Driving device, driving device unit and wind turbine

Damage to a driving device or a ring gear or both due to an excessive force at a meshing portion therebetween is effectively prevented.In the embodiment described above, a driving device includes a driving device body that is provided in one structure at a movable section of a wind turbine and has a drive gear meshing with a ring gear provided in the other structure at the movable section, and an abnormality detection unit that monitors a force generated between the ring gear and the drive gear or the state of the driving device body or monitors both of the face and the state. Output from the drive gear of the driving device body to the ring gear is stopped when the abnormality detection unit detected an abnormality.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is the U.S. National Stage of PCT/JP2017/043049, filed Nov. 30, 2017, which claims priority to Japanese Patent Application No. 2016-237746 filed Dec. 7, 2016. The contents of each of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a driving device and a driving device unit used for a movable section of a wind turbine, and the wind turbine.

BACKGROUND

A wind turbine used as a wind power generator has been known as disclosed in, for example, Japanese Patent Application Publication 2015-140777. The wind turbine includes a nacelle turnably installed at the top of a tower and in which a generator and the like are disposed, and a blade installed rotatably relative to a rotor (hub, main shaft) attached to the nacelle. The wind turbine has a yaw or pitch driving device that rotationally drives one structure relative to the other structure at the movable section of the wind turbine. The yaw driving device turns the nacelle, which is the one structure, relative to the tower, which is the other structure, depending on the wind direction. The pitch driving device adjusts a pitch angle of the blade by turning the shaft of the blade, which is the one structure, relative to the rotor in the nacelle, which is the other structure.

When there is deterioration of the driving device itself, gusts and the like, a large force is generated at a meshing portion between a drive gear, which is an output portion of the driving device, and a ring gear meshing with the drive gear. A plurality of driving devices are usually provided in a single movable section of the wind turbine. When trouble occurs in one of the plurality of driving devices, a high load tends to be imposed in the meshing portion between the drive gear and the ring gear of one or more of the driving devices. When the force generated at the meshing portion becomes large, the driving device or ring gear may be broken. If the driving device is broken, it necessary to replace part or all of the driving device. If the ring gear or a structure around the ring gear is broken, a large-scale repair work will be required, and the operation of the wind turbine has to be stopped for a long period of time.

SUMMARY

In order to address this kind of trouble, Japanese Patent Application Publication 2015-140777 proposes to drop the drive gear from the driving device when a control current of the driving device exceeds the rated value. However, when a gust of wind blows, for example, a large force is generated at the meshing portion between the driving device and the ring gear even when the driving device is stopped and no control current flows therein. Moreover, the time from when a high load is generated to when a damage occurs in the driving device may be extremely short, such as several milliseconds. Monitoring the control current alone cannot prevent the damage occurrence.

The invention has been made in view of the above, one objective is to prevent the occurrence of damage to at least the driving device or the ring gear or both due to an excessive force at the meshing portion between the driving device and the ring gear. Among others, the invention endeavors to effectively avoid the damage that cannot be sufficiently avoided only by monitoring the control current.

A driving device according to one aspect of invention includes a driving device body having a drive gear that is provided in one structure at a movable section of a wind turbine and meshes with a ring gear provided in another structure at the movable section of the wind turbine, and an abnormality detection unit for monitoring at least one selected from the group consisting of a force generated between the ring gear and the drive gear and a state of the driving device body. Output from the drive gear of the driving device body to the ring gear is stopped when the abnormality detection unit detected an abnormality.

In the driving device, the driving device body may include a brake mechanism that brakes rotation transmitted to the drive gear or rotation output from the drive gear, and the abnormality detection unit may monitor operation of the brake mechanism.

In the driving device, the driving device body may include a brake mechanism that brakes rotation transmitted to the drive gear or rotation output from the drive gear, and a brake by the brake mechanism on the rotation may be released when the abnormality detection unit detected an abnormality.

A driving device according to another aspect of the invention includes a driving device body having a drive gear and a brake mechanism. The drive gear is provided in one structure at a movable section of a wind turbine and meshes with a ring gear provided in another structure at the movable section of the wind turbine. The brake mechanism brakes rotation transmitted to the drive gear or rotation output from the drive gear. The driving device further includes an abnormality detection unit for monitoring operation of the brake mechanism. Output from the drive gear of the driving device body to the ring gear may be stopped when the abnormality detection unit detected an abnormality.

In the driving device, a brake by the brake mechanism on the rotation may be released when the abnormality detection unit detected an abnormality.

A driving device unit according to yet another aspect of invention includes a plurality of driving devices provided in a single movable section of a wind turbine. Each of the plurality of driving devices is any one of the above-described driving devices. The abnormality detection unit is separately provided for each driving device. When one abnormality detection unit detected an abnormality, output to the ring gear from the drive gear in the driving device having the abnormality detection unit which detected the abnormality is stopped, and output to the ring gear from the drive gear(s) in the driving device(s) other than the driving device having the abnormality detection unit which detected the abnormality is also stopped.

In the driving device unit, when one abnormality detection unit detected an abnormality, a brake by the brake mechanism on rotation may be released in the driving device having the abnormality detection unit which detected the abnormality, and a brake by the brake mechanism(s) may be released also in the driving device(s) other than the driving device having the abnormality detection unit which detected the abnormality.

A wind turbine according to yet another aspect of the invention includes any of the above-described driving devices or any of the above-described driving device unit.

According to the aspects of the invention, it is possible to effectively prevent damage to at least a driving device or a ring gear or both due to an excessive force at a meshing portion therebetween.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described with reference to the appended drawings. In the drawings, for the sake of ease of illustration and understanding, a scale size, a dimensional ratio, and so on are altered or exaggerated as appropriate from actual values.

FIG. 1is a perspective view of a wind turbine101.FIG. 2is a sectional view showing part of a tower102and a nacelle103. InFIG. 2, as for a driving device10, an outer appearance thereof is shown instead of a cross-section thereof.FIG. 3is a plan view showing an arrangement of the driving devices10in a movable section shown inFIG. 2.FIG. 4is a view of the driving device10as seen from a lateral side, part of which is shown in section.FIG. 5is a view showing an installation portion of the driving device10, part of which is shown in section.FIG. 6is a view showing a brake mechanism of the driving device10, part of which is shown in section.

The driving device10is capable of driving the nacelle103installed so as to be rotatable with respect to the tower102of the wind turbine101or driving a blade105installed so as to be swingable in a pitch direction with respect to a rotor104mounted to the nacelle103. That is, the driving device10can be used as a yaw driving device for carrying out yaw driving so as to cause the nacelle103to rotate with respect to the tower102and also as a pitch driving device for carrying out pitch driving so as to cause a shaft portion of the blade105to rotate with respect to the rotor104. While the following describes, as an example, a case where the driving device10is used as a yaw driving device, the present invention is applicable also to a case where the driving device10is used as a pitch driving device.

As shown inFIG. 1, the wind turbine101includes the tower102, the nacelle103, the rotor104, the blade105, and so on. The tower102extends upward in a vertical direction from the ground. The nacelle103is installed so as to be rotatable with respect to a top portion of the tower102. Rotation of the nacelle103with respect to the tower102is yaw rotation about a longitudinal direction of the tower102as a rotation center. In the illustrated example, the nacelle103is driven by a plurality of driving devices10to rotate with respect to the tower102. Inside the nacelle103, devices necessary for wind power generation are installed. For example, a power transmission shaft, an electric power generator connected to said power transmission shaft, and so on are disposed therein. The rotor104is connected to the power transmission shaft and is rotatable with respect to the nacelle103. A plurality of (in an example shown inFIG. 1, three) blades105are provided and extend from the rotor104in a radial direction about a rotation axis of said rotor104with respect to the nacelle103. The plurality of blades105are arranged at an equal angle from each other.

The blades105are each rotatable in the pitch direction. More specifically, the blades105are each rotatable about a longitudinal direction thereof with respect to the rotor104. A connection point between the blades105and the rotor104is configured as the movable section so that the blades105and the rotor104are rotatable relative to each other. The blades105are driven to rotate by a driving device provided as a pitch driving device. The driving device as the pitch driving device may be configured similarly to an after-mentioned driving device10as a yaw driving device.

As shown inFIG. 2, the nacelle103is installed so as to be rotatable at a bottom portion103athereof with respect to the top portion of the tower102via a bearing106. A ring gear107having internal teeth formed on an inner periphery thereof is fixed to the top portion of the tower102. The ring gear107are not limited in terms of its teeth to the internal teeth provided on the inner periphery thereof and may have external teeth provided on an outer periphery thereof. In the drawings, the teeth of the ring gear107are not shown.

As shown inFIG. 2andFIG. 3, with respect to the nacelle103(a first structure) and the tower102(a second structure) configured to rotate relative to each other, the plurality of driving devices10are provided in the nacelle103. Each of the driving devices10includes a drive gear24ameshing with the teeth of the ring gear10provided in the tower102. As shown inFIG. 4, each of the driving devices10is provided with an electric motor23including a motor drive unit and a motor brake unit, which will be mentioned later, and a reducer25receiving power transmitted from said electric motor23(particularly, the motor drive unit). The motor drive unit outputs a driving force (rotational power), and the motor brake unit can reduce the driving force (rotational power) outputted from the motor drive unit by braking the motor drive unit. The term “braking” used herein is to be broadly construed, and a definition thereof embraces retaining a stopped state of an object that has been stopped and stopping a moving object.

By driving the driving devices10thus configured, it is possible to cause the nacelle103(the first structure) which is one structure at the movable section of the wind turbine101to rotate with respect to the tower102(the second structure) which is the other structure at the movable section of the wind turbine101. Particularly, the plurality of driving devices10included in the wind turbine are operated in a synchronized manner and thus provides drive power of a magnitude sufficient to be able to cause the nacelle103, which is a heavy object, to properly swivel with respect to the tower102. The driving devices10operate based on a control signal sent from an after-mentioned controller110(a control unit, seeFIG. 7) to the electric motor23(the motor drive unit and the motor brake unit). The plurality of driving devices10collectively constitute a driving device unit9. Further, the driving device10and the controller110constitute the wind turbine drive system5.

As shown inFIG. 3, the ring gear107is formed in a circumferential shape and has a center axis Cm. The nacelle103rotates about the center axis Cm of the ring gear107. In an example shown, the center axis Cm of the ring gear107agrees with the longitudinal direction of the tower102. In the following description, a direction parallel to the center axis Cm of the ring gear107is simply referred to also as an “axial direction dl.”

In the wind turbine101shown, as shown inFIG. 3, there are provided a pair of driving device groups arranged in rotational symmetry about the center axis Cm of the ring gear107. Each driving device group includes three driving devices10. In the illustrated example, six driving devices10included in the pair of driving device groups constitute the driving device unit9. Bodies20of the driving devices are arranged along a circumference cl1(seeFIG. 3) about the center axis Cm of the ring gear107. The three driving devices10included in each driving device group are arranged at given intervals along the circumference cl1.

Next, a description is given of the driving device10. Each driving device10includes the driving device body20having the drive gear24aengaged with the ring gear107, and an abnormality detection unit80that monitors the state of the driving device body20and detects its abnormality. In the illustrated example, the driving device body20is fixed to the nacelle103. As shown inFIG. 5, each of the driving devices10is fixed to the nacelle103(the first structure) via a fastener30disposed so as to extend through a through hole22aformed through a flange22of the driving device body20.

As shown inFIG. 4, the driving device body20is provided with an output shaft24having the drive gear24athat meshes with the ring gear107, the case21rotatably retaining the output shaft24, and the electric motor23fixed to the case21. Furthermore, the driving device body20is provided further with the reducer25housed in the case21and connecting the electric motor23to the output shaft24. The reducer25decelerates an input (rotational power) from the electric motor23while increasing a torque thereof and transmits the input to the output shaft24. While there is no particular limitation on a specific configuration of the reducer25thus described, typically, the reducer25can adopt an eccentric oscillating gear-type speed reducing mechanism, a planetary gear-type speed reducing mechanism, or a speed reducing mechanism obtained by combining the eccentric oscillating gear-type speed reducing mechanism with the planetary gear-type speed reducing mechanism.

An end portion of the output shaft24distal from the reducer25extends out from the case21, and the drive gear24ais formed at this extending-out portion of the output shaft24. As shown inFIG. 2andFIG. 5, the output shaft24penetrates through a through hole103bformed through the bottom portion103aof the nacelle103and meshes with the ring gear107. The drive gear24ahas a shape adapted to the ring gear107. As one example, the drive gear24acan be formed as a pinion gear having external teeth configured to mesh with the internal teeth of the ring gear107. Each of the driving devices10has a longitudinal direction axis agreeing with a rotation axis Cr of the output shaft24. In a state where each of the driving devices10is fixed to the nacelle103, the rotation axis Cr of the output shaft24is parallel to an axial direction dl of the wind turbine101.

The case21is formed in a cylindrical shape as shown inFIG. 4and is disposed so that a longitudinal direction axis thereof is positioned on the rotation axis Cr as shown inFIG. 5. The case21is open at both ends thereof along the rotation axis Cr. The drive gear24aof the output shaft24is exposed from an opening of the case21near the tower102. The electric motor23is mounted to an opening of the case21on an opposite side to the tower102. Furthermore, the case21includes the flange22. As shown inFIG. 3, the flange22of this example is formed in an annular shape and extends along a circumference cl3about the rotation axis Cr of the output shaft24. As shown inFIG. 4andFIG. 5, the through hole22ais formed through the flange22so as to extend in the axial direction dl. A plurality of the through holes22aare formed on the circumference cl3about the rotation axis Cr of the output shaft24. In the illustrated example, twelve through holes22aare formed.

The fastener30penetrates through the flange20by extending through each of the through holes22aformed through the flange22of the driving device body20. In the example shown inFIG. 5, the fastener30includes a bolt30aand a nut30b. The bolt30apenetrates through the flange22of the driving device body20and the bottom portion103aof the nacelle103. The nut30bis screwed with the bolt30ain a direction from the tower102. The fastener30formed of a combination of the bolt30aand the nut30bis provided with respect to each of the through holes22aof the driving device body20. In the example shown, the driving device bodies20are mounted to the nacelle103at twelve locations thereon by use of twelve fasteners30.

The fastener30is not limited to the illustrated example. The fastener30may be configured such that, instead of using the nut30b, a female screw with which a male screw of the bolt30acan be screwed is formed along a through hole of the nacelle103. In this case, the fastener30is formed of the bolt30a, and the male screw of the bolt30ameshes with the female screw in the through hole of the nacelle103, thus making it possible to fix the driving device body20to the nacelle103.

Next, a description is given of the electric motor23. In the illustrated example, the electric motor23includes a motor drive unit48and a motor brake unit50.FIG. 6is the view schematically showing a partial cross-section of the electric motor23. The motor brake unit50is a brake mechanism that brakes a rotational motion conveyed to the drive gear24a. However, as will be described later, instead of or in addition to the motor brake unit50, the driving device body20may include various forms of brake mechanism that puts a brake on the rotational motion conveyed to the drive gear24aor the rotation output from the drive gear24a.

The electric motor23provided with a motor drive unit48and a motor brake unit50is provided in each of the driving devices10, and one motor brake unit50is mounted to each motor drive unit48. The motor drive unit48can be formed of any device capable of controlling, based on a command from the controller110(seeFIG. 7), the number of rotations of a drive shaft48a. The illustrated motor brake unit50includes a mechanism as an electromagnetic brake for, based on a command from the controller110(seeFIG. 7), braking rotation of the drive shaft48aof the motor drive unit48or releasing the drive shaft48afrom being braked. In a state where rotation of the drive shaft48ais braked, the number of rotations of the drive shaft48ais reduced, and thus eventually, the drive shaft48acan be completely stopped from rotating. On the other hand, in a state where the drive shaft48ais released from being braked, without being braked by the motor brake unit50, the drive shaft48acan rotate basically at an original number of rotations corresponding to electric power supplied to the motor drive unit48. The driving force (rotational power) output from the drive shaft48aof the motor drive unit48is transmitted to the output shaft24via the reducer25.

The motor brake unit50of this example is mounted to an end portion of a cover72of the motor drive unit48on an opposite side to the reducer25and includes a housing51, a friction plate56, an armature57, an elastic member55, an electromagnet53, a first friction plate connecting portion77, and so on. The housing51is a structure housing the friction plate56, the armature57, the elastic member55, the electromagnet53, the first friction plate connecting portion77, and so on and is fixed to the cover72of the motor drive unit48. The friction plate56is connected to the drive shaft48aof the motor drive unit48via the first friction plate connecting portion77. In a through hole of the friction plate56, the drive shaft48ais disposed in a state where one end portion thereof penetrates through the through hole.

The first friction plate connecting portion77of this example includes a spline shaft77aand a slide shaft77b. The spline shaft77ais fixed to an outer periphery of the one end portion of the drive shaft48athrough key coupling via a key member (not shown) and engagement with a stopper ring77c. The slide shaft77bis mounted to the spline shaft77aso as to be slidable in an axial direction. Furthermore, in the first friction plate connecting portion77, there is provided a spring mechanism (not shown) for situating the slide shaft77bat a predetermined position in the axial direction with respect to the spline shaft77a. An inner periphery of the friction plate56is fixed to an edge portion of an outer periphery of a flange-shaped portion of the slide shaft77b, so that the friction plate56is coupled integrally with the slide shaft77b.

In the motor brake unit50having the above-described configuration, when the drive shaft48arotates, the spline shaft77a, the slide shaft77b, and the friction plate56also rotate together with the drive shaft48a. In a state where the after-mentioned electromagnet53is excited, the slide shaft77band the friction plate56that are retained so as to be slidable in the axial direction with respect to the drive shaft48aand the spline shaft77aare situated at a predetermined position in the axial direction of the spline shaft77aby the spring mechanism. When disposed at this predetermined position, the friction plate56is separated from the armature57and a friction plate58, which will be mentioned later.

The armature57is provided so as to be contactable with the friction plate56. The armature57is provided as a member for generating a braking force for braking rotation of the drive shaft48aby contacting with the friction plate56. Furthermore, in this example, the friction plate58is provided at a location on one end portion of the cover72of the motor drive unit48, where the friction plate58is opposed to the friction plate56. The friction plate58is installed at such a position as to be contactable with the friction plate56.

The elastic member55is retained in an electromagnetic body53aof the electromagnet53, which will be mentioned later, and biases the armature57in a direction from the electromagnet53toward the friction plate56. Particularly, as a plurality of elastic members55of this example, in the electromagnetic body53a, two inner peripheral and outer peripheral elastic members55are arranged in a circumferential direction concentrically about the drive shaft48a. The above-mentioned form of arranging the elastic members55is merely an example, and the elastic members55may be arranged in any other form.

The electromagnet53includes the electromagnetic body53aand a coil portion53band attracts the armature57by a magnetic force so as to separate the armature57from the friction plate56. To the housing51, the electromagnetic body53ais fixed at an end portion thereof on an opposite side to where the electromagnetic body53ais opposed to the armature57. The electromagnetic body53ahas a plurality of elastic member retaining holes53copen toward the armature57, and the elastic members55are disposed in the elastic member retaining holes53c, respectively. The coil portion53bis installed inside the electromagnetic body53aand disposed along the circumferential direction of the electromagnetic body53a. Supplying and shutting off of an electric current to the coil portion53bis performed based on a command of the controller110.

For example, when the motor brake unit50releases the drive shaft48afrom being braked, based on a command of the controller110, an electric current is supplied to the coil portion53bto energize the electromagnet53. When the electromagnet53is energized and thus is brought into an exited state, the armature57is attracted to the coil portion53bby a magnetic force generated at the electromagnet53. At this time, the armature57is attracted to the electromagnet53against an elastic force (a spring force) of the plurality of elastic members55. With this configuration, the armature57is separated from the friction plate56, and thus the drive shaft48ais released from being braked. Accordingly, in a state where the electromagnet53is excited and thus the drive shaft48ais released from being braked, the armature57is brought into a state of contacting with the electromagnetic body53a.

On the other hand, when the motor brake unit50brakes the drive shaft48a, based on a command of the controller110, a supply of an electric current to the coil portion53bis shut off to demagnetize the electromagnet53. When the electromagnet53is brought into a demagnetized state, the armature57is biased toward the friction plate56by an elastic force of the plurality of elastic members55, and thus the armature57contacts with the friction plate56. With this configuration, a friction force is generated between the armature57and the friction plate56, and thus rotation of the drive shaft48ais brakedFIG. 6shows a state where the electromagnet53is demagnetized, which is a state where rotation of the drive shaft48ais braked.

Furthermore, in a state where the electromagnet53is demagnetized and thus the drive shaft48ais braked, the friction plate56is in contact also with the friction plate58under a biasing force acting from the armature57. Accordingly, when the electromagnet53is demagnetized, the friction plate56is brought into a state of being sandwiched between the armature57and the friction plate58under a biasing force from the plurality of elastic members55. With this configuration, by a friction force generated between the armature57and the friction plate56and a friction force generated between the friction plate56and the friction plate58, rotation of the drive shaft48ais braked.

Next, a description is given of the abnormality detection unit80that monitors the state of the above-described driving device body20to detect an abnormality thereof. In the illustrated example, the abnormality detection unit80monitors a force generated between the ring gear107and the drive gear24a, the state of the driving device body20, and the operation of the brake mechanism (motor brake unit50). More specifically, the abnormality detection unit80includes a load sensor81, an oil sensor82, and a brake mechanism sensor83. Each of the sensors81,82,83will be described below.

The load sensor81detects a force generated at the meshing portion between the ring gear107and the drive gear24a. The load sensor81may include various sensors capable of acquiring indices and characteristics related to the force generated at the meshing portion. Thus, the load sensor81directly or indirectly detects the force generated at the meshing portion.

In the example shown inFIG. 5, the load sensor81is configured as a sensor that measures a change in the state of the fastener30. The fastener30is a member for fixing the driving device body20to the nacelle103. Therefore, the change in state of the fastener30is associated with generation of a force (load) on the meshing portion between the ring gear107and the drive gear24a. Therefore, by detecting the amount of change in the state of fastener30, it is possible to detect the magnitude of the stress (load) between the drive gear24aand the ring gear107.

Specifically, the load sensor81may be formed of a known sensor for measuring one or more selected from the group consisting of a load applied to the fastener30, a displacement of the fastener30with respect to the nacelle103, and a relative position of the fastener30to the nacelle103. In the example shown, an axial force sensor is used as the load sensor81, and thus it is possible to measure a load (an axial force) applied to the fastener30in a particular direction. As shown inFIG. 5, the load sensor81is fixedly retained by use of a jig49with respect to the nacelle103, which is one structure at the movable section. The axial force sensor constituting the sensor40contacts with a head portion of the bolt30aas a component of the fastener30.

There is, however, no limitation to this example. As shown by a chain double-dashed line inFIG. 5, the load sensor81may contact with a distal end portion of the bolt30aon an opposite side to the head portion or may contact with the nut30b. Furthermore, the sensor40may detect a load applied to a fastening bolt fastening the nacelle103to the case21. As another example, when a strain gauge is used as the load sensor81, it becomes possible to measure the stress applied to the fastener. As yet another example, when a magnetic sensor or a photoelectric sensor is used as the sensor81, it becomes possible to measure a position and a displacement of the fastener30in a non-contact manner.

In the sensor that monitors the control current of the motor described in the prior art, excessive force may be generated at the meshing portion between the ring gear107and the drive gear24awhen the wind turbine catches a gust of wind that tries to rotate the nacelle103relative to the tower102. The sensor monitoring the control current of the motor is not able to detect a load generated in the meshing portion when the driving device10is not operated. Moreover, even when the driving device10is operating, it is not possible to directly estimate the magnitude of the force generated in the meshing portion by using the control current of the motor since the internal efficiency of the driving device affects. Further, as shown in the illustrated example, in the movable section in which the driving devices10are used, when a target driving device10is stopped and a driving force is output from the driving device body20of another driving device10, an excessive force may be generated between the drive gear24aof the target driving device10and the ring gear107. However, when the target driving device10is stopped in such a situation, it is not possible to detect abnormality even if the control current of the driving device10is monitored.

As described above, in the prior art which cannot detect these situations, it was not possible to avoid damage of the driving device body20and the ring gear107caused by the excessive load generated in the meshing portion. In particular, if the ring gear107and its surrounding structures are broken, a long repair period is required so that it has a high impact on the operation of the wind turbine. The load sensor81detects a force generated at the meshing portion between the ring gear107and the drive gear24a. Therefore, by using the detection result of the load sensor81, it is possible to effectively avoid breakage of the driving device body20and breakage of the ring gear107and its surrounding structure which may significantly affects the operation of the wind turbine.

Next, a description is given of the oil sensor82. As described above, the driving device body20includes the reducer25configured as an eccentric oscillating type reducer or a planetary gear type reducer, and other mechanism. Therefore, oil serving as lubricant typically fills the case21that accommodates the mechanism including the reducer25and the like. The condition of the oil inside the driving device body20accurately reflects the state of the internal mechanism of the drive body20. As shown inFIG. 4, at least a sensing portion of the oil sensor82is disposed in the oil. The oil sensor82monitors the condition of the oil used in the driving device body20, for example, the color and water content of the oil. From the color and water content of oil, it is possible to determine inclusion of foreign matter (for example, wear powder) in the oil, the degree of oxidation of the oil, etc., and further investigate the possibility of future damage. That is, by using the oil sensor82, it is possible to detect aging deterioration of the driving device body20.

The above-described prior art in which the control current of the motor is monitored can only detect an abnormal condition that has already occurred. Therefore, it has not been possible to predict in advance the cause of a failure that may require a long-term repair. Moreover, the time from when a high load is generated to when a damage occurs in the driving device may be extremely short, such as several milliseconds. Such damage could not be avoided with the prior art of monitoring the control current alone. Whereas the oil sensor82can diagnose aging deterioration of the driving device body20. Therefore, by using the detection result of the oil sensor82, it is possible to effectively avoid breakage of the driving device body20and breakage of the ring gear107and its surrounding structure which may significantly affects the operation of the wind turbine.

The state monitoring sensor that monitors the state of the driving device body20is not limited to the oil sensor82. For example, instead of or in addition to the oil sensor82, the state monitoring sensor may include a camera that captures components included in the driving device body20, or a displacement sensor that monitors a displacement of the component(s) included in the driving device body20, or a sensor that monitors a load occurred on the component(s) included in the driving device body20.

The brake mechanism sensor83monitors the operation of the brake mechanism. The brake mechanism is the mechanism that brakes the rotation transmitted to the drive gear24aor the rotation output from the drive gear24a. In the example shown inFIG. 6, the brake mechanism includes the motor brake unit50. The motor brake unit50is incorporated in the motor23and has an armature57that operates based on a control signal from the controller110. In the example shown inFIG. 6, the brake mechanism sensor83monitors the position of the armature57along the axial direction dl.

More specifically, the brake mechanism sensor83shown inFIG. 6includes a detection target portion83battached to the armature57, and a detection unit83athat detects the position and displacement of the detection target portion83bin a direction parallel to the axial direction dl. The detection target portion83bin this example is permanent magnet fixed to the armature57and may be attached to a part of the outer peripheral portion of the armature57close to the electromagnet53. The detection unit83ais provided as a sensor capable of detecting the position and displacement of the detection target portion83bthat moves together with the armature57. That is, the detection unit83adetects the position and displacement of the detection target portion83bin the direction parallel to the rotation axis Cr of the drive shaft48a, to detect the position and displacement of the armature57in the direction parallel to the rotation axis Cr of the drive shaft48a. The illustrated detection unit83ais provided as a sensor that measures an intensity and a direction of a magnetic field generated by the detection target portion83which is permanent magnet, and fixed to an inner wall of the housing51. The detection unit83adetects the position and displacement of the detection target portion83bby measuring the intensity and direction of the magnetic field generated by the detection target portion83b. Thus, the detection unit83ais preferably fixed to the housing51at a position corresponding to the detection target portion83bin the direction parallel to the rotation axis Cr of the drive shaft48a.

By using the brake mechanism sensor83, it is possible to detect an abnormal state in which a malfunction of the motor brake unit50that serves as the brake mechanism occurs due to adhesion of the armature57or the like. For example, if a strong wind blows in a state where some trouble occurs in the brake mechanism and the operation of the drive gear24ais restrained, an excessive force may be generated at the meshing portion between the drive gear24aand the ring gear107. Such a situation cannot be detected by the prior art that monitors the control current. Further, as shown in the illustrated example, in the movable section in which the driving devices10are used, when a trouble occurs in the brake mechanism of the target driving device10so that the drive gear24ais restrained and a driving force is output from the driving device body20of another driving device10, an excessive force may be generated between the drive gear24aof the target driving device10and the ring gear107. However, when the target driving device10is stopped in such a situation, it is not possible to detect abnormality even if the control current of the driving device10is monitored. In this respect, the brake mechanism sensor83monitors the operation of the motor brake unit50constituting the brake mechanism. Therefore, by using the detection result of the brake mechanism sensor83, it is possible to effectively avoid breakage of the driving device body20and breakage of the ring gear107and its surrounding structure which may significantly affects the operation of the wind turbine.

Furthermore, for example, when the electric motor23of any of the driving devices10outputs a driving force in a state where the operation of the drive gear24ais unintentionally restrained due to an abnormality occurred in the brake mechanism, the driving force acts as an external force on the meshing portion between the drive gear24aand the ring gear107. Within a very short time, such as only several milliseconds after the output of the driving force acting as the external force, breakage of the driving device body20and the ring gear107may happen. Such breakage cannot be effectively avoided by monitoring the control current. Whereas the brake mechanism sensor83is able to detect an abnormality of the motor brake unit50constituting the brake mechanism. Therefore, it is possible to predict the occurrence of an excessive load on the meshing portion from the detection result of the brake mechanism sensor83and to effectively avoid the breakage.

The abnormality detection unit80including the load sensor81, the oil sensor82and the brake mechanism sensor83is separately provided for each driving device body20. That is, each driving device10includes a separate abnormality detection unit80, and an abnormality is detected for the corresponding driving device10.

FIG. 7is a block diagram for describing the functions of the controller110. As shown inFIG. 7, the controller110receives detection results from the abnormality detection units80provided in the plurality of driving devices10(in this example, six driving devices10) respectively. That is, the load sensor81, the oil sensor82, and the brake mechanism sensor83that constitute the abnormality detection unit80for the corresponding driving device10are connected to the control device110. The control device110may output a control signal for controlling the motor drive unit48and the motor brake unit50provided in each driving device10. There is no particular limitation on an installation position of the controller110. The controller110may be provided integrally with any of the elements constituting the wind turbine101(for example, the tower102, the nacelle103, the rotor104, or the blade105) or independently of these elements.

When the abnormality detection unit80for any of the driving devices10detected an abnormality, the control device110stops the output of the driving force from the drive gear24ain the driving device body20of that driving device10to the ring gear107. The driving force from the drive gear24acan be stopped typically by interrupting the power supply to the motor23using the controller110. By stopping the output from the drive gear24ato the ring gear107in a state where the excessive force is applied to the meshing portion between the drive gear24aand the ring gear107, it is possible to avoid a further increase in load on the meshing portion. Moreover, when damage caused by aging deterioration of the driving device body20is predicted from the condition of oil, the output of the driving force from the driving device body20may be stopped to effectively avoid the breakage of the ring gear107connected to the driving device body20and the surrounding structure thereof. Further, when a failure of the motor brake unit50is found, it is possible to effectively avoid further damage to the driving device body20and further damage to the ring gear107connected to the driving device body20and the surrounding structure thereof.

When the abnormality detection unit80for any of the driving devices10detected an abnormality, the control device110removes a brake on the rotation by the brake mechanism (motor brake unit50) of the corresponding driving device10. That is, when the abnormality detection unit80detected an abnormality, the control device110sends a control signal to release the brake on the rotation by the brake mechanism (motor brake unit50). In the illustrated example, the release of the rotational brake performed by the motor brake unit50can be realized by supplying power to the motor brake unit50using the controller110. For example, if the rotation of the drive gear24ais restricted by the braking force of the brake mechanism when an external force such as gust works, an excessive load may be imposed at the meshing portion between the drive gear24aand the ring gear107. To avoid this, the control device110removes a brake on the rotation by the brake mechanism (motor brake unit50) of the corresponding driving device10when the abnormality detection unit80for the driving device10detected an abnormality.

Furthermore, in addition to stopping the output of the driving force from the drive gear24ato the ring gear107in one driving device10when the abnormality detection unit80for the driving device10detected an abnormality, the control device110also stop the output of the driving force from the drive gear24ato the ring gear107in the driving devices other than the driving device for which the abnormality has been detected. Furthermore, when the abnormality detection unit80for one driving device10detected an abnormality, in addition to releasing the brake on the rotation by the motor brake unit50in the corresponding driving device10, the control device110releases brakes of the brake mechanisms in the driving devices other than the driving device10for which the abnormality has been detected. As described above, when more than one driving device10is provided in a single movable section, the drive force output from the drive gear24aof one driving device10to the ring gear107acts as an external force on the meshing portion between the drive gear(s)24aof other driving device(s)10and the ring gear107. Therefore, when an abnormality is found in any of the driving devices, it is avoided that the driving force of the driving device10is applied as an external force to the meshing portion(s) between other driving device(s)10and the ring gear107, and further the brake force(s) of the brake mechanism(s) are removed from the driving devices10so that each driving device10is allowed to move flexibly to accommodate to the external force. In this way, it is possible to more effectively avoid damage to the driving device body20and damage to the ring gear107connected to the driving device body20and the surrounding structure thereof.

In the movable section between the nacelle103and the tower102, stopping the output of the driving force from the drive gear24ain the driving device10to the ring gear107and releasing the brake on the rotation by the brake mechanism50in the driving device10is called a free yaw control. In the free yaw control, free relative rotation between the nacelle103(the first structure) and the tower102(the second structure) is permitted, and a braking force and a drive force that might inhibit the free relative rotation between the nacelle103and the tower102are reduced or canceled. In a case where the motor drive unit48and the motor brake unit50as mentioned above are provided, the controller110shuts off energization with respect to the motor drive unit48so as to stop the drive shaft48afrom rotating and also controls energization with respect to the motor brake unit50so that a braking force is not applied from the motor brake unit50to the motor drive unit48(namely, the drive shaft48a).

Furthermore, in a case where any other drive unit and any other braking unit are provided, the controller110controls the any other drive means and the any other brake means to eliminate a braking force and a drive force that might inhibit free relative rotation between the nacelle103and the tower102. For example, in a case where there is provided a braking device (not shown), such as a caliper brake, for directly braking a rotational operation of the ring gear107, the controller110controls said braking device so that a braking force is not applied from said braking device to the ring gear107.

With the controller110performing the above-mentioned free yaw control, the drive gear24aof each driving device10and the ring gear107are placed in a freely rotatable state, and thus the nacelle103can freely rotate with respect to the tower102. Such free rotation can effectively prevent a load between each drive gear24aand the ring gear107from becoming excessive, and thus trouble such as a breakage of the various elements constituting each of the driving devices10or the ring gear107can be avoided before it happens.

In the embodiment described above, the driving device10includes the driving device body20that is provided in one structure at the movable section of the wind turbine101and has the drive gear24ameshing with the ring gear107provided in the other structure at the movable section, and the abnormality detection unit80that monitors the force generated between the ring gear107and the drive gear24aor the condition of the oil in the driving device body20or monitors both. When the abnormality detection unit80detected an abnormality, the output from the drive gear24ain the driving device body20to the ring gear107is stopped. In the driving device10, the abnormality detection unit80is able to monitor not only an abnormality that the magnitude of the output from the driving device body20becomes excessive, for example, the control current of the driving device body20becomes excessive, but also able to detect the state where a large external force is applied and monitor the progress of aging. Moreover, the output of the driving force from the driving device body20is stopped (restricted) when an abnormality is found, so breakage of the driving device10and damage to the ring gear107and its surrounding structure can be effectively avoided regardless of whether the control current of the driving device10becomes excessive or not. Further, if the output of the driving force from the driving device body20is started while there is an abnormality, the driving device10and the ring gear107may be instantaneously damaged. In this respect, the driving device10described above is able to detect occurrence of an excessive external force even when the drive force output from the driving device body20is stopped, and further, to predict (detect) an abnormality of the device body20caused by aging based on the condition of the oil. Thus, the abnormality detection unit80detects an abnormality in the state where the output of the driving force from the driving device body20is stopped, and it is possible to effectively copes with instantaneous damage of the driving device10, the ring gear107, and the like.

Further, in the embodiment described above, the driving device body20includes the brake mechanism (motor brake unit50) for braking the rotation transmitted to the drive gear drive gear or the rotation output from the drive gear24a. The abnormality detection unit80monitors the operation of the brake mechanism50. That is, the abnormality detection unit detects a state in which the operation of the drive gear24aand the ring gear107at the meshing portion is unintentionally restricted due to an abnormal operation of the brake mechanism50, and it is avoided that the driving force is output from the drive gear24ato the ring gear107while the abnormality is being detected. Therefore, it can be effectively prevented in advance that an excessive external force is applied on the meshing portion and that the control current of the driving device10becomes excessive. Consequently, it is possible to effectively avoid damage to the driving device, ring gear and the like.

Further, in the embodiment described above, the driving device body20includes the brake mechanism (motor brake unit50) for braking the rotation transmitted to the drive gear24aor the rotation output from the drive gear24a. When the abnormality detection unit80detected an abnormality, a brake on the rotation performed by the brake mechanism (motor brake unit50) is removed. In the driving device10configured as described above, it is possible avoid that an excessive external force is applied to the meshing portion while the operation of the drive gear24aand the ring gear107at the meshing portion is restricted by the brake mechanism50without the control current becoming excessive. Consequently, it is possible to effectively avoid damage to the driving device, ring gear and the like.

In the embodiment described above, the driving device10includes the drive gear24athat is provided in one structure at the movable section of the wind turbine101and meshes with the ring gear107provided in the other structure at the movable section, the driving device body20that has the brake mechanism (motor brake unit50) for braking rotation transmitted to the drive gear24aor rotation output from the drive gear24a, and the abnormality detection unit80that monitors the operation of the brake mechanism50. When the abnormality detection unit80detected an abnormality, the output from the drive gear24ain the driving device body20to the ring gear107is stopped. In the driving device10, the abnormality detection unit80can detect a state in which a brake is applied on the rotation of the drive gear24aby the brake mechanism50due to an abnormality occurred in the brake mechanism. That is, the abnormality detection unit80can detect a state in which the operation at the meshing portion between the drive gear24aand the ring gear107is restricted. Moreover, the output of the driving force from the driving device body20is stopped (restricted) when the abnormality is detected, so breakage of the driving device10and damage to the ring gear107and its surrounding structure can be effectively avoided regardless of whether the control current of the driving device10becomes excessive or not. Further, if the output of the driving force from the driving device body20is started while the operation of the meshing portion is restricted, the driving device10and the ring gear107may be instantaneously damaged. The driving device10described above is able to detect the restricted state of the meshing portion between the drive gear24aand the ring gear107caused by the abnormality of the brake mechanism50while the output of the driving force from the driving device body20is stopped. Since the abnormality detection unit80detects an abnormality in the state where the output of the driving force from the driving device body20is stopped, it is possible to effectively copes with instantaneous damage of the driving device10, the ring gear107, and the like.

Moreover, in the above embodiment, when the abnormality detection unit80detected an abnormality, a brake on the rotation performed by the brake mechanism (motor brake unit50) is removed. In the above driving device10, the abnormality detection unit80can detect a state in which movement of the meshing portion is unintentionally restricted due to the abnormality of the brake mechanism50, and this unintended restriction can be eliminated. Accordingly, it is possible to effectively avoid that an excessive external force is applied to the meshing portion between the drive gear24aand the ring gear107while the movement thereof is unintentionally restricted and consequently the driving device10, the ring gear107and the like are damaged without the excessive control current.

Furthermore, in the embodiment described above, the wind turbine101and the driving device unit9include the plurality of driving devices10provided in the single movable section. The abnormality detection unit80is separately provided for each driving device10. In the wind turbine101and the driving device unit9, a driving force output from the drive gear24aof one driving device10to the ring gear107acts as an external force to the meshing portion between the ring gear107and the drive gear24aof other driving device10whose movement is restricted by the brake mechanism50. Further, a braking force that constrains the movement of the drive gear24aand the ring gear107by the brake mechanism50of one driving device10serves as an external force applied to the meshing portion between the ring gear107and the drive gear24aof other driving device10outputting the driving force. When one abnormality detection unit80detected an abnormality in the wind turbine101and the driving device unit9described above, in addition to stopping the output of the driving force to the ring gear107from the drive gear24aof the driving device10in which this abnormality detection unit80is provided, it is configured to stop the output of the driving force to the ring gear107from the drive gear(s)24ain the driving device(s)10other than the driving device10in which the abnormality detection unit80is provided. Thus the advantageous effects described above will be notably exerted and it is possible to effectively avoid damage to the driving devices10, the ring gear107and the like.

Furthermore, in the embodiment described above, the wind turbine101and the driving device unit9include the plurality of driving devices10provided in the single movable section. The abnormality detection unit80is separately provided for each driving device10. In the wind turbine101and the driving device unit9, a driving force output from the drive gear24aof one driving device10to the ring gear107acts as an external force to the meshing portion between the ring gear107and the drive gear24aof other driving device10whose movement is restricted by the brake mechanism50. Further, the force that constrains the movement of the drive gear24aand the ring gear107by the brake mechanism50of one driving device10serves as an external force applied to the meshing portion between the ring gear107and the drive gear24aof other driving device10outputting the driving force. In the wind turbine101and the driving device unit9described herein, when one abnormality detection unit80detected an abnormality, a brake by the brake mechanism50on the rotation is released in the driving device10provided with the abnormality detection unit80, and a brake by the brake mechanism(s)50is released also in the driving device(s)10other than the driving device10in which the abnormality detection unit80detected the abnormality is provided. Thus the advantageous effects described above will be notably exerted and it is possible to effectively avoid damage to the driving devices10, the ring gear107and the like.

Various modifications can be made to the foregoing embodiment. The following describes one modification example. In the following description, elements that can be configured in a similar manner to those in the foregoing embodiment are denoted by the same reference characters as those used for corresponding elements in the foregoing embodiment, and duplicate descriptions thereof are omitted.

For example, in the embodiment described above, the abnormality detection unit80includes the load sensor81, the oil sensor82, and the brake mechanism sensor83. However, the invention is not limited to the above-described example, and the abnormality detection unit80may include one or more selected from the group consisting of the load sensor81, the oil sensor82, and the brake mechanism sensor83. Alternatively the abnormality detection unit80may include other sensor in addition to one or more selected from the group consisting of the load sensor81, the oil sensor82, and the brake mechanism sensor83. As the other sensor, for example, an anemometer may be used. The abnormality detection unit80may further include an anemometer that detects the degree of gust that may act on the meshing portion as an external force, and when the wind speed measured by the anemometer reaches a predetermined value or more, output of the drive force from the drive gear24aof the driving device body20to the ring gear107may be stopped. In addition, when the wind speed measured by the anemometer reaches the predetermined value or more, a brake by the brake mechanism50on the rotation may be released.

Further, the abnormality detection unit80may include a sensor that monitors the control current of the electric motor23. That is, when the control current of the electric motor23becomes excessive, the output of the driving force from the drive gear24aof the driving device body20to the ring gear107may be stopped. Further, when the control current of the electric motor23becomes excessive, a brake the brake mechanism50on the rotation may be released.

Furthermore, configuration of the load sensor81, the oil sensor82and the brake mechanism sensor83described above may be changed as appropriate. For example, the load sensor81is not limited to the sensor that detect the state quantity of the fastener30but may be any type of sensor capable of detecting any state quantity varying depending on a magnitude of a “load between the drive gear24aand the ring gear107.” For example, a sensor capable of measuring an amount of a force acting on the reducer25(for example, a sensor for detecting a distortion generated in the reducer25) can be installed in the reducer25of each of the driving devices10and this sensor may be used as the load sensor81.

Furthermore, in the above-described embodiment, an example is described in which the output of the driving force is stopped by stopping the power supply to the motor23when the abnormality detection unit80detected an abnormality. For example, a clutch mechanism85(seeFIG. 4) may be provided between the electric motor23and the reducer25to switch between power transmission and shutoff. When an abnormality is detected, the clutch mechanism85may be released to interrupt the power transmission to the reducer25from the electric motor23, and thereby the output of the driving force from the drive gear24ato the ring gear107may be stopped.

Furthermore, in the embodiment described above, the brake mechanism is configured as the motor drive unit48that is incorporated in the electric motor23and brakes the rotation of the drive shaft48aof the motor drive unit48. However, the invention is not limited to this, and the brake mechanism may be a mechanism that brakes the rotation of one or more selected from the group consisting of any component of the reducer25, the output shaft24, and the drive gear24a.

Furthermore, in the above-described embodiment, a brake by the brake mechanism50on rotation is released when the abnormality detection unit80detected an abnormality. However the invention is not limited thereto. Alternatively, the interlocking between the component whose rotation is braked by the brake mechanism50and the drive gear24amay be released when the abnormality detection unit80detected an abnormality. Specifically, in the above-described embodiment, the clutch mechanism85(seeFIG. 4) may be provided between the drive shaft48aand the drive gear24awhose rotation is braked by the motor brake unit50, and the interlock between the drive shaft48aand the drive gear24amay be released when an abnormality is detected. Even in the above-described modification example, it is possible to achieve the same advantageous effects as those in the above embodiment.