Moment compensation for a flexible planetary bolt

Abstract

Gearbox for a wind turbine with at least one planetary stage comprising a ring gear, a sun gear, a planet carrier (101) and at least one planet gear; wherein the planet carrier (101) has at least one cheek (101a), at least one pin (105) and at least one socket (107); wherein a first axial end of the pin (105) is fixed in the cheek (101a); wherein at least a part of the pin (105) projects into the bushing (107); wherein a second axial end of the pin (105) is fixed in the bushing (107); wherein the planet gear is rotatable on the bushing (107) and wherein a toothing of the planet gear meshes with a toothing of the ring gear and a toothing of the sun gear; characterized in that the planet gear has helical teeth; wherein a toothing of the planetary gear is oriented such that M F ax and M F rad,net are directed in opposite directions; whereby M F axa torque acting on the bushing (107) which is caused by an axial force that arises during the operation of the wind turbine in the engagement of the teeth of the ring gear and the planet gear, and an axial force that arises during the operation of the wind turbine in the engagement of the teeth of the sun gear and the planet gear; and wherein M F rad,net a torque acting on the bushing (107) is defined as a radial force that arises during the operation of the wind turbine in the engagement of the teeth of the ring gear and the planet gear, and a radial force that arises during the operation of the wind turbine in the engagement of the teeth of the sun gear and the planet gear.

Description

[0001] The invention relates to a transmission according to the preamble of claim 1.

[0002] Planetary gears with so-called flexpins are known from the prior art. Flexpins are described, for example, in German patent application DE 1 500 451 A1. A flexpin is a flexible planetary pin. It consists of a pin and a bushing. The pin is fixed in a web of a planet carrier and projects into the bushing. The bushing is fixed to the pin in such a way that one axial end of the bushing is free-floating. The resulting deformability achieves a more balanced load distribution in the gear teeth of the planetary stage.

[0003] In helical gearing, forces act in the axial direction. Therefore, in a helical planetary gear stage, a tilting moment acts on the planets, the direction of which is radial, meaning orthogonal to the axis of rotation of the respective planet gear. With a flexpin, this tilting moment would lead to misalignment of the planet gears. For this reason, flexpins have so far only been used in spur gear planetary gear stages. However, spur gearing leads to increased noise emissions.

[0004] The invention is based on the objective of eliminating the disadvantages inherent in solutions known from the prior art. In particular, load balancing in a planetary stage is to be achieved without increasing noise emissions.

[0005] This problem is solved by a transmission according to claim 1 and a method according to the independent method claim. Preferred embodiments are contained in dependent claim 2 and result from Fig. 1.

[0006] The gearbox according to the invention is a gearbox for a wind turbine. The gearbox has at least one planetary gear stage. A planetary gear stage is a gear stage with a ring gear, a sun gear, a planet carrier, and at least one planet gear. The planet gear is rotatably mounted in the planet carrier and meshes with the ring gear and the sun gear. Exactly two of the three components—ring gear, planet carrier, and sun gear—are rotatably mounted; the third component is fixed against rotation relative to a gearbox housing. In particular, the ring gear can be fixed against rotation in the gearbox housing, while the planet carrier and the sun gear are rotatably mounted.

[0007] The planet carrier has at least one cheek. A cheek is a support structure in which planetary bolts are fixed. A rotatable planet carrier is usually mounted so that its cheek can rotate within a rotationally fixed structure, such as the gearbox housing.

[0008] The planetary bolts of the planet carrier according to the invention are each formed by a pin and a bushing. Accordingly, the planet carrier has at least one pin and at least one bushing.

[0009] A bushing is a rotationally symmetric body with at least one cavity. The cavity and the body are rotationally symmetric about a common axis. Furthermore, the first cavity is open, i.e., it has exactly one opening. The opening is rotationally symmetric about the same axis. In particular, at least part of the bushing can have the shape of a hollow cylinder.

[0010] The bushing and the pin together form a flexpin. The bushing serves to hold at least one planetary gear. The planetary gear is rotatably mounted in the bushing. One axis of rotation of the planetary gear corresponds to the axis of symmetry of the bushing.

[0011] The bushing either forms an inner ring of a bearing, with which the planetary gear is mounted in the bushing, or a bearing seat on which an inner ring of the bearing can be fixed. Accordingly, part of the surface of the bushing preferably has the shape of a lateral surface of a right circular cylinder.

[0012] Preferably, in addition to the bushing, the pin is also rotationally symmetrical to the axis of rotation of the planetary gear.

[0013] The journal has two axial ends – a first end and a second end. In total, the journal consists of three parts: the first end, the second end, and an intermediate piece. The first and second ends are axially spaced apart. The intermediate piece connects the first and second ends. Specifically, the intermediate piece can be located between a first and a second plane that are radially oriented, meaning they are perpendicular to the axis of rotation of the planetary gear. The first end of the journal and the intermediate piece are located on opposite sides of the first plane. Similarly, the second end of the journal and the intermediate piece are located on opposite sides of the second plane.

[0014] The first end of the pin is fixed in the cheek. The fixing is preferably rigid, meaning that the first end of the pin is immovable relative to the first cheek. At least a portion of the pin projects into the bushing. This means that at least a portion of the pin projects through the opening into the first cavity of the bushing. This also means that at least a portion of the bushing encloses the pin. This same portion also forms at least a portion of the cavity of the bushing. The portion of the pin projecting into the bushing includes the second axial end of the pin. In particular, the second axial end of the pin is located within the cavity of the bushing.

[0015] The second end of the pin is fixed in the bushing. Preferably, the fixing is rigid, that is, such that the second axial end of the pin is immovable relative to the part of the bushing in which the second axial end is fixed.

[0016] A radial gap remains between the journal and the bushing. This gap extends completely around the axis of rotation of the planetary gear. It is a portion of the bushing cavity that is not filled by the journal. Preferably, the gap is rotationally symmetrical about the axis of rotation. This is equivalent to the fact that at least one part of the journal is axially centered in the bushing. Therefore, the central axis of at least one part of the journal and the central axis of the bushing are identical in the unloaded state.

[0017] Preferably, at least a part of the gap is arranged axially between the cheek of the planet carrier or the area of ​​the cheek in which the first axial end of the pin is fixed, and the area of ​​the bushing in which the second axial end of the pin is fixed.

[0018] The space is filled with a compliant medium. In particular, the medium can be a fluid, such as lubricant and / or air.

[0019] According to the invention, the planetary gear has helical teeth. This results in a reduction of noise emissions.

[0020] To prevent misalignment of the planet gear due to axial forces occurring in the gear teeth, the gear teeth are oriented such that M Fax and M Frad.net are directed in opposite directions. This means that the direction vectors of M Fax and M Frad,net They are directed in opposite directions. The direction vectors therefore run parallel to each other and have opposite signs.

[0021] According to H. Linke, "Spurge Gear Teeth - Calculation - Materials - Manufacturing" (Carl Hanser Verlag, 1996), the orientation of a tooth describes its helix direction. The helix direction is characterized by a sign of the helix angle of the tooth. In this case, the helix angle of the planetary gear teeth is chosen such that M Fax and M Frad,net are directed in opposite directions.

[0022] M Fax This refers to a torque acting on the bushing, caused by a first axial force and a second axial force. The first axial force arises during the operation of the wind turbine through the meshing of the ring gear and the planetary gear. During operation, the gearbox rotates in a direction that defines the orientation of the rotor blades. The gearbox then transmits torque from the rotor to a generator within the wind turbine.

[0023] The second axial force arises during the operation of the wind turbine in the engagement of the gears of the sun gear and the planet gear.

[0024] The first axial force and the second axial force are axially aligned with respect to the axis of rotation of the planetary gear, meaning they run parallel to the axis of rotation. A direction vector of the torque acting on the bushing is therefore radial with respect to the axis of rotation, meaning it is orthogonal to the axis of rotation.

[0025] M Frad,netThis refers to a torque acting on the bushing, caused by a first radial force and a second radial force. The first radial force arises during the operation of the wind turbine through the meshing of the ring gear and the planet gear. Similarly, the second radial force arises during the operation of the wind turbine through the meshing of the sun gear and the planet gear. Both the first and second radial forces are radial with respect to the axis of rotation of the planet gear, meaning they are perpendicular to the axis of rotation. Furthermore, the first and second radial forces are opposite to each other.

[0026] The invention requires that the first radial force and the second radial force are unequal in magnitude. This means they do not cancel each other out. The result is a non-zero radial force acting on the bushing. This force is spaced apart from the second axial end of the pin, which is fixed in the bushing. The bushing forms a lever that is supported at the second end of the pin. The resulting radial force thus generates the torque M. Frad,net caused.

[0027] Since M Fax and M Frad,net According to the invention, when directed in opposite directions, a torque acting on the planetary gear results that is smaller in magnitude than M. Fax and M Frad,net The smaller this torque, the smaller the misalignment of the planetary gear. Misalignment of the planetary gear is completely avoided if M Fax and M Frad,net are equal in amount.

[0028] The magnitude of the first radial force and the magnitude of the second radial force are a function of the tangential load and the pressure angle of the respective gear mesh. The pressure angles in the mesh of the planet gear and ring gear, and in the mesh of the planet gear and sun gear, can be suitably determined by a person skilled in the art using methods belonging to the prior art. If, for example, the sum of the profile shifts increases, the center distance decreases. Consequently, the pressure angle also decreases. Furthermore, the pressure angle can be changed by increasing or decreasing the number of teeth on the planet gear.

[0029] In a preferred further education course, the one with M is involved. Fax and M Frad,netThe torques referred to are those present when the gearbox is operated at its rated torque. The rated torque, in turn, is present when the wind turbine is itself operated at its rated torque.

[0030] The rated torque of the gearbox is the torque applied to a shaft of the gearbox, such as an input shaft, when the gearbox is operated as designed. The rated torque is therefore the torque for which the gearbox was designed.

[0031] A method according to the invention provides that the gearbox is operated with its rated torque.

[0032] A preferred embodiment of the invention is described in Fig. 1 shown. In detail: Fig. 1 a planet carrier with planet bolts.

[0033] The in Fig.The planet carrier 101 shown in Figure 1 has a first cheek 101a and a second cheek 101b. A planet bolt 103 is fixed with a first axial end in the first cheek 101a and with a second axial end in the second cheek 101b.

[0034] The planetary bolt 103 consists of a pin 105 and a bushing 107. The pin 105 is fixed in the first web 101a. A portion of the pin 105 with a second axial end projects into the bushing 107. This second axial end of the pin 105 is fixed in the bushing 107. The bushing 107, or rather a projection of the pin 105 formed by the sleeve 103, is fixed in the second web 101b.

[0035] The bushing 103 serves to receive and support at least one planet gear. The bushing either forms an inner ring of a bearing, with which the planet gear is supported on the bushing, or a bearing seat on which a bearing ring of the bearing can be fixed. Accordingly, one of the cylindrical surfaces of the bushing 103 has the shape of a cylindrical surface of a right circular cylinder. Both the bushing 103 and the journal 105 are rotationally symmetrical about an axis of rotation of the planet gear.

[0036] A gap 109 runs between the pin 105 and the bushing 107. The gap 109 is rotationally symmetrical to the axis of rotation of the planetary gear and is filled with air and / or lubricant.

[0037] Due to the gap 109, the planetary pin 103 is flexible. This allows the bushing 107 to tilt relative to the pin 105 about an axis radial to the axis of rotation of the planetary gear. This enables load equalization in the gear teeth of the planetary stage.

[0038] The planet gear meshes with a ring gear and a sun gear. The planet gear, ring gear, and sun gear have helical teeth. Therefore, an axial force F, i.e., a force parallel to the axis of rotation of the planet gear, occurs during the meshing of the planet gear and the ring gear. ax,PL,RG . A force F acting in the opposite direction to this ax,S,PL occurs in the gear mesh of the planetary gear and the sun gear. The forces F ax,PL,RG and F ax,S,PL cause a torque M acting on the bushing 107 Fax .

[0039] In the tooth mesh of the planetary gear and the ring gear, a force F directed radially with respect to the axis of rotation of the planetary gear also occurs.rad,PL,RG a corresponding, opposing force F rad,S,PL It occurs in the tooth mesh of the planetary gear and the sun gear.

[0040] Are the two forces F rad,PL,RG and F rad,S,PL Different in magnitude, this results in a radial force F acting on the bushing 107. rad,net Since the resulting radial force F rad,net When the pin 105 engages the bushing 107 at a connection point axially offset to the connection point between the pin 105 and the bushing 107, a torque M acts on the bushing 107. Frad,net .

[0041] The two torques M Fax and M Frad,net They are opposite in direction and therefore cancel each other out. The resulting torque is smaller in magnitude than M. Fax and smaller than M Frad,net Reference sign 101 Planetary Carriers 101a first cheek 101b second cheek 103 planetary bolts 105 cones 107 socket 109 space

Claims

[1] Gearbox for a wind turbine with at least one planetary stage comprising a ring gear, a sun gear, a planet carrier (101) and at least one planet gear; wherein the planet carrier (101) has at least one cheek (101a), at least one pin (105) and at least one socket (107); wherein a first axial end of the pin (105) is fixed in the cheek (101a); wherein at least a part of the pin (105) projects into the bushing (107); wherein a second axial end of the pin (105) is fixed in the bushing (107); wherein the planet gear is rotatable on the bushing (107) and wherein a toothing of the planet gear meshes with a toothing of the ring gear and a toothing of the sun gear; characterized by that the planetary gear has helical teeth; wherein a toothing of the planetary gear is oriented such that M Fax and M Frad,net are directed in opposite directions; whereby M Faxa torque acting on the bushing (107) which is caused by an axial force that arises during the operation of the wind turbine in the engagement of the teeth of the ring gear and the planet gear, and an axial force that arises during the operation of the wind turbine in the engagement of the teeth of the sun gear and the planet gear; and wherein M Frad,net a torque acting on the bushing (107) is defined as a radial force that arises during the operation of the wind turbine in the engagement of the teeth of the ring gear and the planet gear, and a radial force that arises during the operation of the wind turbine in the engagement of the teeth of the sun gear and the planet gear. [2] Gearbox according to the preceding claim; characterized by that those with M Fax and M Frad.net The torques referred to are torques that occur when the gearbox is operated with a rated torque. [3] Method for operating a gearbox according to the preceding claim; characterized by that the gearbox is operated with the rated torque.

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