Pelton wheel, comprising buckets having roots mechanically joined to a hub, and associated production method

Abstract

The invention relates to a Pelton wheel (1) having a central axis (X) and comprising: - a hub (2); - a plurality of one-piece parts (3) each consisting of at least one bucket (30) extended by a root (31) at one of its longitudinal ends and distributed over the periphery of the hub, with each root bearing radially against a peripheral edge of the hub; - at least one clamping flange (4) bearing against at least one of the main faces (21) of the hub and at least one of the lateral edges of the bucket roots; - a plurality of clamping screws (5) screwed into the hub thus laterally clamping the flange against the at least one main face of the hub and the at least one of the lateral edges of the bucket roots.

Description

[0001] Description

[0002] Title: Pelton type wheel, with buckets with heels mechanically assembled to a hub, Associated manufacturing process.

[0003] technical field

[0004] The present invention relates to the field of hydraulic turbines, intended for use in hydroelectric power plants, and more particularly to so-called Pelton turbines.

[0005] The present invention aims to facilitate the manufacture of a Pelton turbine wheel and to reduce the associated costs.

[0006] Previous technique

[0007] A Pelton turbine consists of a rotating wheel, fitted with blades called "buckets" around its periphery, and one or more fixed injectors that send water at very high speed onto the buckets. The whole assembly is surrounded by a steel sheet casing designed to protect the wheel and to drain the water.

[0008] A Pelton wheel has a general shape of a disc equipped with buckets, each resembling half a nutshell, placed around the circumference.

[0009] Most often constructed in one piece, Pelton wheels are cast using ferrous materials highly alloyed with chromium and nickel.

[0010] The wheels consist of a central rim and peripheral troughs.

[0011] The molding or machining of these wheels is a complex and delicate operation, requiring numerous and costly metallurgical controls.

[0012] As a result, the manufacturing and therefore supply times to hydroelectric power plant operators who would need them in case of maintenance and / or breakdown are long.

[0013] Therefore, there is a need to simplify the manufacturing of Pelton-type wheels and to reduce the associated time and costs.

[0014] The general aim of the invention is therefore to meet at least partially this need. Description of the invention

[0015] To achieve this, the invention first relates to a Pelton-type wheel with a central axis (X) and comprising:

[0016] - a hub;

[0017] - a plurality of monobloc parts each consisting of at least one trough extended by a heel at one of its longitudinal ends and distributed around the periphery of the hub with each heel bearing radially against a peripheral edge of the hub;

[0018] - at least one clamping flange, resting against at least one of the main faces of the hub and at least one of the lateral edges of the trough heels;

[0019] - a plurality of clamping screws, screwed into the hub by laterally clamping the flange against said at least one main face of the hub and said at least one of the lateral edges of the trough heels.

[0020] The screws are preferably fitted with anti-loosening washers of the cam-effect type such as those marketed under the reference Nord_Lock or other types of washers that secure tightening.

[0021] According to an advantageous embodiment, the Pelton wheel comprises a single clamping flange, one of the lateral edges of the trough heels being clamped and laterally supported against a lateral edge of the hub while the other of the lateral edges of the heels is clamped and laterally supported against the single clamping flange.

[0022] According to this method, the cross-section of each trough heel is trapezoidal in shape so that the clamping of the flange constitutes a mechanical dovetail joint between each trough heel and the flange and the hub.

[0023] In an advantageous embodiment, the Pelton wheel includes a sealing gasket arranged around each clamping screw and between the hub and the clamping flange. This prevents any liquid from seeping into the interface between the hub and the flange.

[0024] In an advantageous embodiment, the Pelton wheel includes a sealing cap fixed to each screw head. The cap prevents the screws from coming into contact with liquid, thus reducing corrosion and the risk of leakage. The cap is preferably secured by bonding with silicone, polyurethane sealant, or any other sealant in grooves provided for this purpose.

[0025] Advantageously, the hub includes a peripheral edge, smaller in diameter than its peripheral edge supporting the trough heels, adapted to center the clamping flange.

[0026] The constituent material of the hub and flange is preferably chosen from stainless steel, aluminum, bronze, cast iron, composite materials or an alloy based on at least one of these.

[0027] The constituent material of the one-piece trough parts is preferably chosen from stainless steel, aluminum, bronze, cast iron, composite materials or an alloy based on at least one of these.

[0028] The invention also relates to a method for making a Pelton type wheel, comprising the following steps: i / producing by machining and / or 3D printing a plurality of one-piece parts, each consisting of at least one bucket extended by a heel projecting on one of its longitudinal sides; ii / producing by forging and then machining a hub and at least one clamping flange; iii / positioning the plurality of one-piece parts contiguously on a peripheral edge of the hub; iv / placing at least one clamping flange laterally against a main face of the hub and one of the lateral edges of the bucket heels; v / tightening by screwing the flange against the main face of the hub and the lateral edge of the bucket heels.

[0029] The invention finally relates to the use of a Pelton wheel, as described above, as a moving wheel of a hydraulic turbine in a hydroelectric power station.

[0030] Thus, the invention essentially consists of proposing a mechanically assembled Pelton wheel made from one-piece components incorporating buckets mounted on the periphery of a hub and then secured by screwing a clamping flange onto the hub. The advantages of the invention are numerous, including easier, faster, and less expensive manufacturing than a one-piece Pelton wheel produced by molding and machining according to the prior art.

[0031] Other advantages and features will become clearer upon reading the detailed description, which is provided for illustrative purposes only and is not exhaustive, with reference to the following figures.

[0032] Brief description of the drawings

[0033] [Fig 1] Figure 1 is an exploded view of a Pelton type wheel according to the invention.

[0034] [Fig IA] Figure IA is a detail view along A of Figure 1, showing a one-piece part according to the invention, consisting of a bucket extended by a heel for the mechanical assembly of the Pelton wheel.

[0035] [Fig 2] Figure 2 is a front view of the Pelton wheel according to Figure 1, in mechanically assembled configuration.

[0036] [Fig 2A] Figure 2A is a longitudinal sectional view along AA of the Pelton wheel of Figure 2.

[0037] [Fig 2B] Figure 2B is a detail view along B of Figure 2A, showing the mechanical tightening of the flange by screw on a trough heel.

[0038] [Fig 3] Figure 3 is a front view of a one-piece hub of a Pelton wheel according to figures 1 and 2.

[0039] [Fig 3A] Figure 3A is a longitudinal sectional view along AA of the hub of Figure 3.

[0040] [Fig 4] Figure 4 is a front view of a clamping flange of a Pelton wheel according to figures 1 and 2.

[0041] [Fig 4A] Figure 4A is a longitudinal sectional view along AA of the clamping flange of Figure 4.

[0042] Detailed description

[0043] The various figures show a Pelton wheel 1 with central axis X, which is mechanically assembled according to the invention. This Pelton wheel 1 comprises, firstly, a machined hub 2 of axisymmetric shape, which includes an outer peripheral edge 20, a main face 21, an inner peripheral edge 21 of smaller diameter than the outer edge 20, and a lateral edge 23 which is extended from the outer edge 20. In addition, a plurality of tapped holes 24 are regularly distributed angularly from the main face 21, parallel to the axis of the hub.

[0044] The wheel 1 also includes a plurality of one-piece parts 3, each consisting of at least one bucket 30 extended at one of its longitudinal ends by a heel 31. As illustrated, the cross-section of the heel 31 is trapezoidal.

[0045] All these one-piece pieces 3 are distributed around the periphery of the hub with each heel 31 bearing radially against the outer peripheral edge 20 of the hub.

[0046] The wheel 1 also includes a single clamping flange 4 with a clamping portion 40 and a plurality of regularly spaced holes 41. The flange 4 is centered and guided on the inner peripheral edge 22 of the hub and laterally supported against the main face 21 of the hub. The clamping portion 41 is laterally supported against one of the lateral edges of the bucket heels 31.

[0047] A plurality of clamping screws 5 is screwed individually into each tapped hole 24 of the hub 2 through the holes 41 and with the screw heads bearing against the flange 4. Thus, the flange 4 is clamped laterally against the main face 21 of the hub and one of the lateral edges of the trough heels 31 which are therefore mechanically locked.

[0048] As illustrated, due to the complementary shapes with the trapezoidal section of the trough heels 31, the clamping portion 41 of the flange and the lateral edge 24 of the hub, the resulting mechanical connection is of the dovetail type, which further improves the positioning and mechanical locking of the monobloc parts 3 around the hub 2. The edges are preferably chamfered, in order to ensure optimal contact between the different bearing faces.

[0049] To perfect the sealing of the Pelton wheel 1 and prevent any liquid infiltration within it, a sealing gasket 6 is arranged around each clamping screw 5 and between the hub 2 and the clamping flange 4. In addition, a sealing cap 7 is fixed by bonding with silicone, polyurethane sealant or any other sealing fluid in the grooves provided for this purpose, on each clamping screw head.

[0050] To produce such a Pelton wheel 1, the following steps are carried out: produce by machining and / or 3D printing a plurality of monobloc parts 3; produce by forging and then machining the hub 2 and the clamping flange 4; position the plurality of monobloc parts 3 edge-to-edge on the peripheral edge 20 of the hub 2; laterally support at least one clamping flange 4 against the main face

[0051] 21 of the hub and one of the lateral edges of the trough heels 31. tightening of the flange 4 by screwing the screws 5 into the hub 4 and through the flange 4 against the main face 21 of the hub and the lateral edge of the trough heels 31.

[0052] Other advantages and improvements may be made without going outside the scope of the invention.

[0053] The invention is not limited to the examples just described; in particular, features of the illustrated examples can be combined in unillustrated variants.

[0054] If in the illustrated example all the one-piece bucket parts are identical, the invention can be realized with one-piece parts that would be of different dimensions while allowing their close positioning around the hub.

Claims

Demands 1. Pelton-type wheel (1), with central axis (X) and comprising: - a hub (2); - a plurality of monobloc parts (3) each consisting of at least one trough (30) extended by a heel (31) at one of its longitudinal ends and distributed around the periphery of the hub with each heel bearing radially against a peripheral edge of the hub; - a single clamping flange (4), one of the lateral edges of the trough heels being clamped and laterally supported against a lateral edge of the hub while the other of the lateral edges of the heels is clamped and laterally supported against the single clamping flange; - a plurality of clamping screws (5), screwed into the hub by laterally clamping the flange against said at least one main face of the hub and said at least one of the lateral edges of the trough heels, the cross-section of each trough heel being trapezoidal in shape so that clamping the flange constitutes a mechanical dovetail connection between each trough heel and the flange and the hub.

2. Pelton wheel according to any one of the preceding claims, comprising a sealing gasket (6) arranged around each clamping screw and between the hub and the clamping flange.

3. Pelton wheel according to any one of the preceding claims, comprising a sealing cap (7) fixed on each clamping screw head.

4. Pelton wheel according to any one of the preceding claims, the hub comprising a peripheral edge (22), of smaller diameter than its peripheral support edge (20) of the trough heels, adapted to center the clamping flange.

5. Pelton wheel according to any one of the preceding claims, the constituent material of the hub and flange being selected from stainless steel, aluminum, bronze, cast iron, composite materials or an alloy based on at least one of these.

6. Pelton wheel according to any one of the preceding claims, the constituent material of the one-piece bucket parts being selected from stainless steel, aluminum, bronze, cast iron, composite materials or an alloy based on at least one of these.

7. Method for producing a Pelton type wheel (1) according to any one of the preceding claims, comprising the following steps: i / producing by machining and / or 3D printing a plurality of one-piece parts (3) each consisting of at least one bucket (30) extended by a heel (31) projecting on one of its longitudinal sides; ii / producing by forging and then machining a hub (2) and at least one clamping flange (4); iii / positioning the plurality of one-piece parts in a contiguous manner on a peripheral edge (20) of the hub; iv / laterally supporting at least one clamping flange against a main face (21) of the hub and one of the lateral edges of the bucket heels; v / tightening by screwing the flange against the main face of the hub and the lateral edge of the bucket heels.

8. Use of a Pelton wheel (1) according to any one of claims 1 to 7, as a moving wheel of a hydraulic turbine of a hydroelectric power station.

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