GB2345039A

GB2345039A - Cycloid propeller/turbine

Info

Publication number: GB2345039A
Application number: GB9926165A
Authority: GB
Inventors: Herbert Perfahl
Original assignee: Voith Schiffstechnik GmbH and Co KG
Current assignee: Voith Turbo Schneider Propulsion GmbH and Co KG
Priority date: 1998-11-05
Filing date: 1999-11-05
Publication date: 2000-06-28
Anticipated expiration: 2019-11-05
Also published as: GB2345039A8; GB9926165D0; DE19850954C1; GB2345039B

Abstract

The blades 1 are cyclically adjustable about their respective axes, as the rotor rotates about a central axis, by means of a joystick acting through kinematic mechanism 12,13,14 and toothed members 2,3. The tooth profiles of the members 2,3 are non-circular to ensure intersection of normals to the blade chords at a control point N.

Description

2345039 Ship's propulsion constructed as a cycloid propelle

The invention relates to a cycloid propeller according to the precharacterising clause of Claim 1, as described in German Patent 196 02 043 C2.

The structural elements and theoretical fundamental principles of the ship's propulsion constructed as a cycloid propeller have been represented in many different ways in the literature, e.g. in Voith-Druck 9.94 2000 and also in Voith Sonderdruck 1803, which represents an extract from "Voith Forschung und Konstruktion" [Voith Research and Construction] No. 18, Article 3, May 1967. Here many details can also be found on the kinematics of the blades, which serve to bring about the cyclical adjustment of the blades during a rotation on the circular path (see Figures 6 to 9). Statements on the theoretical fundamental principles of the cyclical blade adjustment are found in the firstmentioned document. 15

DE 196 02 043 Cl describes a cycloid propeller with blades which are mounted on a rotor. In this case too the swivel axes of the blades run parallel to the axis of rotation of the rotor. On the shaft of the individual blade a drive unit engages with a set of gears which can be driven by the rod assembly of the blade propulsion kinematics.

The inventor has now recognised that with the conventional kinematics of the blade adjustment the theoretical fundamental principles for it cannot be exactly satisfied, i.e. that the "normal law" to be observed for the blade adjustment is not complied with, i.e. that the normals on the blade chords have to join exactly in the respective control point.

This is where the invention now intervenes.

2 The object of the invention is to construct the Voith-Schneider propeller in such a manner the "normal law" mentioned above can be largely complied with, i.e. that in every driving state the normals on the blade chords meet exactly in the so-called control point. This object is achieved in accordance with the invention by the features

Claims

of Claim 1.

By means of this described achievement it can also be ensured that the acceleration of the individual blades that occurs can be reduced so that the blade stresses can be crucially reduced. In connection with the object just mentioned, this admittedly represents a certain compromise, which results in an optimal object when designing the respective ship's propulsion, since the very varying marginal conditions have to be taken into consideration for each individual propeller design.

It is known that a pair of gears can be formed by non-circular toothed wheels, in which connection details and other corresponding references can be gathered from Konstruction 48 (1996) pages 256 to 262.

A preferred embodiment of the invention is described below by means of the attached drawings, in which Figure 1 shows a basic top view of the circular motion of the blades, Figure
2 shows constructive details for this view and representation and Figure 3 shows a longitudinal section through the mounting of the single blade and the toothed wheels.
3 From the representation in Figure 1 one can see in principle the slidercrank kinematics with the connecting rod 12, the rocker 13 and the coupling rod 14, which basically form the slider-crank kinematics. This propulsive kinematics is the construction to be 5 encountered today in the Voith cycloid propeller.

In the German Patent Specification mentioned at the beginning, this socalled slidercrank kinematics is brought into relationship with a gear pair, by which finally the individual blade is swivelled. Here the two gearwheels are designated by 2 and 3, with the driving wheel 3 being securely connected to the coupling rod 14 and the driven wheel 2 being securely connected via the blade shaft 8 to the individual blade 1 (see Figure 3). The individual blades now revolve on the blade circle of rotation 20 with their generally vertically aligned blade axes or also shaft axes 9 and the associated control point for the kinematics is indicated by N in Figure 1.

From Figure 3 can also be seen the mounting of the blade shaft in an upper bearing 22 and a lower bearing 21 and also corresponding seals 17, which seal the interior of the rotor housing 15 against water.

With the construction of the toothed wheels as non-circular toothed wheels it is now possible to design the shape of the blade angle curve as desired and in particular to ensure that the normals on the chords of the blade sections join exactly at the control point, in which case the position of the control point N changes in accordance with the journey conditions, according to the required angular adjustment of the individual blades.
4. A cycloid propeller substantially as described herein with reference to accompanying drawings.

4 The maximum adjustment of a blade is normally roughly 110 to 120, so that here the non-circular toothed wheels are not completely meshed, but practically formed by toothed quadrants. it can be seen that the reference diameter of the toothed wheels continually changes, in which case of course the sum of the individual reference diameters of the toothed driving wheel and toothed driven wheel is a constant value (= centre distance). The maximum change in the transmission ratios of the pairs of toothed wheels is to be fixed for example at roughly 15 to 20 % of the minimum transmission.

It may be very advantageous to reduce the acceleration of the blades and consequently the forces that accordingly occur in an extreme region or towards the extreme region of the blade setting angle by a reference diameter of the driven toothed wheel that increases in each case, i.e. of that toothed wheel which is coupled with the 15 blade shaft in each case.

The invention can be applied not only in a ship's propulsion, but also in a turbine or another centrifugal machine. Water, air or other media are possible as the medium here.

Claims 1 A cycloid propeller with blades that can swivel cyclically by means of a joystick and blade kinematics, the swivel axes of which are disposed parallel to one another and to the axis of rotation of the rotor mounted in the stator, wherein in each case blades are coupled with the blade kinematics by means of a pair of toothed wheels, one of which is attached to the blade shaft in each case, the non-circular toothed wheels in each case forming the pairs of toothed wheels.

2. A cycloid propeller according to Claim 1, in which the reference diameter of the ddving wheel in the extreme range or towards the extreme range of the blade adjustment angle is smaller than the mean range thereof and is accordingly larger in the driven toothed wheel.

3. A cycloid propeller according to Claim 1 or 2, in which the maximum difference in the reference diameter on the respective toothed wheel is 15 % of the minimum value.