rough. Other examples of gear components that produce metal chips are the synchronizer rings (scoring) or the shift claws, etc. Furthermore, the non-metallic wear of clutch linings can also contribute to contamination of the oil.

From the DE 197 31 960 A1 For example, a particle detector suitable for detecting and monitoring the state of a component is known. The particle detector has first and second spaced-apart magnets to collect the metal particles. The metal particles bridge the space between the magnets, causing a voltage drop that indicates the presence of particles on the device. The output signal is sensed in order to determine the state of the component and the time to clean the particle detector.

Another metal particle detector is in the US 8074493 shown and described. In this solution, ferromagnetic metal particles also accumulate on the magnet. In addition to the two contacts, an additional neutral contact is present, which is arranged between the conventional contacts.

The systems known from this prior art can only detect ferromagnetic metal particles. For example, components of the transmission could be made of aluminum, titanium, aluminum alloys or magnesium. These particles are not detected. Furthermore, other wear parts, such as e.g. the clutch lining, made of non-metallic particles. These wear parts also contaminate the medium and are also not recognized. Changes in the medium due to water retention are also not detectable with the devices known from the aforementioned prior art. Consequently, particles resulting from wear of these materials can not be detected.

Furthermore, the known from the prior art systems have the disadvantage that many particles are not detected, since the detection device is already existing chips at its limits of detection. For example, because the magnet surface is partially or completely covered with already attracted particles, or drive the metal particles outside of the magnetic field over. The detection can only detect the particles "held down" on the magnet, but not the remaining amount in the medium Sudden misalignment of the components or increased wear are detected only too late, since only a contact bridge between the electrodes has to be formed a device according to the DE 197 31 960 no continuous measurement possible, which detects an increase of metal chips. For continuous measurements, a large number of additional intermediate electrodes would be modeled on the US 8074493 necessary.

The composition of the medium can not be tested continuously. Thus, with the known technical devices, an increased water content in the oil can not be detected.

The invention has for its object to provide a measuring arrangement with which nonferromagnetic particles in the medium, as well as other changes in the medium can be detected in a simple manner.

To solve this problem, a measuring arrangement according to the features of claim 1 is given.

The invention takes into account the problem that media are rarely changed and small contaminants can already lead to system damage. The invention solves the disadvantages of the prior art by all non-ferromagnetic substances, but also ferromagnetic substances can be detected continuously. Furthermore, compositions of a medium or also the age of the medium can be determined with the idea according to the invention.

A medium is understood below to mean a fluid medium, ie a liquid, or a gaseous medium.

Also, the decomposition state of the oil and thus its lubricity can with the Structure of the invention are monitored, for example, burned oil has a different conductivity than hardly used oil. The invention also fulfills the function of transmission oil condition monitoring.

The invention can be used not only in oil circuits, but also in braking, fuel, cooling circuits, etc. Because even here, the liquid composition or liquid decomposition can be monitored and checked.

The advantages of the invention are, however, in particular a cost-effective structure, as well as an easily implementable evaluation.

The invention is based on the idea not to use magnets, but to detect the state of the oil or medium by an electrical resistance measurement or capacitance measurement using two electrodes in a flow channel. In the case of ohmic measurement, there is a resistance between the electrodes, which is determined by the condition of the oil.

Advantageous embodiments of the measuring arrangement according to the invention emerge from the features of the claims dependent on claim 1.

In an advantageous embodiment of the measuring arrangement according to the invention, it is provided that this is designed to measure an ohmic resistance between the anode and cathode, wherein the voltage or current source is a DC voltage source. Particles in the medium or a change in the medium changes the electrical resistance. By a simple resistance measurement, the state of the medium can be determined in a simple manner.

According to another advantageous embodiment of the measuring arrangement according to the invention it is provided that this is designed to measure an electrical capacitance. The capacitance is formed by the anode and the cathode, wherein the voltage or current source is an AC voltage source. A capacitive current flows through the alternating current, the medium representing a dielectric. By changing the dielectric, the capacitance changes. By simply measuring the capacitance, the condition of the medium can be determined in a simple manner.

According to a further advantageous embodiment, the measuring channel is a tubular channel which has an inlet and an outlet which comprises an axially in the measuring channel extending, inner, rod-shaped electrode, which is designed as the anode or cathode, and a tubular, outer Electrode, which is designed as a cathode or anode comprises. This embodiment has the advantage that it can be easily integrated into a media line, wherein the detector relative to the feed line can be increased in diameter.

A potential separation is simply possible because the outer and inner electrodes are electrically insulated against leads at the input and the output.

According to another favorable embodiment, the measuring channel is arranged in an oil circuit, wherein the measuring channel is arranged between an oil filter and an oil pump. Conveniently, the measuring channel is arranged in an oil circuit for a transmission. In vehicles, therefore, a required oil change can be signaled safely when a certain threshold is exceeded.

According to another advantageous embodiment, the measuring arrangement comprises an ionization cage, which is designed in particular as an ion separator. This allows the foreign particles to influence even more targeted, detect and possibly even filter out of the medium.

The invention is also based on the object to provide a method for detecting foreign particles in a medium and / or a change in a composition of the medium with which nonferromagnetic particles in the medium, as well as other changes in the medium can be easily detected.

To solve this problem, a method according to the features of claim 10 is given. The method for detecting foreign particles in a medium and / or a change in a composition of the medium, in particular oil, in a closed circuit is characterized by a measuring arrangement according to the invention, as described above.

Further features, advantages and details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing. Show it:

1 A first embodiment of a measuring arrangement for detecting foreign particles in a medium

2 an embodiment of an oil circuit, in which the measuring arrangement according to 1 is used,

3 a detailed representation of the measuring arrangement according to 1 .

4 a second embodiment of a measuring arrangement for detecting foreign particles in a medium, and

5 A third embodiment of a measuring arrangement for detecting foreign particles in a medium.

Corresponding parts are in the 1 to 5 provided with the same reference numerals. Also details of the embodiment explained in more detail below may constitute an invention per se or be part of an inventive subject matter.

The invention is based on the finding that detection of foreign bodies in the media circulation, e.g. in an oil circuit, by indirect resistance measurement is very suitable. An advantageous positioning of the measuring channel is after an oil filter. However, two measurements are conceivable, namely before and after the oil filter. By the measuring arrangement, the filter effect can be determined. For positioning, for example, an oil pressure or oil suction line is recommended.

1 shows a first embodiment of a measuring arrangement 1 to detect foreign bodies or foreign particles in a medium 2 and / or for detecting a change in the medium 2 , The measuring arrangement 1 can, as in 2 illustrated in an oil circuit 3 a vehicle transmission, for example, be placed at the location of the arrow A. However, it is also conceivable that the measuring arrangement is used for measuring the compressed air quality in commercial vehicles or for measuring the quality of the air supply in clean rooms.

In the following, the invention will be explained by way of example with reference to a fluid medium. However, the invention can also be used for a gaseous medium.

The measuring arrangement 1 serves to detect foreign particles 4 , of metal and non-metal particles and / or of ferromagnetic and non-magnetic particles. Magnetic metal particles can be micrometallic chips resulting from wear of gears. Non-magnetic metal particles may be aluminum particles, titanium or aluminum alloy particles. Non-metallic particles may be particles from a clutch lining. Also, for example, caused by water inclusions or burnt oil change in the oil can be detected.

As 3 shows, become a voltage source 5 , an anode 6 and a cathode 7 used with the voltage source 5 form a closed circuit. The voltage source is a constant voltage source with a voltage of eg 50 V to 150 V. Alternatively, a constant current source can be used. In this case, a voltage can be measured at the electrodes. The electrodes or anode and cathode can be reversed.

As 3 further shows is an in-circuit current meter 8th present, with the medium in a measuring channel 9 between the anode 6 and the cathode 7 flows and is traversed by a current of the voltage source, wherein the ammeter 8th for the detection of foreign bodies 4 in oil and to detect the change of oil.

As 1 shows, points the measuring channel 9 a tubular channel having an entrance 10 and an exit 11 having. In the measuring channel 9 is an axially extending, inner, rod-shaped electrode 12 arranged as the anode 6 is executed. The measuring channel 9 comprises a tubular outer electrode 13 that as the cathode 7 is executed.

1 also shows an oil supply 14 that, like the departure line 15 , a smaller diameter than the cathode 7 Has. For isolation of the cathode 7 opposite the oil supply 14 and the departure line 15 are first insulation elements 16 present, for a galvanic isolation of the potential of the cathode 7 and the wires 14 . 15 to care. Also, one is opposite the cathode 7 insulated supply line 17 available. The supply line 17 is with a second isolation element 18 opposite the cathode 7 isolated. The supply line 17 is electric with the anode 6 connected. In the measuring channel 9 An electric field is formed 18a between the anode 6 and the cathode 7 out.

This arrangement is for measuring an ohmic resistance between anode 6 and cathode 7 executed, the voltage source 5 is a DC voltage source.

In 3 is still a running on different paths current flow 19 between the anode 6 and the cathode 7 located.

Like arrow A in 2 is shown is the measuring channel 9 in an oil circuit 3 or between an oil filter 20 and an oil pump 21 arranged. The measuring channel 9 is in an oil circuit 3 for a transmission 22 arranged.

2 shows in principle a conventional machine. The oil pump 21 is at one Pressure control device 23 connected, located in a pressure distribution device 24 and a circuit with an oil cooler 25 splits, with the oil cooler the transmission lubrication 26 provided. In a known manner, an oil pan 27 for an oil sump 29 present in which a permanent magnet 28 serves to collect ferromagnetic particles.

With the facilities 23 and 24 a control device TCU is connected, which uses parameters such as oil temperature in the oil sump or speeds.

The in the 1 to 3 In other words, the devices shown can be described as follows.

Between oil filter 20 and oil pump 21 the supply line is so "modified" that the oil line inner wall, an inserted into the oil line conductor to a voltage source and a voltage / current measuring device, the components or the circuit of the detector according to the invention could serve as an anode, the in the Although the oil between the cathode and the anode closes the circuit, it forms a high resistance in the foreign particle-free state.

In order to determine the foreign particle content of the oil, the test setup according to the invention is supplied with a relatively high voltage (about 100 V DC). Increases the metal particle content in the oil, so are small electrically good conductive partial connections between the anode and cathode, thus increasing the measured voltage / current, since the resistance (oil) decreases.

Water inclusions in the oil as well as clutch abrasion particles and other impurities lead to changes in the resistance and must therefore also be detected.

In vehicle operation, the oil flows from the oil filter in the direction of the oil pump. In this case, the detector unit according to the invention could be located between the oil filter and the oil pump.

The media supply line, in particular oil supply line is increased in diameter at the detector unit according to the invention. The detector unit and oil supply line are galvanically separated from each other by means of an insulator. The insulator could, for example, be a ceramic element. In 1 there are already foreign particles 4 , in particular metal particles, in the medium / oil. The metal particles drift in the liquid oil and therefore also follow the movement of the oil circuit. Have the metal particles the upstream oil filter 20 As a result, they thus drive through the measuring arrangement designed as a detector unit 1 , The expanded oil supply line, which is part of the detector unit, includes the, with respect to the oil pipe diameter centrally arranged anode 6 , which externally with a voltage (eg, about 100 V DC) is applied.

Here is the electrical connection of the anode 6 galvanic from the cathode 7 separated. The function of the cathode 7 takes over the pipeline. At the cathode 7 For example, there is a voltage of 0 volts. Also the cathode 7 is isolated from the rest of the oil line. The oil between anode 6 and cathode 7 has a certain resistance. Due to the applied voltage forms between the anode 6 and the cathode 7 the electric field 18a out. The foreign particles 4 in the oil change the electrical conductivity between the anode 6 and the cathode 7 and thus the developing electric field 18a , A voltmeter or ammeter in the circuit detects differences in the incoming charges. The described arrangement of cathode 7 and anode 6 can also be exchanged. For example, the oil line could also be the function of the anode 6 take.

In the AC voltage case, not only the resistance, but the capacitance is measured. The advantages of capacity measurement are their accuracy. By means of an electrical resonant circuit already minimal changes can be detected.

3 shows the diagram and the operation of the "closed" circuit between the anode 6 and cathode 7 , 3 represents only a section of the circuit. Isolators, etc. are not shown.

As already mentioned, the circuit is always closed. The oil therefore conducts electricity from the cathode 7 to the anode 6 , This is in 3 exemplified only in the lower half of the media line. In principle, however, a similar current flow can also occur in the upper half. It has the oil without the foreign particles 4 for example, a natural resistance of 1 MOhm. In the case of alternating voltage, capacitances of approx. 1 nF can be detected.

Metal particles in the oil reduce this resistance or, in the case of an alternating voltage, the capacitance. The electric charge is transferred in such a metal particle with a very low resistance. The path to be laid back from the electrical charge thus has less resistance because of the metal particles than in oil without metal particles. Overall, the total resistance of the path between the cathode decreases 7 and the anode 6 , This can be brought about in the circuit Ampere or voltmeter are detected. In 3 the circuit is supplied with a constant voltage source / power source.

Alternatively or additionally, the measuring arrangement 1 for measuring an electrical capacitance passing through the anode 6 and the cathode 7 is formed, be executed, wherein the voltage or current source is an AC voltage source. In the alternating voltage case, the dielectric and the effective plate spacings in the presence of foreign particles 4 change. The AC voltage source can also be used to measure the electrical resistance in the measuring channel 9 to determine.

4 shows another embodiment of the measuring arrangement 1 , In this case, the anode extends 6 into the area of the oil supply 14 into it. The administration 30 that the anode 6 contacted, is in the field of oil supply 14 led out. The reference numerals 36 . 37 represent a possible short circuit detection.

In 4 are the same parts with the same reference numerals as in 1 Mistake. The difference from the aforementioned embodiment, however, lies in the arrangement of the anode 6 , Such is the anode 6 no longer directly in the area of the cathode 7 arranged. Due to the external positioning of the anode 6 the advantage arises that various errors, such as insulation faults or short circuits can be detected. If a short circuit is not detected, the system would mistakenly contain excessive foreign particles 4 detect and actually initiate not necessary safety measures, such as the shutdown of the transmission. Therefore, such short circuits must be recognized and thus excluded. A short circuit could be caused for example by the failure of an insulator. To determine the short-circuit position or the cause of the short circuit, the arrangement is suitable 4 , So can the insulator between the housing and cathode 7 the short circuit will be detected. Even with the other insulators short circuits can be excluded. cathode 7 and anode 6 can also be exchanged in this variant. In this arrangement, it is particularly advantageous that in case of failure of an insulator, the device still works.

In 5 is a variant with a charge grid cage or Ionisationskäfig 31 shown. This is in the area of the oil supply 14 arranged. In 5 the flow direction is also directed from left to right. Foreign particles in the oil hit the ionisation cage 31 , which is designed as a metal grid. When impinging foreign particles 32 on the ionization cage 31 These are charged electrically. The ionization cage 31 is designed as a cathode, so that these foreign particles 32 charged negatively. foreign particles 34 , on the other hand, on the ionization cage 31 flow past, so do not come in contact with it, keep their original charge. The negatively charged particles 32 be correspondingly from the rod cathode 33 attracted, with the positively charged particles 34 from the anode 35 be attracted. Upon impact of the charged particles on the rod cathode 33 or the anode 35 they give away their cargo. This charge transfer can be measured by a measuring device or an ampere or voltmeter. Based on this measurement, the number and size of the particles can be determined. About a switch 36 can be between the rod cathode 33 and the ionization cage 31 change. In this case, the ionization cage should 31 from the rod cathode 33 be disconnected (not shown). Alternatively, the ionization cage 31 and the rod cathode 33 but also be connected to the power source at the same time (not shown). In one case, the ionization cage 31 be addressed and this load the particles. In the other case, the rod cathode 33 for particle detection via the switch 36 involved in the circuit.

It is also conceivable that the ionization cage 31 is used as a particle separator. If the particles are to stick to the cage grid, the surface of the grid bars and / or the tube surface should be provided, for example, with a graphite coating. Consequently, already on the ionization cage 31 numerous particles get stuck, which otherwise could not be removed. It creates a filtering effect. If this effect is not desired, the surface can be coated with a noble metal, such as platinum.

In all described embodiments or variants signals are measured, which can be evaluated via, for example, a central control unit. A setpoint / actual value comparison can always be carried out. Deviations in the specified tolerance range do not require any measures. Significant deviations can be output via the control unit as an error or warning message to the vehicle cockpit. In particularly severe cases, the system can be switched off for self-protection. For example, the use of incorrect oil could be detected immediately. For example, if the manufacturer requires a 5W30 engine oil, the customer fills another oil when changing the oil, e.g. a 5W40 engine oil, after, this could also be detected early. Thus, later damage can be avoided.

LIST OF REFERENCE NUMBERS

1

measuring arrangement

2

media

3

Oil circuit

4

foreign particles

5

voltage source

6

anode

7

cathode

8th

ammeter

9

measuring channel

10

entrance

11

output

12

rod-shaped electrode

13

outer electrode

14

oil supply

15

outgoing line

16

First insulation elements

17

supply

18

Second isolation element

18a

electric field

19

current flow

20

oil filter

21

oil pump

22

transmission

23

Pressure control device

24

Pressure distribution facility

25

oil cooler

26

gear lubrication

27

oil pan

28

permanent magnet

29

oil sump

30

supply

31

Ionisationskäfig

32

negatively charged particles

33

cathode bar

34

positively charged particles

35

anode

36

Short circuit detection

37

Short circuit detection

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely 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.

Cited patent literature

• DE 19731960 A1 [0003]
• US 8074493 [0004, 0006]
• DE 19731960 [0006]

Claims (10)

Measuring arrangement ( 1 ) for the detection of foreign particles ( 4 ) in a medium ( 2 ) and / or for detecting a change in the medium, characterized by a voltage or current source ( 5 ), an anode ( 6 ) and a cathode ( 7 ), wherein the anode ( 6 ) and the cathode ( 7 ) with the voltage or the current source ( 5 ) are connected together to form an electrical circuit, and a current or voltmeter ( 8th ), wherein between the anode ( 6 ) and the cathode ( 7 ) a measuring channel is formed in which the medium is located during operation and which is connected to a current of the voltage or current source ( 5 ) can be acted upon, wherein the current or voltmeter ( 8th ) for the detection of foreign particles ( 4 ) is carried out in the medium and / or for detecting the change of the medium. Measuring arrangement according to Claim 1, characterized by an embodiment for measuring an ohmic resistance between the anode ( 6 ) and cathode ( 7 ), the voltage or current source ( 5 ) is a DC or AC voltage source. Measuring arrangement according to Claim 1 or 2, characterized by an embodiment for measuring an electrical capacitance passing through the anode ( 6 ) the cathode ( 7 ) is formed, wherein the voltage or current source ( 5 ) is an AC voltage source. Measuring arrangement according to one of the preceding claims, characterized in that the measuring channel is a tubular channel having an entrance ( 10 ) and an output ( 11 ), which has an axially in the measuring channel extending, inner, rod-shaped electrode ( 12 ), which is used as the anode ( 6 ) or as the cathode ( 7 ), and a tubular, outer electrode ( 13 ) acting as the cathode ( 7 ) or as the anode ( 6 ) is executed comprises. Measuring arrangement according to claim 4, characterized in that the outer and inner electrodes ( 12 . 13 ) against supply lines ( 14 . 15 ) at the entrance ( 10 ) and at the exit ( 11 ) are electrically isolated. Measuring arrangement according to one of the preceding claims, characterized in that the measuring channel in an oil circuit ( 3 ) is arranged. Measuring arrangement according to claim 6, characterized in that the measuring channel between an oil filter ( 20 ) and an oil pump ( 21 ) is arranged. Measuring arrangement according to claim 6 or 7, characterized in that the measuring channel in an oil circuit ( 3 ) for a transmission ( 22 ) is arranged. Measuring arrangement according to one of the preceding claims, characterized by an ionization cage ( 31 ), which is designed in particular as an ion separator.  Method for detecting foreign particles in a medium and / or a change in a composition of the medium, in particular oil, in a closed circuit, characterized by a measuring arrangement according to one of the preceding claims.

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