Rotor blade pitch adjusting device and turbomachine containing the same

An adjusting device is provided for pivoting blades of a rotor via a transmission that is actuatable by a co-rotating, axially-displaceable actuating shaft. The adjusting device includes a roller bearing having a first side or ring that is attachable to the actuating shaft and a second side or ring connected with an actuating body that is non-rotatably supported in a support body. The adjusting device further includes a screw drive that axially displaces the actuating body within the support body to thereby linearly actuate the transmission.

This application claims priority to German patent application no. 10 2010 021 988.6 filed on May 29, 2010, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The invention generally relates to an adjusting device for changing the rotational position or pitch of one or more blades of a rotor, e.g., of a wind turbine, via a transmission that is actuatable by an actuating shaft, which rotates together with the rotor and is axially displaceable relative to the rotor. The adjusting device includes a roller bearing having a first side or ring that is attachable to the actuating shaft and a second side or ring that is connected with an actuating body. A support body supports the actuating body in a non-rotatable manner, but permits axial displacement of the actuating body relative to the support body.

BACKGROUND ART

DE 36 19 406 A1 discloses an adjusting device for adjustable rotor blades, in particular of a turbine or a propeller pump. With reference to the drawings of DE 36 19 406 A1, the known adjusting device includes a machine shaft2and an actuating shaft6, via which the position or pitch of the rotor blades, which are rotatably disposed in a hub, is adjustable using a hydraulically-actuated piston40. The actuating shaft6is rotatable with the machine shaft2, but is axially displaceable relative to the machine shaft2. A bearing14supports the actuating shaft6so that it is rotatable relative to the hydraulically-actuated piston40. An actuating cylinder42accommodates the axially-displaceable piston40and is disposed on a machine housing in a stationary manner.

SUMMARY

In one aspect of the present teachings, an adjusting device is taught that is capable of providing an improved linear actuation of an actuating shaft.

In another aspect of the present teachings, an adjusting device is provided for actuating a transmission that adjusts the rotational position or pitch of one or more blades of a rotor. The transmission is actuatable by an actuating shaft that rotates together with the rotor, but is axially-displaceable relative to the rotor. The adjusting device includes a roller bearing having one side (e.g., a first bearing ring) configured to be attached to the actuating shaft and another side (e.g., a second bearing ring) connected with an actuating body that is supported in a support body so as to be axially displaceable, but rotationally-fixed (non-rotatable). The adjusting device further comprises a screw drive configured to axially displace the actuating body that is supported in the support body.

As utilized herein, the term “screw drive” is intended to encompass mechanical linear actuators configured or adapted to convert or translate a turning, pivoting or rotating motion into linear motion utilizing at least two helically-threaded structural elements. Representative examples of suitable screw drives include, but are not limited to, a lead screw, a power screw, a translation screw, a ball screw, a roller screw, a planetary roller screw and a satellite roller screw. Generally speaking, the screw drive may preferably include a first element that comprises, e.g., a bolt or screw having an outer thread that is rotatably driven by a motor having a rotatable output drive shaft. A second element includes an inner thread disposed around or at least adjacent to the outer thread of the first element. Rotation of the first element causes the second element to displace in the axial direction relative to the first element and this movement in the axial direction is imparted to the actuating shaft, as will be further discussed below. Naturally, the arrangement of the threads on the first and second elements may be interchanged or reversed, such that, e.g., the element having the inner thread is rotatably driven by the motor and the element having the outer thread is axially displaceable relative to the element with the inner thread.

The above-described screw drive can be operated at least substantially dry, i.e. no fluids are necessary in order to actuate the actuating shaft, which is particularly advantageous in applications of the present teachings, in which environmental contamination or pollution caused by leaking fluids (e.g., hydraulic fluids or oils) must be prevented or at least substantially eliminated.

In addition or in the alternative, such a screw drive can be constructed with a relatively narrow diameter, so that it can minimize space requirements and can even be utilized inside of relatively narrow hollow shafts.

Furthermore, even though such screw drives may have a relatively small construction, it is still possible to transmit relatively large linear actuating forces.

In one embodiment, the actuating body can include an inner thread. A complementary outer thread of a lead screw engages the inner thread. The lead screw is retained at a bearing point of the support body so as to be rotatable, but the lead screw is not axially displaceable. The lead screw includes a driven part that is connectable to a rotary drive (e.g., motor with a rotatable output shaft). The rotary drive can thus drive (rotate) the lead screw, whereby the actuating body is moved in the axial direction by the rotational movement of the lead screw. However, in an inverse variant, the actuating body can instead have the outer thread and a pipe-shaped shaft having an inner thread can be driven by the rotary drive. In another alternative, the actuating body can comprise a nut, in which the inner thread is formed.

The lead screw and the actuating shaft can be oriented along the same rotational axis. In this case, the axial actuating forces can be transmitted to the actuating shaft from the actuating body and/or the lead screw in a stress-free manner.

The axially-fixed lead screw can be rotatably supported at one terminal end of a hollow circular cylindrical support body. The lead screw is thus axially fixed in the support body, i.e. the axial positions of the lead screw and the support body are rigid or immovable. The lead screw is supported on the support body so that it is only rotatable.

The lead screw can be supported at the bearing point (terminal end) of the support body, e.g., by a roller bearing. Representative examples of suitable roller bearings include, but are not limited to, a two-row tapered roller bearing, a spherical roller bearing and two angular contact roller bearings, e.g., disposed in a back-to-back arrangement (also known as an “O” arrangement).

In all of the above-noted embodiments, the lead screw may optionally have a free end that projects into a recess of the support body.

In addition or in the alternative, the actuating shaft can have a terminal-end cavity, e.g., an axial bore, for the insertion of the free end of the lead screw. That is, the cavity or axial bore is preferably connected to the recess of the support body and allows the actuating shaft to axially displace relative to the lead screw without contacting the free end of the lead screw. In such an embodiment, a structure can be achieved, in which the adjusting device has a relative compact axial length or extension.

In a further development, the actuating body can include a radial projection that engages in an axial groove of the support body. The engagement of the radial projection in the axial groove of the non-rotatable support body prevents the actuating body from rotating together with the lead screw when the lead screw rotates. Instead of a single projection, the actuating body may have a plurality of radial projections that all engage in a common axially-extending groove. In the alternative, the support body may have a plurality of axially-extending grooves, each one engaging a respective radial projection. In the latter embodiment, the plurality of axially-extending grooves could be, e.g., distributed equal-distantly from each other around the inner circumference of the support body. In this case, the projections would extend radially outward into the associated axially-extending grooves at equal-distant spacings around the outer circumference of the actuating body. The arrangement of the projection(s) and groove(s) may be reversed, such that the actuating body has one or more grooves and the support body has one or more projections. The actuating body and the support body can also be formed, e.g., in the shape of a spline shaft profile.

In an additional design, the actuating body can have a cavity that retains a lead screw nut, which thus forms or provides the inner thread of the actuating body. The lead screw nut can be, e.g., connected with the actuating body by an interference-fit or a friction-fit. For example, the lead screw nut can be press-fit into the actuating body. In the alternative, the inner thread can be, e.g., cut directly into the actuating body.

In certain applications of the present teachings, any of the above- or below-described adjusting devices can be used, e.g., in an inking station or dampening (wetting) station of a printing press.

In other applications of the present teachings, any of the above- or below-described adjusting devices may be utilized in a turbomachine, such as a pump, compressor, turbine or turbine generator, which includes a rotor with blades and a transmission for adjusting the position or pitch of the blades. The transmission is actuatable by a co-rotating, axially-displaceable actuating shaft that is linearly displaced by an adjusting device according to the present teachings. Presently preferred applications of the present teachings include, but are not limited to, wind turbines, gas turbines, steam turbines and industrial ventilators.

In summary, inventive solutions are taught herein for the linear displacement of a rotating shaft, and particularly for adjusting (rotating) a position (pitch) of rotor blades relative to the rotational axis of the rotor. For example, in certain embodiments of the present teachings, adjusting devices are disclosed that can avoid or prevent fluid leakages, because a hydraulic system is not necessary. Instead, a mechanical linear actuator is utilized that operates without fluids and/or hydraulic liquids, such as, e.g., oil. Such an adjusting device can be characterized as a “dry system” and can be advantageously utilized in applications disposed above or near water where fluid leakages could lead to contamination of the surrounding water, such as off-shore wind turbines. In certain embodiments of the present teachings, the adjusting device is distinguished by exhibiting good controllability. Furthermore, adjusting devices according to the present teachings can be operated very economically, because energy for the blade pitch adjustment is necessary only during an adjusting movement (linear actuation that is converted into rotation of the blade about its pivot axis).

Further objects, aspects, advantageous and elements of the present teachings will become apparent to the skilled person after reading the following description and appended claims in view of the attached drawings.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A turbine rotor1is depicted inFIG. 1as a representative turbomachine or turbomachinery that includes two blades3as an example. However, another number (e.g., 3 or more) of blades3could also be provided in modifications of this embodiment. Each blade3is pivotably supported on a rotor shaft7via a pivot axle5. One arm9is connected with each pivot axle5and/or with each blade3. The two arms9are each respectively connected with a common fork13via a connecting rod11. The two arms9, the two connecting rods11and the common fork13form a transmission15, by which the position or pitch (i.e. a pivotal position) of the blades3can be changed and/or adjusted. That is, the pivot axle5is pivoted by the transmission15.

As used herein, the term “transmission” is intended to encompass any type of mechanism configured or adapted to convert linear motion into rotational or pivoting motion. Representative examples of suitable transmissions include, but are not limited to, a Scotch yoke, a crank mechanism and a crank-slide mechanism. It is preferred that the transmission includes a first portion of a structural element that is linearly or axially movable by the actuating shaft (as will be further described below) and this linear motion is converted into pivotal movement of the rotor blade3about its pivot axis, which is perpendicular to the rotational axis of the actuating shaft17. By pivoting the rotor blade3about its pivot axis, the rotational position or pitch of the rotor blade3can be changed or adjusted.

Thus, the transmission15is linearly actuated by the axially-displaceable actuating shaft17. During operation of the turbomachine, the transmission15rotates together with the blades3, the rotor shaft7and the actuating shaft17about the rotational axis D. Thus, the actuating shaft17is both rotatable and axially displaceable in order to be able to change and/or adjust the position (pitch) of the blades3.

For reference purposes, it is noted that the actuating shaft17is axially displaceable relative to a stationary, i.e. not co-rotating, reference point29, e.g., a mounting or support plate. In order to achieve the combined rotational and axial movement, an inner ring19of a roller bearing21sits on the actuating shaft17at the end of the actuating shaft17that is opposite of the transmission15. Preferably, the inner ring19is axially-fixed relative to the actuating shaft17by being disposed within a circumferentially-extending groove defined in the outer surface of the actuating shaft17. An outer ring23of the roller bearing21is connected with an actuating body25, e.g., by being disposed in a circumferentially-extending groove defined in the inner surface of the actuating body25. In the embodiment depicted inFIG. 1, the actuating body25includes a pot25aand a rod25b. The pot25ais preferably a hollow cylinder with one end that is partially closed and/or fixedly connected to the rod25b. Further, the rod25bis not rotatable, but is movable in the axial direction relative to the reference point29.

Due to the rotational decoupling provided by the roller bearing21, the rotating actuating shaft17can be axially (linearly) moved by the not-rotating actuating body25. That is, the actuating body25is supported in a support body27so as to be rotationally fixed. The actuating body25is thus axially displaceable relative to the support body27, but is supported so as to be non-rotatable relative to the support body27. The support body27is rigidly affixed to the stationary reference point (mounting plate)29. Torque is supplied to the adjusting device by a rotary drive (motor)31, which is also fixed in a stationary manner, i.e. it does not co-rotate with the turbine rotor1and/or with the rotor shaft7.

A modified embodiment of the actuator device is shown inFIG. 2. In this modified embodiment, the actuating body25includes an inner thread33that is engaged with, and is axially movably guided along, a lead screw35. The actuating body25may optionally include a recess for a lead screw nut36that forms or provides the inner thread33of the actuating body25. In the alternative, the inner thread33may be formed directly on the inner surface of the actuating body25. The lead screw35is rotatably supported at a bearing point37of the support body27, but it is not movable or displaceable in the axial direction. The lead screw35has a driven part (shaft)39, to which the rotary drive31is connectable.

In the embodiment illustrated inFIG. 2, the lead screw35and the actuating shaft17are oriented and extend in series along the same rotational axis D. The lead screw35is rotatably supported at one terminal end41of the support body27so as to be axially fixed, i.e. it does not move in the axial direction. In this exemplary embodiment, the support body27is a hollow circular cylinder having one end that is partially closed and/or constricted to receive the bearing37. The lead screw35has a free end43that projects into a recess45defined within the actuating body25. The actuating shaft17has a terminal-end cavity47, e.g., an axial bore, for the insertion of the free end43of the lead screw35. That is, the free end43of the actuating shaft17and the cavity47thus form a telescoping arrangement (e.g., a telescopic cylinder), which provides a relatively compact overall axial length when the actuating shaft17is fully retracted towards the reference point29.

The actuating body25has at least one radial projection49, e.g., in the form of a fitted key or spline, which engages in at least one axial groove51defined in the support body27. The actuating body27is axially displaceable while being supported in a rotationally-fixed (non-rotatable) manner in the support body27due to the engagement of the projection(s)49and the axial groove(s)51.

In an alternative embodiment, the support body27can instead have a polygonal cross-section, such as a rectangle, a square or a triangle. In such an embodiment, the outer surface of the actuating body25preferably has a corresponding or complementary polygonal shape, so that rotation of the actuating body25relative to the support body27is prevented by the complementary (nested) shapes.

In addition or in the alternative, a second roller bearing may be provided within the cavity47of the actuating shaft17to rotatably support the free end43, thereby preventing the free end43from vibrating or oscillating during operation. In such an embodiment, the roller bearing is preferably axially displaceable relative to the actuating shaft17, so that axial movement of the actuating shaft17relative to the lead screw35can be compensated.

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