US1872038A - Rudder arrangement - Google Patents

Description

Aug. 16, 1932. F. HITZLER RUDDER ARRANGEMENT Filed Oct. 7, 1930' 2 Sheets-Sheet l INVENTOR FRANZ H1 721.2

A TTQR/YEXS Aug. 16, 1932. F. HITZLER 1,872,038

RUDDER ARRANGEMENT Filed Oct. 7, 1 30 2 Sheets-Sheet 2 mam/r0? 7722275 5 223162" 5y g/MMCQ Patented Aug. 16, 1932 UNITED RUDDER ARRANGEMENT Application filed October 7, 1930, Serial No. 487,007, and in Germany August 2, 1930.

The subject of the present invention is a rudder arrangement in which three or more rudders rotatably mounted in the body of the ship are used, the shafts of these rudders 6 being connected together by rods or gearings.

It is novel to arrange the rudder surfaces in such a manner that, for example, in the case of single screw ships with three rudders two thereof are arranged at the same distance 9 behind the screws on opposite sides of the screw shaft and within the range of the screw stream, whilst the third rudder is arranged along the axis of the screw lateral rudders in such a manner that inflow conditions and rudder action of this middle rudder are considerably improved relatively to known rudder arrangements.

Fig. 1 is a general diagram of the invention applied to a single screw vessel,

Fig. 2 is a similar diagram of the invention applied to a twin screw vessel,

Fig. 3 is a diagram illustrating the flow of fluid around the rudders of the invention,

Fig. 4 is a. view of the rudder shafts con- 25 nection,

Fig. 5 shows the use of modified rudders with the invention and, I

Fig. 6 is a. diagram illustrating stream flow as modified by the invention.

An example of construction of the invention is illustrated in Figure 1. In the horizontal section along the screw axis, a indicates the screw, 6 the two lateral rudders, c the middle rudder, (Z the shafts of the lateral rudders and e the shaft of the middle rudder. The flow conditions when moving the rudders are indicated by stream lines and it will be seen that the part of the propeller stream included by the lateral rudders re ceives a restriction, whereas when setting the rudders it flows between the lateral rudders and is diverted. The restriction of the cross section of flow between the rudders relatively to that at the inlet edge thereof corresponds in the example of construction to the distances 8 and 26 indicated in the drawing and apparently increases with the rudder angle.

Consequently the inflow speed for the middle rudder in the arrangement of the lateral behind the two res PATENT OFFICE W rudders according to the inventionis considerably higher than without these as is'also the rudder action which asis well known considerably increases with the inflow veloc ity. A further favourable action resides therein that the propeller stream, before reaching the middle rudder, 'is whirled by the lateral rudders acting as guide'surfaces and its whirling movement is reduced, further' therein that the inflow angle for the suction side of the middle rudder, mainly with larger rudder angles, is reduced whereby flowing ofl" phenomena on the suction side. of the rudder are prevented. The latter ac tion, however, only occurs when the distance of the middle rudder from the lateral rudders is such that the shaft of the middle rudder is within the angle formed by the extensions of-the side ruddersurfaces in their hard rudder posit-ions'so that the water flowing from the'pressure side of the lateral rudder located on the outside of the circle of rotation flows against the suction side of the middle rudder. j V 1 i Rudder arrangements are known in which as in accordance with the present invention the inflow conditions and rudder actions are improved as regards the rudders located at the back by stepping the rudder surfaces in the inflow direction. In such cases, however, i

the middle rudder located behind the screw serves to direct the screw stream at the beginning of the movement of therudder towards the lateral rudder located on the inner side of the circle of rotation so that for these rudders the inflow velocity is increased relatively to the dead water velocity, as without the action of the middle rudder it wouldlie wholly or for the larger part in" dead water, whilst the outer lateral rudders when steering remains in any case in dead water, that is to say does not partake of the favourable action of the middle rudder.

In contrast with this a feature of the present invention resides in the fact that all rud- 9 ders during the steering operation lie in the screw stream and a further feature residesin the fact that when operating the rudders the inflow velocity for the middle rudder is increased so that the inflow velocity for the two lateral rudders corresponds substantially with the velocity of the stream leaving the screw and for the middle rudder to an increased velocity produced by the restriction of the stream by flowing between the lateral rudders.

In Figure 2 is illustrated a further example of construction of the invention for twin screw ships. The two lateral rudders which are again indicated by b, are located within the range of the screw streams of the screws 9 and h, the middle rudder 0 in the middle plane of the ship. The rudders in this case are constructed as rudders having a water cutting shape. From the stream linesindicated it will be seen that in this example of construction for twin screw ships fundamentally the same actions are obtained as in the example of construction for single screw ships according to Figure 1.

In Figure 3 is illustrated an example cf construction in which the rudders during the setting of the rudders acquire differently large rudder angles and in this example of construction the middle rudder 0 moves in advance of the lateral rudders b so that by reason of the gradual reduction ofthe passage 7 area between the middle rudder and the inner lateral rudders the inflow velocities of rudder actions are further increased within the range of the two rudders. 1 I

The arrangement according to the invention can also be used for triple screw ships in which case the side rudders are arranged within the range of the outer screws and the middle rudder along the axis of the middle screw. V i Fig. 4 shows the connection of the rudder shafts. The shafts d and e are rigidly connected with levers i interconnected by bars 76. Therudders always move in the samedirection and are rotated through the same angle due to the equal leng'th of the connecting members. The rotary moment necessary for steering is transmitted by a" rudder quadrant to one of the rudder shafts and simultane ously to the other shafts. I

Instead of balance rudders it is also possible to use for the lateral rudders rudders of a different construction for example rudders with a fixed leading head shown in Fig. 5 without modifying the nature of the inven tion. The arrangement according to the invention is also applicable in all cases where air or water streams are to be used for'depth or lateral steering.

A rudder lying in the direction of the flow is arranged in front of a second rudder in such a way that in operation the back edge of the forward rudder situated at the exterior edge of the back rudder until there is only little space left in between, this movement taking place in such a way that when the angle between the rudders increases, the flow-in velocity increases for the backrudder and that a tearing 0d of the flow at the back side of the rudder is eliminated because the flow is directed to that side. From practical experience it is known, that the flow is torn off in the case of bent rudders as well as straight rudders, just behind the forward edge of the back of the rudder, approximately at the point p of Fig. 6, the stream being here separated from the rudder body and being changed into a turbulence. The change of direction of the stream around the forward edge of the rudder takes place by means of the steam or directed by the forward rudder, in accordance with this invention. So to say, the angle of flow is diminished by the forward rudder for the back side of theback rudder, the velocity is, however, increased simultaneously so thatthe rudder pressure can be considerably increased beyond the critical angle of flow.

I claim 1. In the device of the character described, two forward rudders arranged in the same cross-ship plane, a third back rudder arran ed in the middle and behind said two forward rudders, a shaft for each of said rudders rotatably mounted in the ship body,

means connect-in said rudder shafts with each other, and a driving device rotating said rudder shafts simultaneously in the same direction, the bacl: edge of the one of said two forward rudders which lies at the exterior side of the circle of rotation of the ship approaching in operation the forward edge of said third back rudder so that the flow velocity for said third rudder increases with the increase of the rudder angle and a'tearing off of the flow is avoided.

2. The device in accordance with claim 1 wherein the first-mentioned two rudders are arranged behind the screw symmetrically to the middleplane of the ship, said third-mentioned rudder being arranged. within said plane, the guiding surfaces of the two firstmentione'd rudders diminishing the losses due to the rotation of the screw stream and increasing the-energy thereof during its flow to the third-mentioned rudder.

3. The device in accordance with'claim 1, wherein said m ans for connecting said rudder shafts with each other in operation produce diflerent rudder angles for said rudders.

In testin'iony,whereof- I have allixed my signature.

FRAN Z HITZLER.

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