Plain bearing bush for plain bearings with increased load-bearing capacity

A plain bearing bush includes a cylindrical main body having a first shell surface and a second shell surface. The first and second shell surfaces include a plurality of exchange bores for a lubricant. At least one of the exchange bores has a first diameter on the first shell surface and a second diameter on the second shell surface, with the second diameter being greater than the first diameter for an increase in a load-bearing capability of the plain bearing bush. Two of the exchange bores are arranged in axial spaced-apart relation and connected to one another by a pocket depression.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application Is the U.S. National Stage of International Application No. PCT/EP2021/075743, filed Sep. 20, 2021, which designated the United States and has been published as International Publication No. WO 2022/063710 A1 and which claims the priority of European Patent Application, Serial No. 20198055.4, flied Sep. 24, 2020, pursuant to 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The invention relates to a plain bearing bush, by way of which a load-bearing capability of a plain bearing can be increased. The invention likewise relates to a corresponding plain bearing and to a planetary transmission which is equipped with a plain bearing of this type. Furthermore, the invention relates to a wind power plant and an industrial application which in each case have a planetary transmission of this type. The invention likewise relates to a computer program product, by way of which the operating behavior of a corresponding plain bearing bush can be simulated.

Document DE 29 45 821 A1 discloses a bearing which comprises a bearing body, in which a floating bush is arranged rotatably. A shaft is received rotatably in a floating bush. Radially oriented channels are configured in the floating bush, through which channels oil can be fed. The channels are of widened configuration on a side which faces the oil supply.

Laid-open specification DE 35 37 449 A1 has disclosed a bearing system with floating bushes which have radial bores, via which oil can be fed in the direction of a rotatably mounted shaft. Here, the radial bores are of widened configuration at an end which faces the oil supply.

U.S. Pat. No. 4,371,219 A has disclosed a cylindrical plain bearing bush with exchange bores for lubricant which run in the radial direction, in the case of which plain bearing bush the exchange bores have a greater diameter on a radially outer shell surface of the plain bearing bush down on a radially inner shell surface of the plain bearing bush.

CN 105 134 780 A has disclosed a cylindrical plain bearing bush with exchange bores for lubricant which run in the radial direction, in the case of which cylindrical plain bearing bush the exchange bores have a greater diameter on a radially inner shell surface of the plain bearing bush than on a radially outer shell surface of the plain bearing bush.

DE 10 2017 216 192 A1 has disclosed a radial plain bearing for mounting a shaft, the radial plain bearing having a cylindrical plain bearing bush with exchange bores for lubricant which run in the radial direction.

DE 10 2017 223 390 A1 has disclosed a radial plain bearing for mounting a shaft of a transmission for a wind power plant, the radial plain bearing having a cylindrical plain bearing bush.

Plain bearings are used in a multiplicity of applications which require a high bearing load-bearing capability, minimum bearing friction losses and a high bearing service life. A simple and cost-efficient production of plain bearings of this type is likewise sought. There is a requirement for a plain bearing which provides an improvement in at least one of the above-described objectives.

SUMMARY OF THE INVENTION

The addressed object is achieved by way of a plain bearing bush as set forth hereinafter. Preferred refinements are specified in the subclaims in the following description, which preferred refinements can represent one aspect of the invention in each case individually or in combination. If one feature is shown in combination with another feature, this serves only for simplified illustration of the invention and is not in any way to mean that this feature cannot be a development of the invention even without the other feature.

The plain bearing bush according to the invention comprises a cylindrical main body. The cylindrical main body has a first shell surface and a second shell surface. The first and second shell surface are connected to one another via a plurality of supply bores, with the result that the lubricant can pass through a supply bore from the first to the second shell surface and vice versa. At least one of the exchange bores has a first diameter on the first shell surface and a second diameter on a second shell surface. Here, the diameter is to be understood to be a dimension substantially perpendicularly with respect to a flow direction of the lubricant. The second diameter is greater than the first diameter. As a result, a flow speed of the lubricant is lower on the second shell surface than on the first shell surface. Furthermore, there is an increased flow resistance in regions of the exchange bores with the second diameter. As a consequence, there is a higher drag action of the lubricant on the plain bearing bush. An increased lubricating gap height can in turn be achieved by way of the increased drag action. Therefore, an increased load-bearing capability of the plain bearing, in which the plain bearing bush is to be used, is achieved by way of the second diameter which is greater than the first diameter. Exchange bores with different diameters on the first and second shell surface can be produced in a simple way. The drag action is increased and the load-bearing capability is enhanced by way of the modified geometry.

In the case of the claimed plain bearing bush, the at least one exchange bore is arranged offset axially with respect to a lubricant feed opening. Here, an axial direction is to be understood to be a direction substantially parallel to the main rotational axis of the plain bearing bush. The lubricant feed opening is configured in a component of the plain bearing, which component lies opposite the plain bearing bush. Lubricant which is conducted through the at least one exchange bore therefore flows along on the first shell surface before it reaches the at least one exchange bore. The exchange bores are correspondingly arranged in such a way that lubricant is output in a laminar manner on the second shell surface. In particular, the exchange bores can be offset axially with respect to main bores which have a greater diameter than the exchange bores and which are arranged so as to lie substantially opposite a lubricant feed opening.

Moreover, at least two, in particular three or more exchange bores which are spaced apart axially on the second shell surface which is, in particular, the outer surface of the main body are connected to one another by way of a pocket depression. In the region of the pocket depression, the flow speed of the lubricant is decreased further and represents an additional flow resistance, with the result that the drag action on the plain bearing bush is increased further. The pocket depressions can be produced by way of machining methods with or without the removal of material and/or by way of mechanical and/or chemical action. The pocket depressions can be produced, in particular, by way of milling, etching or eroding. The load-bearing capability of the claimed plain bearing bush is increased further by means of the pocket depressions. Furthermore, a plurality of pocket depressions can be configured on the second shell surface, which pocket depressions can be arranged circumferentially to form an arrowhead pattern or arc pattern. For example, the pocket depressions can be oriented in such a way that an arrow tip which points in or counter to the circulating direction is indicated on the second shell surface in a middle region of the plain bearing bush. The arrow pattern can be configured along an intended rotational direction of the plain bearing bush or counter to this rotational direction. As a result, an improved lubricant supply can be achieved on the second shell surface, and more uniform running of the plain bearing bush can be ensured.

The pocket depressions can be configured, for example, as a channel and/or groove which is open so as to point away from the first shell surface. The pocket depression can have, for example, a rounded (in particular, substantially U-shaped) or rectangular flow cross section in the direction of the exchange bores which are connected to one another via the pocket depression. For example, the respective pocket depression runs in a beveled manner with respect to the axial direction and with respect to the circumferential direction of the main body on a substantially constant radius with respect to an axial center line of the cylindrical main body. In particular, at least part of the pocket depressions which are provided in a common axial region of the main body, preferably all the pocket depressions which are provided in the common axial region of the main body, run in parallel to one another in a developed illustration of the main body. In one embodiment of the claimed plain bearing bush, at least two pocket depressions which follow one another in the circumferential direction are connected to one another for an exchange of lubricant. The pocket depressions which are connected to one another can run at an angle with respect to one another, one of the exchange bores opening, in particular, in the one and in the other pocket depression. The common exchange bore is preferably positioned in a point of an imaginary angle of the pocket depressions which are connected to one another in an angular manner. As a result, it is possible that the pocket depressions which are connected to one another configure a zigzag pattern which is preferably of closed configuration in the circumferential direction.

In one embodiment of the claimed plain bearing bush, the first shell surface is a side of the plain bearing bush, which side faces a lubricant supply. Accordingly, the second shell surface is a side of the plain bearing bush, which side faces away from the lubricant supply. In proper operation, the lubricant can be conducted through the exchange bores from the first to the second shell surface. In proper operation of a plain bearing which is equipped with the claimed plain bearing bush, the lubricating gap of the plain bearing is configured on the second shell surface. A liquid resistance is increased in the lubricant by way of the second diameter of the at least one exchange bore on the second shell surface, as a result of which liquid resistance more lubricant is conveyed into the lubricating gap. The lubricating gap can be configured as an internal lubricating gap and/or as an external lubricating gap. The lubricating film height is increased both in the case of an internal lubricating gap and an external lubricating gap. As a result, the effect of the claimed plain bearing bush is achieved to an increased extent.

Furthermore, the second diameter can be configured by way of a countersunk depression and/or a stepped bore. As a result of a countersunk depression which is of substantially conical configuration, the flow speed of the lubricant can be decreased substantially continuously. Countersunk depressions can be produced precisely and cost-efficiently in a simple way by way of countersink tools. A stepped bore (that is to say, an exchange bore with different diameters in sections) can likewise be produced rapidly and cost-efficiently. Bores of different diameters can be produced with increased precision, with the result that a reduction in the flow speed of the lubricant can be set in a correspondingly precise manner, depending on the ratio between the first and second diameter. The claimed plain bearing bush can therefore be adapted to different applications in a simple way. A countersunk depression on a step or can likewise be combined in order thus to achieve their respective advantages in a combined manner.

In a further embodiment of the claimed plain bearing bush, the second diameter of the replacement ball can correspond to from 1.05 to 6.00 times the first diameter. As a result, an advantageous reduction in the flow speed of the lubricant is achieved on the second shell surface, and a flow resistance is generated. As a result, a corresponding increase in the drag action of the lubricant on the plain bearing bush is in turn brought about. At the same time, a corresponding second diameter provides smooth running for the claimed plain bearing bush, furthermore.

Furthermore, the claimed plain bearing bush can be configured as a floating bush. The floating bush is arranged between a stationary and a rotating component of the plain bearing, and configures an internal lubricating gap and an external lubricating gap between them. As a consequence of the increased drag action which is exerted on the plain bearing bush in proper operation, it follows a rotational movement of the rotating component more rapidly. The lubricating gap height in the internal lubricating gap and/or in the external lubricating gap is thus increased, and therefore also the load-bearing capability of the plain bearing. By virtue of the fact that there are an internal lubricating gap and an external lubricating gap in the case of a floating bush, a particularly increased load-bearing capability is achieved by way of the claimed plain bearing bush. In particular, the damping action in the lubricating gaps is improved, and an improved load distribution is achieved in the case of axial distance deviations. An improved start-up behavior after a standstill is likewise achieved, and the temperature is reduced during operation.

In a further embodiment of the claimed plain bearing bush, the at least one exchange bore comprises an outlet portion which has the second diameter at least in sections. The outlet portion opens on the second shell surface. The outlet portion has a length which is from 10% to 100% of a bore length of the exchange bore. In a manner which corresponds to this, the at least one exchange bore comprises an inlet portion which, starting from the first shell surface, extends through the plain bearing bush and merges into the outlet portion or adjoins the latter. The at least one exchange bore has the first diameter in the inlet portion. The longer the outlet portion, the greater the reduction in the flow speed of the lubricant which can be achieved, and turbulence formation in the lubricant is avoided at the same time. Accordingly, a homogeneous discharge of the lubricant on the second shell surface can be achieved. This applies both to the outlet portions with the second diameter which are configured by way of a countersunk depression and also those which are configured by way of a stepped bore.

Moreover, the countersunk depression, by way of which the second diameter of the at least one exchange bore is configured, can have an opening angle which is from 45° to 135°. As a result, a particularly advantageous reduction in the flow speed of the lubricant is achieved. Opening angles of this type can be produced rapidly and cost-efficiently in a simple way by way of correspondingly shaped countersink tools.

The addressed object on which the invention is based is also achieved by way of a plain bearing according to the invention. The plain bearing comprises a rotating component which is arranged rotatably on a plain bearing bush. The plain bearing likewise comprises a stationary component. The plain bearing bush is configured according to the invention in accordance with one of the embodiments shown above. As a result of the use of a plain bearing bush of this type, the plain bearing has an increased load-bearing capability. In particular, the claimed plain bearing can have a Sommerfeld number of from 0.10 to 10.00. The claimed plain bearing therefore provides a load-bearing capability and as a consequence also a load-bearing capability reserve which opens up challenging fields of application, for example in planetary transmissions of rock crushers or cement mills.

Furthermore, the object outlined at the outset is achieved by way of a planetary transmission according to the invention. The planetary transmission comprises a planetary carrier, to which a plurality of planetary gears are attached rotatably. Here, the planetary gears are mounted rotatably on the planetary carder in each case by means of a plain bearing. According to the invention, at least one of the plain bearings is configured in accordance with the embodiments shown above.

The addressed object on which the invention is based is likewise achieved by way of a wind power plant according to the invention. The wind power plant comprises a nacelle, on which a multiple-blade rotor is arranged rotatably. A drive train is arranged in the nacelle, to which drive train a planetary transmission belongs which is connected in a torque-transmitting manner to the multiple-blade rotor and a generator. According to the invention, the planetary transmission is configured in accordance with one of the embodiments specified above.

The addressed object is likewise achieved by way of an industrial application according to the invention which comprises a drive unit and an output unit. The drive unit and the output unit are connected to one another in a torque-transmitting manner via a planetary transmission. The drive unit is, for example, configured as an electric motor, an internal combustion engine or a hydraulic motor, and provides drive power which is to be transmitted via the planetary transmission to the output unit. The output unit can be configured, for example, as a mill, a vertical mill, a sugar mill, a cement mill, a rock crusher, a conveyor belt, a pump, a roller press, a flat conveyor, a tube mill, a rotary kiln, a slewing gear, a stirring unit, a lifting apparatus, a garbage compactor or a car crusher. To this end, the output unit is connected via the planetary transmission to the drive unit. According to the invention, the transmission is configured in accordance with one of the embodiments outlined above. As a result of the claimed plain bearing bush, the planetary transmission according to the invention has an increased load-bearing capacity and reliability. As a result, the maintenance complexity for the planetary transmission is decreased, which in turn increases the economic efficiency of the industrial application according to the invention.

The object described at the outset is likewise achieved by way of a computer program product according to the invention, by way of which an operating behavior of a plain bearing bush in a plain bearing can be simulated. Here, at least one lubricating gap, for example an internal lubricating gap and/or an external lubricating gap, is simulated which is configured on the plain bearing as a result of a rotational movement. Here, in particular, the present lubricating gap height can be simulated in a manner which is dependent on the present operating state. To this end, the computer program product can comprise runnable simulation routines for fluid dynamic mechanisms and data interfaces, via which operating parameters such as a rotational speed, a temperature of the lubricant or radial loading of the plain bearing can be stipulated, or a simulation result can be output. The computer program product comprises a dataset, by way of which at least the plain bearing bush is modeled. According to the invention, the plain bearing bush is configured in accordance with one of the embodiments outlined above. Which load-bearing capability exists in the plain bearing with the plain bearing bush can be predicted or at least have its plausibility tested by means of the computer program product according to the invention. Furthermore, the plain bearing bush according to the invention can be adapted in terms of design by means of the computer program product according to the invention, and the plain bearing can thus be optimized readily. To this end, the computer program product can be configured, for example, as what is known as a digital twin. Digital twins of this type are shown, for example, in laid-open specification US 2017/286572 A1. The disclosure of US 2017/286572 A1 is incorporated in the present application by reference.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.1depicts a first embodiment of the claimed plain bearing bush10. The plain bearing bush10comprises a substantially cylindrical main body11which has a first shell surface12which is configured as an inner surface17. Corresponding to this, the plain bearing bush10also has a second shell surface14which is configured as an outer surface19. The plain bearing bush10can be used in a plain bearing40, in the operation of which a rotational movement25takes place about a main rotational axis15. The main rotational axis15is also an axis of symmetry of the plain bearing bush10. The plain bearing bush10is supplied with lubricant30in operation of the plain bearing40. The lubricant30is provided on the side of the first shell surface12(that is to say, the inner side17) via a lubricant supply33, and is transported via main bores16to the second shell surface14(that is to say, the outer surface19). The main bores16are configured so as to be spaced apart substantially uniformly and circumferentially on the plain bearing bush10in an axially middle region23. Spaced apart along an axial direction32, the plain bearing bush10has a plurality of exchange bores20which have diameters which are overall smaller than the main bores16. The exchange bores20are also configured such that they are spaced apart substantially uniformly in the circumferential direction24. Furthermore, the exchange bores20are arranged in such a way that they configure an arrowhead pattern26in interaction with in each case one main bore16. In a manner which corresponds to the arrowhead pattern26, two exchange bores20on the second shell surface14are connected to one another in pairs by way of pocket depressions28. In operation of the plain bearing40, the exchange bores20are configured to permit a passage of lubricant30in the radial direction34, with the result that the second shell surface14is wetted with lubricant30. The wetting of the second shell surface14is assisted by the pocket depressions28.

In addition toFIG.1,FIG.2shows the first embodiment of the claimed plain bearing bush10in a longitudinal section. On the first shell surface12, that is to say the inner side17, at least one of the exchange bores20has a first diameter27, into which the lubricant30enters in proper operation of the plain bearing40. On the second shell surface14, that is to say the outer surface19, the at least one exchange bore20has a second diameter29which is greater than the first diameter27. A flow speed31of the lubricant30is decreased during the passage through the at least one exchange bore20. The differences in the flow speed31of the lubricant30are illustrated inFIG.2by way of arrows of different length. In the region of the second shell surface14, the at least one exchange bore20has a countersunk depression36, by way of which a flow cross section in the exchange bore20is increased, and thus reduces the flow speed31.

The first embodiment of the claimed plain bearing bush10according toFIG.1andFIG.2is shown inFIG.3in a detailed view in a sectional illustration. The exchange bore20is configured as a countersunk depression36, and has an inlet portion35with the first diameter27and an outlet portion39which adjoins it or merges into it and has a second diameter29in the region of the second shell surface14. The length43of the outlet portion39corresponds to from 10% to 100% of a bore length41of the exchange bore20. The length43of the outlet portion39is substantially a dimension of the countersunk depression36along the radial direction34. A length43of this type of the outlet portion39will bring about a sufficient reduction in the flow speed31of the lubricant30, by way of which a drag force45is produced on the plain bearing bush10on the second shell surface14. The drag force45produces a drag action, by way of which the plain bearing bush10follows a rotational movement25of the plain bearing40. An increased drag force45is brought about by way of the second diameter39, the opening angle37and the length43of the outlet portion39. The countersunk depression36can be produced in a cost-efficient way by means of a countersink tool.

A second embodiment of the claimed plain bearing bush10is shown inFIG.4in a detailed view in a sectional illustration. The embodiment according toFIG.4can also be combined with the embodiment according toFIG.1,FIG.2andFIG.3. The exchange bore20is configured substantially as a stepped bore, and has an inlet portion35with the first diameter27and an outlet portion39which adjoins it or merges into it with the second diameter29. The length43of the outlet portion39corresponds to from 10% to 100% of a bore length47of the exchange bore20. The length43of the outlet portion39is substantially a dimension of the stepped bore along the radial direction34. A length43of this type of the outlet portion39will bring about a sufficient reduction in the flow speed31of the lubricant30, by way of which a drag force45is produced on the plain bearing bush10on the second shell surface14. The drag force45brings about a drag action, by way of which the plain bearing bush10follows a rotational movement25of the plain bearing40. An increased drag force45is brought about by way of the second diameter39and the length43of the outlet portion39.

FIG.5diagrammatically shows one embodiment of the claimed plain bearing40in cross section which is used in a planetary transmission50(not shown in greater detail). As rotating component42, the plain bearing40comprises a planetary gear46which is arranged rotatably on a planetary carrier55of the planetary transmission50. Furthermore, as stationary component44, the plain bearing40comprises an axle48which is connected fixedly to the planetary carrier55for conjoint rotation. Lubricant30is transported via a lubricant supply33to the plain bearing40by way of the stationary component44. The lubricant supply44is configured as lubricant channels (not shown in greater detail). The plain bearing40also comprises a plain bearing bush10which is configured as a floating bush53. The plain bearing bush10is arranged between the stationary component44and the rotating component42, with the result that a lubricant gap49can be formed in each case in pairs between them. By way of a rotational movement25of the rotating component42, lubricant30is conveyed into an external lubricating gap54between the plain bearing bush10and the rotating component42. A lubricating gap height51is produced at the external lubricating gap54in a manner which is dependent on the speed of the rotational movement25. The plain bearing bush10is provided with exchange bores20, through which lubricant30exits in the region of the external lubricating gap54. As a result, a drag force45(that is to say, a drag action) is exerted on the plain bearing bush10, with the result that the plain bearing bush10follows the rotational movement25of the rotating component42more closely. The plain bearing bush rotational speed18which results in this way is lower than a rotational speed21of the rotating component42. An internal lubricating gap52is formed between the stationary component44and the plain bearing bush10, which internal lubricating gap52has a lubricating gap height51in a manner which is dependent on the plain bearing bush rotational speed21. The plain bearing bush10is provided with exchange bores20, as shown inFIG.3orFIG.4, with the result that an increased drag force45is exerted in the external lubricating gap54on the plain bearing bush10in proper operation of the plain bearing40. As a consequence of this, the lubricating film height51is increased at the external lubricating gap54and/or at the internal lubricating gap52. The higher the lubricating gap height51at the internal lubricating gap52and/or at the external lubricating gap54, the higher a load-bearing capability56of the plain bearing40. The load-bearing capability56is a measure of what radial loads58in terms of magnitude can load the plain bearing40in proper use. The load-bearing capability56of the plain bearing40is increased by way of the claimed plain bearing bush10which is configured as a floating bush53. The same effect as in the case of the external lubricating gap54can also be achieved in the case of the internal lubricating gap52if the flow direction of the lubricant30is temporarily reversed. Furthermore, the plain bearing bush10is modeled in a computer program product80which is configured to simulate the operating behavior of the plain bearing bush10in operation of the plain bearing40.

FIG.6shows a sectioned oblique view of one exemplary embodiment of the claimed wind power plant60which comprises a nacelle61, to which a multiple-blade rotor62is attached rotatably. A drive train66of the wind power plant60is received in the nacelle61, which drive train66comprises a main shaft63which is connected in a torque-transmitting manner to the multiple-blade rotor62. The drive train66also comprises a generator64which is connected via a transmission65in a torque-transmitting manner to the main shaft63. Here, the transmission65is configured as a planetary transmission50in accordance with one of the above-described embodiments.

One embodiment of the claimed industrial application70is shown diagrammatically inFIG.7. The industrial application70comprises an output unit72which can be configured, for example, as an electric motor, a wind power plant, an internal combustion engine or a hydraulic motor. The drive power (that is to say, a rotational movement25) is provided by way of the drive unit72, which drive power is fed to a transmission75. The drive power is fed to an output unit74with conversion of the present rotational speed and the present torque. The output unit84can be configured, for example, as a mechanical application, with the result that the industrial application70is configured as a mill, a vertical mill, a sugar mill, a cement mill, a rock crusher, a conveyor belt, a pump, a roller press, a flat conveyor, a tube mill, a rotary kiln, a slewing gear, a stirring unit, a stirred comminutor, a lifting apparatus, a garbage compactor or a car crusher. According to the invention, the transmission75, via which the drive unit72is connected to the output unit74, is configured as a planetary transmission50in accordance with one of the embodiments outlined above. Accordingly, the transmission75is provided with at least one plain bearing40in accordance with one of the embodiments shown above, and has a plain bearing bush10in accordance with at least one of the above-described embodiments.