DE102017210783A1 - bearings - Google Patents

Abstract

The present invention relates to a slide bearing (2), in particular an internal combustion engine, with a bearing shell (1), which is arranged on a bearing block (3) and equipped with a printed conductor track (4) for wear measurement and / or temperature measurement.
It is essential to the invention that the printed conductor (4) on the bearing shell (1) and the bearing block (3) each have a contact (5a, 5b) and between the contacts (5a, 5b) a dielectric (6) with a known dielectric constant ( ε _R ) is arranged.

Description

The present invention relates to a sliding bearing, in particular an internal combustion engine, with a bearing shell according to the preamble of claim 1. The invention also relates to a machine, in particular an internal combustion engine with such a sliding bearing.

Internal combustion engines, for example in motor vehicles, have a crankshaft for converting a linear piston movement into a rotary movement. For this purpose, the crankshaft is rotatably mounted in hydrodynamic sliding bearings. Since in this case both high thermal loads and large forces must be absorbed, bearing shells are often used from a high-quality, especially metallic, material, which in turn are stored in the actual engine block, for example, aluminum, magnesium or steel. Between the bearing shell and the rotating component, such as a crankshaft, is preferably a hydrostatic support film, preferably made of lubricating oil, designed to reduce friction, the bearings are in turn subject to wear during operation and must therefore be monitored for wear and replaced if necessary. For this purpose, the internal combustion engine shut down, dismantled and the bearing shell to be checked. But this is associated with great expense, so that a sensory monitoring of the state of wear of the sliding bearing or the bearing shells is desired. For example, wear of a polymer layer on the bearing shell can be measured by means of integrated conductor tracks. Alternatively or additionally, during operation, temperature monitoring of the bearing is often desirable or necessary to timely detect overloads or malfunctions such as inadequate lubrication. Due to the wear or the temperature change, the conductor tracks change their geometry, in particular their thickness, or their electrical properties, in particular their resistivity, which can be detected metrologically by measuring the total resistance of a conductor track. However, this electrical conductors are necessary, which must be performed, for example, around a bearing shell to the outside. Depending on the installation situation, this is undesirable and temperature effects and contamination can lead to a falsification of the measurement results.

The DE 10 2014 200 712 A1 describes such a plain bearing with sensor. The sensor is designed as a measuring layer or as a functional layer system. The layer system has a thickness of only a few micrometers. The layer system is connected by means of electrical conductors with a signal pick-off element to supply measurement signals to an evaluation unit.

Furthermore, the describes EP 0 844 469 B1 a thermoresistive sensor on a shaft of a bearing, which is capacitively or inductively coupled to a bearing shell.

Electrical contacting with wires, plugs, tracks or the like is often undesirable because, for example, solder pads on printed pads are susceptible to vibration and temperature variations, connectors are expensive to mount and sensitive to corrosion, and inductive wireless signal transmission to the surrounding metallic materials practically impossible. Similarly, an active radio transmission is eliminated due to the usually high operating temperatures.

It is desired to further improve the signal transmission of a sensor to a bearing shell of a plain bearing.

This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea of capacitively transmitting a sensor signal. Here, the actual sensor, that is, for example, a printed conductor in a polymer layer of a bearing shell, a capacitor associated with a arranged between capacitor plates dielectric. The dielectric has a known dielectric constant ε _R. The printed circuit trace on the inside of the bearing shell, which faces, for example, a rotating crankshaft of an internal combustion engine, has for example been formed by means of a photolithographic process in the surface of the bearing shell or it has been etched or applied in some other way. This interconnect are assigned on or in the bearing shell contacts in the form of a respective capacitor plate to apply a voltage or a current flow to the conductor track. In the bearing block or that component on or in which the bearing shell is in turn mounted contacts are also arranged in the form of capacitor plates, which cooperate with the contacts or capacitor plates of the printed conductor track. Thus, a capacitance C of the capacitor formed therefrom is known from the surfaces of the capacitor plates, their mutual distance and the dielectric constant ε _R of the dielectric disposed between the capacitor plates. Now, if an AC voltage is applied to the capacitor can from the behavior of this by the capacitor and the electrical resistance R the printed circuit trace electrical RC element formed on the electrical properties of the actual sensor, ie the state of wear and / or the temperature and / or an associated phase position of the current flowing through the formed from the conductor and the capacitors RC element, based on the applied AC voltage are closed.

In the context of the invention, it is expressly included in that electrical contacts are passed through the material of the bearing blocks for the bearing shells or through the actual engine block of the internal combustion engine. Alternatively, the actual sensor, so for example a printed conductor, in a polymer material on the bearing shell contactless, so galvanically separated, are only capacitive tapped. It is also possible to connect an inductance to the conductor in series. When excited with the resonant frequency can be from the amplitude of the current to the quality of the resonant circuit thus formed and thus to its ohmic resistance R shut down.

In an advantageous development of the solution according to the invention, the sensor is arranged on the rotating component as a crankshaft side facing the bearing shell. The sensor is then preferably embedded in a polymer layer known from motor vehicle technology or a lower one of possibly several layers thereof, which in turn is covered by an oil film for reducing the friction. During operation of the sliding bearing, the polymer layer and thus the printed conductor embedded therein are eventually worn and / or subjected to temperature changes, whereby the electrical properties of the printed conductor are changed.

mit einer Länge L, einem als rechteckig angenommenen Querschnitt mit einer Breite B und einer verschleißabhängigen Dicke D sowie einem temperaturabhängigen spezifischen Widerstand p(T). Der Widerstand R kann messtechnisch erfasst und ausgewertet werden, wobei zur Temperaturbestimmung eine vorher im kalten Zustand oder bei sonstiger bekannter Temperatur und nicht verschlissener Leiterbahn des Lagers vorgenommene Vergleichsmessung herangezogen werden kann Verschleiß in Form von Abtrag der Polymerschicht kann sich in einem Anstieg des Widerstands R in Folge der verringerten Dicke D oder sogar einer völligen Unterbrechung des Leiters bemerkbar machen, sobald der Abtrag die Leiterbahn erfasst. Möglich und messtechnisch erfassbar sind dann auch Unterbrechungen der Leiterbahn und/oder auch zeitweilige Überbrückungen einzelner Abschnitte einer zum Beispiel mäanderförmigen Leiterbahn durch eine elektrisch leitfähige Welle oder häufige und schnelle Änderungen des Widerstands R aufgrund der Bewegung der Welle. So können sowohl ein übermäßiger Anstieg oder Abfall des Widerstands R oder auch allein die Häufigkeit und Geschwindigkeit einer Änderung darauf hinweisen, dass der Verschleiß der Polymerschicht die Leiterbahn erreicht hat und die Lagerschale ausgetauscht werden muss. Parallel zu dieser Verschleißüberwachung kann ein allmählich ansteigender oder sinkender Widerstand R auf eine steigende oder sinkende Temperatur hinweisen, wenn ein für Metalle beziehungsweise Kaltleiter in der Regel ein positiver Temperaturkoeffizient des Widerstands vorliegt. Ein Überschreiten eines Schwellenwertes des Widerstands zeigt dann das Überschreiten einer bestimmten Temperatur an, was Gegenmaßnahmen wie etwa Abschaltung oder Lastverringerung erfordert. Bei einem Heißleiter mit negativem Temperaturkoeffizienten würde ein Verschleiß in einem Unterschreiten eines Schwellenwertes des Widerstands resultieren, was ebenfalls messtechnisch erfassbar und auswertbar ist.Generally, the ohmic resistance of a conductor section is given by the formula: $$\text{R}=\text{L}*\mathrm{\rho }\left(\text{T}\right)/\left(\text{B}*\text{D}\right)$$

having a length L, a cross-section assumed to be rectangular and having a width B and a wear-dependent thickness D and a temperature-dependent resistivity p (T). The resistance R can be detected and evaluated by measurement, wherein for the determination of temperature previously taken in the cold state or other known temperature and non-worn trace of the bearing comparison measurement can be used wear in the form of erosion of the polymer layer may result in an increase in resistance R as a result of the reduced thickness D or even a complete interruption of the conductor make noticeable, as soon as the removal detects the trace. Possible and metrologically detectable are then also interruptions of the conductor track and / or temporary bridging of individual sections of a meandering track, for example, by an electrically conductive shaft or frequent and rapid changes in the resistance R due to the movement of the shaft. Thus, both an excessive increase or decrease in resistance R or even the frequency and speed of a change indicate that the wear of the polymer layer has reached the track and the bearing shell must be replaced. In parallel to this wear monitoring can be a gradually increasing or decreasing resistance R indicate a rising or falling temperature, if there is a positive temperature coefficient of resistance for metals or PTC thermistors in the rule. Exceeding a threshold of resistance then indicates exceeding a certain temperature, requiring countermeasures such as shutdown or load reduction. In the case of a thermistor with a negative temperature coefficient, wear would result in falling below a threshold value of the resistance, which can likewise be detected and evaluated by measurement.

In a further advantageous embodiment of the solution according to the invention, a layer thickness of the sensor in the range of a few micrometers is selected. For example, the dielectric 4 Micrometer thick be formed and the tracks or sensors with 1 to 2 microns thickness or height.

In this case, it is possible for a person skilled in the art to choose according to the sensor size and the electrical resistances, the applied voltage, their frequency and the current intensity in order to read out a meaningful measurement result of the sensor.

In a further advantageous embodiment of the solution according to the invention, an electrically insulating layer, for example of a plastic material, is applied to the bearing shell on the inside and / or outside in order to electrically insulate the actual conductor track or the contact plates of the capacitor. Thus, parasitic capacitances can be reduced with other metallic components of the sliding bearing.

For the embodiment of the conductor track, in one embodiment of the solution according to the invention, it is proposed that this conductor track be formed by means of a photolithographic method on the inside of the bearing shell, which, for example, faces the rotating crankshaft or is applied. Alternatively, the printed conductor and / or its electrical connections can also be formed in an aerosol jet printing process and / or in an inkjet printing process. For example, all components can be formed in an inkjet printing process or only the electrical connections and the actual interconnect in an aerosol-jet printing process. In principle, however, it may also be electrically conductive wires which are glued on the inside of the bearing shell, and whose contact extends around a lateral edge of the bearing shell to the outside.

Similarly, on the bearing block for the bearing shell, the capacitor plates for a capacitive tap the actual trace on the bearing shell also in a photolithographic process or otherwise, as described above, be formed and also performed around the bearing block around, for example with a signal evaluation device to establish an electrical connection.

In a further advantageous embodiment of the solution according to the invention recesses are formed in the bearing block, which extend in particular radially outward. In the recesses in each case an electrical conductor, so a wire, arranged, which are equipped on the one hand with a contact plate to form a capacitor and on the other hand, for example, connected to a signal evaluation. The contact plates of the conductors cooperate with contact plates associated with the printed circuit trace. It is understood that the electrical conductors are electrically insulated, for example by means of a molded insulation against the bearing block.

In a further advantageous embodiment of the solution according to the invention, a contact or a contact plate on the bearing block is arranged in a recess in order to cooperate with a contact or a contact plate on the bearing shell. It is understood that the contact plate on the bearing block is electrically isolated on the one hand and on the other hand, a dielectric is provided between the contact plates and third, the contact plate on or in the bearing block has electrical connections to apply the capacitor, for example, with AC voltage.

A third contact with a capacitance, which is not needed for the measurement of the resistance of the sensor, can be provided in a preferred embodiment in order to allow comparative measurements of the capacitances alone or of the conductor track. If changes in the capacitances are detected, the calculation of the resistance R can be corrected accordingly and the accuracy can be increased. For this purpose, either only one of the two capacities or both can be assigned a further capacity.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

• 1 eine Schnittdarstellung durch ein erfindungsgemäßes Gleitlager mit Lagerschale,
• 2 eine Schaltung zur Signalauswertung,
• 3 einen schematischen Schichtaufbau eines erfindungsgemäßen Gleitlagers,
• 4 einen alternativen schematischen Schichtaufbau eines Gleitlagers,
• 5 einen weiteren schematischen Schichtaufbau eines erfindungsgemäßen Gleitlagers,
• 6 eine Draufsicht auf einen Lagerbock,
• 7 eine weitere Schaltung zur Signalauswertung.

Show, each schematically

• 1 a sectional view through an inventive slide bearing with bearing shell,
• 2 a circuit for signal evaluation,
• 3 a schematic layer structure of a sliding bearing according to the invention,
• 4 an alternative schematic layer structure of a sliding bearing,
• 5 a further schematic layer structure of a sliding bearing according to the invention,
• 6 a top view of a bearing block,
• 7 another circuit for signal evaluation.

According to the 1 has a slide bearing according to the invention 2 , in particular for an internal combustion engine of a motor vehicle, a bearing shell 1 on, in turn, on or in a bearing bridge, also bearing block 3 called, or stored on or in an engine block of the internal combustion engine. The bearing shell 2 usually consists of a high-quality metallic material and used for storage, for example, a crankshaft 14 (see. 3 to 5 ). By the rotation of this crankshaft 14 takes place despite the hydrodynamic lubrication, for example by means of an oil film 15 , a wear taking place, which leads to a removal of the material of the bearing shell 1 or an additional coating described below, for example a polymer layer 10 , leads. To monitor this wear and the operating temperature sensors are known, on the one hand a sudden failure of the bearing and thus Prevent connected consequential damage and on the other hand, an unnecessary early shutdown of the internal combustion engine to their disassembly and maintenance or replacement of the bearing shells 1 to carry out, avoid.

The sensor is here in the form of a printed conductor 4 running over two capacitor plates 5a is contacted, preferably on the crankshaft 14 opposite outside 8th the bearing shell 1 are arranged. It is understood that the conductor track 4 with the capacitor plates 5a are connected via electrically conductive connections, for example, also printed conductor tracks, which surround an outer side of the bearing shell 1 lead around, so at least partially perpendicular to the plane. This capacitor plates 5a are each capacitor plates 5b assigned to the or in the bearing block 3 are arranged such that they are the bearing shell 1 or the capacitor plates 5a are facing. It is between the respective pairs of capacitor plates 5a . 5b one dielectric each 6 arranged with known dielectric constant ε _R. From the mutual distance of the capacitor plates 5a . 5b , their surfaces and the dielectric constant ε ₀ and the dielectric constant ε _{R of} the dielectric 6 is the capacity of each formed capacitors known and thus their electrical properties.

The capacitors are each via electrical conductors 12 with a signal evaluation device 13 connected. These are the electrical conductors 12 for example in the form of copper wires, through recesses 11 or holes in the bearing block 3 guided and preferably electrically insulated by means of a potting compound. In this case, an immediate evaluation of the signals of the sensor or the printed conductor track 4 in the signal evaluation device 13 take place or this is only used for signal forwarding, if it is designed for example as a contact for a connector to supply the signals, for example, a central control of the internal combustion engine. In principle, a radio module for wireless signal transmission can also be provided here.

In 2 is schematically reproduced the circuit diagram for evaluation. By means of an AC voltage source 18 is about the capacitors C1 . C2 a particular high-frequency AC voltage V to the conductor track 4 with resistance known in the wear-free state R created. In the course of use of the bearing shell 1 There is a wear and / or temperature changes, in particular the conductor track 4 , so that change their electrical properties, in particular their electrical resistance R , In particular, the complex total resistance Z = Ri / (2 * pi * f * C) can thus be determined, which indicates the condition of the sensor. For this purpose, a device for detecting the current intensity A and / or the associated phase position φ of the current, by the out of the conductor track 4 as well as the capacitors C1 . C2 formed RC element flows, based on the applied AC voltage. Although it is already possible to draw conclusions about Z from the measurement of only one of the variables A and φ, both values are preferably recorded in order to enable a more accurate evaluation.

In terms of circuit technology, it would also be possible to connect the described RC element in series with an inductance (not illustrated) to form an RLC resonant circuit. When excited with the resonant frequency can be from the amplitude of the current to the quality of the resonant circuit and thus to the ohmic resistance R shut down.

It can be determined, for example by a test series, when the wear of the bearing shell 1 or a change in resistance R the conductor track 4 makes an exchange or a repair required to issue a corresponding warning signal, for example via the central engine control of the internal combustion engine.

In 3 is schematically a layer structure of a sliding bearing 2 with a bearing shell 1 shown. The plain bearing 2 serves for example for the rotatable mounting of a crankshaft 14 in an internal combustion engine or in general a shaft. The plain bearing 2 but can also be used inter alia in rotor bearings of a wind turbine, in generators or other fields of technology. The bearing shell 1 consists in the usual way of a high-quality metal alloy, but which is subject to wear during operation. The bearing shell 1 is in turn on or in a bearing block 3 , a bearing bridge or arranged for example on an engine block of an internal combustion engine.

To reduce the friction between crankshaft 14 and bearing shell 1 serves a hydrodynamic sliding layer, in particular an oil film 15 , Likewise, a functional polymer coating 10 be provided to reduce friction. To the printed conductors 4 of the metallic material of the bearing shell 1 Isolate is on the inside 7 the bearing shell 1 an electrically insulating layer 9a for example, applied from a plastic material.

In the embodiment shown here is a printed circuit trace 4 on the electrically insulating layer 9a arranged, for example, printed or applied in any other way. In principle, it can also be wires that for example, between the insulating layer 9a and the polymer coating 10 are poured. For signal pickup from the printed conductor 4 serve contacts 5a . 5b on the one hand on the outside 8th the bearing shell 1 and on the other side on the inside 16 of the bearing block 3 are arranged. It is understood that also here each electrically insulating layers 9b . 9c each between bearing shell 1 and contact 5a and bearing block 3 and contact 5b are provided. In addition, between the preferably plate-shaped contacts 5a . 5b is a dielectric 6 arranged with known dielectric constant ε _R , so that from the known geometry of the contacts 5a . 5b whose mutual distance and from ε _R the capacitance C of the capacitor thus formed is known.

It is understood that all of the above components have sufficient resistance and temperature resistance to not be destroyed during normal operation of, for example, an internal combustion engine. Furthermore, it can be seen that the printed conductor 4 with corresponding electrical connections with the contacts 5a is connected, for example by means of wires around the bearing shell 1 run around the outside. Likewise, the contacts 5b for example, with the signal transmission device 13 out 1 by means of electrical conductors 12 in recesses 11 as in 1 described connected.

During operation of the plain bearing 2 subject to the bearing shell 1 and in particular the functional polymer coating 10 Abrasion or wear and are also exposed to temperature changes. This results in a changing electrical resistance of the printed circuit trace 4 What caused by an AC circuit as in 2 can be monitored shown. If, for example, a specified limit value is undershot or exceeded, a warning signal can be issued in order to maintain the bearing 2 or the bearing shell 1 to induce.

An alternative embodiment of the sliding bearing is in 4 shown. Here is the contact 5b in a recess 17 on the inside 16 of the bearing block 3 used. This is below the contact 5b an electrically insulating layer 9c arranged to the contact 5b from the bearing block 3 to isolate. The insulating layer 9c can also be the side of the entire recess 17 fill up. The contact 5b closes at the top flush with the surrounding bearing block 3 from.

Another alternative embodiment of the sliding bearing 2 is in 5 shown. Here is the contact 5b between the dielectric 6 and the insulating layer 9c arranged.

In principle, the contacts 5a . 5b partially also in the insulating layer 9a and the polymer coating 10 or in the insulating layers 9b . 9c and the interposed dielectric 6 be admitted.

The bearing shell described above 1 or a sliding bearing equipped therewith 2 preferably comes as a bearing for a crankshaft 14 used in an internal combustion engine. In principle, however, it can also be used in bearings of wind or water turbines, generators or in other fields of technology.

In 6 the top view of a bearing block 3 for a bearing shell 1 shown. Here are on the bearing block 3 the contact plates 5b also executed in print, so formed for example photolithographically. In principle, the contact plates 5a . 5b as well as the conductor track 4 and other electrical connections are also formed in an aerosol jet printing process and / or in an inkjet printing process. Electrical contacts are used to make contact with the contact plates 12 , which are preferably also executed in print and around the bearing block 3 may be formed around leading to the signal evaluation device 13 to make an electrical connection.

Finally, in 7 another circuit for signal evaluation is shown. The circuit is off 2 another capacitor C3 assigned, which preferably according to the above-described capacitors C1 and C2 is trained. By means of this capacitor C3 can compare measurements of capacities C1 and C2 alone and / or the track 4 respectively. Be changes in capacity C1 and or C2 or the conductor track 4 can determine the calculation of the resistance R Corrected accordingly and the accuracy increased. It is understood that, as shown in FIG 7 additionally or alternatively also the capacitor C2 another capacitor can be assigned.

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 102014200712 A1 [0003]
• EP 0844469 B1 [0004]

Claims (9)

Sliding bearing (2), in particular an internal combustion engine, with a bearing shell (1) which is arranged on a bearing block (3) and equipped with a printed conductor track (4) for wear measurement and / or temperature measurement, characterized in that the conductor track (4) on the bearing shell (1) and the bearing block (3) in each case a contact (5a, 5b) is assigned and between the contacts (5a, 5b) a dielectric (6) with a known dielectric constant (ε _R ) is arranged. Slide bearing after Claim 1 , characterized in that the bearing shell (1) on its inner (7) and / or outer side (8) is provided with an electrically insulating layer (9). Slide bearing after Claim 1 or 2 , characterized in that the bearing shell (1) on its inner side (8) is equipped with a polymer coating (10). Slide bearing according to one of Claims 1 to 3 , characterized in that the contacts (5a, 5b) are printed. Slide bearing according to one of Claims 1 to 4 , characterized in that for contacting the contacts (5b) in the bearing shell (1) has a recess (11) for receiving an electrical conductor (12) is formed. Slide bearing according to one of Claims 1 to 5 , characterized in that a contact (5b) in a recess (17) on an inner side (16) of the bearing block (3) is arranged. Slide bearing according to one of Claims 1 to 5 , characterized in that the contacts (5a, 5b) can be acted upon by an AC voltage and a current strength and / or current phase position relative to the AC voltage across the contacts (5a, 5b) can be measured. Slide bearing according to one of Claims 1 to 6 , characterized in that the contacts (5a, 5b) is associated with a signal transmission device (13). Internal combustion engine with at least one sliding bearing (2) according to one of Claims 1 to 7 ,

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