Patent Application
20100329868
The present invention relates to a gear unit for wind turbines. More particularly, the present invention relates to a planetary gear transmission unit with a planet shaft locking mechanism, to a gearbox comprising such a planetary gear transmission unit and to a wind turbine comprising such a gearbox.
Gearboxes for wind turbines may comprise at least one planetary gear transmission unit comprising a planet carrier, planet gears, a sun gear and a ring gear.
It is an object of the present invention to provide a planetary gear transmission unit which does not show one or more of the above described disadvantages and possible other disadvantages.
It is also an object of the present invention to provide a planetary gear transmission unit with a planet shaft locking mechanism, to a gearbox comprising such a planetary gear transmission unit and to a wind turbine comprising such a gearbox.
In a first aspect, the present invention provides a planetary gear transmission unit in which planet gears on a planet carrier are mounted between a sun gear and a ring gear for mutual interaction, wherein the planet carrier is provided with planet shafts distributed uniformly around the planet carrier's axis, each planet shaft supporting in a rotatable manner a pair of planet gears by means of planet bearings. The planetary gear transmission unit comprises a planet shaft locking mechanism between at least one planet shaft and the planet carrier for preventing the at least one planet shaft from rotating around its own axis with respect to the planet carrier, the planet shaft locking mechanism being provided in a direction substantially parallel to the planet shaft between an axial end face of the planet shaft and the planet carrier.
According to embodiments of the invention a planetary gear transmission unit having a planet shaft locking mechanism will prevent the at least one planet shaft from rotating around its own axis with respect to the planet carrier without restricting other movements of the planet shaft with respect to the planet carrier. Hence, a planetary gear transmission unit according to embodiments of the invention prevents the at least one planet shaft from rotating around its own axis without further restriction of the degrees of freedom of the planet shaft compared to a similar assembly of the planet shaft without such locking mechanism for preventing rotation.
An advantage of a planetary gear transmission unit according to embodiments of the invention is that, because rotation of a planet shaft around its own axis with respect to the planet carrier is prevented, the chance to cause damage related to such a rotation during operation of the planetary gear transmission unit is reduced. As a consequence, lifetime of the planetary gear transmission unit according to embodiments of the invention may be increased.
Hence, the invention results in a free of wear contact between planet shaft and planet carrier as far as a rotation of the planet shaft around its axis with respect to the planet carrier is concerned, thereby allowing any other possible movement of the planet shaft with respect to the planet carrier for example in order to have still a maximum degree of freedom of the planet shaft with respect to the planet carrier for other movements and without disturbing the load distribution between the planet gears of a pair on one planet shaft.
According to embodiments of the invention, a planet shaft locking mechanism may be provided to each of the planet shafts such that each planet shaft of the planet carrier is prevented from rotating around its own axis with respect to the planet carrier, whereas other movements of the planet shaft with respect to the planet carrier are not hindered considerably.
According to an embodiment of a planetary gear transmission unit in accordance with the invention, the planet shaft locking mechanism may comprise a gear coupling, which may also be referred to as a barrel gear coupling.
The gear coupling may comprise:
The first and second gear coupling parts may also be referred to as hubs.
According to another embodiment of a planetary gear transmission unit in accordance with the invention, the first and second gear coupling parts may be hubs with external gear teeth. In that case, the intermediate part may comprise two sets of internal gear teeth complementary to the aforementioned external gear teeth on the coupling parts. According to other embodiments of a planetary gear transmission unit in accordance with the invention, the first and second gear coupling parts may be hubs with internal gear teeth. In that case, instead, the intermediate part may be a shaft with external complementary gear teeth which may be used for connecting the first and second gear coupling parts.
According to embodiments of the invention, the first and second gear coupling part have internal gear teeth and the intermediate part is a sleeve having complementary internal gearing. According these embodiments, the sleeve is slid over the first and second gear coupling parts.
The intermediate part may be positioned between the axial end face of a planet shaft and the planet carrier and has a length L′ corresponding to a distance L″ between the planet shaft end face and the planet carrier.
The intermediate part may be in slidable connection with the first and second coupling parts.
According to embodiments of a planetary gear transmission unit in accordance with the invention, the gear coupling may furthermore comprise a fail safe mechanism, which may also be referred to as a so-called weakest link.
The fail safe mechanism may, according to embodiments of the invention, be a torque limiting pin.
The gear coupling may furthermore comprise a lubrication mechanism.
According to another embodiment of a planetary gear transmission unit in accordance with the invention, the planet shaft locking mechanism may comprise a double pin coupling.
The double pin coupling may comprise three parts, a first connecting part for connecting the double pin coupling to the planet carrier, a second connecting part for connecting the double pin coupling to the planet shaft and an intermediate part in between the first and second connecting part.
The double pin coupling may, according to embodiments of the invention, furthermore comprise a hollow pin for connecting the second connecting part to the intermediate part.
According to still further embodiments in accordance with the invention, the double pin coupling may furthermore comprise a spring in the second connecting part. This spring is for preventing movement of the intermediate part between the first connecting part and the second connecting part during operation of the planetary gear transmission unit.
In a further aspect of the invention, a gearbox is provided comprising at least one planetary gear transmission unit according to embodiments of the present invention.
In still a further aspect of the invention, a wind turbine is provided comprising a gearbox comprising at least one planetary gear transmission unit according to embodiments of the present invention.
The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.
It has to be noted that same reference signs in the different figures refer to same, similar or analogous elements.
a and
In the description different embodiments will be used to describe the invention. Therefore reference will be made to different drawings. It has to be understood that these drawings are intended to be non-limiting, the invention is only limited by the claims. The drawings are thus for illustrative purposes, the size of some of the elements in the drawings may be exaggerated for clarity purposes.
The term “comprising” is not to be interpreted as limiting the invention in any way. The term “comprising”, used in the claims, is not intended to be restricted to what means is described thereafter; it does not exclude other elements, parts or steps.
The term “connected” as used in the claims and in the description has not to be interpreted as being restricted to direct connections, unless otherwise specified. Thus, part A being connected to part B is not limited to part A being in direct contact to part B, but also includes indirect contact between part A and part B, in other words also includes the case where intermediate parts are present in between part A and part B. Not all embodiments of the invention comprise all features of the invention. In the following description and claims, any of the claimed embodiments can be used in any combination.
The present invention will be described by means of different embodiments. It has to be understood that these embodiments are only for the ease of understanding the invention and are not intended to limit the invention in any way.
The present invention provides a planetary type gear transmission unit, a gearbox comprising such a planetary type gear transmission unit and a wind turbine comprising such a gearbox.
In one aspect, the present invention provides such a planetary gear transmission unit in which planet gears on a planet carrier are mounted between a sun gear and a ring gear for mutual interaction, wherein the planet carrier is provided with planet shafts distributed uniformly around the planet carrier's axis, each planet shaft supporting in a rotatable manner a pair of planet gears by means of planet bearings. The planetary gear transmission unit comprises a planet shaft locking mechanism between at least one planet shaft and the planet carrier for preventing the at least one planet shaft from rotating around its own axis with respect to the planet carrier, the planet shaft locking mechanism being provided in a direction substantially parallel to the planet shaft between an axial end face of the planet shaft and the planet carrier.
On the one hand, the planet shaft locking mechanism should be flexible in a way that it allows required movement between the planet shaft and the planet carrier. On the other hand, the planet shaft locking mechanism should be stiff in a way that it prevents rotation of the planet shaft around a planet shaft axis in reference to the planet carrier. As a result, when the planetary gear transmission unit according to embodiments of the invention is in operation, tension or stress created by a load in the planet carrier near the planet shaft locking mechanism can be kept low.
In other words, the planet shaft locking mechanism according to embodiments of the present invention will prevent a planet shaft from rotating around its own axis with respect to the planet carrier without restricting other movements of the planet shaft with respect to the planet carrier in order to avoid further restriction of the degrees of freedom of the planet shaft compared to a similar assembly of the planet shaft without such locking mechanism for preventing such rotation.
An advantage of a planetary gear transmission unit according to embodiments of the invention is that, since a rotation of a planet shaft, or, in extension, of all the planet shafts is prevented by the planet shaft locking mechanism, the chance that damage to a planet shaft is caused during operation of the planetary gear transmission unit is reduced. As a consequence, the lifetime of the planetary gear transmission unit may be increased.
Hence, the invention results in a free of wear contact between planet shaft and planet carrier as far as a rotation of the planet shaft around its axis with respect to the planet carrier is concerned, thereby possibly allowing any other possible movement of the planet shaft with respect to the planet carrier for example in order to have still a maximum degree of freedom of the planet shaft with respect to the planet carrier for other movements and without disturbing the load distribution between the planet gears of a pair on one planet shaft.
According to embodiments of the invention, the planet shaft locking mechanism may, for example, be any non-switchable coupling, such as a gear coupling, a double pin coupling, a cross slot coupling, a jaw coupling or a metal disc coupling. However the invention is not limited to embodiments of planetary gear transmission units having such non-switchable couplings.
Although non-switchable couplings are known and designed for transferring rotational energy between two shafts or between a shaft and a rotational component, e.g. a gear, it is not straightforward to choose a suitable non-switchable coupling for application in a planetary gear transmission unit for the above described purpose.
Indeed, according to the present invention, the planet shaft locking mechanism has to be suitable for transferring torque. It was surprisingly found that the non-switchable couplings as described above are suitable for being used for the purpose of the invention.
According to a first embodiment of the invention, the planet shaft locking mechanism may comprise a gear coupling which may also be referred to as barrel gear coupling.
According to embodiments of the present embodiment the planetary gear transmission unit 20 furthermore comprises a planet shaft locking mechanism 18 in the form of a gear coupling, which may also be referred to as barrel gear coupling, the planet shaft locking mechanism 18 preventing the rotation of a planet shaft 13 around its own axis with respect to the planet carrier 14. The planet shaft locking mechanism 18 is provided in between the planet shaft 13 and the planet carrier 14 (see
The gear coupling 18, which is schematically illustrated in detail in
When mounted in the planetary gear transmission unit 20 between the planet shaft 13 and the planet carrier 14 the gear coupling 18 is positioned such that the first gear coupling part 19 is closest to a rotor side of the planetary gear transmission unit 20 and the second gear coupling part 21 is closest to a generator side of the planetary gear transmission unit 20. With rotor side and generator side is respectively meant the side of the planetary gear transmission unit 20 to which the rotor is attached and the side of the planetary gear transmission unit 20 to which the generator is attached, in
The first and second gear coupling parts 19, 21 are prevented from rotating with respect to one another by means of an intermediate part which is in this case sleeve 22, which may also be referred to as a barrel. The sleeve 22 may, according to the present embodiment, comprise two internal gear teeth 23 (see
According to other embodiments in which the first and second gear coupling part 19, 21 have internal gear teeth, these parts 19, 21 may be prevented from rotating with respect to one another by means of an intermediate part in the form of a shaft with complementary external toothing instead of by means of a sleeve 22, which shaft is in that case slid in the internal gear teeth of the coupling parts 19 and 21 (not shown in the drawings). It is clear that in such a way the intermediate part 22, for as far as its torsional stiffness is sufficiently high, is preventing the rotation of the first coupling part 19 with respect to the second coupling part 21.
However, small axial and possibly radial movements as well as other small rotational movements of the intermediate part 22 with respect to the first coupling part 19 and the second coupling part 21 are still possible, since the intermediate part 22 is in slidable connection with the coupling parts 19 and 21. According to embodiments of the invention, movement of the intermediate part 22 in an axial direction is limited and is preferably less than the smallest length L in axial direction of the external teeth of the gear coupling parts 19 and 21 (see
Because the planet shaft locking mechanism 18 is positioned between the axial end face 100 of a planet shaft 13 and the planet carrier 14, axial movement of the planet shaft locking mechanism 18 can be easily obtained. Indeed, by choosing the length L′ of the intermediate part 22 (see
The second gear coupling part 21 may be provided with holes 101 for attaching it to the axial end face 100 of the planet shaft 13 by means of bolts 24. Hereby, the axial end face 100 of the planet shaft 13 may be provided with corresponding threaded holes 102.
In order to simplify the assembly, the planet carrier 14 may be provided with holes 103 having an internal diameter D which is larger than or at least equal to the external diameter D′ of the sleeve 22 and/or the diameter D″ of a gear coupling parts 19 or 21, the holes 103 being aligned with the planet shafts 13 centre positions. In that way the parts of the planet shaft locking mechanism 18, i.e. the sleeve 22 (or shaft) and corresponding gear coupling parts 19 and 21, can easily be introduced through the holes 103 in the planet carrier 14 during assembly.
For connecting or fixing the first gear coupling part 19 to the planet carrier 14 a mounting flange 25 may be provided, having an external diameter E which is bigger than the internal diameter D of the holes 103 of the planet carrier 14. The mounting flange 25 may near its centre be provided with holes 104 at positions corresponding to threaded holes 105 in the first gear coupling part 19 for fixedly connecting the mounting flange 25 to the first gear coupling part 19 by means of bolts 26. Furthermore, the mounting flange 25 may near its outer border also be provided with holes 106 corresponding to threaded holes 107 in the planet carrier 14 for connecting the mounting flange 25 to the planet carrier 14 by means of bolts 108. The threaded holes 107 may therefore be positioned around the holes 103, preferably in that side of the planet carrier 14 which is directed to the rotor (R), in particular on a flange part 109 forming the holes 3 in the planet carrier 14.
The different steps of mounting the gear coupling 18 into the planetary gear transmission unit 20 will be described later with respect to
A gear coupling 18 according to the first embodiment of the invention allows axial, radial and small angular movement of the corresponding planet shaft 13 with respect to the planet carrier 14, but prevents large angular movement of the planet shaft 13 around its axis with respect to the planet carrier 14. Preventing large angular movement of the planet shaft 13 around its axis with respect to the planet carrier 14 is caused by torsional stiffness of the gear coupling 18.
According to embodiments of the invention, the gear coupling 18 may furthermore comprise a fail safe mechanism, also referred to as a so-called weakest link. The weakest link may, for example, be a torque limiting pin (see
The gear coupling 18 in a planetary gear transmission unit according to the first embodiment of the present invention may furthermore comprise a lubrication mechanism. The lubrication mechanism is for keeping the gear teeth on the first and second gear coupling parts 19, 21 and the gear teeth on the sleeve 22 lubricated.
In a last step, the pre-assembled part A is introduced in the sleeve 22 by sliding the second gear coupling part 21 in it in the axial direction, after which the mounting flange 25 is connected fixedly to the planet carrier 14 by screwing bolts 108 into threaded holes 107 on the flange 109.
According to a second embodiment of the invention the planet shaft locking mechanism may comprise a so-called double pin coupling.
According to the present embodiment the planetary gear transmission unit 20 furthermore comprises a planet shaft locking mechanism 18 in the form of a double pin coupling, the planet shaft locking mechanism 18 preventing rotation of a planet shaft 13 around its own axis with respect to the planet carrier 14. The planet shaft locking mechanism 18 in the form of a double pin coupling is provided in between the planet shaft 13 and the planet carrier 14 (see
A double pin coupling 18 according to the second embodiment is schematically illustrated in
Similar as described in the first embodiment, the intermediate part 36 is for preventing a rotation between the first connecting part 34 and the second connecting part 35. Hereby, the pins 38 are, in the axial direction, with their one end slidably provided in holes in the intermediate part 34 and with their other end slidably provided in holes in the second connecting part 35. Similarly, the pins 37 are, in the axial direction, with their one end slidably provided in holes in the intermediate part 34 and with their other end slidably provided in holes in the first connecting part 34.
The double pin coupling 18 furthermore comprises a lubrication mechanism (illustrated by dark arrows in
According to the second embodiment of the invention the first connecting part 34 is at one side, also referred to as rotor side (R), connected to the planet carrier 14 by means of bolts 42. At the other side, also referred to as generator side (G) the second connecting part 35 is connected to the end face of the planet shaft 13 by means of bolts 43.
The double pin coupling 18 may furthermore comprise a spring 44 in the first connecting part 34. This spring 44 is for preventing movement of the intermediate part 36 between the first connecting part 34 and the second connecting part 35 during operation of the planetary gear transmission unit 20.
Furthermore, the double pin coupling 18 may comprise a seal 45 in between the second connecting part 35 and the intermediate part 36.
Hereinafter, an example of how a double pin coupling 18 according to the second embodiment of the invention can be mounted into a planetary gear transmission unit 20 will be described. It has to be understood that this example is only for the ease of explanation and is not intended to limit the invention in any way. Any other suitable way to mount the double pin coupling 18 according to the second embodiment into the planetary gear transmission unit 20 is intended to be within the scope of the present invention. First, the second connecting part 35 may be coupled to the planet shaft 13 by screwing bolts 43 into threaded holes in the planet shaft 13. Next, a seal 45 may be provided to a side of the intermediate part 36 which has to be connected to the second connecting part 35. After providing the seal 45 the intermediate part 36 may be pushed against the second connecting part 35 such that the seal 45 is in between the intermediate part 36 and the second connecting part 35. Hereby the pins 38 are introduced in corresponding holes in the intermediate part 36 and the second connecting part 35, so that a rotation of the second connecting part 35 with respect to the intermediate part 36 is possible. In a last step, the pins 37 and springs 44 may be introduced by axially sliding them into holes in the intermediate part 36, after which the first connecting part 34 is slid in the axial direction over pins 37 and springs 44 and is connected to the planet carrier 14 by screwing bolts 42 into threaded holes in the planet carrier 14.
Hereby, the pins 37 are with their one end in the holes in the intermediate part 36 and with their other end in the first connecting part 34 for preventing a rotation of the intermediate part 36 with respect to the first connecting part 34. Axial location of the intermediate part 36 with regard to the first and second connecting parts 34 and 35 is obtained by positioning it in between the planet shaft axial end face 100 and the planet carrier 14.
It is clear that the planet shaft locking mechanism 18 in accordance with the second embodiment of a planetary transmission gear unit 20 according to the invention, prevents rotation of the first connecting part 34 and the second connecting part 35 with respect to one another, while small movements in other modes are still possible.
The invention may, for example, be interesting for applications whereby the planetary gear transmission unit 20 is provided with a bogie plate held by studs to a driving part of the planet carrier 14 and wherein the planet shafts 13 are mounted on the bogie plate with a high degree of freedom, for example by means of a ball joint or the like. According to particular embodiments, the planet shafts 13 may extend at both sides of the bogie plate, each side of the planet shaft 13 supporting a planet gear 12 in a rotatable manner.
The embodiments described above are not intended to limit the invention in any way. According to still further embodiments according to the present invention, the planet shaft locking mechanism 18 may, as already described earlier, also comprise any other, non-switchable coupling such as e.g. but not limited to a cross slot coupling, a jaw coupling or a metal disc coupling.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09008477.3 | Jun 2009 | EP | regional |
