JPS6332930Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the structure of the runner of a once-through water turbine, and is intended to improve strength and reliability.

As shown in FIG. 1, which shows a typical structure of a once-through water turbine, a runner 1 has a rotating shaft 2 rotatably supported by a casing 4 via a bearing 3 with a built-in seal, and a runner 1 is rotatably supported by a casing 4 on the upstream side of the runner 1. An inlet pipe 5 is connected to the casing 4. In the vicinity of the runner 1, on the outlet side of the inlet pipe 5, an airfoil-shaped guide vane 6 for adjusting the amount of water entering the runner 1 is provided so as to be openable and closable. On the other hand, a water discharge pipe 8 having a gradual contraction part 7 connected to the casing 4 is provided on the downstream side of the runner 1, and water flowing from the inlet pipe 5 is adjusted by a guide vane 6 and enters the runner 1. Water is discharged from the outer periphery of the lower part of the pipe 1 and drained to the outside through a water discharge pipe 8.

As shown in Figures 2a and 2b, the runner 1 of this once-through water turbine includes a large number of runner blades 1a processed into an airfoil cross section, and a disc-shaped support plate for supporting the runner blades 1a. End plate 1b
and a partition plate 1c, and grooves 1d for attaching runner blades corresponding to the cross-sectional shape of the runner blade 1a are formed at equal intervals on the outer circumference of the end plate 1b and the partition plate 1c. It is said to be a welded structure that is inserted and welded.

The fixed parts of the runner blade 1a of the runner 1 to both end plates 1b and the partition plate 1c are parts that convert water energy into rotational energy and transmit it. The runner blades 1a are made of a thin plate and processed to have an airfoil-shaped cross section, so stress concentrates on the fixed parts, generating extremely large stress. I will do it. Also, during welding, the end plate 1b, which is a relatively thick plate,
Also, between the partition plate 1c and the thin runner blade 1a, the runner blade 1a is easily overheated, causing burn-through and coarsening of the structure of the base material, which causes a decrease in strength and reliability. Further, forming a large number of grooves having the same cross-sectional shape of the runner blade 1a on the end plate or partition plate serving as a support plate is a very complicated process.

The object of the present invention is to provide a runner for a once-through water turbine that can eliminate such conventional drawbacks, prevent stress concentration, and improve strength and reliability. The structure of the present invention that achieves this object has at least two disc-shaped support plates, and grooves for mounting runner blades are formed at equal intervals on the outer circumference of these support plates, and the blades are inserted into the grooves. In the runner of a once-through water turbine in which runner blades are welded and fixed, grooves for attaching runner blades of the same width are formed at equal intervals on the outer circumference of the support plate, and grooves for attaching the runner blades to the support plate are formed at regular intervals on the outer circumference of the support plate. The blades are formed to have the same thickness corresponding to the grooves, the blades through which water flows are formed to have a predetermined airfoil-shaped cross section, and the connecting portions between these fixed parts and the blades are formed in a smooth arc shape. .

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

Figures 3 to 6 show one embodiment of the runner of the once-through water turbine of the present invention, Figure 3 is a perspective view of the runner blade, and Figures 4a and 4b are A in Figure 3, respectively.
5 is a partially enlarged view of an end plate or partition plate that is a support plate, and FIGS. 6a and 6b are sectional views of a fixed portion between a runner blade and a support plate, respectively.

As shown in FIG. 3, the runner blade 1a constituting the runner 1 has a fixed portion 1e that is fixed to the end plate 1b or the partition plate 1c, which is a supporting plate, with the same thickness as the material, and its cross section is formed to have the same width. The wing portion 1f through which water flows and flows is formed to have an airfoil cross-sectional shape necessary for the characteristics of the runner 1. For example, as shown in FIG. 4a, this wing portion 1f may be made by cutting only the wing surface from an arc-shaped material and leaving the shape of the material on the underside of the wing, or, as shown in FIG. 4b, Both the wing surface and the back surface of the wing are cut from material to create an airfoil-shaped cross section. The connecting portion between the fixing portion 1e and the wing portion 1f, which creates a step, is formed into a smooth arc shape to alleviate stress concentration.
Therefore, in the runner blade 1a shown in FIG. 4a, the connection part between the blade part 1f and the fixed part 1e on the blade surface is formed in an arc shape, and in the runner blade 1a shown in FIG. The connecting portion between the wing part 1f on the back surface of the wing and the fixed part 1e is connected by an arc of radius R ₁ and R ₂ as shown in FIGS. 6a and 6b.
Moreover, the fixed part 1e is the end plate 1b or the partition plate 1c.
The width is the sum of the thickness T and the length of the welding leg (see Figures 6a and b).

Furthermore, as shown in FIG. 5, the end plate 1b and partition plate 1c, which serve as support plates for supporting the runner blade 1a, are formed with a groove 1g of the same width corresponding to the fixed part 1e of the runner blade 1a, and one end of the groove is opened on the outer periphery of the end plate 1b or the partition plate 1c.

Next, such fixing of the runner blade 1a and the end plate 1b or the partition plate 1c is performed as shown in FIG.
As shown in b, after inserting the fixed part 1e of the runner blade 1a from the open end of the groove 1g of the end plate 1b and the partition plate 1c, the end plate 1b or the partition plate 1c is inserted.
When welding to both sides of the end plate 1b or partition plate 1c, as shown in Figure 6a, the fixing part 1e should protrude from both sides of the end plate 1b or partition plate 1c, and the When only welding is performed, the fixing portion 1e is inserted so as to protrude toward the welding side, as shown in FIG. 6b, and welding is performed. After welding, the runner blade 1a protruding from the outer periphery of the end plate 1b or the partition plate 1c is cut off by machining or the like to complete the runner.

By using a runner with such a structure, the end plate 1
It is extremely easy to process the groove 1g provided in the partition plate 1c, and the gap between the runner blade 1a and the runner blade 1a inserted into the groove 1g is small, and the fixed part 1e of the runner blade 1a can be inserted into the specified position by simply inserting the fixed part 1e of the runner blade 1a along the groove 1g. position and angle, allowing for accurate positioning. In addition, the fixed part 1 of the runner blade 1a
Since the thickness of the plate e is increased and the connecting portion that causes a step with the wing portion 1f is connected with a smooth circular arc, stress concentration can be alleviated and strength can be improved. Furthermore, since the fixed part 1e which becomes the welding part is thick, reliable welding can be performed, and overheating and burn-through during welding can be prevented, thereby preventing a decrease in strength.

It goes without saying that the present invention can be applied not only to runners having partition plates as described in the above embodiments, but also to runners without partition plates.

As described above in detail with the embodiments, according to the present invention, the end plates of the runner blades constituting the runner or the fixed portions to the partition plates are made to have the same thickness, and the blade portions through which water flows have a cross-sectional airfoil shape. year,
Since grooves of the same width were formed on the support plate,
It is possible to improve the strength and reliability of the runner.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway perspective view showing the typical structure of a once-through water turbine, Figure 2 a and b are for conventional runners, a is a perspective view of the runner blade, and b is a partially enlarged view of the end plate or partition plate. 3 to 6 show one embodiment of the runner of the once-through water turbine of the present invention, FIG. 3 is a perspective view of the runner blade, and FIGS. 4a and 4b are A-A in FIG. 3, respectively. Arrow sectional view,
FIG. 5 is a partially enlarged view of the end plate or partition plate which is a support plate, and FIGS. 6a and 6b are sectional views of the fixed portion of the runner blade and the support plate, respectively. In the drawings, 1 is a runner, 1a is a runner blade, 1b is an end plate, 1c is a partition plate, 1e is a fixed part,
1f is a wing portion, and 1g is a groove.

Claims (1)

[Scope of utility model registration request] A once-through water turbine that has at least two disc-shaped support plates, grooves for installing runner blades are formed at equal intervals on the outer circumference of these support plates, and the runner blades inserted into these grooves are fixed by welding. In the runner, grooves for attaching runner blades of the same width are formed at equal intervals on the outer circumference of the support plate, and the fixing portions of the runner blades to the support plate are formed with the same thickness corresponding to the grooves. A runner for a once-through water turbine, characterized in that the blade portion through which water flows is formed to have a predetermined airfoil-shaped cross section, and the connecting portion between the fixed portion and the blade portion is formed in a smooth arc shape.