JPS6346700Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a runner structure that can simplify the water sealing mechanism of the runner shaft of a once-through water turbine, which is one of the impulse type water turbines.

<Prior art> In order to prevent leakage of internal fluid and mixing of external air, there is a space between the runner shaft of a cross-flow turbine developed for small hydroelectric power generation and the shaft penetration part of the casing through which this runner shaft passes. A sealing material such as gland packing is interposed. Since the sealing material is usually attached to the inner circumferential surface of the shaft penetrating portion, the outer circumferential surface of the runner shaft that comes into sliding contact with the sealing material is plated or plated with a wear-resistant material. Furthermore, in order to prevent the sealing performance from deteriorating due to abrasion of the sealing material, the pressing pressure of the sealing material against the runner shaft is periodically adjusted, but eventually the sealing material must be replaced.

<Purpose of the invention> The present invention makes it possible to obtain sufficient sealing performance without increasing the sealing pressure of the sealing material, prolonging the replacement life of the sealing material, and improving the plating with wear-resistant material on the outer peripheral surface of the runner shaft. The purpose is to provide a rational runner structure that does not require depositing money.

<Summary of the invention> This invention focuses on the fact that as the runner rotates, the internal pressure becomes negative, and the outer circumferential surface of the runner shaft facing the shaft penetration part, which is closer to the fluid than the sealing material, and the inside of the runner. A negative pressure suction passage communicating with the runner shaft is formed in the runner shaft, and the leakage fluid flowing between the shaft penetration part and the runner shaft is sucked into the inside of the runner using the negative pressure, and this leakage fluid is transferred to the sealing material side. This makes it difficult for the water to flow out.

<Example> As shown in Figure 1, which shows the cross-sectional structure of the main part of an example in which the once-through water turbine according to the present invention is applied to a cross-flow water turbine, a casing is formed in the shape of a passage through which a fluid (not shown) passes. 11 is formed with a pair of shaft penetrating portions 13 through which the runner shafts 12a and 12b pass, respectively.
a and 12b are rotatably supported on the casing 11 by bearings (not shown) outside the shaft penetrating portion 13. Each end of the runner shaft 12 inside the casing 11 is provided with a disc-shaped end plate 1.
4 are integrally provided, and end portions of runner blades 15 parallel to the runner shafts 12a, 12b are integrally connected to the outer peripheral edge of the end plate 14 at regular intervals. That is, the runner shafts 12a and 12b are coaxially integrally connected by the runner blade 15 via the end plate 14, and these as a whole form the runner 1.
6. In this embodiment, the runner shaft is of a split type so that the flow of fluid within the runner 16 is not interfered with by the runner shaft, but it is of course possible to use a single continuous shaft.

A sealing material 17 held on the inner circumferential surface of the shaft penetrating portion 13 is located between the runner shafts 12a, 12b and the shaft penetrating portion 13. In this embodiment, since a strong sealing ability is not required, felt is used. I am using a product manufactured by Hollow portions 18a and 18b communicating with the inside of the runner 16 are formed inside the runner shafts 12a and 12b, and the hollow portion 1 of one of the runner shafts 12a is
8a communicates with the outside so that air can be introduced into the runner 16. Note that the structure of the hollow portion 18a of one runner shaft 12a may be the same as that of the hollow portion 18b of the other runner shaft 12b. An annular liquid reservoir 19 is formed on the inner periphery of the shaft penetrating portion 13 between the inside of the casing 11 and the sealing material 17.
9 and the hollow portions 18a, 18b, respectively, are provided in the runner shafts 12a, 12b. In this embodiment, the communication path 20 and the hollow parts 18a and 18b constitute a negative pressure suction passage, and there is no particular problem even if the liquid reservoir part 19 is not formed in the shaft penetrating part 13.

Therefore, when the runner 16 rotates due to the passage of fluid, a negative pressure is created inside the runner 16, and as a result, the leaked fluid flowing between the shaft penetrating portion 13 and the runner shafts 12a and 12b is communicated via the liquid reservoir portion 19. It passes through the passage 20 and the hollow portions 18a and 18b, and is sucked into the runner 16, and there is no risk of it flowing out to the sealing material 17 side.

<Effects of the invention> According to the invention, a negative pressure suction passage is formed in the runner shaft, one side opening between the runner shaft and the shaft penetration part of the casing, and the other opening inside the runner. The rotation creates a negative pressure inside the runner, and the fluid flowing between the runner shaft and the shaft penetration part is sucked into the runner through the negative pressure suction passage, and the fluid flows from between the runner shaft and the shaft penetration part to the outside. will no longer leak. Therefore, there is no need to take special consideration to the sealing ability of the sealing material or to line the outer periphery of the runner shaft with a wear-resistant material, and it is possible to reduce manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the structure of the main part of an embodiment in which the runner structure of a once-through water turbine according to the present invention is applied to a cross-flow water turbine, and Fig. 2 is an enlarged view of the part seen from the arrow. So, 11 is the casing, 1
2a, 12b are runner shafts, 13 is a shaft penetration part, 16
17 is a runner, 17 is a sealing material, 18a and 18b are hollow parts, and 20 is a communication path.

Claims (1)

[Scope of utility model registration request] The shaft has a casing through which a fluid passes, a runner rotatably housed in the casing, and a shaft penetrating portion provided integrally with the casing and through which a runner shaft integral with the runner passes. In a once-through water turbine in which a sealing material is interposed between a penetration part and a runner shaft, an opening is provided on the outer circumferential surface of the runner shaft facing the shaft penetration part, which is closer to the fluid than the sealing material, and to the inside of the runner. A runner structure for a once-through water turbine, characterized in that a negative pressure suction passage is provided on the runner shaft.