EP4288681A1

EP4288681A1 - Sound-proofed planetary gearbox, and wind turbine comprising such a gearbox

Info

Publication number: EP4288681A1
Application number: EP22708308.6A
Authority: EP
Inventors: Franz Mitsch
Original assignee: FM Energie GmbH and Co KG
Current assignee: FM Energie GmbH and Co KG
Priority date: 2021-02-08
Filing date: 2022-02-04
Publication date: 2023-12-13
Also published as: WO2022167155A1

Abstract

The invention relates to a planetary gearbox for higher gear ratios which can be used in machines and plants, in particular wind turbines, in which high torques and powers have to be transmitted. More particularly, the invention relates to such a planetary gearbox which, owing to a special novel design, is particularly sound-proofed with respect to sound events, in particular radially and torsionally directed sound events, which occur frequently during operation of the machine or plant.

Description

SOUND-COUPLED PLANETARY GEAR AND WIND TURBINE WITH SUCH GEAR

The invention relates to a planetary gear for higher gear ratios, which can be used in machines and systems, in particular wind turbines, in which high torques and power levels have to be transmitted. The invention relates in particular to such a planetary gear which, thanks to a special new design, is particularly sound-decoupled with regard to particularly radially and torsional sound events that frequently occur during operation of the machine or system.

Planetary gears are very often used in mechanical engineering to achieve higher translations. A planetary gear consists of four main components, namely the sun gear, planetary gears, ring gear and planetary gear carrier. The wheels can be moved differently. In the case of the epicyclic transmission, the sun gear and the planetary gears are the rotating gear members; the planet ring gear, on the other hand, stands still and is installed in a fixed position between the input-side and output-side planet carrier. In this design, the planet carriers are in orbit around the sun. With such an epicyclic gear, higher gear ratios can be achieved than with the standard gear and that is why the gears of large systems, in particular wind power plants, are constructed in this way.

The conventional planetary gears for wind turbines have no or only the usual damping devices, so that all of the loads mentioned must be absorbed and borne by the individual parts of the wheels, bearings and gears. It is now also possible to dampen the bearings of the individual moving wheels using elastic bushings (WO 2015/055291).

However, one main problem has remained and has increased due to the use of ever larger wind turbines with ever higher torques to be transmitted, especially when several gear/planetary stages have to be used. And that is the noise development that occurs amplified by a large planetary gear, as is commonly used in wind turbines.

Every gear generates structure-borne noise when the gear teeth roll off. This is transferred from the planets to the planet ring gear. As a rule, the planet ring gear in wind turbines is fixed and installed between the housing halves. The structure-borne noise generated by the gearing is thus transmitted to the gear housing. The gearbox housing as such is fixed, or also soundproofed, connected to the machine frame and thus also to the tower. The structure-borne noise insulation between the gearbox and the machine carrier must transmit the large torques while at the same time decoupling the noise. It has been shown that noise directed primarily radially or torsionally to the rotor/gearbox shaft, especially in the 2nd gear stage, frequently leads to problems and complaints. These undesired sound events occur particularly in the frequency range between 150 and 250 Hertz and are difficult to control with the usual means.

The task was therefore to modify conventional planetary gears in such a way that they have improved sound decoupling with regard to radial or torsional vibrations in the audible frequency range, in particular between 100 and 300 Hz.

This object was achieved by the planetary gear described below and characterized in the claims.

The object of the invention is therefore a sound-decoupled planetary gear for avoiding or reducing radially and/or torsional sound events. It comprises an outer transmission flange on the input side in the axial direction, an outer transmission flange on the output side and a fixed ring gear arranged in between, wherein according to the invention

(i) a separate middle, cylindrical gear part is positioned between the two gear flanges, in which the fixed ring gear finds space, said two outer gear parts and the middle gear part being firmly connected to one another with the aid of fastening means (2),

(ii) said ring gear is positioned with its entire frontal periphery out of contact with the inner surface of the surrounding central cylindrical gear portion through a gap, and

(iii) elastic annular components are provided, which are arranged on both sides of the fixed ring gear and are clamped or connected via their elastic part to the two side surfaces of the ring gear on the one hand and to the respective adjacent outer gear flange components on the other.

The task of the gap and the annular elastic components is to separate the planetary ring gear in terms of structure-borne noise from the input-side and output-side transmission housings. The two transmission housings are no longer, as mentioned, usually connected to one another via the planetary ring gear, but by an additional central cylindrical ring that forms an outer tube for the planetary ring gear. According to the invention, the inner diameter of this cylindrical ring, which acts as an outer tube, is selected to be larger than the outer diameter of the planetary ring gear. so that the resulting gap cannot come into contact between the outer tube or the other planet carrier parts connected to it and the ring gear.

In order to ensure the function described, both ring-shaped elastic components attached to the left and right of the ring gear essentially consist of a ring-shaped outer sheet, a ring-shaped inner sheet and an elastic layer arranged between the said sheets, with the ring-shaped outer sheet being attached to the respective adjacent transmission flange and the ring-shaped Inner sheet of the respective adjacent side surface of the ring gear facing. The diameter of the ring-shaped outer sheet is larger than the diameter of the ring-shaped inner sheet and thus has a protruding area which is not provided with the elastic layer but with bores and serves to be connected to the respective outer transmission flange. The elastomer layer is attached between the two sheets in the area of the inner sheet. Said annular elastic components are connected to the relevant side surfaces of the ring gear by means of fastening means, for example screw connections, in each case on or on their annular inner sheets. In this construction according to the invention, the ring gear of the planet is held in place by its ring-shaped side surfaces with that part of the adjacent ring-shaped components which have the elastic layers, and is therefore not directly connected to the transmission flanges, as has been usual in the prior art , or.

Connected planet carrier parts. In this way, sound transmission radially outwards or torsional can be largely avoided, and only axial sound can be transmitted to a certain extent.

The elastic ring-shaped components can be composed of two or more ring segments, which is significantly more advantageous with regard to the production of such components. In the case of large wind turbines with correspondingly large ring gears with a diameter of up to 250 cm, the ring with the elastic layers can consist of, for example, 10, 15 or 20 individual segments.

However, another problem that arises from the assembly of the components must be avoided here, namely the impermeability to liquids, in particular oils, inside the transmission. For this it is necessary that the two or more circular segments of the ring-shaped components have suitable sealing means. For convenience, these sealing means may be embossments or formations, such as ridges or lips, of the elastomeric layer at all or some of the joints. With axial tension of the ring segments or with torsional shear forces, these for a seal. It is also important that the side surfaces (39) of the individual ring segments, which are common contact surfaces when they are assembled, are level with one another so that the sealing means are effective. Likewise, after the individual ring segments have been joined, the ring surface should be as planar as possible. The elastomers suitable for the annular elastic components are known in principle in the prior art. In the simplest case, natural rubber or rubbers derived from it can be used. However, the usual modern plastics, such as polyurethanes, are also very suitable because of their higher strength. In the case of higher torques, the elastic elements are exposed to relatively high shearing forces, so that sufficient strength of the elastomer layer of the elements must be ensured. The elastomers should also be resistant to the fluids or oils in the transmission. This also applies in particular to the seals between the individual circular segment ducks of the elastic ring-shaped components on both sides of the ring gear. If the plastics used are sufficiently strong but not resistant to organic oils, oil-resistant seals can also be used.

The planetary gears according to the invention can preferably be used as a second planetary/gear stage to reduce radially and/or torsional structure-borne noise, particularly in the range between 150 and 250 Hz, and are therefore ideally suited for installation in wind turbines. In principle, the planetary gears according to the invention can also be used for the first planetary stage, in which higher torques usually occur.

The subject matter of the invention is therefore also a wind power plant comprising a tower, nacelle, rotor, gearbox and generator, in which the gearbox is a planetary gearbox as described and characterized.

The invention is described in more detail below with reference to the illustrations.

Fig. 1 shows in cross section (a) and in side view (b)(c) a planetary gear with fixed ring gear and planet carrier parts according to the prior art. The other gears and parts of a planetary gear are omitted.

The ring gear (4) consists of the actual gear rim (4.1) and the ring-shaped rim (4.2). This edge is firmly connected to both the input-side gear flange (1) and the output-side gear flange (8) via the screw connections (2), so that any radially directed sound from the ring gear of the ring gear is directed outwards directly into the flange parts. Fig. 2 shows a perspective exploded graphic of a planetary gear according to the invention without inner components, such as sun gear and planetary gears in half view. The object depicted in this way comprises a first outer transmission flange (1) which has a large number of axial bores (1.1) on its outer circumference. Already shown are bolts (2) which are inserted through the holes (1.1) and are so long that they can be passed through all other components.

A first ring-shaped component (3) follows, which is essential to the invention. In this specific case, this component consists of a large number of circle segments (3.5), which are tightly joined together. In the case shown, the complete ring element (3) would be made up of 15 circle segments (3.5). The ring element (3) or each individual circle segment (3.5) consists of an outer sheet (33) and an inner sheet (32). The outer plate faces the transmission component (1), and the inner plate is arranged opposite the ring gear (4) following in the row of the exploded diagram. An elastic layer (31) with a layer thickness (34) of 10-20 mm is provided between the outer and inner sheet metal. The outer sheet (33) has a larger outer diameter than the inner sheet (32). The ring-shaped elastomer layer between the outer and inner sheet metal is completely covered by the inner sheet metal (32), ie it has the same outer diameter. The outer sheet (33) of the ring-shaped component (3), or each individual segment thereof, has a projection (33') on the outer circumference, in which a large number of bores (3.1) are provided, which are arranged in number and alignment correspond to the number and arrangement of the bores (1.1) in the gearbox flange (1). The screw bolts (2) are guided through these holes after assembly. The ring element (3) has additional bores for accommodating screws. The bores have a larger diameter in the area of the sheet metal (33) and in the elastomer layer in order to be able to accommodate the screw head together with the required screw tightening tool. The holes in the plates (32) have the diameter of the screw shank. (4.1) there are appropriate threaded holes to fasten the ring elements (3) to the ring gear (4) with the screws (6).

Components (5) and (4) follow. The central cylindrical or ring-shaped gear part (5) is at least as wide as the ring gear (4) with the gear rim (4.5) inserted underneath. The ring-shaped gear part (5) is preferably wider than the ring gear. The difference between the width of the component (5) and the ring gear (4) therefore results in the preload of the elastomer elements (3) and (3').

The component (5) also has a large number of bores (5.1), which correspond in number and orientation to the number and arrangement of the bores (1.1) and (3.1) in the transmission flange (1) and in the component (3). The ring gear (4) has an outer diameter which is smaller than the inner diameter of the component (5) arranged above it. The diameters are selected in such a way that a gap with a gap thickness of 5 - 15 mm is formed. Thus, the inner surface (5.3) of the middle ring (5) has no contact whatsoever with the outer surface (4.3) of the ring gear (4). The ring gear (4) has threaded bores (4.1) on both sides in order to connect the components (3)(4)(3') to one another via the elastic elements (31 (34). In addition to the threaded bores, it is possible to improve power transmission also provide additional pins to transmit the shear forces.

The component (3') on the rear side of the ring gear (4) or the outer ring (5) corresponds essentially to the ring element (3) on the front side of the ring gear (4)/outer ring (5). This still has screw connections (6) here, which are required in order to connect the components (3')(4) and (3) to one another via the elastic layers (31).

Finally, the rear outer transmission component (8) is shown, which has bores (8.1) arranged on the outer circumference in order to be connected and clamped to the components (1)(3)(5) and (3') by the screw bolts (2). will.

2 also shows an enlarged section of the elastic ring-shaped component (3) in the area of two colliding circle or ring segments (3.5)(3.5'). Appropriate arrangement and shaping as a sealing bead (36)(37(38) causes parts of the elastomer layer (31) to provide an adequate seal after they have been joined together.

Fig. 3 shows individual sections of the planetary gear according to the invention. In particular, an enlarged perspective detail section in the area of the ring gear (4), the ring-shaped gear part (5), the lateral elastic parts (3)(3') and the gear flanges (1)(8). The explanations under Fig. 2 are to be applied.

Fig. 4 shows individual representations of the elastic ring elements (3) (3 ') according to the invention or their circle segments (3.5), from which they are composed.

(а) and (b) show in the middle a single circle segment (3.5) of the ring-shaped component (3) according to the invention with 5 bores (3.1) and 3 bores (3.2) with screw connections

(B). Left and right side views of parts (3) and (3') are shown. The individual segments (3.5) touch with their flat surfaces (39): sealing means in the form of appropriately dimensioned sealing beads (36)(37)(38) are provided at the bottom and at the corners of the individual segments (3.5).

(c) shows an enlarged section of a corner area of a circular segment of the annular elastic gear part (3) or (3') according to the invention. In summary, the following can be stated:

An elastic ring element (3) or (3') according to the invention is a sandwich element consisting of an elastomer (31) and two flat discs (32) and (33)(33'), as already described above. The task of these elements is to separate the planet ring gear (4) from the transmission housings (1) and (8) in terms of structure-borne noise. According to the invention, the two gear housings are no longer connected to one another via the planetary ring gear, but by an additional ring, the planetary outer tube (5). Since the inner diameter of the outer tube is larger than the outer diameter of the planetary hollow tube, a gap (9) is created which prevents sound transmission. The said sandwich rings (3) and (3'), which can be composed of a large number of ring segments (3.5)(3.5') for manufacturing reasons, are inserted in the axial direction in front of and behind the planetary ring gear and inserted between the planetary ring gear and respective transmission housing (1) (8) jammed. Basically, the rings (3)(3') or the elastomer circle segments (3.5) are axially prestressed to such an extent that the torsional torques that occur are transmitted as thrust via the circle segments. The power transmission required for the torque between the elastic rings (3)(3') or their circular segments and the ring gear (4) or the gear housing (1)(8) takes place as required by friction. At the same time, the elastomer circular segments (3.5) are drilled through bores (3.1) in the circumference (33') of the outer sheet (33) that protrudes beyond the diameter of the elastomer and bores (5.1) in the planetary outer tube (5) as well as bores (1.1) and (8.1) in the two housing halves (1) (8) with the axially arranged bolts (2). The circular segments (3.5) of the elastic rings (3) (3') contain additional, usually circular, recesses or bores (3.2) for receiving one or more fastening screws (6), whereby the inner plate (32) with the planet Ring gear (4) is connected axially. In this way, the torsional moment is safely transmitted via frictional locking due to the preload of the elastomer elements and at the same time by the screw connection. The planet ring gear is thus completely decoupled from the gearbox housing.

In the planetary stage, when the planets mesh in the ring gear, vibrations are mainly generated in the radial direction and especially in the circumferential direction. While the elastomer elements have a high degree of rigidity in the axial direction, they are relatively flexible in the thrust direction, i.e. in the radial direction and in the torsional direction, which means good insulation of the structure-borne noise that occurs. The ratio between axial stiffness and shear stiffness is approximately 100:1.

Claims

Patent Claims:

1 . Sound-decoupled planetary gear with a fixed ring gear for avoiding or reducing radially and/or torsional noise events, comprising in the axial direction a drive-side gear flange (1), an output-side gear flange (8) and a fixed ring gear (4) in between, characterized in that

(I) between the gear flanges (1) (8) a separate middle, cylindrical gear part (5) is positioned, in which the fixed ring gear (4) takes place, said three components (1) (5) (8) with are firmly connected to one another with the aid of fastening means (2),

(ii) the fixed ring gear (4) is arranged with its entire end circumference (4.3) without contact with the inner surface (5.3) of the surrounding central cylindrical gear part (5) through a free gap (9), and

(iii) elastic ring-shaped components (3)(3') are provided, which are arranged on both sides of the fixed ring gear (4) and on the one hand with its side surfaces (4.2) and on the other hand with the respective adjacent transmission flange components (1)(8) are connected.

2. Sound-decoupled planetary gear according to claim 1, characterized in that the two ring-shaped components (3) (3') essentially each consist of a ring-shaped outer sheet (33), a ring-shaped inner sheet (32) and an elastic layer ( 31)(34), with the annular outer sheet (33) facing the respective transmission flange (1)(8) and the annular inner sheet (32) facing the respective side (4.2) of the ring gear (4), and the annular outer sheet (33 ) is larger in outer diameter than the annular inner sheet (32) and thus has a protruding area (33') which is not provided with the elastic layer (31) (34).

3. Sound-decoupled planetary gear according to claim 2, characterized in that the two ring-shaped components (3) (3') are connected to the side surfaces (4.2) of the ring gear (4) by means of fastening means (6) in each case on or on their ring-shaped inner sheets (32). are connected, whereby the elastic layers (31) (34) of the components (3) (3 ') between the gear flange in question (1) or (8) and the central cylindrical gear part (5) are connected.

8th Sound-decoupled planetary gear according to Claim 3, characterized in that the fastening means (6) are guided through corresponding bores (3.2) (3.2') and (4.1) in the components (3)(4)(3'). Sound-decoupled planetary gear according to one of claims 1 - 4, characterized in that the fastening means (2) through corresponding bores (1.1) (3.1) (5.1) (3.1 ') and (8.1) in the components (1) (3) (5 )(3') and (8) are guided. Sound-decoupled planetary gear according to one of Claims 1 - 5, characterized in that the two ring-shaped components (3) (3') consist of two or more ring segments (3.5) (3.5'). Sound-decoupled planetary gear according to Claim 6, characterized in that the two or more circular segments (3.5)(3.5') of the annular components (3)(3') are joined and connected to one another in such a way that the connection points are sealed by suitable seals, in particular shaped Expressions of the elastomeric layer in these areas (36) (37) (38) are sufficiently impervious to liquids, including oils. Sound-decoupled planetary gear according to Claim 7, characterized in that the circular segments (3.5)(3.5') have flat side faces (39) and, when joined together, form a flat annular surface. Sound-decoupled planetary gear according to one of Claims 1 - 8, characterized in that the elastic annular components (3) (3') have an elastomer which has a sufficiently high resistance to shearing forces which occur during operation at high torques. Wind power plant comprising tower, nacelle, rotor, gearbox and generator, characterized in that the gearbox is a planetary gearbox according to one of Claims 1 - 9. Use of a planetary gear according to one of Claims 1 - 9 as the first and second planetary/gear stage. Use of a planetary gear according to claim 11 as a second planetary/gear stage for reducing radially and/or torsional structure-borne noise, in particular in the range between 150 and 250 Hz.

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