DE2413199A1 - PROPELLER OR TURBINE WHEEL - Google Patents

Description

DR. ING. E. HOFFMANN · DIPJ .. INQ. W. EITLE DR. RER. NAT. K. HOFFMANN PATEIiTANW ¹ OLD D-8000 MDNCHEN 81. ARABELLASTRASSE 4 TELEPHONE (0811) 911087

AB Volvo Penta, Gothenburg (Sweden) Propeller or turbine wheel

The invention relates to a propeller or turbine wheel or the like. With blades or blades, which by means of a Drive for propelling a surrounding gaseous or liquid fluid or under the effect of the Flow of the fluid surrounding them can be set in rotation, and in particular on a propeller for ships.

Conventional screws with a fixed blade angle have the disadvantage that they are not very effective and, moreover, are not able to brake the engine running with maximum force. To this disadvantage To remedy this, a drive screw was built that has automatically adjustable blades, i.e. their Blade angle of attack increases automatically with increasing speed. This is how one achieves when accelerating

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a higher efficiency, but at the same time reaches the disadvantage that the motor during acceleration immediately rises to the highest speed without the drive screw is able to brake the maximum torque of the motor.

The invention is therefore based on the object of creating a propeller or a turbine wheel which on ships, can brake an engine running at full power at any speed.

This object is achieved according to the invention with a propeller or a turbine wheel of the type mentioned at the beginning, which is characterized by a first set of blades (I5, 21, 41) with a predetermined fixed blade pitch angle, and by a second set of blades (10, 10, cooperating with the first). 23, 42) its blade angle depending on the speed of the blades and. the axial speed of the fluid flowing around the blades is adjustable.

The invention will now be described with reference to FIG the accompanying drawing is described and explained in more detail. Show it

1 shows a graphic representation of various engine load curves when using a conventional screw with a fixed angle of attack;

Fig. 2 is a schematic plan view of a verauben-

hub and a blade profile of an automatically adjustable Leaf;

FIG. 3 is a graph similar to FIG. 1, from which the values for the screw from FIG. 2 are increased

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can be found;

4 shows a sheet profile of a sheet with a fixed Angle of attack and a blade with an automatically adjustable angle of attack according to the invention;

FIG. 5 is a graphic representation similar to FIG. 1 for a Screw according to FIG. 4;

6 shows a schematic perspective illustration of a embodiment of a screw according to the invention;

7 is a schematic perspective view of a further embodiment of a screw according to the invention, and

8 shows a schematic perspective view of a detail from a turbine wheel according to the invention.

To better understand the principle of the invention now briefly discussed the basics with reference to FIGS. 1 to 3.

Fig. 1 shows a simplified graphic representation of various load curves F ₁ to F ^, when using a conventional screw with a fixed angle of attack. For the sake of simplicity, the torque curve is shown as a straight line, which is why it is very similar to a curve for a diesel engine. The curves F ₁ and F ^, show the engine load at various constant speeds, the curve F ₁ a load on the engine at

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Standstill of the boat shows, F-, a load at maximum Speed, and Fp a medium speed.

When accelerating, i.e. with full fuel supply, a boat with a screw with a fixed blade angle of attack, the screw blades work at low speeds with a large angle of incidence. The screw causes great resistance in the water. Such screws are generally designed so that the greatest possible torque of the engine is used, while the speed only reaches 60% of the maximum engine speed. This relationship is illustrated by curve F ₁ , which shows that the greatest torque is achieved for the first time during acceleration, whereupon the engine speed increases with increasing boat speed, so that the greatest engine power is achieved at the highest speed of the boat, as from the Curve F- is shown. At lower speeds, for example when towing another boat, the full drive force cannot be braked, as can be seen from the graphic representation, since the highest speed of the motor cannot be reached.

The screw from Fig. 2 shows opposite properties. In the case of this screw, the blades 10 (only one of which is shown here) are mounted freely rotatable in the hub 11 by means of a bearing 12. It can be seen from the drawing that the bearing 12 initially lies on the actual blade profile, and that for this reason the blade 10 has an arm 13 at its inner end. In fact, the blade itself can be bent at its inner end to match the arm. The bearing 12 lies on or near the axis of rotation 14 of the hub 11. This screw has the property that the screw blade adjusts itself automatically.

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that the angle of incidence is constant with respect to the direction of flow of the working medium. Thus, the angle of attack changes with the relationship between engine speed and boat speed. However, the propeller blades would then turn too easily, and when accelerating. with full fuel supply - the engine would reach its highest speed without the screw being able to brake the maximum torque. This relationship is illustrated by curve L ₁ in the load diagram from FIG. 3, which corresponds to the diagram from FIG. 1. The curve L ₁ relates to a load on the engine when the boat is at a standstill, while _{L 1 relates to the maximum speed and L 2} to a speed lying between these values. With increasing speed, the angle of attack and the braked torque increase, so that the greatest possible driving force can be achieved at maximum speed. When accelerating, this propeller is more effective than a propeller with stationary blades; however, since it slows down the engine output less strongly, the maximum compressive force of the screw is also lower.

Let by the simultaneous arrangement of self-adjusting blades and stationary blades according to the invention avoid the disadvantages of the constructions described above. Fig. 4 shows schematically a adjustable blade 10 with a stationary blade 15, both on a common hub 11 or each on can be arranged on their own and axially separated from the other hub. The automatically adjustable Sheet 10 is constructed as described above became, which is known per se, and automatically with a constant angle of incidence with respect to the oncoming Water can adjust its speed vectorially

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from the speed of the screw and the axial speed the fluid, i.e. more or less the boat speed, is determined. Thus, when the axial speed is low, the blade 10 turns itself with a low angle of attack. However, it takes

"at the same time also in the" resulting wing "the curvature, this" resulting wing "from the stationary sheet 15 and the movable sheet -10 consists. ' The stationary sheet 15 is here essentially the same angle of attack as the adjustable blade at maximum screw speed and maximum speed of the

.Bootes have, or more generally said, if the relationship between axial speed and speed is equal to the ratio between maximum axial speed and maximum speed.

By choosing the optimal ratio between the total area of the stationary and adjustable blades, it is possible to achieve a screw combination that can brake the full engine power both when the boat is stationary and at its maximum speed. This ratio is from the graph in Fig 5, in which the curve M shows the engine load when the boat is stationary, while the curve Mp shows the maximum speed. It can also be seen that the full power can be braked fairly constantly at all speeds between these values. The ratio between the surfaces should be such that the force exerted by the blades on the force in the direction of rotation is basically independent of the ratio between the rotational speed and the speed. In this connection it has been shown that with an optimally dimensioned screw the total area of the movable blades should be up to 60 to 85 %, preferably 10% of the total blade area.

Fig. 6 shows a schematic representation of an invention

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contemporary screw that has a hub 20 with two blades 21 with a constant angle of attack and with two has automatically adjustable blades 23 which are mounted freely rotatable by means of a bearing 22.

Fig. T shows a three-bladed screw in which each Blade on the hub 30 has a stationary part J51 and a having movable part 32. In this embodiment, each blade can have an intermediate wing looking similar.

With the help of the invention, the advantage can be achieved that the maximum speed of the boat is, for example, less is heavily dependent on wind and weather, if the acceleration time is shortened, which is especially for planing and semi-planing boats is applicable. The larger thrust line can be used, for example, especially at low speeds Use fish steamers or tugs and thus offers the possibility of a less complex construction in comparison to screws in which the angle of attack is changed with the help of mechanical influence on the blades.

From the graph in Fig. 5 it can be seen that that the screw, which basically depends on the boat speed, drives the engine with a torque loaded, which with the exception of the lowest speed range, basically with the increasing engine speed quadrupled.t. It follows that the engine is no apply such a large torque at low speed, must, since the highest possible speed only serves to accelerate the inertial screw mass Screw also for use in a single shaft gas turbine engine at.

The principle of the invention is not limited to the exemplary embodiments Hue Fig. 6 and 7 limited, the stationary and

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have adjustable blades mounted on the same hub are, but it also extends to the stationary and adjustable blades that are separate from each other are attached to their own hubs. These hubs can either be axially separated from one another on the same Shaft or be mounted on different shafts, the shafts of the motor with the same or with different Speed can be driven. In the latter case, a corresponding adjustment of the angle of attack is necessary made in that, for example, the slower rotating screw a correspondingly larger Angle of attack receives.

Even if the invention has been described above only with reference to screws for boats and ships it also refers to other propellers or the like, for example turbine wheels, pump wheels, Impellers, etc., in which the blades rotate be moved to drive a surrounding fluid, or on the other hand, the leaves under the Exposure to a fluid are rotated. Fig. 8 shows in a schematic representation part of a Turbine or impeller 40, which alternates between a stationary blade 41 and two adjustable blades arranged in a row behind it Has sheets 42. Optionally, the wheel can also have a series of stationary blades, and axially Distance from this row is a row of adjustable blades. Similarly, as in connection with the Screws has already been described above, the stationary and moving blades on sleepy wheels be arranged.

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Claims (7)

Claims Propeller or turbine wheel or the like. With blades w. Wings, which by means of a drive for driving of a gaseous or liquid fluid surrounding them or under the effect of the flow of the surrounding them Fluid can be set in rotation, marked ze i c h η e t, by a first sentence Blades (15,21,41) with a given fixed blade pitch angle, and by a second set of blades (10,23, 4-2) cooperating with the first, the blade pitch angle thereof depending on the speed of the blades and the axial speed of the flow around the blades Fluid is adjustable. 2. Rotating device according to claim 1, characterized in that the blades (15) of the first set have such an angle of attack that the blades (15, lo, 21,23, ² H, 42) of both sets have substantially the same blade angle, when the ratio between the maximum axial speed and the maximum speed is. 3. Rotating device according to claim 1 or 2, characterized ge kenn ze lehn et that the ratio between the surfaces of both sets of blades (15,10,21,23,41,42) is held so that the resulting force in the direction of rotation, which acts by means of the fluid on the leaves or by means of the leaves on the fluid, in principle depends on the relationship between the axial speed and the speed « -10- - io- 4. Rotating device according to claim 3 *, characterized in that the surface "of the second Set of sheets (10,23,42) $ 60 to $ 85, preferably $ 70, the total area of both sets of sheets is .. 5. Rotating device according to one of claims 1 to 4, characterized · in that both sets of blades are arranged on a common hub. 6. Rotating device according to one of claims 1 to 4, characterized in that the two Sets of blades are arranged on two axially separated hubs on a common shaft. 7. Rotating device according to one of claims 1 to 4, characterized in that the two Sets of blades are arranged on two hubs, each on its own shaft .. 409840/0797 Blank page