JP7822987B2 - Sediment inflow control devices and hydraulic machinery - Google Patents

Description

Embodiments of the present invention relate to sediment inflow prevention devices and hydraulic machinery.

Figure 9 is an elevational cross-sectional view of a conventional hydraulic machine. Figure 10 is an elevational cross-sectional view of the back pressure chamber formed by the upper part of the runner and the upper cover of a conventional hydraulic machine. Figures 9 and 10 show the general configuration of a Francis turbine as an example of a conventional hydraulic machine.

In a Francis turbine, water generally flows from an upper reservoir (not shown) through an iron pipe (not shown), a circular cylindrical casing 21, stay vanes 22 arranged on the inner periphery of the casing 21, and guide vanes 23 that adjust the flow rate, before being directed to the runner 12. After performing work in the runner 12, the water flows through a draft pipe 26 and is directed to a lower reservoir (not shown).

The runner 12 is directly connected to the main shaft 11, which rotates around the rotation axis CL. An upper cover 24 is disposed above the runner 12 so as to face the upper surface of the runner 12 and cover the upper surface of the runner 12. Furthermore, a lower cover 25 is disposed below the runner 12 so as to face the lower surface of the runner 12 and cover the lower surface of the runner 12.

The runner 12 and upper cover 24 form a gap called the back pressure chamber 27. Furthermore, the runner 12 and lower cover 25 form a gap called the lateral pressure chamber 28. A portion of the water flowing into the runner 12 from the guide vane 23 flows as a bypass flow into the back pressure chamber 27 and lateral pressure chamber 28, before joining the water flowing out of the runner 12. Therefore, the back pressure chamber 27 and lateral pressure chamber 28 serve as bypass flow paths in which a portion of the working water flowing in from the guide vane 23 flows parallel to the main flow of working water flowing into the runner 12. The bypass flow through these bypass flow paths is directed to the draft pipe 26 without performing work in the runner 12. A high bypass flow rate reduces the efficiency of the hydromachine.

In the case of the back pressure chamber 27, the bypass flow enters the back pressure chamber 27 from the back pressure chamber inlet 27a and flows out radially inward from the runner seal 27b (Figure 10), which is formed to restrict the amount of water flow passing through the back pressure chamber 27. It then passes through multiple balance holes 12h (Figure 10) provided in the runner 12 to reduce axial thrust, and flows out into the draft pipe 26.

Japanese Patent Application Publication No. 9-4556 Japanese Utility Model Application Laid-Open Publication No. 6-40372 Special Publication No. 63-3433

In hydraulic machinery that uses sediment-rich water, the bypass flow that flows into the back pressure chamber 27 and side pressure chamber 28 is also sediment-rich water. As a result, the runner 12, upper cover 24, and lower cover 25 are subject to sediment wear due to this sediment-rich water.

Sediment in the bypass flow that flows into the back pressure chamber 27 also flows into the runner seal 27b due to the pressure difference between the inlet and outlet of the runner 12. This causes the parts that make up the runner seal 27b to wear, increasing the gap, increasing water leakage from this part, and ultimately reducing the efficiency of the hydraulic machinery.

Similarly, the sediment in the bypass flow that flows into the side pressure chamber 28 also flows into the runner seal 28b due to the pressure difference between the inlet and outlet of the runner 12. This causes the parts that make up the runner seal 28b to wear, increasing the gap, increasing water leakage from this part, and ultimately reducing the efficiency of the hydraulic machinery.

To date, measures to address this issue with the back pressure chamber 27 and side pressure chamber 28 have included increasing the thickness of the parts subject to wear, periodically replacing the parts subject to wear, or repairing and continuing to use these parts. However, these measures have the problem of reducing the operating efficiency of the hydraulic machinery.

The object of the present invention is to provide a sediment inflow prevention device and hydraulic machine that can reduce sediment wear, particularly in the back pressure chamber, thereby improving efficiency and operating rate, even in hydraulic machines that use water containing a large amount of sediment as working fluid.

In order to achieve the above-mentioned object, the sediment inflow prevention device of this embodiment is a sediment inflow prevention device for a hydraulic machine having a runner that is directly connected to a main shaft extending vertically and rotates around a rotation axis by working water containing sediment, and is characterized in that it comprises a crown that connects the upper parts of the runner blades of the runner, an upper cover that is arranged to cover the upper surface of the runner, which is the upper surface of the crown, and forms a back pressure chamber between itself and the runner upper surface, and a sediment prevention wall that is attached to the lower surface of the upper cover of the upper cover inside the back pressure chamber so as to divide the back pressure chamber into a radially inner region and a radially outer region, and forms a radial flow path between itself and the runner upper surface , and the sediment prevention wall is characterized in that it is either mesh-shaped, lattice-shaped, or porous .

1 is a partial cross-sectional elevation view showing a hydraulic machine including a sediment inflow prevention device according to a first embodiment. 4 is a partial cross-sectional view schematically showing the flow of a bypass flow in a back pressure chamber for explaining the operation of the sediment inflow suppression device according to the first embodiment. FIG. 5 is a graph showing the radial velocity distribution of a bypass flow in a back pressure chamber near an upper surface of a runner, for explaining the operation of the sediment inflow prevention device according to the first embodiment. FIG. 10 is a partial cross-sectional elevation view showing a sediment control wall of a hydraulic machine according to a second embodiment. FIG. 11 is a circumferential development view showing a sediment control wall of a hydraulic machine according to a third embodiment. FIG. 10 is a cross-sectional elevation view showing a sediment inflow prevention device for a hydraulic machine according to a fourth embodiment. FIG. 10 is a cross-sectional elevation view showing a sediment inflow prevention device for a hydraulic machine according to a fifth embodiment. FIG. 10 is a cross-sectional elevation view showing a modified example of the sediment inflow prevention device for a hydraulic machine according to the fifth embodiment. FIG. 1 is a cross-sectional elevation view showing a conventional hydraulic machine. FIG. 1 is an elevational cross-sectional view showing a back pressure chamber formed by an upper portion of a runner and an upper cover of a conventional hydraulic machine.

The following describes a sediment inflow prevention device and a hydraulic machine according to an embodiment of the present invention, with reference to the drawings. Here, parts that are the same as those in the conventional hydraulic machine described in the background art are given the same reference numerals, and redundant descriptions will be omitted. Also, below, parts that are the same or similar to each other are given the same reference numerals, and redundant descriptions will be omitted. Furthermore, in the following embodiments, a Francis turbine is used as an example of a hydraulic machine, but this is not limiting. The hydraulic machines according to the following embodiments may be applied to hydraulic machines other than Francis turbines, or to hydraulic machines other than hydraulic machines, such as pumps.

[First embodiment]
FIG. 1 is a partial cross-sectional elevation view showing a hydraulic machine 10 including a sediment inflow prevention device 30 according to a first embodiment.

The runner 12 has a crown 12a, a band 12b, and multiple runner vanes 12c. The crown 12a is directly connected to the main shaft 11 at its central portion and extends radially outward in the circumferential direction. The band 12b is disposed below the crown 12a. The multiple runner vanes 12c are disposed circumferentially at intervals in the space between the crown 12a and the band 12b and are connected to the crown 12a and the band 12b.

An annular runner upper protrusion 12w is formed at the radially central position on the top surface of the crown 12a, protruding upward.

The upper cover 24, located above the crown 12a, is a stepped disk with a hole in the center. A circular opposing wall 24a is formed on the underside of the upper cover 24, protruding downward, at a position radially outward of the runner upper protrusion 12w, ensuring a gap between the upper cover 24 and the runner upper protrusion 12w.

In this way, the runner seal 27b is formed by the annular runner upward protrusion 12w, the annular opposing wall 24a, and the gap that forms the annular flow path between them.

As a result, a back pressure chamber 27 is formed, which is the space sandwiched between the upper surface of the crown 12a of the runner 12 and the lower surface of the upper cover 24.

An upper cover wall portion 24w extending downward is formed at the radial tip of the upper cover 24. The radial inner surface of the upper cover wall portion 24w and the runner tip surface 12t at the radial tip of the crown 12a face each other via a gap, forming a back pressure chamber inlet 27a.

The back pressure chamber 27, which serves as a bypass flow path, is an annular flow path for flow from the radial outside to the inside, with the back pressure chamber inlet 27a as the inlet flow path and the runner seal 27b as the outlet flow path. The bypass flow flows into the back pressure chamber 27 from the back pressure chamber inlet 27a and flows out radially inward from the runner seal 27b, which is formed to restrict the amount of water flow passing through the back pressure chamber 27. The bypass flow then passes through multiple balance holes 12h provided in the runner 12 to reduce axial thrust, and flows out into the draft pipe 26.

A ring-shaped sediment control wall 31 serving as a sediment inflow control device 30 is provided on the underside of the upper cover 24 at a position radially between the runner tip surface 12t of the crown 12a and the runner seal 27b. The ring-shaped sediment control wall 31 extends downward from the underside of the upper cover 24. A radial flow path 32 is formed between the lower end of the sediment control wall 31 and the upper surface of the crown 12a.

The sediment control wall 31 may be formed integrally with the upper cover 24. Alternatively, the sediment control wall 31 may be formed separately from the upper cover 24 so that it can be attached and detached to the upper cover 24. If it is formed so that it can be attached and detached, it is fixed to the upper cover 24, for example, with bolts, or by fitting it to the upper cover 24 and then pushing in a connecting member.

Figure 2 is a partial cross-sectional view showing the bypass flow within the back pressure chamber 27, illustrating the operation of the sediment inflow suppression device 30 according to the first embodiment.

Before explaining the flow, let's first explain the dimensions. The radial width of the flow path of the runner seal 27b, formed by the annular runner upper protrusion 12w and the annular opposing wall 24a, is represented by d0, as shown in Figure 2. The gap width d0 of the runner seal 27b is, for example, approximately 0.5 to 4 mm. The minimum dimension is the width below which there is no room to prevent contact between the runner upper protrusion 12w and the annular opposing wall 24a due to vibration. The maximum dimension is the width above which bypass flow increases, making it impossible to ensure the efficiency of the hydromachine.

The annular sediment suppression wall 31 serving as the sediment inflow suppression device 30 has its radially outer suppression wall outer surface 31w positioned at a radius r from the center of rotation CL. The maximum value of radius r is radius R, which is the distance from the center of rotation CL to the runner tip surface 12t. Radius r will be explained later with reference to Figure 3. The sediment suppression wall 31 divides the back pressure chamber 27 into a radially inner region and a radially outer region. Hereinafter, the space in the radially outer region will be referred to as the back pressure chamber inner/outer space 27p, and the space in the radially inner region will be referred to as the back pressure chamber inner space 27q.

The gap dimension between the suppression wall lower surface 31u, which is the lower surface of the sediment suppression wall 31, and the runner upper surface 12u, which is the upper surface of the crown 12a of the runner 12, is represented by gap width d1, as shown in Figure 2. Here, gap width d1 is greater than minimum width dmin and less than maximum width dmax. The minimum width dmin is set so that the flow path cross-sectional area of the radial flow path 32 formed thereby is greater than the flow path area of the runner seal 27b resulting from gap width d0. In other words, minimum width dmin is the gap width d1 that provides the flow path cross-sectional area of the radial flow path 32 equal to the flow path area of the runner seal 27b resulting from gap width d0. If gap width d1 is smaller than minimum width dmin, the bypass flow rate will depend more on the flow path cross-sectional area of the radial flow path 32 than on the flow path cross-sectional area of the runner seal 27b, thereby reducing the significance of the runner seal 27b. The maximum width dmax of the gap width d1 is determined by the maximum particle size of the sediment that flows from the radial flow passage 32 into the back pressure chamber inner space 27q and reaches the runner seal 27b. If the gap width d1 is larger than the maximum width dmax, sediment of an unacceptable particle size will reach the runner seal 27b.

Next, the flow of the bypass flow will be explained. Each curved arrow is a conceptual streamline that shows the main flow condition within the back pressure chamber 27 of the bypass flow that has flowed into the back pressure chamber 27. Note that below, the water flow indicated by the streamline will be represented using the same symbol as the streamline.

The bypass flow branches off from the main flow (streamline F0) that flows from the guide vane 23 (Figure 1) into the runner blade 12c (Figure 1) and flows into the back pressure chamber 27 from the back pressure chamber inlet 27a. The bypass flow that flows into the back pressure chamber 27 as sediment water passes through the runner seal 27b and ultimately flows out into the draft pipe 26. The flow within the back pressure chamber inner and outer space 27p is described in detail below.

The bypass flow that flows into the back pressure chamber 27 from the back pressure chamber inlet 27a flows upward along the upper cover wall portion 24w, reaches the upper cover lower surface 24u, and flows radially inward along the upper cover lower surface 24u, as shown by flow line F1.

The bypass flow, which flows radially inward along the lower surface 24u of the upper cover, reaches the outer surface 31w of the sediment control wall 31, which is radially outside the wall, as shown by flow line F2, and flows downward along the outer surface 31w.

The bypass flow that flows downward along the outer surface 31w of the suppression wall reaches the radial flow passage 32, which is the flow passage between the lower surface 31u of the suppression wall and the upper surface 12u of the runner, and as shown by flow line F3, most of it flows along the radial flow passage 32 into the back pressure chamber inner space 27q.

On the other hand, near the runner upper surface 12u, which is the upper surface of the crown 12a of the rotating runner 12, the rotation of the runner 12 causes the bypass flow to swirl due to the viscosity of the water. As a result, centrifugal force caused by the swirling flow acts on the bypass flow in this area. As a result, the flow shown by streamline F4 is generated.

Because the bypass flow is not strong, the relatively heavy sediment in the bypass flow falls to the runner upper surface 12u before flowing into the radial flow path 32, and rides the flow shown by streamline F4, moving radially outward. Because centrifugal force is stronger radially outward, sediment once riding on the flow shown by streamline F4 also moves radially outward. Note that even if sediment riding on the flow shown by streamline F1 falls downward and reaches the runner upper surface 12u before reaching the outer surface 31w of the containment wall, it is thought that it will similarly move radially outward.

Figure 3 is a graph showing the radial velocity distribution of the bypass flow in the back pressure chamber 27 near the runner upper surface 12u to explain the operation of the sediment inflow suppression device 30 according to the first embodiment. The horizontal axis represents the radial distance ratio β. Here, β is the ratio (r/R) of the radius r, which is the distance from the center of rotation CL to the outer surface 31w of the suppression wall, to the radius R, which is the distance from the center of rotation CL to the runner tip surface 12t. The vertical axis represents the near-surface radial velocity Vr, which is the average radial velocity of the water flow F4 near the runner upper surface 12u at the radius position corresponding to the value of β.

In order for the sediment in the bypass flow to ride on the water flow F4 (Figure 2) moving radially outward, β > β ₀ is required. More specifically, as shown in Figure 3, if the minimum velocity that moves sediment radially outward is Vrm and the corresponding β value is βm, then β ≥ βm must be satisfied. Experimental results show that βm is approximately 0.3.

As shown in Figure 3, the near-surface radial velocity Vr increases as the value of β approaches 1, so the first viewpoint is that the closer the position of the restraint wall outer surface 31w is to the runner tip surface 12t, the more reliably the soil and sand will move radially outward.

On the other hand, when the sediment that moves radially outward on water flow F4 reaches the runner tip surface 12t, it is likely to be transferred to water flow F1, become water flow F2, and then become water flow F4, circulating within the backpressure chamber inner and outer space 27p between the upper cover wall portion 24w and the outer surface 31w of the suppression wall within the backpressure chamber 27, and remaining within the backpressure chamber inner and outer space 27p. Therefore, there is a second viewpoint that it is preferable to ensure the volume of the backpressure chamber inner and outer space 27p so that the density of the accumulated sediment does not become excessive.

The position of the outer surface 31w of the restraint wall can be determined by taking into account both the first and second perspectives.

As described above, according to this embodiment, by providing a sediment inflow suppression device 30 having a sediment suppression wall 31, sediment in the bypass flow is prevented from flowing radially inward beyond the sediment suppression wall 31 and reaching the runner seal 27b, thereby reducing sediment wear on the runner seal 27b and its surrounding area.

Second Embodiment
4 is a partial cross-sectional elevation view showing a sediment control wall 31a of a hydraulic machine 10 according to a second embodiment. This embodiment is a modification of the first embodiment, and a sediment control wall 31a is provided instead of the sediment control wall 31 in the first embodiment. In other respects, the second embodiment is similar to the first embodiment.

The sediment control wall 31a has holes or gaps large enough to prevent the passage of sediment in the bypass flow that is larger than a certain size. The sediment control wall 31a may, for example, be in the form of a mesh or lattice formed by intersecting multiple linear members. Alternatively, it may be a plate-shaped member with multiple holes formed in it.

The holes or gaps provided in the sediment control wall 31a are preferably equal to or smaller than the gap spacing d0 (Figure 2) of the runner seal 27b. For example, if the gap spacing d0 of the runner seal 27b is approximately 0.5 mm to 4 mm, the holes or gaps provided in the sediment control wall 31a may be equal to or smaller than 4 mm.

The sediment inflow suppression device 30a having the sediment suppression wall 31a in this embodiment configured as described above has the following functions and effects.

In this embodiment, the sediment control wall 31a has holes and gaps that allow water in the bypass flow to pass through but prevent sediment of a certain size or larger from passing through. Therefore, as in the first embodiment, sediment of a certain size or larger remains in the backpressure chamber inner and outer spaces 27p and does not flow from the radial flow paths 32 into the radially inner part of the backpressure chamber 27.

Furthermore, compared to when the only flow path from the back pressure chamber inner/outer space 27p to the radially inward direction is the radial flow path 32, flow path resistance is reduced, and the increase in pressure within the back pressure chamber inner/outer space 27p can be suppressed. As a result, the increase in pressure acting on the runner upper surface 12u can be suppressed. As a result, the increase in downward thrust force can be suppressed, and the load on the thrust bearing (not shown) can be reduced.

[Third embodiment]
FIG. 5 is a circumferential development view showing the sediment control wall 31b of the hydraulic machine 10 according to the third embodiment.

This embodiment is a modification of the first embodiment, and instead of the annular sediment control wall 31 serving as the sediment inflow control device 30 in the first embodiment, a sediment control wall 31b serving as the sediment inflow control device 30b is provided.

The sediment control wall 31b has wall portions 31f spaced apart in the circumferential direction and connecting portions 31g connecting the upper ends of each wall portion 31f. A gap portion 31h is formed between each pair of wall portions 31f adjacent to each other in the circumferential direction.

The circumferential width d2 of the gap 31h provided in the sediment control wall 31b is preferably equal to or less than the gap spacing d0 (Figure 2) of the runner seal 27b. For example, if the gap spacing d0 of the runner seal 27b is approximately 0.5 mm to 4 mm, the hole or gap provided in the sediment control wall 31a may be 4 mm or less.

Furthermore, the circumferential width d2 of the gap 31h is set so that the sum of the circumferential flow path cross-sectional area formed by this and the flow path cross-sectional area of the radial flow path 32 is not less than the flow path area at the runner seal 27b due to the gap width d0, but is greater than the flow path area at the runner seal 27b. In other words, the flow rate of the bypass flow is set so that it is primarily determined by the runner seal 27b.

Instead of the sediment control wall 31b of this embodiment, multiple rod-shaped members extending from the upper cover 24 toward the runner 12 may be arranged at intervals in the circumferential direction to form a fence-like structure.

The sediment suppression wall 31b in this embodiment or modified example as described above provides the same functions and effects as the sediment suppression wall 31a in the second embodiment. That is, as in the first embodiment, sediment of a certain size or larger remains in the backpressure chamber inner and outer spaces 27p and does not flow from the radial flow paths 32 into the radially inner side of the backpressure chamber 27. Furthermore, compared to when the only flow path from the backpressure chamber inner and outer spaces 27p to the radially inner side is the radial flow path 32, flow path resistance is reduced, and an increase in pressure within the backpressure chamber inner and outer spaces 27p can be suppressed. As a result, an increase in pressure acting on the runner upper surface 12u can be suppressed. As a result, an increase in downward thrust force can be suppressed, reducing the burden on the thrust bearing (not shown).

[Fourth embodiment]
FIG. 6 is a cross-sectional elevation view showing a sediment inflow suppression device 30c of a hydraulic machine 10 according to a fourth embodiment.

This embodiment is a variation of the first embodiment, and the sediment inflow suppression device 30c further includes a balance pipe 35 in addition to the sediment suppression wall 31. The rest of the configuration is the same as the first embodiment.

The first end of the balance pipe 35 penetrates the upper cover 24 and opens into the back pressure chamber inner/outer space 27p of the back pressure chamber 27. The second end of the balance pipe 35 is connected to the draft pipe 26 and opens into the draft pipe 26. Note that the connection destination of the second end is not limited to the draft pipe 26, as long as it is at a location lower than the pressure in the back pressure chamber inner/outer space 27p and can ensure a pressure difference similar to that of the draft pipe 26.

The balance pipe 35 is provided to suppress the thrust force acting on the runner 12, but the flow F5 discharged through the balance pipe 35 to the draft pipe 26 increases the bypass flow and is not converted into rotational energy of the runner 12. If this amount is large, it will reduce the efficiency of the hydromachine 10. For this reason, the pressure difference between the balance pipe 35 and the draft pipe 26, or the flow rate passing through the balance pipe 35, is determined so as to maximize the thrust force suppression effect and minimize the reduction in efficiency of the hydromachine 10.

The sediment inflow suppression device 30c in this embodiment, configured as described above, suppresses the increase in pressure within the back pressure chamber 27 and suppresses the thrust force that pushes the runner 12 downward along the rotation axis CL. Furthermore, sediment that moves back and forth between the back pressure chamber inlet 27a and the sediment suppression wall 31 and accumulates, i.e., sediment that accumulates within the back pressure chamber inner and outer space 27p of the back pressure chamber 27, can be discharged into the suction pipe 26 due to the pressure difference between the back pressure chamber inner and outer space 27p and the suction pipe 26.

In this way, according to this embodiment, the sediment control wall 31 prevents sediment wear on the runner seal 27b, while discharging sediment accumulated in the back pressure chamber 27, thereby eliminating the need to stop the hydraulic machine 10 and open the back pressure chamber 27. As a result, the operating efficiency and reliability of the hydraulic machine 10 can be improved.

Fifth Embodiment
7 is a cross-sectional elevation view showing a sediment inflow suppression device 30d of a hydraulic machine 10 according to a fifth embodiment. This embodiment is a modification of the first embodiment, and the sediment inflow suppression device 30d includes a sediment discharge pipe 37 and a valve 37v provided on the sediment discharge pipe 37 in addition to the sediment suppression wall 31. The rest of the configuration is the same as that of the first embodiment.

The first end of the sediment discharge pipe 37 penetrates the upper cover 24 and opens into the back pressure chamber inner/outer space 27p of the back pressure chamber 27. The second end of the sediment discharge pipe 37 is connected to the draft pipe 26 and opens into the draft pipe 26. Note that the connection of the second end is not limited to the draft pipe 26, as long as it is at a location lower than the inlet pressure of the runner 12.

The sediment discharge pipe 37 has an opening and piping diameter larger than the sediment to be discharged. The valve 37v may be opened and closed freely depending on the operation of the hydraulic machine 10. For example, it may be closed during steady-state operation of the hydraulic machine 10 and temporarily opened after a certain period of operation to discharge sediment accumulated in the back pressure chamber inner and outer spaces 27p. The valve 37v may be opened and closed manually at regular intervals before the accumulation of sediment reaches a level that could adversely affect the operation of the hydraulic machine 10. Alternatively, an observation window (not shown) may be provided in the upper cover 24, and the valve 37v may be opened manually when it is determined that the amount of sediment accumulation has reached a reference value. Alternatively, the valve 37v may be opened automatically at regular intervals using a combination of a timer and the valve 37v. Alternatively, the amount of sediment accumulation may be detected by a sensor, and the valve 37v may be opened automatically when it exceeds a certain level.

In this way, according to this embodiment, the sediment suppression wall 31 prevents sediment wear on the runner seal 27b while allowing sediment accumulated in the back pressure chamber 27 to be discharged. This allows sediment to be discharged efficiently without having to stop the hydraulic machine 10 and open the back pressure chamber 27, thereby improving the operating efficiency and reliability of the hydraulic machine 10.

Figure 8 is a cross-sectional elevation view showing a modified example of a sediment inflow suppression device 30d for a hydraulic machine 10 according to the fifth embodiment.

The difference from the embodiment is that the first end of the sediment discharge pipe 37, the sediment discharge pipe inlet 37a, is located close to the runner top surface 12u within the backpressure chamber inner/outer space 27p. The portion of the sediment discharge pipe 37 within the backpressure chamber inner/outer space 27p is supported by the upper cover 24 as needed.

The sediment discharge pipe inlet 37a has a shape that is, for example, flattened vertically and widened horizontally in order to widen the portion adjacent to the runner upper surface 12u.

It is preferable that the lower end of the sediment discharge pipe inlet 37a be close to the runner upper surface 12u, but a gap is provided to prevent contact due to vibrations, etc. In other words, the lower end of the sediment discharge pipe inlet 37a does not need to come into contact with the runner upper surface 12u, and opening the valve 37v and generating flow F6 will have a greater effect on discharging sediment than if the lower end of the sediment discharge pipe inlet 37a were located higher.

The embodiments described above make it possible to provide a sediment inflow prevention device and hydraulic machine that can reduce sediment wear, particularly in the back pressure chamber, thereby improving efficiency and operating rate, even in hydraulic machines that use water containing a large amount of sediment as working water.

[Other embodiments]
Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. For example, features of the second or third embodiment may be combined with features of the fourth or fifth embodiment. Alternatively, features of the fourth and fifth embodiments may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

10... Hydraulic machine, 11... Main shaft, 12... Runner, 12a... Crown, 12b... Band, 12c... Runner blade, 12h... Balance hole, 12t... Runner tip surface, 12u... Runner upper surface, 12w... Runner upper protrusion, 21... Casing, 22... Stay vane, 23... Guide vane, 24... Upper cover, 24a... Opposing wall, 24u... Upper cover lower surface, 24w... Upper cover wall portion, 25... Lower cover, 26... Draft pipe, 27... Back pressure chamber, 27 a...back pressure chamber inlet, 27b...runner seal, 27p...back pressure chamber outer/outer space, 27q...back pressure chamber inner space, 28...lateral pressure chamber, 30, 30a, 30b, 30c, 30d...sediment inflow suppression device, 31, 31a, 31b...sediment suppression wall, 31f...wall portion, 31g...connecting portion, 31h...gap portion, 31u...sediment suppression wall underside, 31w...sediment suppression wall outer surface, 32...radial flow path, 35...balance pipe, 37...sediment discharge pipe, 37a...sediment discharge pipe inlet, 37v...valve

Claims (8)

A sediment inflow prevention device for a hydraulic machine having a runner that is directly connected to a main shaft extending in a vertical direction and rotates around a rotation axis by working water containing sediment,
a crown connecting the upper portions of the runner blades of the runner;
an upper cover disposed to cover an upper surface of a runner, which is an upper surface of the crown, and forming a back pressure chamber between the upper cover and the runner upper surface;
a sediment control wall that is attached to a lower surface of the upper cover of the upper cover so as to divide the back pressure chamber into a radially inner region and a radially outer region and that forms a radial flow path between the upper surface of the runner and the lower surface of the upper cover;
Equipped with
The sediment inflow control device is characterized in that the sediment control wall is formed in any one of a mesh shape, a lattice shape, and a porous shape . The sediment inflow suppression device described in claim 1, characterized in that the distance r from the rotation axis to the radial outer surface of the sediment suppression wall is in the range of 0.3 or more and less than 1 relative to the radius R of the runner. The sediment inflow prevention device described in claim 1, characterized in that the distance between the lower surface of the sediment prevention wall and the upper surface of the runner is within a predetermined range. The sediment inflow suppression device described in claim 1, characterized in that the sediment suppression wall has gaps formed at intervals in the circumferential direction. The hydraulic machine further includes a draft pipe that guides the working water flowing out of the runner to a lower pond,
The back pressure chamber further includes a balance pipe connecting a radially outer portion of the sediment suppression wall and a low pressure portion.
The sediment inflow suppression device according to claim 1. The hydraulic machine further includes a draft pipe that guides the working water flowing out of the runner to a lower pond,
The back pressure chamber further includes a sediment discharge pipe connecting a radially outer portion of the sediment suppression wall and a low pressure portion.
The sediment inflow suppression device according to claim 1. The sediment inflow prevention device described in claim 6, characterized in that the sediment discharge pipe is provided with a valve that can be opened and closed freely. the runner;
The sediment inflow suppression device according to any one of claims 1 to 7 ,
A hydraulic machine comprising: