JP2020029775A - Water turbine blade attaching structure of hydraulic generating apparatus - Google Patents

Abstract

To provide a water turbine blade attaching structure capable of preventing deterioration in strength caused by creep deformation and fretting wear in a hub of a water turbine blade when the water turbine blade made of a fiber-reinforced plastic material receives a variable load from flowing water.SOLUTION: A hydraulic generating apparatus includes water turbine blades 1 formed of a fiber-reinforced plastic material, and a power generator for generating power by receiving the rotation of the water turbine blades. A water turbine shaft 20 is inserted into a through-hole 50 of the water turbine blades 1. A pair of flange members 51 and 52 are disposed on both side faces of a hub 10 of the water turbine blades 1. The hub 10 and the flange members 51 and 52 are fastened by a bolt 53. The flange members 51 and 52 are attached to the water turbine shaft 20. A fastening force holding member 55 longer than an axial width of the hub 10, both ends of which are brought into contact with the flange members 51 and 52 by the fastening of the bolt 53 is interposed between an inner circumference face of a bolt hole 10a of the hub 10 and an outer peripheral face of the bolt 53.SELECTED DRAWING: Figure 3

Description

  TECHNICAL FIELD The present invention relates to a turbine blade mounting structure of a hydraulic power generation device that includes a turbine blade made of a fiber-reinforced plastic material and is installed in a water channel to generate power with water power.

  The hydraulic power generator includes a water turbine blade that converts water energy into rotational energy, and a generator that converts rotational energy into electric energy. In addition, as necessary, a gearbox for increasing the speed of rotation of the turbine blade and transmitting the rotation to the generator, a control device for controlling the generator, and the like are provided.

  When a turbine blade of a small-output hydroelectric generator is made of a fiber-reinforced plastic material and is attached to a turbine shaft serving as an input shaft of a gearbox, a turbine blade mounting structure shown in FIG. 10 has conventionally been adopted. In this turbine blade mounting structure, first, both side surfaces of the hub 10 of the water turbine blade 1 are sandwiched between a pair of flange members 51 and 52, and the pair of flange members 51 and 52 and the hub 10 are fastened and fixed with bolts 53. Then, an assembly including the water turbine blade 1 and the pair of flange members 51 and 52 is attached to the water turbine shaft 20 at the flange members 51 and 52 so as to be axially immovable and non-rotatable. When the water turbine blade 1 rotates under the force of water, the rotational torque is transmitted to the flange members 51 and 52 by frictional force, and the water turbine shaft 20 rotates.

  Patent Literature 1 relates to a vertical shaft type hydroelectric power generator, and describes that a vertical rotating shaft and three blades are fastened and fixed using bolts and nuts.

JP 2017-8927 A

  In a hydroelectric generator installed in a water channel, turbine blades receive various fluctuating loads from flowing water. For example, it receives a fluctuating load due to a change in the velocity of flowing water. When the turbine blade is a propeller turbine whose rotation axis is parallel to the direction of water flow, if the upper part of the turbine blade rises above the water surface due to a decrease in the water level of the water channel, the blades will rotate with the rotation of the turbine blade. By repeating the state of submerging in water and the state of coming out of water, a large alternating load is received.

  The water level of the canal decreases when the amount of precipitation is small or when the water in the canal is used for irrigation. In addition, when heavy rains are expected during the rainy season, typhoons, etc., the flow rate of the waterway may be limited in order to avoid overflow from the waterway.

  As shown in FIG. 10, when the turbine blade 1 receives the variable load F1, the blade bends in the load direction, and the bending is transmitted to the hub 10 from the root of the blade. Then, the hub 10 sandwiched between the flange members 51 and 52 on both sides continuously receives the compressive force F2 from both the flange members 51 and 52. As a result, the hub 10 is creep-deformed and the axial width is reduced, the bolt 53 connecting the turbine blade 1 and the flange members 51 and 52 is loosened, and the tightening force is reduced.

  Further, a gap is formed between the hub 10 and the flange members 51 and 52 due to the alternating load, or the gap is closed, so that fretting wear or the like is generated on the contact surface of the hub 10 with the flange members 51 and 52. May cause. A resin material of a fiber reinforced plastic material, for example, a vinyl ester resin, is superior in water resistance to an unsaturated polyester resin, and hardly deteriorates in strength even in contact with water. On the other hand, the fiber material of the fiber reinforced plastic material leads to deterioration in strength due to contact with water. Since the outer skin of the turbine blade is made of a resin material, the decrease in strength is not promoted even when it comes into contact with water. However, if fretting wear or the like occurs on the hub 10, the fiber material of the turbine blade comes into contact with water from that portion, and This leads to a decrease in the strength of the wing 1.

  If the water turbine blade 1 is made of a metal material, creep deformation and fretting wear of the hub 10 can be prevented. However, if it is attempted to secure the same strength with a metal material as when using a fiber-reinforced plastic material, the weight of the water turbine blade 1 increases. Therefore, it is necessary to increase the rigidity of the gear supporting the water wheel axle 20, which increases the cost.

  It is also conceivable that the water turbine blade 1 is made of a relatively lightweight aluminum material. However, since steel is mainly used for the water wheel axle 20 and the gearbox, if the turbine wheel 1 is made of aluminum, aluminum and steel, which are dissimilar metals, will be immersed in water, and electric erosion will occur. Can occur. Therefore, it is difficult to apply aluminum.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic power turbine capable of preventing strength deterioration caused by creep deformation and fretting wear of a hub of a turbine blade when the turbine blade made of fiber-reinforced plastic material receives a fluctuating load from running water. An object of the present invention is to provide a turbine blade mounting structure for a power generator.

A turbine blade mounting structure for a hydraulic power unit according to the present invention is a hydraulic power unit including a turbine blade made of a fiber-reinforced plastic material, and a generator that generates electric power by rotating the turbine blade. A water turbine wing mounting structure that is mounted so as to rotate integrally with the axle,
The turbine blade has a solid hub in the center, and the turbine shaft is inserted through a through hole provided in the hub,
A pair of flange members are arranged on both side surfaces of the hub, bolts are inserted through bolt holes provided in the hub and the pair of flange members, and the hub and the pair of flange members are fastened by the bolts.
The pair of flange members are attached to the water wheel axle,
Between the inner peripheral surface of the bolt hole of the hub and the outer peripheral surface of the bolt, the length is shorter than the axial width of the hub, and both ends abut against the pair of flange members by tightening the bolt. It is characterized in that an urging member is interposed.

  According to this configuration, when the bolts for fastening the hub and the pair of flange members are tightened, the hub is elastically deformed and its axial width is reduced, so that both ends of the fastening force holding member contact the pair of flange members. Touch In this state, when the turbine blade receives a fluctuating load and a compressive force acts on the center of the turbine blade from the pair of flange members, the tightening force holding member receives the compressive force, and a large compressive force is applied to the hub. This prevents creep deformation of the hub. As described above, by preventing the creep deformation of the hub, it is possible to prevent the bolt from being loosened and to prevent a decrease in the tightening force between the hub and the flange member.

  Also, since the tightening force between the hub and the flange member is secured, even if an alternating load is applied to the turbine blade, there is no gap between the hub and the flange member, and the gap is not closed. Fretting wear does not occur on the contact surface of the hub with the flange member. Therefore, penetration of water into the fiber reinforced plastic material of the turbine blade is suppressed, and a decrease in the strength of the turbine blade due to deterioration of the material of the fiber reinforced plastic material can be prevented.

In this invention, it is preferable that the pair of flange members have the same thickness in the length direction of the bolt and the same contact area with the hub.
In this case, since the magnitude of the compressive force received from the flange members on both sides by the hub can be made substantially the same, an even frictional force acts between the hub and each flange member, and the balance is good.

In the present invention, it is preferable that a chamfer is provided at an edge of a contact surface of the flange member with the hub.
When the chamfered portion is provided, edge load is reduced, and occurrence of fretting wear can be prevented.

  The water turbine blade mounting structure of the hydraulic power generator according to the present invention is suitable for a case where the water turbine blade is a propeller turbine having a plurality of blades. In particular, the water turbine blade, which is the propeller turbine, is suitable for a case where the rotation axis is parallel to the water flow direction. In any case, since the turbine blade receives a large fluctuating load, the effect of adopting the turbine blade mounting structure of the present invention is large.

  A turbine blade mounting structure for a hydraulic power generator according to the present invention is a hydraulic turbine including a turbine blade made of a fiber-reinforced plastic material and a generator configured to generate power by receiving rotation of the turbine blade. A turbine impeller mounting structure that is mounted so as to rotate integrally with an axle, wherein the turbine impeller has a solid hub at a central portion, and the water turbine axle is inserted into a through hole provided in the hub. A pair of flange members are disposed on both side surfaces of the hub, bolts are inserted through bolt holes provided in the hub and the pair of flange members, and the hub is fastened to the pair of flange members by the bolts. A pair of flange members are attached to the water wheel axle, and between the inner peripheral surface of the bolt hole of the hub and the outer peripheral surface of the bolt, the length is shorter than the axial width of the hub. Due to the presence of a clamping force holding member whose both ends abut the pair of flange members by tightening the bolt, the turbine blade receives a fluctuating load from running water, and the hub of the turbine blade undergoes creep deformation and fretting wear. It is possible to prevent a reduction in strength that occurs.

FIG. 1 is a front view of a hydraulic power generation device to which a water turbine blade mounting structure according to a first embodiment of the present invention is applied. It is a side view of the same hydroelectric generator. FIG. 3 is a side view showing a main part of FIG. 2, and a part is shown in a cross section. It is the elements on larger scale of FIG. It is sectional drawing of the hub of a water turbine blade, and a clamping force holding member. It is sectional drawing which shows the water turbine blade mounting structure which concerns on 2nd Embodiment of this invention. 7A is an enlarged view of a VIIA portion in FIG. 6, and FIG. 7B is an enlarged view of a VIIB portion in FIG. It is sectional drawing which shows the water turbine blade mounting structure which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the water turbine blade mounting structure which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the conventional water turbine blade attachment structure.

[First Embodiment]
<Hydroelectric generator>
FIG. 1 and FIG. 2 are a front view and a side view of a hydroelectric power generator to which the turbine blade mounting structure according to the first embodiment is applied. This hydraulic power generation device is installed in a water channel to generate power using water power, and includes a water turbine blade 1, a speed increaser 2, a generator 3, and a support device 4. In addition, a control device (not shown) for controlling the generator 3 is provided.

  The water turbine blade 1 is a propeller turbine in which a plurality of (for example, five) blades 11 extend radially from an outer periphery of a hub 10 located at a central portion, and a rotation axis O is parallel to a direction A of a water flow in a water channel. Is provided. The tip of each blade 11 is inclined toward the upstream side. The hub 10 and the blade 11 are formed integrally. A spinner 12 is mounted on the front surface of the hub 10 on the upstream side. These hub 10, blade 11 and spinner 12 are made of fiber reinforced plastic material.

  The speed increaser 2 speeds up the rotation of the turbine blade 1. A water wheel shaft 20 serving as an input shaft of the gearbox 2 projects upstream from the gearbox 2, and the water turbine blade 1 is fixed to the water wheel shaft 20 so as to rotate integrally therewith.

  As shown in FIG. 3, the speed increasing mechanism 21 of the speed increasing device 2 includes a pair of bevel gears 22 and 23 that mesh with each other. The input-side bevel gear 22 is attached to the water wheel 20 and the output-side bevel gear 23 is attached to a rotation transmission shaft 24 extending in the vertical direction. The rotation transmission shaft 24 is a shaft that transmits the torque increased by the gearbox 21 to the generator 3, and is provided inside the support 25. As shown in FIG. 2, the support column 25 has an upper end fixed to the support device 4 and a lower end supporting the gearbox 2.

  In FIG. 2, the generator 3 has a generator shaft 30 extending downward, and the generator shaft 30 is connected to the rotation transmission shaft 24 via a rotation connection tool 31. As a result, the rotation of the water turbine blade 1 is accelerated by the speed increaser 2 and transmitted to the generator 3 so that the generator 3 generates power. The generator 3 is, for example, a three-phase AC generator.

  As shown in FIGS. 1 and 2, the support device 4 includes two beams 40 provided between the side walls 5 on both sides of the water channel, and a gantry 41 mounted on the beams 40. It has two generator stands 42 installed on the gantry 41 and a base plate 43 provided so as to connect the upper portions of the two generator stands 42. The generator 3 is arranged between the gantry 41 and the base plate 43 and is fixed to the base plate 43.

<Water turbine blade mounting structure>
The mounting structure of the water turbine blade 1 to the water shaft 20 will be described.
As shown in FIG. 3, the water wheel axle 20 has a large-diameter portion 20a protruding upstream (left side in FIG. 3) from the gearbox 2, and a small-diameter portion 20b extending upstream from the tip of the large-diameter portion 20a. And a male screw 20c is formed on the outer peripheral surface of the small-diameter portion 20b except for the base end.

In the water turbine blade 1, a pair of annular flange members 51, 52 are fastened and fixed by bolts 53 to both the upstream and downstream sides of the hub 10. The hub 10 has a cylindrical shape having a through hole 50 at the center, and is formed solid.
The upstream flange member 51 has a smaller inner diameter than the through hole 50 of the hub 10 and can be fitted to the small diameter portion 20 b of the water wheel shaft 20. The downstream flange member 52 has a cylindrical portion 54 whose inner peripheral surface can be fitted to the large diameter portion 20 a of the water wheel shaft 20 and whose outer peripheral surface can be fitted to the through hole 50 of the hub 10.

  As shown in FIG. 4, the bolt 53 is inserted through the bolt holes 10a, 51a, 52a provided in the hub 10 and the pair of flange members 51, 52 of the turbine blade 1. In the case of this embodiment, the bolt hole 52a of the downstream flange member 52 is a screw hole, and the screw portion 53a of the bolt 53 inserted into the bolt hole 51a, 10a from the upstream side is inserted into the screw hole 52a. By screwing, the water turbine blade 1 and the pair of flange members 51 and 52 are fastened. The bolt hole 52a of the downstream flange member 52 is not a screw hole, but a nut (not shown) is screwed into a screw portion 53a of a bolt 53 that penetrates the bolt hole 52a. The members 51 and 52 may be fastened.

  The bolt hole 10 a of the hub 10 has a larger inner diameter than the bolt holes 51 a and 52 a of the flange members 51 and 52, and a clamping force holding member 55 is provided between the inner peripheral surface of the bolt hole 10 a of the hub 10 and the outer peripheral surface of the bolt 53. Is interposed. The fastening force holding member 55 is made of a material that has a higher hardness than the fiber-reinforced plastic material of the water turbine blade 1 and is hardly rusted in water, for example, a metal material such as stainless steel (SUS304). The fastening force holding member 55 of this embodiment has a cylindrical shape that fits inside the bolt hole 10a.

As shown in FIG. 5, the length of the tightening force holding member 55 is slightly shorter than the axial width of the hub 10. Specifically, the length of the fastening force holding member 55 is determined as follows. That is, when the length of the tightening force holding member 55 is 1 and the axial width of the hub 10 is L,
l = L-dl (Equation 1)
Holds. Here, dl is the displacement amount of the upper limit of the elastic deformation of the hub 10. Although the size of dl is exaggerated in FIG. 5, the actual size of dl is so small that it is difficult to visually recognize it.

  The fastening force holding member 55 may be simply fitted to the inner peripheral surface of the bolt hole 10a of the hub 10, but may be fixed by an adhesive. When the fastening force holding member 55 is fixed with an adhesive, the fastening force holding member 55 may be fixed such that the fastening force holding member 55 is located at the center of the bolt hole 10a as shown in FIG.

A method of attaching the turbine blade 1 to the water shaft 20 will be described.
First, flange members 51 and 52 are fastened to both sides of the hub 10 with bolts 53 on the water turbine blade 1 in which the tightening force holding members 55 are fitted into the bolt holes 10a of the hub 10 as shown in FIG. Assemble. As shown in FIG. 3, this assembly is attached to the water wheel axle 20 with the water wheel axle 20 inserted through the through hole 50 of the hub 10.

  Specifically, the upstream flange member 51 is fitted to the base end of the small diameter portion 20b of the water wheel shaft 20, and the cylindrical portion 54 of the downstream flange member 52 is fitted to the large diameter portion 20a of the water wheel shaft 20. Combine. Then, the upstream flange member 51 is brought into contact with the stepped surface 20d of the large diameter portion 20a and the small diameter portion 20b, and the upstream flange member 51 is screwed to the male screw 20c of the small diameter portion 20b. Attached so that it cannot move in the axial direction with respect to 20. Further, by engaging the key 57 with the key groove provided in the large diameter portion 20 a of the water wheel shaft 20 and the cylindrical portion 54 of the downstream flange member 52, the downstream flange member 52 is rotated to the water wheel shaft 20. Attach impossible.

<Operation of the turbine blade mounting structure>
When the bolt 53 for fastening the hub 10 to the pair of flange members 51 and 52 is tightened, the hub 10 is elastically deformed and its axial width is reduced, so that both ends of the fastening force holding member 55 are connected to the pair of flange members. Abuts 51 and 52. In this state, when the turbine blade 1 receives a fluctuating load and a compressive force acts on the central portion of the turbine blade 1 from the pair of flange members 51 and 52, the tightening force holding member 55 receives the compressive force. Since a large compressive force is not applied to the hub 10, creep deformation of the hub 10 is prevented. Thus, by preventing creep deformation of the hub 10, the bolt 53 can be prevented from being loosened, and a decrease in the tightening force between the hub 10 and the flange members 51, 52 can be avoided.

  When the length 1 of the tightening force holding member 55 is set to a length that satisfies Expression 1, the hub 10 is deformed to the upper limit of elastic deformation while the bolt 53 is tightened. Therefore, the bolt 53 is firmly tightened, and the bolt 53 is more difficult to be loosened.

  Note that the tightening force holding member 55 may have any shape and size capable of enhancing the tightening force of the bolt 53 by setting the dimensional relationship of Expression 1, and need not necessarily be cylindrical. For example, a member having a U-shaped or groove-shaped cross section may be used.

  Further, since the tightening force between the hub 10 and the flange members 51 and 52 is secured, even if an alternating load acts on the water turbine blade 1, a gap is formed between the hub 10 and the flange members 51 and 52, The gap does not close and fretting wear does not occur on the contact surface of the hub 10 with the flange members 51 and 52. Therefore, permeation of water into the fiber reinforced plastic material of the turbine blade 1 is suppressed, and a decrease in strength due to deterioration of the material of the turbine blade 1 can be prevented.

When the tightening force holding member 55 is fixed to the inner peripheral surface of the bolt hole 10a of the hub 10 by an adhesive, the inner circumferential surface of the bolt hole 10a due to the movement of the tightening force holding member 55 in the bolt hole 10a. The damage of is suppressed. Thereby, the permeation of water from the inner peripheral surface of the bolt hole 10a to the inside of the fiber reinforced plastic material is also suppressed.
When the fastening force holding member 55 is fixed by an adhesive as shown in FIG. 5, when the fastening force holding member 55 is fixed to the center of the bolt hole 10a, the elastic deformation of the hub 10 due to the tightening of the bolt 53 causes the shaft to be deformed. This is preferable because the operations are performed equally on both sides of the direction.

  As described above, the penetration of water into the fiber reinforced plastic material of the water turbine blade 1 is suppressed, so that it is not necessary to use an expensive fiber reinforced plastic material having high water resistance. Further, since the tightening force holding member 55 is cylindrical, not only the processing of the tightening force holding member 55 itself, but also the processing of the bolt hole 10a is easy. Therefore, it is possible to prevent the strength of the turbine blade 1 from being reduced at low cost.

  Further, since the fastening force holding member 55 is interposed between the inner peripheral surface of the bolt hole 10a of the hub 10 and the outer peripheral surface of the bolt 53, the bolt 53 does not contact the inner peripheral surface of the bolt hole 10a. Therefore, even if the thrust direction fluctuating load which the water turbine blade 1 receives from water is generated, it is possible to prevent abrasion of the inner peripheral surface layer portion of the bolt hole 10a. As a result, permeation of water into the fiber reinforced plastic material, which is the material of the turbine blade 1, is suppressed, and a decrease in strength due to deterioration of the material of the turbine blade 1 can be prevented.

[Second embodiment]
FIG. 6 shows a second embodiment of the water turbine blade mounting structure. In this turbine blade mounting structure, a pair of flange members 51 and 52 fastened to the hub 10 of the turbine blade 1 have the same axial width and the same contact area with the hub 10. As shown in FIGS. 7A and 7B, chamfers 61 and 62 having an arc-shaped cross section are provided at the edges of the contact surfaces of the flange members 51 and 52 with the hub 10. The chamfers 61 and 62 may have other cross-sectional shapes. For example, a curve shape such as a quadratic curve may be used. In some cases, the shape may be a linear cutout.

  As described above, when the pair of flange members 51 and 52 have the same axial width and the same contact area with the hub 10, the magnitude of the compressive force that the hub 10 receives from the flange members 51 and 52 on both sides is large. Since the heights can be made substantially the same, a uniform frictional force acts between the hub 10 and each of the flange members 51 and 52, and the balance is good. Further, if the chamfered portions 61 and 62 are provided at the edges of the contact surfaces of the flange members 51 and 52 with the hub 10, the edge load can be reduced, and the occurrence of fretting wear can be prevented.

[Third Embodiment]
In the first embodiment (FIG. 4) and the second embodiment (FIG. 6), the screw portion 53a of the bolt 53 does not overlap the bolt hole 10a of the hub 10 in the axial direction, but the third embodiment shown in FIG. As in the embodiment, a part of the screw portion 53a of the bolt 53 may overlap the bolt hole 10a of the hub 10 in the axial direction. In this case, since the screw portion 53a of the bolt 53 is screwed into the entire axial direction of the bolt hole 52a, which is a screw hole, a large fastening force is obtained.

[Fourth embodiment]
However, when a part of the screw portion 53a of the bolt 53 overlaps the bolt hole 10a of the hub 10 in the axial direction as shown in FIG. 8, the screw portion 53a comes into contact with the tightening force holding member 55 to maintain the tightening force. There is a concern that the member 55 will be worn. In order to prevent such abrasion of the tightening force holding member 55, it is preferable to configure as shown in FIG. In the fourth embodiment shown in FIG. 9, a recess 58 having a circular cross section that extends to the outer periphery of the bolt hole 52 a is provided on the axially inner side surface of the flange member 52 on the downstream side. Is fitted at the upstream end. The screw portion 53a of the bolt 53 is screwed into a bolt hole 52a which is a screw hole. The proximal end position of the screw portion 53a is within the axial range of the recess 58 or the bolt hole 52a. That is, the threaded portion 53a of the bolt 53 is located outside the water turbine blade 1 in the axial direction. Thereby, a part of the screw portion 53 of the bolt 53 does not come into contact with the fastening force holding member 55, and wear of the fastening force holding member 55 is reduced.

  Each of the above embodiments shows a turbine blade mounting structure applied to a hydraulic power generator in which the turbine blade 1 is a propeller turbine and the axis of rotation O of which is parallel to the direction of the water flow. Can be applied even when the rotation axis O is not parallel to the water flow direction. Further, the present invention can be applied to a hydraulic power generator in which the turbine blade 1 is not a propeller turbine.

  The embodiments for carrying out the present invention have been described based on the embodiments. However, the embodiments disclosed herein are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 ... Water turbine blade 3 ... Generator 10 ... Hub 10a, 51a, 52a ... Bolt hole 11 ... Blade 20 ... Water wheel shaft 50 ... Through hole 51, 52 ... Flange member 53 ... Bolt 55 ... Tightening force holding members 61, 62 ... Chamfer O: Rotary axis

Claims (5)

In a hydroelectric power generator including a turbine blade made of a fiber-reinforced plastic material and a generator for generating electric power by receiving rotation of the turbine blade, the turbine blade is mounted so that the turbine blade is integrally rotated with respect to the turbine shaft. Structure,
The turbine blade has a solid hub in the center, and the turbine shaft is inserted through a through hole provided in the hub,
A pair of flange members are arranged on both side surfaces of the hub, bolts are inserted through bolt holes provided in the hub and the pair of flange members, and the hub and the pair of flange members are fastened by the bolts.
The pair of flange members are attached to the water wheel axle,
Between the inner peripheral surface of the bolt hole of the hub and the outer peripheral surface of the bolt, the length is shorter than the axial width of the hub, and both ends abut against the pair of flange members by tightening the bolt. A water turbine blade mounting structure for a hydraulic power generator, wherein an urging member is interposed.   2. The hydraulic structure according to claim 1, wherein the pair of flange members have the same thickness in the length direction of the bolt and the same contact area with the hub. 3. Turbine blade mounting structure for power generator.   3. The turbine blade mounting structure for a hydraulic power generator according to claim 1, wherein a chamfered portion is provided at an edge of a contact surface of the flange member with the hub. 4.   The turbine blade mounting structure for a hydraulic power plant according to any one of claims 1 to 3, wherein the turbine blade is a propeller turbine having a plurality of blades.   The turbine blade mounting structure for a hydraulic power plant according to claim 4, wherein the turbine blade serving as the propeller turbine has a rotation axis parallel to a water flow direction.

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