BUSHING FOR A SLIDING BEARING, SLIDING BEARING MEASURING ARRANGEMENT AND METHOD

Description

[0001] The present invention relates to a bushing for a plain bearing, a plain bearing comprising a bushing, a plain bearing measuring arrangement and a method for determining the wear of a bushing of a plain bearing.

[0002] For conventional plain bearing bushes used to support a shaft, the maximum service life of the plain bearing bush is usually estimated based on the average characteristics of the bearing bush and taking into account the expected rotational speeds of the shaft over a certain period of time. Based on the estimated maximum service life of the plain bearing bush, the plain bearing bush is replaced before the maximum expected service life, taking into account a certain safety factor to prevent damage to the plain bearing bush, which could otherwise cause machine downtime or similar problems.

[0003] Because plain bearing bushings are subject to manufacturing and production-related variations during production, such as deviations within a manufacturing tolerance and variations in material composition, plain bearing bushings have different properties in use. Consequently, each plain bearing bushing has a specific maximum service life for a specific application scenario, which differs from the service life of another plain bearing bushing.

[0004] In the conventional use of plain bearing bushes, a large number of plain bearing bushes are tested to determine an expected minimum service life for the plain bearing bushes. Based on the tested minimum service life, a service life for the application is determined using an additional safety factor, after which the plain bearing bush should be replaced. This service life, reduced by the safety factor, is calculated to minimize the probability of damage to the plain bearing bush during use. The resulting service life for the application until replacement thus represents a service life that can be achieved with a certain probability by each plain bearing bush without being damaged during use.

[0005] As a result, on the one hand, comparatively durable plain bearing bushes are replaced much too early, and on the other hand, it cannot be ruled out that individual plain bearing bushes may be damaged due to peak loads during use.

[0006] US 4,721,399 A describes a plain bearing comprising a support base carrying a sliding layer and mounted in a bearing housing. For local determination of the temperature of the sliding layer, a heat conductor is inserted into the support base, which transfers the heat to a temperature sensing and measuring element located in the bearing housing. The heat conductor is positioned in a plug and surrounded by a sheath. To establish intimate contact between the heating conductor and the temperature sensing and measuring element, the latter is preloaded towards the heating conductor by a spring. With the help of guide rails, the support base can be rotated into the bearing housing by retracting the element from the guide rail against the force of the spring and running along the circumference of the support base until it is aligned with the heat conductor.

[0007] EP 0 029 736 A1 describes a method and apparatus for diagnosing the operating conditions of a bearing, wherein pressures of an oil film formed on a sliding surface of the bearing journal are detected at multiple locations, and the pressure difference between the oil film pressures detected at the multiple points is calculated. The deflection of the bearing relative to the shaft is determined from the calculated pressure difference of the oil film, so that the operating conditions of the bearing are assessed based on its deflection. Temperatures of the bearing surface layer and the noise generated by the bearing are also measured and analyzed. The bearing condition, as indicated by the oil film pressure, is compared with the bearing conditions as indicated by the bearing surface layer temperature and the bearing noise.

[0008] EP 1 602 842 A1 describes a plain bearing with a first bearing ring having a first bearing surface and a second bearing ring having a second bearing surface. The first bearing surface and the second bearing surface are each spherical or cylindrical and are kept at a distance from one another by a sliding lining arranged between the first bearing surface and the second bearing surface and fastened to one of the two bearing rings. The plain bearing has the special feature that at least one sensor is fastened to the first bearing ring for detecting a measured variable that depends on the distance of the sensor from the second bearing surface.

[0009] US Pat. No. 6,080,982 A describes fiber optic filaments embedded in a bearing surface. Within a mechanical bearing system, the filaments wear along with the wear of the bearing surface. Based on the observed amount of light transmitted through the filaments, the deterioration of the filaments is measurably related to the wear of the bearing surface. Light is used for observation.

[0010] DE 20 2019 101776 U1 describes a plastic sliding element for lubricant-free mounting in a plain bearing, wherein the sliding element comprises a molded part made of plastic, in particular manufactured by injection molding, which has a sliding surface for the movable guidance of two bearing parts relative to one another, wherein an electrical functional circuit with a sensor function for detecting an operating parameter is arranged on the molded part, wherein the functional circuit comprises at least one conductor track structure which is formed on the molded part as a carrier of the conductor track structure, wherein the functional circuit is preferably applied to the preferably prefabricated molded part made of plastic by an additive manufacturing process.

[0011] It is therefore an object of the present invention to provide a bushing for a plain bearing which improves the usability of the bushing in use and which in particular helps to extend the service life of a bushing in use or a service life of the bushing while avoiding damage to the bushing.

[0012] The above-described object is achieved by the subject matter of the independent claims, preferred embodiments are the subject matter of the dependent claims.

[0013] One aspect of the invention relates to a bushing for a plain bearing as defined in claim 1.

[0014] Advantageously, the present bushing for a plain bearing, hereinafter generally referred to simply as a bushing, allows the service life of a bushing to be extended by detecting a condition of the bushing. In particular, the present bushing advantageously allows the service life of the bushing to be detected, so that the service life of the bushing can be brought closer to the maximum service life of the bushing in use.

[0015] Furthermore, it is possible, particularly by means of the at least one detector element, to detect various states of the bushing, so that a plurality of criteria can be used to assess safe use, so that the bushing can be advantageously protected particularly reliably against damage during use. In the exemplary case of the rotatable bearing of a machine shaft using the present bushing, the bushing thus makes it possible to prevent a machine failure or a failure of the machine shaft due to damage to the plain bearing or the bushing, and furthermore to reduce the material used for the sliding bearing of the machine shaft by requiring less frequent replacement of the bushing.Targeted detection of one or more bushing conditions thus enables further cost savings through less frequent bushing replacement, reduction of monitoring and maintenance effort for plain bearings, and additional safety against machine failures caused by a damaged or defective bushing for a plain bearing.

[0016] In exemplary embodiments of the bushing, the bushing can have a cylindrical shape and, initially, i.e., before wear, in particular have a substantially constant outer diameter and / or a substantially constant inner diameter. The bushing can be particularly suitable or configured to rotatably support a shaft, such as a shaft for a machine. In other words, the bushing can be particularly configured to support a shaft such that the shaft rotates in the bushing while the bushing itself does not rotate, i.e., is stationary or is non-rotatably mounted in a housing.

[0017] In further exemplary embodiments, the bushing may, in particular, have a contoured outer surface and / or one or more flanges. By means of the contoured outer surface and / or the one or more flanges, the bushing can be secured to or in a housing of a plain bearing, so that rotation of the bushing during use can be prevented, while a shaft rotatably mounted in the bushing can rotate smoothly.

[0018] Furthermore, the at least one detector element can be designed or configured, in particular, as a passive detector element, so that a state of the socket can only be detected by electrically contacting the detector element, for example, through a test plug of a plain bearing measuring arrangement. In alternative embodiments, the at least one detector element can be designed or configured as an active detector element, which, for example, has a transmitter element that transmits a detected state of the socket to the plain bearing measuring arrangement. While a passive detector element advantageously enables reliable detection of a state of the socket in a simple manner, an active detector element offers the advantage of particularly low-complexity remote diagnosis.

[0019] In the following, various terms are used repeatedly, the understanding of which is intended to be facilitated by the following definitions.

[0020] Axial direction: Bushings of plain bearings are often essentially cylindrical or have a contoured hollow shape in sections or regions. The axial direction roughly represents the cylindrical axis or the axis of the contoured hollow shape and, in other words, is subject to only minor deviations from the cylindrical axis or the axis of the contoured hollow shape.

[0021] Radial direction: Similar to the axial direction as defined and described above, the radial direction means a direction substantially perpendicular to the axial direction.

[0022] Cross-section: A cross-section of a bushing for a plain bearing can be defined in various ways and represents a sectional view or observation in a specific orientation. For example, a cross-section can be defined essentially along a radial direction of the bushing, meaning a section whose surface is designed such that the radial direction of the bushing lies within it. If the orientation of the cross-section is not explicitly stated below, it means a cross-section whose surface is designed such that the radial direction of the bushing lies within it.

[0023] Electrically contactable or contactable: The detector element of this bushing for a plain bearing is configured to be electrically contactable. Thus, the electrically contactable detector element can be electrically contacted, for example, using a test plug or a test contact, so that an electrical quantity can be detected by the test plug, and in particular, a measurable current flows between the detector element and the test plug or the test contact of a test plug. When the term "contactable" is used below, it always means "electrically contactable."

[0024] In preferred embodiments of the bushing, the condition of the bushing may include at least one of a wall thickness of the bushing, a porosity of the bushing, or an elastic property of the bushing.

[0025] In other words, the condition of the bushing may include at least one of a wall thickness of the bushing or an element of the bushing, a porosity of the bushing or an element of the bushing, or an elastic property of the bushing.

[0026] Advantageously, the detection of a condition such as the wall thickness of the bushing, porosity of the bushing, and / or an elastic property of the bushing allows the service life of the bushing to be brought very close to the maximum service life of the bushing for a specific application. Furthermore, a targeted replacement of the bushing before it is damaged is possible, thus preventing machine downtime due to damage to the plain bearing. Furthermore, by replacing the bushing less frequently, the material used for the sliding bearing of a machine shaft can be reduced, thus providing a particularly resource-efficient bearing arrangement.

[0027] In exemplary embodiments, only individual states such as a wall thickness of the bushing, a porosity of the bushing, or an elastic property of the bushing can be detected, or a combination of the states such as a wall thickness of the bushing, a porosity of the bushing, or an elastic property of the bushing can be detected.

[0028] The detection of a single condition can be advantageously both simple and targeted. If the wall thickness of the plain bearing is the only critical parameter for a specific application of a bushing for a plain bearing, which, above a certain value, requires replacement of the plain bearing to prevent damage to the bushing or plain bearing, then detecting precisely this single condition represents the best and most reliable way to improve the service life of the plain bearing. The same applies analogously to the other conditions of porosity and elastic properties.

[0029] If, on the other hand, several states of a bushing for a plain bearing are defined as critical states which, above a certain value, require the replacement of a plain bearing in order to avoid damage to the bushing or the plain bearing, a combined detection of several states offers the opportunity to improve the use of the plain bearing in use.

[0030] The state or states of the socket can be detected, for example, by measuring absolute currents, voltages, by capacitive measurement, by inductive measurement, etc. Furthermore, the state or states of the socket can be detected in a relative manner by measuring currents, voltages, by capacitive measurement, by inductive measurement, etc., in particular by comparative measurement between a plurality of detector elements.

[0031] The at least one detector element is configured to be electrically contacted by a test plug in order to detect the state of the socket.

[0032] By electrically contacting the at least one detector element with a test plug, the state of the socket can advantageously be detected or monitored by a measuring arrangement.

[0033] In exemplary embodiments, the socket may have exactly two detector elements that are configured to be electrically contacted by a test plug, wherein, for example, a current or a voltage is detected between the detector elements, an inductive measurement, and / or a capacitive measurement is carried out between the detector elements.

[0034] In further exemplary embodiments, a single detector element or a plurality of detector elements may be configured to be electrically contacted by a single test plug. Furthermore, a plurality of detector elements may be configured to be contacted by multiple test plugs, wherein each test plug may electrically contact one or more detector elements.

[0035] A state of the bushing can be detected by means of the one or more detector elements. A state can include at least one of a wall thickness of the bushing, a porosity of the bushing, or a specific elastic property of the bushing. The state of the bushing can be detected, for example, electrically and / or capacitively and / or inductively.

[0036] For example, a detector element, together with a shaft rotatably mounted in the bushing, can form a capacitor, wherein the bushing or a section of the bushing essentially acts as a separating means for the capacitor elements. If the bushing or a section of the bushing, i.e. the separating means, becomes worn, the capacitance of the capacitor formed changes, which can be detected by the detector element. Additionally or alternatively, for example, a voltage or a current can be detected between two detector elements, which changes depending on the wall thickness and / or the porosity and / or an elastic property of the bushing or the section of the bushing. Furthermore, additionally or alternatively, a plurality of detector elements can form one or more capacitors with respect to one another, the capacitance of which changes depending on the wall thickness and / or the porosity and / or an elastic property of the bushing orof the section of the socket changes.

[0037] In preferred embodiments of the bushing, the bushing can have a sliding element which faces a shaft to be mounted in the bushing, and the bushing can have a holding element which is arranged at least in sections radially outside the sliding element.

[0038] In other words, the bushing can, in particular, comprise a sliding element configured to support a shaft in a slidingly rotatable manner, and a retaining element that radially encompasses or surrounds the sliding element at least in sections. The bushing can be configured to be rigidly arranged in a plain bearing or a housing of a plain bearing by means of the retaining element, so that the sliding element does not rotate with the shaft to be supported therein.

[0039] The sliding element can, in particular, form a layer that exhibits particularly low sliding friction relative to the shaft to be mounted in the bushing. At the same time, the retaining element can be designed to be particularly rigid and / or stiff to enable stable, and in particular, rotationally fixed, fixation of the bushing in the plain bearing.

[0040] Thus, the multi-layer design of the bushing, in particular the multi-layer design of the bushing in the radial direction, can provide a bushing with advantageous properties for the sliding support of a shaft and for the rotationally fixed fixing of the bushing in a plain bearing.

[0041] In exemplary embodiments of the bushing, the bushing, and in particular the sliding element, can have an inner diameter in the range of approximately 10 mm to approximately 500 mm, but is not limited thereto. Furthermore, the sliding element can in particular have a wall thickness in the range of approximately 0.2 mm to approximately 60 mm, preferably in the range of approximately 1 mm to approximately 20 mm.

[0042] In preferred embodiments of the bushing, the sliding element and / or the holding element can be electrical insulators.

[0043] In other words, the socket in particular can be an electrical insulator in part or in its entirety.

[0044] Preferably, the socket, wherein the sliding element and / or the holding element is an electrical insulator, enables the state of the socket to be detected very precisely or accurately by electrically contacting the detector element. Because the sliding element and / or the holding element are electrical insulators, changes in the state of the socket, i.e., in the state of the sliding element and / or the holding element, have a particularly strong effect on electrically detectable properties, such as capacitance or current flow.

[0045] In the exemplary case of a metallic shaft being mounted in a polymer sliding element, a change in the wall thickness of the sliding element can have a particularly strong effect on a measurable current strength between two detector elements, or, for example, also on the capacitive value that can be detected at the sliding element.

[0046] In exemplary embodiments of the bushing, the sliding element and / or the retaining element can be formed from or comprise a polymer. For example, the sliding element and / or the retaining element can comprise or consist of plastic, such as PTFE, PA, PP, PE, EP, PMMA, PEEK, or PUR, or optionally, in particular, can comprise or consist of a fiber-reinforced plastic, such as PTFE, PA, PP, PE, EP, PMMA, PEEK, or PUR, with a carbon, aramid, or glass fiber content in the range of 0.1% to 40%.

[0047] In further exemplary embodiments of the bushing, the sliding element and / or the retaining element can be formed from or comprise a ceramic material. For example, the sliding element and / or the retaining element can comprise or consist of a technical ceramic, such as silicon carbide, boron carbide, boron nitride, or carbon fiber-reinforced carbon.

[0048] In particular, the holding element can comprise or be made of a material with greater electrical insulation than the sliding element. This enables the properties or condition of the sliding element to be specifically detected.

[0049] In alternative embodiments, at least one of the sliding element and the retaining element may comprise or consist of a metallic material. For example, at least one of the sliding element and the retaining element may comprise or consist of lead, tin, bronze, aluminum, steel, or another metallic material.

[0050] In preferred embodiments of the socket, two or more detector elements can be arranged on a radially outer side of the sliding element, and the holding element can have at least one opening, so that the two or more detector elements can be electrically contacted by means of a test plug through the at least one opening.

[0051] In other words, the at least one detector element can be arranged on an outer peripheral side of the sliding element. Furthermore, the holding element can have at least one opening through which the at least one detector element can be electrically contacted by means of one or more test plugs.

[0052] Advantageously, the detector element, which is arranged on a radially outer side of the sliding element, enables in particular the state of the sliding element of the bushing to be detected.

[0053] For the exemplary case of a metal shaft being supported in a polymer or ceramic sliding element, a state in which the sliding element is used up, i.e., the sliding element has almost no or no wall thickness left, would be detectable as a maximum or minimum value in an electrical or capacitive measurement. Upon detection of a critical or nearly critical wall thickness of the sliding element, a measurement signal can be output based on the detection using the electrically contacting test plug. This measurement signal can be converted as required to indicate a necessary replacement of the sliding element, the bushing, or the entire plain bearing. A measurement signal or an output signal based on the measurement signal can, for example, be an acoustic or optical signal, such as a warning tone, a lamp, text on a display, or output to a graphical user interface.

[0054] Because the holding element has openings through which the at least one detector element can be electrically contacted, the detection can relate in particular to the sliding element and is subject to only minor or no distortions by the holding element.

[0055] By arranging two or more detector elements on a radially outer side of the sliding element, a state of the bushing, and in particular a state of the sliding element, can be detected using multiple detector elements. For example, a state can be detected by the conductivity of the detector element between two detector elements.

[0056] Similarly, a capacitive comparison can be performed between two or more detector elements. Additionally, states can be detected at multiple sections of the bushing or sliding element, allowing a comparison between the states at geometrically different sections of the bushing or sliding element.

[0057] For example, a detector element, together with a shaft rotatably mounted in the sliding element, can form a capacitor, wherein the sliding element and optionally a region of the holding element essentially acts as a separating agent, i.e. as a dielectric medium for the capacitor elements. If the sliding element, i.e. the separating agent, wears out, the capacitance of the capacitor formed changes, which can be detected by the detector element. Additionally or alternatively, for example, a voltage or a current can be detected between two detector elements, which changes depending on the wall thickness and / or the porosity and / or an elastic property of the sliding element. Furthermore, additionally or alternatively, a plurality of detector elements can form one or more capacitors, the capacitor(s) of whichwhose capacities vary depending on the wall thickness and / or porosity and / or an elastic property of the sliding element.

[0058] In particular, a plurality of detector elements can be arranged in pairs on the radially outer side of the sliding element, wherein a first pair of detector elements can be arranged, for example, diametrically, i.e., opposite one another with respect to the axis of the bushing, to a second pair of detector elements. The detector elements of a pair of detector elements can, for example, be arranged spaced from one another both substantially in the axial direction of the sliding element and substantially in the circumferential direction of the sliding element. Furthermore, the detector elements of a respective pair of detector elements can be configured to be electrically contactable by a single test plug. For this purpose, the test plug can, in particular, have a pair of test contacts, such that each detector element of a pair of detector elements can be electrically contactable by a test contact of a test plug.

[0059] The at least one opening of the holding element may, for example, extend substantially radially, but is not limited thereto.

[0060] In exemplary embodiments, the holding element can be configured to encompass the sliding element such that the sliding element is arranged radially within the holding element in a non-rotatable or rotationally fixed manner. Furthermore, the holding element itself can be configured to be rotationally fixed in a housing. By means of the at least one opening in the holding element, the at least one detector element can thus be electrically contacted with a test plug with repeatable accuracy.

[0061] The at least one detector element has a contact section that is elastically resilient in the radial direction.

[0062] Advantageously, the at least one detector element, which has a contact section that is elastically resilient in the radial direction, enables reliable electrical contacting of the at least one detector element with a test plug to be ensured.

[0063] In particular, the resilient contact section of the at least one detector element allows the resilient contact section to elastically deform upon electrical contact with a test plug, while maintaining electrical contact between the test plug and the detector element. In particular, due to the resilient contact section, which undergoes resilient deformation, contact between the test plug or test contacts of the test plug and the detector element can be ensured with a predetermined contact force.

[0064] Thus, damage to both the detector element and a test plug for electrically contacting the detector element can advantageously be avoided, while at the same time a predetermined electrical contact between the test plug and the detector element with a predetermined contact force is ensured.

[0065] In exemplary embodiments, the at least one detector element can have a resilient contact section with respect to directions other than the radial direction or directions other than the radial direction. Furthermore, the at least one detector element can have a plurality of resilient contact sections.

[0066] In preferred embodiments of the socket, the at least one detector element can be a metal plate.

[0067] For example, the at least one detector element can be a copper plate, a galvanized iron plate, or another electrically contactable metal plate. If multiple detector elements are arranged on the socket, the multiple detector elements can be similar or identical metal plates, or different metal plates.

[0068] Advantageously, the design of the at least one detector element as a metal plate enables the state of the socket, in particular the state of a sliding element of the socket, to be detected in a passive manner, so that the detector element itself is insensitive to a change in the state of the socket.

[0069] Furthermore, the design of the at least one detector element as a metal plate enables a particularly simple and cost-effective bushing for a plain bearing to be provided, wherein different states of the bushing can be detected and the application is not limited to the detection of a specific state.

[0070] In particular, the at least one detector element can be a bent metal plate, wherein, for example, a connecting section of the detector element faces radially inward toward the socket, and an elastically resilient contact section of the detector element extends radially outward, obliquely away from the connecting section.

[0071] In alternative embodiments, the at least one detector element can be configured as an active detector element for detecting a specific measured variable. For example, the at least one detector element can have an RFID chip, which can in particular be embedded in the detector element or completely enclosed by the detector element.

[0072] The detector element can, for example, have a wall thickness in the range of approximately 0.1 mm to approximately 3.0 mm, preferably in the range of approximately 0.3 mm to approximately 1.5 mm. Furthermore, an elastically resilient contact section of the detector element, in an exemplary state, wherein the detector element is not contacted by a test plug, can extend radially outward in the range of approximately 1.0 mm to approximately 10 mm. Further, by way of example, the detector element can, for example, have a side length in the range of approximately 0.5 mm to approximately 20 mm, preferably in the range of approximately 3 mm to approximately 10 mm. The geometry of the detector element is not limited to the dimensions specified above.For example, the detector element can be geometrically designed in relation to the socket, and in particular in relation to the sliding element of the socket, wherein the detector element, for example, has a wall thickness in the range of approximately 0.1% to approximately 2% of the outer diameter of the socket or of the sliding element, an elastically resilient contact section of the detector element, in an exemplary state, wherein the detector element is not contacted by a test plug, extends radially outwards in the range of approximately 1% to approximately 10% mm of the outer diameter of the socket or of the sliding element, and has a side length in the range of approximately 0.1% to approximately 5% of the outer diameter of the socket or of the sliding element.

[0073] A further aspect of the invention relates to a plain bearing comprising: a socket according to any one of the preceding aspects, as well as preferred, exemplary, and / or alternative embodiments; and a housing in which the socket is arranged in a replaceable or non-replaceable manner.

[0074] In other words, in exemplary embodiments, the present plain bearing may be configured such that a bushing is interchangeably disposed therein. In alternative embodiments, however, the present plain bearing may be configured such that a bushing is non-interchangeably disposed therein.

[0075] The aspects described above, as well as preferred, exemplary and / or alternative embodiments of the bushing for a plain bearing and their effects equally relate to the plain bearing comprising a bushing and a housing in which the bushing is arranged in an interchangeable or non-interchangeable manner.

[0076] Advantageously, a replaceable arrangement of the bushing in the housing of the plain bearing allows the bushing to be replaced once it has reached its maximum service life. Consequently, a replaceable arrangement of the bushing in the plain bearing can provide a cost-effective and resource-efficient long-term plain bearing.

[0077] In addition, a non-replaceable arrangement of the bushing in the housing of a plain bearing enables the bushing to be fixed particularly rigidly in the housing of the plain bearing, so that a particularly reliable electrical contact of a detector element arranged on the bushing can be ensured by means of a test plug.

[0078] In exemplary embodiments, the socket can be arranged in or on the housing in an interchangeable manner by means of a bayonet lock or a fixing flange.

[0079] In contrast, in alternative embodiments, the socket can be arranged in a non-replaceable manner in or on the housing by clamping, locking or gluing.

[0080] In preferred embodiments of the plain bearing, the housing can have at least one receiving opening in order to partially receive a test plug which is configured to electrically contact the at least one detector element, and the test plug can be guided in the at least one receiving opening to the at least one detector element and / or can be fixed in the at least one receiving opening.

[0081] The receiving opening by means of which the test plug can be guided and / or fixed advantageously makes it possible to ensure reliable electrical contact between the at least one detector element and the test plug.

[0082] In exemplary embodiments, the receiving opening can be conical or tapered, at least in sections, to guide the test plug in a targeted manner toward the detector element. Furthermore, the receiving opening can have a coding for aligning the test plug, so that the test plug can be guided toward the detector element in a predetermined orientation.

[0083] In further exemplary embodiments, the receiving opening can have locking elements, in particular a bayonet receptacle or a thread, in order to fix the test plug in the receiving opening and thus enable a repeatable electrical contact of the detector element by the test plug.

[0084] For example, a shaft of the test plug can be screwed into the housing by means of the receiving opening. Furthermore, the test plug can be configured to be arranged in the receiving opening in a lockable and / or releasable manner by having a fastening section complementary to the receiving opening. In other words, a test plug can be secured, in particular, reversibly, i.e., releasably, in the receiving opening of the housing. For example, a test plug can form a push-pull configuration with the receiving opening for releasably securing the test plug in the receiving opening.

[0085] A further aspect of the invention relates to a sliding bearing measuring arrangement comprising. a plain bearing according to the preceding description; and at least one test plug, wherein the at least one test plug electrically contacts the at least one detector element.

[0086] In particular, the test plug can be configured to be connected to a control unit to detect and output the state of the socket, and in particular the state of a sliding element of the socket. In other words, the test plug can be configured to be connected to a control unit that is configured to measure, evaluate, and output a detected state of the socket or a state of a sliding element of the socket.

[0087] The aspects described above, as well as preferred, exemplary and / or alternative embodiments of the bushing for a plain bearing and of the plain bearing and their effects, relate equally to the plain bearing measuring arrangement comprising a plain bearing bushing and at least one test plug which electrically contacts the at least one detector element.

[0088] Another aspect of the invention relates to a method for determining the wear of a bushing of a plain bearing, comprising the steps: Electrically contacting at least one detector element of the socket with a test plug, wherein the at least one detector element has a contact section that is elastically resilient in the radial direction for electrically contacting a test contact of the test plug, wherein the elastically resilient contact section extends outwards in the radial direction; Measuring a state of the socket by means of the test plug that electrically contacts the at least one detector element; and Outputting a measurement signal based on the detected state of the socket.

[0089] The output of a measurement signal based on the detected state of the socket can, in particular, comprise the output of an acoustic and / or optical signal. For example, a warning signal can sound as soon as a condition is detected as a potentially critical state of the socket. Additionally or alternatively, a lamp can light up in a specific color, or a warning or text message can be output on a display as soon as a condition is detected as a potentially critical state of the socket. Alternatively or additionally, a message can be output to an internal input and output unit of a control unit and / or to an external device, such as a computer or smartphone, for example via email.

[0090] In addition, critical changes in a state, even if a critical state itself has not yet occurred, can be output as an indication by evaluating the change in a state over a predetermined period of time.

[0091] Furthermore, the output of a measurement signal based on the detected state may in particular comprise the output of an absolute state, or comprise the output of a relative state, such as an expected remaining service life based on the detected state and the change of several detected states over a predetermined time.

[0092] The aspects described above, as well as preferred, exemplary and / or alternative embodiments of the bushing for a plain bearing, the plain bearing and the plain bearing measuring arrangement and their effects equally relate to the method for determining the wear of a bushing of a plain bearing.

[0093] In further exemplary embodiments, the method for determining the wear of a bushing of a plain bearing may include a step of calibrating a plain bearing measuring arrangement.

[0094] In particular, the step of calibrating a plain bearing measuring arrangement can be carried out before the further steps and before using the plain bearing for the sliding support of a shaft.

[0095] The step of calibrating a measuring system can be based on simulations and / or tests, whereby a specific detectable measurement signal, such as a specific current, a specific voltage, or a specific capacitance, is assigned to a specific condition of a bushing, such as a wall thickness of the bushing, a porosity of the bushing, or an elastic property of the bushing. During the calibration of the plain bearing measuring system, critical states of the bushing can be defined, which trigger a specific output and indicate, for example, that the bushing of the plain bearing or the plain bearing needs to be replaced.

[0096] Embodiments of the invention are described in more detail below with reference to the accompanying figures. It is to be understood that the present invention is not limited to these embodiments. The claimed invention is defined by the appended claims.

[0097] It shows: Figure 1 shows an oblique view of a bushing for a plain bearing; Figure 2 shows a sectional view of the bushing; Figure 3 shows a housing of a plain bearing; and Figure 4 shows a flowchart of a method for determining the wear of a bushing of a plain bearing.

[0098] Fig. 1 shows a bushing 10 for a plain bearing, which can be configured as an example to rotatably support a shaft. As shown in Fig. 1 As shown, the bushing 10 may have a substantially cylindrical shape, wherein a denotes an axial direction of the bushing 10 and r denotes a radial direction of the bushing 10.

[0099] Furthermore, the bushing 10 can, in particular at an axial end of the bushing 10, have a flange 12, for example, wherein the bushing 10 can be fastened, for example, by means of the flange 12 to a housing 50, as in Fig. 3 shown, can be fixed. The fixing can be effected, for example, by screwing, riveting, gluing, welding or similar. The bushing 10 can be fixed to or in the housing 50 either reversibly or irreversibly. The fixing of the bushing 10 to or in the housing 50 can in particular be rotationally fixed or rotationally secured, so that the bushing 10 does not rotate relative to the housing 50. In particular, the bushing 10 can be fixed to or in the housing 50 in such a way that even when a shaft is rotatably mounted in the bushing 10 at a high speed, the bushing 10 does not rotate.

[0100] As in Fig. 1 Further shown, a plurality of detector elements 40 can be arranged on the socket 10. Each detector element 40 can be arranged in an opening 32 of the socket 10, wherein the opening 32 is larger than the detector element 40 arranged therein.

[0101] As also in Fig. 1 As shown, a pair of detector elements 40 may be arranged adjacent to each other. In particular, a pair of detector elements 40 may be arranged spaced apart from each other in the circumferential direction of the socket 10, so that both detector elements 40 can be connected to a single test plug 60 (in Fig. 1 not shown). A test plug 60 can be guided essentially in the radial direction r toward the detector elements 40 in order to electrically contact them.

[0102] In exemplary embodiments, a plurality of detector elements 40, such as one, two, three, four, five, six, seven, eight, nine, ten, eleven, or twelve detector elements 40, can be arranged on the socket 10. Alternatively, any other number of detector elements 40 can be arranged on the socket 10 to detect one or more states of the socket 10. By means of a plurality of detector elements 40, a state of the socket 10, in particular wear or tear of the socket 10, can advantageously be detected at various locations on the socket 10. In particular, the plurality of detector elements 40 can be electrically contacted sequentially with a single test plug 60 or electrically contacted in parallel, i.e., simultaneously, using multiple test plugs 60 in order to detect a state of the socket 10 at various locations on the socket 10.

[0103] Fig. 2 shows an exemplary cross-section along a radial direction of the bushing 10, for example at an axial position of the bushing 10, at which two detector elements 40 are arranged.

[0104] As in Fig. 2 As shown, two detector elements 40 may be spaced apart from one another in the circumferential direction of the bushing 10. In alternative embodiments, two or more detector elements 40 may be spaced apart from one another in other directions, such as in the axial direction a or diagonally along the circumference of the bushing 10.

[0105] As continued in Fig. 2 As shown, the bushing 10 may have a multi-layer construction. For example, the bushing 10 may be integrally formed from multiple layers or may be formed by nesting an inner element into one or more outer elements.

[0106] In particular, the bushing 10 can have a sliding element 20, which, for example, has a substantially cylindrical shape and is arranged on a radially inner side of the bushing 10. The sliding element 20 can in particular be configured to slidably and rotatably support a shaft (not shown), such as for a machine, for example. Furthermore, the bushing 10 can have a holding element 30, which, for example, has a substantially cylindrical shape and is arranged on a radially outer side of the bushing 10. In particular, the holding element 30 can radially encompass the sliding element 20 at least in sections.

[0107] Furthermore, as in Fig. 2 As shown, the holding element 30 has a plurality of openings 32, for example, to arrange a detector element 40 in each opening 32. The openings 32 can extend substantially in the radial direction r, so that the one or more detector elements 40 can be electrically contacted substantially in the radial direction r by means of a test plug 60.

[0108] As in Fig. 2 As shown, the detector elements 40 can be arranged on a radially outer circumferential side of the sliding element 20. Furthermore, the detector elements 40 can also be arranged in grooves of the sliding element 20, wherein the grooves recess radially inward by a predetermined value relative to the radially outer circumferential side of the sliding element 20. A groove can in particular recess radially inward by a value of approximately 0.01 mm to approximately 1 mm, preferably in the range from approximately 0.02 mm to approximately 0.5 mm, and particularly preferably in the range from approximately 0.05 mm to approximately 0.1 mm, relative to the radially outer circumferential side of the sliding element 20. The arrangement of the one or more detector elements 40 in radially inwardly recessed grooves of the sliding element 20 makes it possible to detect a critical condition of the bushing 10 or the sliding element 20 at an early stage and at various locations on the bushing 10.

[0109] As in Fig. 2 As shown, the one or more detector elements 40 are provided with an elastically resilient contact section 42 which can deform elastically when contacted with a test contact of a test plug 60, in particular can deform elastically radially inwards.

[0110] The elastically resilient contact section 42 of a detector element 40 can be oriented such that it deforms substantially in the radial direction r and in the circumferential direction during a radially inwardly directed elastic deformation, and / or deforms substantially in the radial direction r and in the axial direction a.

[0111] For example, and as in Fig. 2 As indicated, the one or more detector elements 40 may be formed as a bent metal plate, so that the detector element 40 is resiliently configured and integrally configured with the function of elastic recovery capability.

[0112] In alternative embodiments, the detector element 40 can be a flat metal plate, in particular an unbent flat metal plate. In such an embodiment, it is advantageous if the test plug 60 has elastically resilient test contacts for electrically contacting the one or more detector elements 40.

[0113] Consequently, a reliable electrical contact of the one or more detector elements 40 with a test plug 60 can be realized in both ways.

[0114] Fig. 3 shows a representation of a housing 50 of a plain bearing. The housing 50 can have any shape and, in particular, can be configured to be fixable or fixable in order to provide secure support, such as for a machine shaft.

[0115] As in Fig. 3 As shown, the housing 50 can, in particular, have a substantially cylindrical bushing receptacle 52. The bushing receptacle 52 can be configured to support or fix the bushing 10 in a rotationally fixed manner. For this purpose, the bushing receptacle 52 can, for example, have one or more radially inwardly directed projections and / or form a toothing with the holding element 30 of the bushing 10. Alternatively or additionally, the bushing 10 can be reversibly or irreversibly arranged, fixed, or attached to a front side of the housing 50 with a flange 12.

[0116] Furthermore, as in Fig. 3 As indicated, the housing 50 can have one or more receiving openings 54. The receiving opening 54 can be configured to guide a test plug 60 to one or more detector elements 40 and / or to fix or secure a test plug 60 in the receiving opening 54. For this purpose, the receiving opening 54 can be provided in particular in sections with a thread, in particular with an internal thread, and / or projections. For example, the receiving opening 54 can be configured in particular to receive a shaft of the test plug 60, wherein the shaft of the test plug 60 can be fixed, screwed, glued, etc. in the receiving opening. In order to fix the test plug 60 in the receiving opening 54, the test plug 60 can in particular have a fixing section complementary to the receiving opening 54.

[0117] For example, the housing 50 may have one, two, three, four, five, six, seven or eight receiving openings 54 in order to be able to receive and guide and / or fix a test plug 60 therein.

[0118] Further, by way of example, the receiving openings 54 may be configured as through-openings so that a test plug 60 can be guided from an outer side of the housing 50 to one or more detector elements 40 arranged on the socket 10.

[0119] Alternatively, individual or all of the receiving openings 54 can be configured as blind holes, wherein the test plug 60 can be guided from an outer side of the housing 50 to a blind hole bottom of the receiving opening 54. When the test plug 60 hits the blind hole bottom, contact elements arranged in the housing 50 extend toward the one or more detector elements 40 arranged on the socket 10 in order to make electrical contact therewith. Such a mechanism can be suitable for enabling accessibility to a detector element 40 that is oriented toward an underside of the housing 50, wherein the test plug 60 itself does not have to be guided to the detector element 40, but rather electrical contact is made indirectly via contact elements arranged in the housing 50.

[0120] Fig. 4 shows a flowchart of a method for determining the wear of a bushing of a plain bearing. The method for determining the wear of a bushing of a plain bearing comprises, by way of example, the following steps.

[0121] Starting with S11: electrically contacting at least one detector element 40 of the socket 10 with a test plug 60; S12: Measuring a state of the socket 10 using the test plug 60, which electrically contacts the at least one detector element 40; and S13: Outputting a measurement signal based on the detected state of the socket 10.

[0122] The output measurement signal can be processed and converted in various ways before output by means of a control and / or regulation unit, which comprises a memory unit and a processor unit.

[0123] For example, the measurement signal can be converted into an acoustic signal, an optical signal or a haptic signal.

[0124] Furthermore, before step S11, a calibration of a plain bearing measuring arrangement, which in particular comprises a bushing, a housing and a test plug 60, can be carried out.

[0125] A step S01 for calibration can in particular comprise: calibrating a plain bearing measuring arrangement, wherein a specific state of a bushing 10, such as wall thickness of the bushing, porosity of the bushing, or elastic property of the bushing, is assigned a specific measured value that can be electrically detected at the detector elements, such as current intensity, voltage or capacitance.

[0126] By means of step S01, in particular critical states of the bushing 10 can be defined, such as, for example, an insufficient wall thickness of the bushing 10 or an insufficient wall thickness of the sliding element 20, or an excessive porosity of the bushing 10 or the sliding element 20.

[0127] The calibration of the plain bearing measuring arrangement can be carried out in particular on the basis of simulations and / or real tests. Bezugszeichenliste

[0128] 10Socket 12Flange 20Sliding element 22Outer peripheral side of the sliding element 30Retaining element 32Opening 40Detector element 42Resilient contact section 50Housing 52Socket receptacle 54Receptacle opening 60Test plug aaxial direction rradial direction

Claims

1. Bushing (10) for a sliding bearing, wherein the bushing (10): - is substantially cylindrical, and - has at least one electrically contactable detector element (40), which is arranged on the bushing (10), wherein the at least one detector element (40) is configured to detect a state of the bushing (10), characterized in that the at least one detector element (40) has a contact portion (42), which is elastically resilient in the radial direction (r), for electrical contact with a test contact of a test plug (60), and wherein the elastically resilient contact portion (42) extends outwards in the radial direction (r).

2. Bushing (10) according to claim 1, wherein the state of the bushing (10) comprises at least one of: a wall thickness of the bushing (10), a porosity of the bushing (10), or an elastic property of the bushing (10).

3. Bushing (10) according to any one of claims 1 to 2, wherein the bushing (10) has a sliding element (20), which faces a shaft to be supported in the bushing (10), and has a holding element (30), which is arranged at least in portions radially outside the sliding element (20).

4. Bushing (10) according to claim 3, wherein the sliding element (20) and / or the holding element (30) are electrical insulators.

5. Bushing (10) according to claim 3, wherein the sliding element (20) and the holding element (30) are electrical insulators, wherein the holding element (30) comprises a thicker insulating material than the sliding element (20).

6. Bushing (10) according to any one of claims 3 to 5, wherein two or more detector elements (40) are arranged on a radially outer side of the sliding element (20), and wherein the holding element (30) has at least one opening (32), so that the two or more detector elements (40) are electrically contactable by means of a test plug (60), through the at least one opening (32).

7. Bushing (10) according to any one of claims 3 to 6, wherein the sliding element (20) is arranged radially inside the holding element (30) non-rotatably.

8. Bushing (10) according to any one of claims 1 to 7, wherein the at least one detector element (40) is a metal plate.

9. Sliding bearing comprising: - a bushing (10) according to any one of claims 1 to 8; and - a housing (50) in which the bushing (10) is arranged exchangeably or non-exchangeably.

10. Sliding bearing according to claim 9, wherein the housing (50) has at least one receiving opening (54) in order to receive, in regions, a test plug (60) which is configured to contact electrically the at least one detector element (40), and wherein the test plug (60) is guidable in the at least one receiving opening (54) to the at least one detector element (40) and / or is fixable in the at least one receiving opening (54).

11. Sliding bearing measuring arrangement comprising: - sliding bearings according to any one of claims 9 or 10; and - at least one test plug (60), wherein the at least one test plug (60) electrically contacts the at least one detector element (40).

12. Method for determining the wear of a bushing (10) of a sliding bearing, comprising the steps of: - electrically contacting at least one detector element (40) of the bushing (10) with a test plug (60), wherein the at least one detector element (40) has a contact portion (42), which is elastically resilient in the radial direction (r), for electrical contact with a test contact of a test plug (60), and wherein the elastically resilient contact portion (42) extends outwards in the radial direction (r); - measuring a state of the bushing (10) by means of the test plug (60), which electrically contacts the at least one detector element (40); and - outputting a measurement signal on the basis of the detected state of the bushing (10).