Sediment inflow control devices and hydraulic machinery

Abstract

To improve efficiency and an operation rate by alleviating sediment abrasion even in a hydraulic machine which uses water containing a lot of sediment as working water.SOLUTION: According to an embodiment, a sediment inflow suppression device 30 of a hydraulic machine 10 having a runner 12 which is directly connected to a spindle extending in a vertical direction, and rotates around a rotating shaft CL by working water containing sediment comprises: a crown 12a for connecting upper parts of runner blades of the runner 12; an upper cover 24 arranged so as to cover a runner upper face 12u being an upper face of the crown 12a, and forming a backpressure chamber 27 between the runner upper face 12u and itself; and a sediment suppression wall 31 arranged in the backpressure chamber 27, attached to an upper cover lower face 24u so as to partition the backpressure chamber 27 into a radial-direction inside region and a radial-direction outside region, and forming a radial-direction flow passage 32 between the runner upper face 12u and itself.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a sediment inflow control device and a hydraulic machine. [Background technology]

[0002] Fig. 9 is a cross-sectional elevation view of a conventional hydraulic machine. Fig. 10 is a cross-sectional elevation view of a back pressure chamber formed by the upper part of the runner and the upper cover of the conventional hydraulic machine. Figs. 9 and 10 show the schematic configuration of a Francis turbine as an example of a conventional hydraulic machine.

[0003] 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 introduced into a runner 12. After performing work in the runner 12, the water flows through a draft pipe 26 and is introduced into a lower reservoir (not shown).

[0004] The runner 12 is directly connected to the main shaft 11 that rotates around a 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.

[0005] The runner 12 and the upper cover 24 form a gap called a back pressure chamber 27. Furthermore, the runner 12 and the lower cover 25 form a gap called a lateral pressure chamber 28. A portion of the water flowing into the runner 12 from the guide vanes 23 flows as a bypass flow into the back pressure chamber 27 and the lateral pressure chamber 28, and then joins the water flowing out of the runner 12. Therefore, the back pressure chamber 27 and the lateral pressure chamber 28 serve as bypass passages in which a portion of the working water flowing in from the guide vanes 23 flows in parallel with the main flow of working water flowing into the runner 12. The bypass flow that flows through these bypass passages is led to the draft pipe 26 without doing work in the runner 12. If the flow rate of the bypass flow is large, it reduces the efficiency of the hydromachine.

[0006] In the case of the back pressure chamber 27, the bypass flow flows into the back pressure chamber 27 from a back pressure chamber inlet 27a and flows out radially inward from a runner seal 27b (Fig. 10) formed to restrict the amount of water flow passing through the back pressure chamber 27. Thereafter, the bypass flow passes through a plurality of balance holes 12h (Fig. 10) provided in the runner 12 to reduce axial thrust, and flows out into the draft pipe 26. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 9-4556 [Patent Document 2] Japanese Utility Model Application Publication No. 6-40372 [Patent Document 3] Special Publication No. 63-3433 Summary of the Invention [Problem to be solved by the invention]

[0008] In hydraulic machines that use sandy water containing a lot of sediment, the bypass flow that flows into the back pressure chamber 27 and the side pressure chamber 28 is also sandy water. As a result, the runner 12, the upper cover 24, and the lower cover 25 are subjected to wear due to the sandy water.

[0009] The sediment in the bypass flow that has flowed 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 as a result, there is a problem of reducing the efficiency of the hydraulic machine.

[0010] Similarly, the sediment in the bypass flow that has flowed 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, widening the gap and increasing water leakage from this part, which results in a problem of reduced efficiency of the hydraulic machine.

[0011] Conventionally, countermeasures to this problem in the back pressure chamber 27 and the side pressure chamber 28 have been to increase the thickness of the plates in the parts subject to wear, or to replace or repair the parts subject to wear at regular intervals, etc. However, these countermeasures have the problem of reducing the operating efficiency of the hydraulic machine.

[0012] The object of the present invention is to provide a sediment inflow prevention device and a 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 lot of sediment as working water. [Means for solving the problem]

[0013] In order to achieve the above-mentioned object, the sediment inflow suppression device according to this embodiment is a sediment inflow suppression device for a hydraulic machine having a runner that is directly connected to a main shaft extending in the vertical direction and that rotates about a rotation axis by working water containing sediment, and includes: a crown that connects upper portions of the runner blades of the runner; an upper cover that is arranged to cover an upper surface of the runner that is an upper surface of the crown and forms a back pressure chamber between itself and the runner upper surface; and a sediment suppression wall that is attached to a lower surface 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 that forms a radial flow path between itself and the runner upper surface. The sediment control wall is either mesh-shaped, lattice-shaped, or porous. It is characterized by: [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a partial cross-sectional elevation view showing a hydraulic machine including a sediment inflow prevention device according to a first embodiment. [Figure 2] 3 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. [Figure 3] 4 is a graph showing the radial velocity distribution of a bypass flow in a back pressure chamber near the upper surface of a runner, for explaining the operation of the sediment inflow prevention device according to the first embodiment. [Figure 4]FIG. 6 is a partial cross-sectional elevation view showing a sediment control wall of a hydraulic machine according to a second embodiment. [Figure 5] FIG. 10 is a circumferential development view showing a sediment control wall of a hydraulic machine according to a third embodiment. [Figure 6] FIG. 10 is a cross-sectional elevation view showing a sediment inflow prevention device for a hydraulic machine according to a fourth embodiment. [Figure 7] FIG. 10 is a cross-sectional elevation view showing a sediment inflow prevention device for a hydraulic machine according to a fifth embodiment. [Figure 8] 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. [Figure 9] FIG. 1 is a cross-sectional elevation view showing a conventional hydraulic machine. [Figure 10] 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. DETAILED DESCRIPTION OF THE INVENTION

[0015] A sediment inflow suppression device and a hydraulic machine according to an embodiment of the present invention will be described below with reference to the drawings. Here, parts that are the same as those in the conventional hydraulic machine described in the background art will be given the same reference numerals, and redundant descriptions will be omitted. Also, in the following description, parts that are the same or similar to each other will be given the same reference numerals, and redundant descriptions will be omitted. In the following embodiments, a Francis turbine will be 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.

[0016] [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.

[0017] The runner 12 has a crown 12a, a band 12b, and a plurality of runner vanes 12c. The crown 12a is directly connected to the main shaft 11 at its center and extends radially outward in the circumferential direction. The band 12b is disposed below the crown 12a. The plurality of runner vanes 12c are disposed in the space between the crown 12a and the band 12b at intervals in the circumferential direction and are connected to the crown 12a and the band 12b.

[0018] An annular runner upward protrusion 12w is formed on the top surface of the crown 12a at a radially intermediate position thereof so as to protrude upward.

[0019] The upper cover 24, located above the crown 12a, is a stepped disk with a hole in the center. An annular opposing wall 24a is formed on the underside of the upper cover 24 so as to protrude downward, radially outward from the runner upper protrusion 12w and at a position that ensures a gap between the upper cover 24 and the runner upper protrusion 12w.

[0020] In this manner, 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 formed by these.

[0021] As a result, a back pressure chamber 27 is formed, which is a space sandwiched between the upper surface of the crown 12a of the runner 12 and the lower surface of the upper cover 24.

[0022] 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 across a gap, forming a back pressure chamber inlet 27a.

[0023] Therefore, the back pressure chamber 27, which is a bypass flow path, is an annular flow path for flow from the outside to the inside in the radial direction, 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 suppress 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.

[0024] An annular sediment suppression wall 31 serving as a sediment inflow suppression device 30 is provided on the lower surface of the upper cover 24 at a position radially between the runner tip surface 12t of the crown 12a and the runner seal 27b, and is formed to extend downward from the lower surface of the upper cover 24. A radial flow path 32 is formed between the lower end of the sediment suppression wall 31 and the upper surface of the crown 12a.

[0025] The sediment control wall 31 may be formed integrally with the upper cover 24. Alternatively, the sediment control wall 31 may be formed as a separate body from the upper cover 24 so as to be detachable from the upper cover 24. When the sediment control wall 31 is formed as a detachable body, it is fixed to the upper cover 24 by, for example, bolts, or by fitting the sediment control wall 31 to the upper cover 24 and then pushing in a connecting member.

[0026] FIG. 2 is a partial cross-sectional view schematically showing the flow of the bypass flow in the back pressure chamber 27, for explaining the operation of the sediment inflow suppression device 30 according to the first embodiment.

[0027] Before explaining the flow, we will explain the dimensions. The radial width of the flow path of the runner seal 27b, which is 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, about 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.

[0028] The annular sediment suppression wall 31 serving as the sediment inflow suppression device 30 has its radially outer suppression wall outer surface 31w disposed at a position of radius r from the rotation center CL. The maximum value of radius r is radius R, which is the distance from the rotation center CL to the runner tip surface 12t. The radius r will be described later with reference to FIG. 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.

[0029] As shown in FIG. 2, 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 a gap width d1. Here, the gap width d1 is greater than the minimum width dmin and less than the 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 the gap width d0. In other words, the 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 the gap width d0. If the gap width d1 is smaller than the 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 existence 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.

[0030] Next, the flow of the bypass flow will be described. Each curved arrow is a conceptual streamline that shows the main flow state of the bypass flow that has flowed into the back pressure chamber 27 within the back pressure chamber 27. Note that, hereinafter, the water flow indicated by the streamline will be represented by the same symbol as the streamline.

[0031] The bypass flow branches off from the main flow (streamline F0) that flows from the guide vane 23 (FIG. 1) into the runner blade 12c (FIG. 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 finally flows out into the draft pipe 26. The flow in the back pressure chamber inner and outer space 27p will be described in detail below.

[0032] 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, as shown by flow line F1, reaches the upper cover lower surface 24u, and then flows radially inward along the upper cover lower surface 24u.

[0033] The bypass flow flowing radially inward along the lower surface 24u of the upper cover reaches the outer surface 31w of the suppression wall, which is radially outside the sediment suppression wall 31, as shown by flow line F2, and flows downward along the outer surface 31w of the suppression wall.

[0034] The bypass flow that flows downward along the outer surface 31w of the restraint wall reaches the radial flow path 32, which is the flow path in the gap between the lower surface 31u of the restraint wall and the upper surface 12u of the runner, and most of it flows out along the radial flow path 32 into the inner space 27q of the back pressure chamber, as shown by the flow line F3.

[0035] Meanwhile, 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 water. As a result, centrifugal force caused by the swirling flow acts on the bypass flow in this area, resulting in the flow shown by streamline F4.

[0036] Because the bypass flow is not strong, relatively heavy sediment in the bypass flow falls to the runner upper surface 12u before flowing into the radial flow passage 32, and rides on the flow indicated by streamline F4 and moves radially outward. Because centrifugal force is stronger radially outward, sediment once riding on the flow indicated by streamline F4 also moves radially outward. Note that even if sediment riding on the flow indicated by streamline F1 falls downward and reaches the runner upper surface 12u before reaching the suppression wall outer surface 31w, it is thought that it will similarly move radially outward.

[0037] 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 suppression-wall outer surface 31w, 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 corresponding to the value of β.

[0038] In order for the sediment in the bypass flow to ride on the radially outward flow F4 (Figure 2), β > β0 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.

[0039] As shown in Figure 3, the closer the value of β is to 1, the greater the near-surface radial velocity Vr becomes. Therefore, the first viewpoint is that the closer the position of the outer surface 31w of the restraint wall is to the runner tip surface 12t, the more reliably the soil and sand will move radially outward.

[0040] On the other hand, when the sediment that has been carried by the water flow F4 and moved radially outward reaches the runner tip surface 12t, it is likely to be carried by the water flow F1, become the water flow F2, and then become the water flow F4, circulate within the backpressure chamber inner / outer space 27p sandwiched between the upper cover wall portion 24w and the suppression wall outer surface 31w in the backpressure chamber 27, and remain within the backpressure chamber inner / outer space 27p. Therefore, there is a second viewpoint that it is preferable to ensure a sufficient volume for the backpressure chamber inner / outer space 27p so that the density of the accumulated sediment does not become excessive.

[0041] The position of the restraint wall outer surface 31w may be determined taking into consideration both the first and second viewpoints.

[0042] 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 can be 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 surroundings.

[0043] [Second embodiment] 4 is a partial cross-sectional elevation view showing a sediment-suppression wall 31a of a hydraulic machine 10 according to a second embodiment. This embodiment is a modification of the first embodiment, and a sediment-suppression wall 31a is provided instead of the sediment-suppression wall 31 in the first embodiment. In other respects, this embodiment is similar to the first embodiment.

[0044] The sediment control wall 31a has holes or gaps formed therein large enough to prevent the passage of sediment of a certain size or larger in the bypass flow. The sediment control wall 31a may be, for example, a mesh or lattice-like wall formed by intersecting a plurality of linear members. Alternatively, it may be a plate-like member with a plurality of holes formed therein.

[0045] The holes or gaps provided in the sediment suppression wall 31a are preferably equal to or smaller than the gap spacing d0 (FIG. 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 suppression wall 31a may be equal to or smaller than 4 mm.

[0046] The sediment inflow suppression device 30a having the sediment suppression wall 31a of this embodiment configured as described above has the following actions and effects.

[0047] The sediment suppression wall 31a in this embodiment has holes and gaps formed therein 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 side of the backpressure chamber 27.

[0048] 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 an increase in pressure within the back pressure chamber outer / inner space 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, and the load on the thrust bearing (not shown) can be reduced.

[0049] [Third embodiment] FIG. 5 is a circumferential development view showing the sediment-suppression wall 31b of the hydraulic machine 10 according to the third embodiment.

[0050] This embodiment is a modification of the first embodiment, and instead of the annular sediment suppression wall 31 serving as the sediment inflow suppression device 30 in the first embodiment, a sediment suppression wall 31b serving as a sediment inflow suppression device 30b is provided.

[0051] The sediment control wall 31b has wall portions 31f spaced apart from one another in the circumferential direction and connecting portions 31g connecting the upper ends of the wall portions 31f. A gap portion 31h is formed between each pair of wall portions 31f adjacent to one another in the circumferential direction.

[0052] The circumferential width d2 of the gap 31h provided in the sediment suppression wall 31b is preferably equal to or less than the gap spacing d0 (FIG. 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 suppression wall 31a may be 4 mm or less.

[0053] The circumferential width d2 of the gap 31h is set so that the sum of the cross-sectional area of ​​the entire circumference formed thereby and the cross-sectional area of ​​the radial flow passage 32 is not less than the cross-sectional area of ​​the runner seal 27b defined by the gap width d0, but is greater than the cross-sectional area of ​​the runner seal 27b. In other words, the flow rate of the bypass flow is set so that it is mainly determined by the runner seal 27b.

[0054] In addition, instead of the sediment control wall 31b of this embodiment, a plurality of 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.

[0055] The sediment suppression wall 31b in this embodiment or modification 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 / outer space 27p and does not flow from the radial flow passage 32 into the radially inner side of the backpressure chamber 27. Furthermore, compared to when the radial flow passage 32 is the only flow passage from the backpressure chamber inner / outer space 27p to the radially inner side, flow resistance is reduced, and an increase in pressure within the backpressure chamber inner / outer space 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 load on a thrust bearing (not shown).

[0056] [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.

[0057] This embodiment is a modification 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 is the same as the first embodiment.

[0058] A 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. A 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 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.

[0059] The balance pipe 35 is provided to suppress the thrust force acting on the runner 12, but the flow F5 discharged to the draft pipe 26 through the balance pipe 35 increases the bypass flow and is not converted into rotational energy of the runner 12, and if this amount is large, it reduces the efficiency of the hydromachine 10. For this reason, with regard to the bypass flow passing through the balance pipe 35, 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.

[0060] The sediment inflow suppression device 30c of this embodiment configured as described above suppresses an increase in pressure within the back pressure chamber 27 and suppresses the thrust force that presses the runner 12 downward on 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 spaces 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 spaces 27p and the suction pipe 26.

[0061] As described above, according to this embodiment, the sediment suppression 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.

[0062] [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 a sediment suppression wall 31. The rest of the configuration is the same as that of the first embodiment.

[0063] A 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. A 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 destination of the second end is not limited to the draft pipe 26, as long as it is a location lower than the inlet pressure of the runner 12.

[0064] The sediment discharge pipe 37 has a diameter 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 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 / outer space 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 and closed manually when it is determined that the amount of sediment 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 accumulated may be detected by a sensor, and the valve 37v may be opened automatically when it exceeds a certain level.

[0065] As described above, according to this embodiment, the sediment suppression wall 31 prevents the runner seal 27b from being worn away by sediment, while allowing sediment retained in the back pressure chamber 27 to be discharged. Therefore, sediment can be efficiently discharged without stopping the hydraulic machine 10 to open the back pressure chamber 27, thereby improving the operational efficiency and reliability of the hydraulic machine 10.

[0066] FIG. 8 is a cross-sectional elevation view showing a modified example of a sediment inflow suppression device 30d of the hydraulic machine 10 according to the fifth embodiment.

[0067] The difference from the embodiment is that the sediment discharge pipe inlet 37a, which is the first end of the sediment discharge pipe 37, is located close to the runner upper surface 12u in the back pressure chamber inner / outer space 27p. The portion of the sediment discharge pipe 37 inside the back pressure chamber inner / outer space 27p is supported by the upper cover 24 as needed.

[0068] The soil discharge pipe inlet 37a has a shape that is, for example, compressed vertically and widened horizontally in order to widen the portion adjacent to the runner upper surface 12u.

[0069] 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 vibration, etc. In other words, the lower end of the sediment discharge pipe inlet 37a does not need to be in contact with the runner upper surface 12u, and if the valve 37v is opened and flow F6 is generated, the effect of discharging sediment is greater than when the lower end of the sediment discharge pipe inlet 37a is located higher.

[0070] According to the embodiments described above, it is possible to provide a sediment inflow prevention device and a hydraulic machine that can reduce sediment wear, particularly in the back pressure chamber, and improve efficiency and operating rate, even in hydraulic machines that use water containing a lot of sediment as working water.

[0071] [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 within the scope and spirit of the invention, as well as the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0072] 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, 2 7a...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...separate sediment inflow suppression device, 31, 31a, 31b...separate sediment suppression wall, 31f...wall portion, 31g...connecting portion, 31h...gap portion, 31u...underside of suppression wall, 31w...outside surface of suppression wall, 32...radial flow path, 35...balance pipe, 37...separate sediment discharge pipe, 37a...separate sediment discharge pipe inlet, 37v...valve

Claims

1. 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.

2. 2. The sediment inflow suppression device according to claim 1, wherein the distance r from the rotation axis to the radially outer surface of the sediment suppression wall is in the range of 0.3 or more and less than 1 with respect to the radius R of the runner.

3. 2. The sediment inflow suppression device according to claim 1, wherein a distance between the lower surface of the sediment suppression wall and the upper surface of the runner is within a predetermined range.

4. 2. The sediment inflow suppression device according to claim 1, wherein the sediment suppression walls have gaps formed at intervals in the circumferential direction.

5. 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.

6. 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.

7. 7. The sediment inflow prevention device according to claim 6, wherein the sediment discharge pipe is provided with a valve that can be opened and closed.

8. the runner; The sediment inflow suppression device according to any one of claims 1 to 7, A hydraulic machine comprising:

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