GB2190344A

GB2190344A - Shrouded propeller device for a vessel

Info

Publication number: GB2190344A
Application number: GB08710126A
Authority: GB
Inventors: Pyry Vainio; Olavi Ala-Ketola
Original assignee: Hollming Oy
Current assignee: Hollming Oy
Priority date: 1986-04-29
Filing date: 1987-04-29
Publication date: 1987-11-18
Anticipated expiration: 2007-04-29
Also published as: CN87103246A; NL8700999A; SE8701734D0; SE8701734L; FI79991B; GB2190344B; NO871764D0; GB8710126D0; FI861798A; DE3713993C2; NL193424B; JPS62273194A; DE3713993A1; NO871764L; FI79991C; SE466253B; CA1283004C; FI861798A0; CN1010849B

Description

GB2190344A 1 SPECIFICATION zle improves the thurst, one may, in associa

tion with a propeller device, use a smaller Propeller device for a vessel diameter propeller as compared with the situa tion that a propeller without a propeller nozzle The present invention relates to a propeller 70 would be used. This kind of propeller device device for a vessel, which propeller device equipped with a propeller nozzle is formerly comprises two propellers arranged to rotate described for instance in the FI Application on a common rotating shaft in opposite direc- 830 373. A common benefit of the propeller tions, the driving power being brought to the devices described above is that they are sim essentially horizontal shafts of the propellers 75 ple to make turning so that they can be used by a vertical shaft and an angle gear. for steering the boat.

Propeller devices equipped with propellers The object of the present invention is to rotating in opposite directions are known in provide a new type of propeller device, with the Prior Art. When two propellers are inwhich all benefits of the propeller devices stalled to the same propeller device axially 80 known in the Prior Art are attained, but one after the other to rotate in opposite direc- whose efficiency and thrust are essentially tions, the majority of the energy bound to the better than those of the Prior Art propeller whirls of the trailing flow of the front propeller devices. For this, the principal charasteristic can be made use of in the rear propeller with feature of the invention is that the propeller suitable design of the rear propeller. Then the 85 device is equipped with at least one annular load on both propellers will diminish and the propeller nozzle in such a way that at least cavitation conditions improve, and the effici- one of the propellers of the propeller device is ency of the propeller device will increase. As arranged to rotate within said propeller nozzle.

the efficiency will be improved, it is possible Among the benefits of the invention when to use smaller-diameter propellers with the 90 compared with solutions of the Prior Art is consecuence that a vessel equipped with this that a propeller device in accordance with the kind of propeller device will also be able to invention provides a very high thrust with an operate in shallow waters. These propeller de- essentially smaller propeller diameter than vices create high thrusts compared with con- what is required in known propeller devices ventional propeller devices with small propeller 95 for the same thrust. In other words, the effici diameters; on the other hand, due to the high ency of a propeller device in accordance with efficiency of the propeller device, high hrusts the invention is essentially better than the effi are attained with lower engine powers than in ciency of the known systems. Another essen conventional systems. This will reduce the to- tial benefit is that a propeller device in accor tal costs of the system. Propeller devices with 100 dance with the invention can easily be made opposite-rotating propellers have earlier been turning, so that the propeller device can be described for instance in US Patents 2 used for steering the vessel.

691.356, 2 987 031, 3 094 967 and in the The invention will now be described in de DE Patent Publication 870 655 and in the DE tail with reference to the figures of the ac- Publication Print 1 145 048. 105 companying drawing, which schematically illus This kind of propeller device equipped with trate various embodiments of a propeller depropellers rotating in opposite directions can vice in accordance with the invention.

be considered exceptionally feasible when Figures 1A to 1C illustrate various embodi both propellers of the propeller device are ar- ments of a propeller device in accordance ranged to the same side of the angle gear of 110 with the invention, in which propeller devices the propeller device, i.e. when both propellers both propellers are of the pushing type.

either pull or push. Then the angle gear of the Figures 2A to 2D illustrate various embodi propeller device will not create flows interfermerits of a propeller device in accordance ing the operation of the rear propeller; instead, with the invention, in which which propeller energy bound in the swirls of the trailing flow 115 devices one propeller is of the pushing type, of the front propeller can be better made use and the other one is of the pulling type.

of in the rear propeller. First we refer to Figs. 1 A to 1 C, in which a This arrangement has before been described propeller device in accordance with the inven for instance in the SE Patent 433 599. tion is generally indicated with ref. number 10.

On the other hand, also such an arrange- 120 Power is brought to the propeller device in a ment has been used in the Prior Art in which conventional way with a vertical shaft 12, there is, for changing the flow conditions of from which it is transferred by an angle gear the propeller, an annular propeller nozzle 11 to the shafts of the propellers 13 and 14.

around the propeller. A propeller nozzle is In Figs. 1A to 1C both propellers 13 and 14 usually used to improve the thrust of the pro- 125 of the propeller device 10 are of the pushing peller particularly in slow speeds, in which the type. The propellers 13 and 14 are arranged propeller nozzle is used to accelerate the pro- to rotate in opposite rotating directions, for peller flow in order to provide improved instance as is described in the SE patent 433 thrust. This kind of arrangement is generally 599. The propeller shafts are therefore in- used for instance in tugs. As a propeller noz- 130 stalled coaxially one within the other in such a 2 GB2190344A 2 way the shaft of the first propeller 13 or the tioning the first propeller 13 within the propel front propeller is tubular, and it is arranged on ler nozzle 15B in this way, the additional the shaft of the second propeller 14 or the thrust provided by the propeller nozzle 15B to rear propeller with bearings so as to rotate the first propeller 13 is at its maximum.

around it. As stated above, the shafts of the 70 Fig. 1C illustrates another alternative em propellers 13 and 14 are rotated by means of bodiment of a propeller device 10 in accor an angle gear 11 in opposite rotating direc- dance with the invention. In this embodiment tions. the first propeller 13 or the front propeller is The size of the propellers 13 and 14 used arranged as an open propeller and the second in the propeller devices is chosen in the 75 propeller 14 or the rear propeller is arranged known fashion so that the diameter of the within the propeller nozzle 15C. At low first propeller 13 or the front propeller is lar- speeds, an arrangement shown in Fig. 1C is ger than the diameter of the second propeller not as favourable as the embodiment shown 14, whereat the point whirls of the front pro- in Fig. 1 B, but the solution shown in Fig. 1 C peller blades do not cause cavitation in the 80 is feasible at higher speeds. In the embodi second propeller 14 or the rear propeller. As ment shown in Fig. 1C, the second propeller known, it is also feasible to use a larger num- 14 is installed within the propeller nozzle 15C, ber of blades in the second propeller 14 or i.e. axially in the area between the leading the rear propeller than in the first propeller 13 edge 16C and the trailing edge 17C of the or the front propeller. The blade number of 85 propeller nozzle in such a way that said pro the second propeller 14 should favourably be peller 14 is favourably located in the area be selected one higher than the blade number of tween the axial center and the trailing edge the first propeller 13, which is very important 15C of the propeller nozzle 15C. As Fig. 1A, in order to avoid harmonic vibrations between neither Figs. 113 or 1C show the elements the blades of propellers 13 and 14. These 90 with which the propeller nozzle 15A is sup dimensioning principles are generally valid for ported to the propeller device 10; the sup all embodiments of a propeller device in ac- porting elements may be arranged in any suit cordance with the invention. able way.

Fig. 1A illustrates the first embodiment of a Figs. 2A and 213 show different embodi- propeller device in accordance with the inven- 95 ments of a propeller device 20 in accordance tion. As shown in Fig. 1A, the propeller de- with the invention. In these the first one 23 of vice 10 is equipped with propellers 13 and 14 the propellers of the propeller device has been arranged to rotate in opposite directions. The arranged to push and and the second one 24 propeller 10 is also equipped with a propeller of the propellers of the propeller device has nozzle 15A, which is in the axial direction long 100 been arranged to pull. The power is brought enough to cover both propellers 13 and 14 of to the propeller device 20 with the vertical the propeller device 10. In other words, the shaft 22, and the power is further transmitted axial length of the propeller nozzle 15A is by angle gear 21 to the propeller shafts 23 such that both propellers 13 and 14 are axi- and 24.

ally located in the area between the leading 105 Fig. 2A shows an alternative embodiment of edge 16A and the trailing edge 17A of the a propeller device 20 in accordance with the propeller nozzle. The elements with which the invention. As in the embodiment of Fig. 2A, propeller nozzle 15A is supported to the pro- the first propeller 23 of the propeller device, peller device 10 itself are not shown in the the pulling front propeller, is arranged to be figure; the supporting elements may be ar- 110 an open propeller and the second propeller ranged in any suitable way. 23, the pushing rear propeller is arranged Fig. 113 illustrates another embodiment of a within the propeller nozzle 25A. The second propeller device 10 in accordance with the in- propeller 24 is axially arranged between the vention. In this embodiment the first propeller leading edge 26A and the trailing edge 27A in 13 or the front propeller is arranged within 115 such a way that it is favourably located in the the propeller nozzle 1513, and the second pro- range between the center of the axial length peller 14 or the rear propeller is arranged as of the propeller nozzle 25A and the trailing an open propeller. This arrangement may be edge 27A. With this arrangement all the ad considired the most feasible from the point of vantages described above with reference to view of the invention. This is because at the 120 Figs. 1 A to 1 C are attained.

front propeller water flows slower than at the The embodiment illustrated in Fig. 213 other rear propeller, whereat the additional thrust wise corresponds to the embodiment illus provided by the nozzle is also greater. The trated in Fig. 2A, but in Fig. 213 also the first location of the first propeller 13 within the propeller 23, the pulling front propeller, is ar propeller nozzle 1513, i.e. axially between the 125 ranged within the propeller nozzle 2513. There leadigg edge 16B and the trailing edge 17B of fore, according to this embodiment, two pro the propeller nozzle, is favourably so selected peller nozzles 25A and 25B are used in the that the first propeller 13 is located between propeller device 20. The first propeller 23 is the center of the axial length of the propeller also suitable arranged within the propeller noz nozzle 15B and its trailing edge 1713. By posi- 130 zle 25B in such a way that, in the axial direc- 3 GB2190344A 3 tion, it is located between the leading edge accompanying drawing. The invention is by 26B and the trailing edge 27B of the propeller now means restricted to examples illustrated nozzle 2513, in the area between the center of in the figures; many variations are possible the axial length of the nozzle and the trailing within the framework of the inventional idea edge 2713. 70 as defined in the following claims.

A propeller device illustrated in Fig. 2C dif

Claims

fers from those illustrated in Figs. 2A and 213 CLAIMS so that in this

embodiment the first propeller 1. A propeller device for a vessel, which 23, the pulling front propeller, is arranged comprises two propellers mounted to rotate within the propeller nozzle 25C, whereas the 75 about a common axis of rotation in opposite other propeller 24, the pushing rear propeller, directions, and at least one annular propeller is arranged as an open propeller. In this em- nozzle located in such a position that at least bodiment the first propeller 23 is arranged one of the two propellers is arranged for rota within the propeller nozzle 23 in the same tion within said propeller nozzle.

way as in the previous embodiment, i.e. in 80
2. A propeller device as claimed in claim such a way that in the axial direction the first 1, in which the forward of the two propellers propeller 23 is located between the leading is arranged for rotation within the propeller edge 26C and the trailing edge 27C of the nozzle and the rearward propeller is an open propeller nozzle 25C, in the area between the propeller without a surrounding nozzle.

center of the axial length of the nozzle 25C 85
3. A propeller device as claimed in claim and the trailing edge 27C. 1, in which the forward of the two propellers Fig. 21) shows such an embodiment of the is an open propeller without a surrounding invention in which both the first propeller 23 nozzle and the second propeller is arranged and the second propeller 24 are arranged for rotation within the propeller nozzle.

within the common propeller nozzle 251). This 90
4. A propeller device as claimed in claim 1 embodiment is not as favourable as the previ- in which the forward and the rearward of the ous ones, as, due to the design of the propel- two propellers are each arranged for rotation ler device 20, the propeller nozzle 25D must within a separate propeller nozzle.

inevitably be extremely long. The location of
5. A propeller device as claimed in any of the propellers 23 and 24 within the propeller 95 claims 1 to 4 in which the or each propeller nozzle 25D is also not the best possible, as in arranged for rotation within a propeller nozzle this embodiment the first propeller 23 will be is located in the axial direction within the sand located near the leading edge 26D of othe propeller nozzle at a position between the propeller nozzle 25D whereas the second pro- center of the axial length of the nozzle and peller 24 will be located near the trailing edge 100 the trailing edge thereof.

27D of the propeller nozzle.
6. A propeller device as claimed in claim A design in accordance with the invention 1, in which the forward and the rearward of may also be applied otherways than what is the two propellers are located for rotation illustrated in the figures of the drawing. One within a common annular propeller nozzle.

possiblility is to arrange both propellers of the 105
7. A propeller device as claimed in any propeller device to pull. A twin-propeller proone preceding claim in which both of the pro peller-nozzle combination may also be applied pellers are located side by side on the same to conventional power transmission arrange- side of a drive connection thereto.

ments, in other words when power is brought
8. A propeller device as claimed in any to the propellers with a---long-propeller shaft. 110 one of claims 1 to 6 in which the propellers In these cases the power transmission can be are located one forwardly and one rearwardly arranged for instance so that power brought of a drive connection thereto.

to the propellers is divided in the power drive
9. A propeller device as claimed in any line as near the propellers as possible, with one preceding claim in wich a drive connec- for instance a planetery gear and by using 115 tion to the propellers passes through a verti coaxial propeller shafts. This kind of drive line cally extending member about which both pro arrangement is yet complex and inconvenient pellers can pivot for steering the vessel.

to arrange; therefore using a twin-propeller
10. A propeller device as claimed in claim propeller-nozzle combination is considerably 1 and substantially as herein described with more feasible, and it is easier to arrange in 120 reference to the accompanying drawings.

association with propeller devices 10 and 20 Printed for Her Majesty's Stationery Office illustrated in figures, and particularly in the by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987.

embodiments of Fig. 1A to 1C, because in Published at The Patent Office, 25 Southampton Buildings, these arrangements very short propeller shafts London, WC2A l AY, from which copies may be obtained.

can be used. The propeller devices can also be arranged to turn around the vertical shaft 12, 22 in such a way that they can be used for steering the vessel.

The invention has been described only as examples with reference to the figures in the