CA1082534A - Feathering propeller especially for sailing boats - Google Patents

Abstract

FEATHERING PROPELLER ESPECIALLY FOR SAILING BOATS
ABSTRACT OF THE DISCLOSURE
Feathering propeller particularly for auxiliary engines of sailing boats. The propeller comprises a device for transmitting a rotary and a positioning motion to the blades including planetary gear means for converting an angular motion of the drive shaft into an angular motion for inclining the propeller blades and means for halting the angular motion to halt the blades at the required inclination and render the blades of such inclination rigid both with the relative hub and with the drive shaft.

Description

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~ This inventlon relates to a Peathering propeller, and i more particularly to a feathering propeller for auxiliary engines of sailing boats.
As is well known to all those concerned with sailing, the engine, and the propeller driven by it, are used only exceptionally~ for example for manoeuvres in ports or in -cases of emergency, and they are required to disturb running under sail as little as possible. In particular, the propeller must oPfer the minimum possible resistance to the water ~hen ~ 10 not in use, while remaining in position and touched by the 5' , relative water current. ~hree types of propellers are used at present, nàmely:
- fixed - closable (or bei~k type), and - Peathering~
The ixed propeller oP~ers high hydrodyni~mic resistance because oP the Pierce vortices which it creates in the water.
The closable propeller however ofPers a much smalier ~- 1~ resisti~nce because it does not create vortices when the blades !i,~j ~ 20 are closed~ -This type of propeller is the type most frequently used at present. However, reversing with this propeller is dificult and inef~icient.
The Peathering propeller is the least used at present because the embodiments constructed up to the present time have ~wo main disadvi~ntages:
a) they create vortices in the water due to the curvature o~ the blade surfaces, even when the blades are Peathered.
~;~ b) the~ are mechanically complicated (they o~ten comprise pitch variation controls inside the drive shat).
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i` ~o8z534 In calculating the rating~ account is taken of the hydrodynamic resis~ance offered by these three types ~f~
propeller by attributing three different coe~Plcients to them. The rating is notably a decisive factor in the chances of victory of a sailing boat in a regatta. A favourable rating therefore considerably increases the value of the boat itself.
- The rating coefficient for the ~eathering propeller is more favourable than that or the closable propell~r, because the rules have been drawn up in such a manner as to compensate for the disadvantages of the present feathering propellers descr~bed heretofore (points a and b~ .
' '" ,' Consequently one object o~ the invention is a propeller of the stated type which offers a minimum resistance in water to sailing, while possessing a favourable rating in a regatta.
A ~urther object is a propeller o~ good ef~iciency both in forward and reverse running.
-~ A further object of the invention is a simple auto-matic device for arranging the propeller ~or forward or reverse running, based on the direction of rotation of the engine.
A further object is a device which ~acilitates setting of the propeller pitch.
~ 25 These and urther objects which will be evident herein-Y ~ after are attained accord1ng to the in~ention by a ~eathering p~opeller especially ~or ~aili~g boat~ comprl~ing an axially extending hub, a plurality of propeller ~lades ~ourNall-~d by 3ald hub o~ axe~ each in a pl~ne radial to th~
hub to permit ro~ation o~ eaoh blade to vary i~pitch a~gle ,,,~ . .

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- with ~e~pec-t to tlle feathering pQ;:ition 0:~ the blades~ a sleeve member disposed coaxially witllin a~d ~our~alled rotatably withl~ ts by said hub ~or rec~3iv1n~ thex~i~
an e~d portiorL oî apower sha*t and means for CC)~eCt~ng 5 ~aid sleeve member with s~d power ~ha~t, a be~el gear rotatabl~ with each blade, a Iurther bevel gear rotatable with ~a~d ~lee~re member and me~12lg in common with said blade gears arld wherein said hub i~ formed of two e~ell halves each intern~lly o~ semi-cylindrical longitudinal . 10 oonfi~uratio~ coe~:tensive with the ~i~ of the hub and . s¢rew meansoooperati~g with each ~h~ll half Ior joiniDg : - them togethe~ ~aid ~crew means e~cte~di~g tran~verse to: ~ the axis o~ the hu~ at a radial dis~ance there~rom.
. It ha~ bee~ ~ound in ~act that ~rom hydrodyD~ni~
. 15 point OI view the be:st results ~a~r be obtai~ed whe~ the.
- follor~ing two Ieature~ OI the propeller are ~imult~eously attained: , - - a~ elongated ogive l~ke-shaps o~ the hub ha~Ting an in¢reased a~pect ratio tlength/di~meter) 20 - a ~ine adjustm~nt o~ the active pi~ch a~gle o~ the propeller blade~ with respect to the feathering po~ition ~hereoI .
.~ It has been Iurther found that an elon~ated ogive like-shape of the propeller hub may be obtained o~ly l~
25 the hub, whlch in any case ha~ to be made of two halYes ~or . ~ asse~bl~ng purposes of the gear means contaln~d therai~ i~
made of two long1tudinallg extending ~ell hal~es, i.,e. when the hub is longitudinally di~rided in two halv~. HeretoIor a transverse dividir~ was alway~ adopted, but th~s required 30 an inorea?,e in the diameter of the hub in order lio provide space ln the body of the hub f~r the con~eoti~g longritudinal -~ bot-t~. Applicant h~s Pound that bg div~ding longitudinally , i~
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!j the hub~ tran~ersa bolts may ~ u~ed which do not ~ require an i~cr~a~e in the hub diam~ter th~re~y mai~ta-Lning .~ a high ~pect ratioO
i The characteristics, mode oP operation and advantages ~ 5 of the invention will be more evident from the detailed and 3 ~ull description of its preferred e~bodiments, given by way ~ o~ non-limiting example with re~erence to the accompanying .~ `. drawing~. in which:
Fig. 1 is a longitudinal view oP a first embodiment of :~. . . 10 a propeller assembly according ~o the in~ention taken in the . Oplane oP the feathering blades,~with the hub axially sectioned;
Fig. 2 is a transverse view.of the same assembly to a : reduced scale, wqth the hub sectioned on the line II-II of Figure 1s $ 15 Fig. 3 is a section on the line III-III o~ Figure 1, . and ;~ Fig. 4 is an enlarged detail of Figure 1 modified in accordance wqth a second embodiment.

. :~ Although particular rePerence is firstly made to Figure s~,. 20 1, the three figures 1 to 3 should be observed together :. because only in this manner can a complete representation of the invention be obtained.
A complete propeller assembly is indicated overall by the reference numeral 1, and comprises essentially ~ drive - 25 shaft 2, a hub assembly 3 and two blades 4 and 4. The hub assembly 3 is connected to the drive shaft 2 by ~ay of a ~'~ flanged sleeve S locked on to the shaf?t by a key 6 and ring .~ ~uts or nuts 7 and 8 screwed on to the threaded end 9 of the .~ _ 5 ._ ,~
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~ 08Z534 r t 2~ ~ cap 1~ i~3 COIlneCt;ed to a flange 10 of the slee~re 5 by bolts Ol' screws11, and incol~?orat~ at its fro:~li a bevel gear or pi~icn i3. ~he actual hub of the propeller 14 :IB in ths ~orm OI two shellA 14'' and 14" ~oined to,~ether by ~crews 15 extending transv~rse to t,he lo~e;itudina e:x:ten~ion OI the hub to ~o~ an enclo~ure e~closing lnterna the slee~re 5 and cap 12 with the pinio~ 13, orl wl~ch the hub ~ rotatable within l~mit~. A~ clearly ~risible ~rom ~ig. 1 and 3 o~ the drawing the two shell~h~lv~ 14' ~ld 14' have their mutua}ly e~gagi~g edge~ 14a and 14b exte~di~y3 according to a lo~itlldinal plane o~ sy~metry OI the assembly"
i.e. the hub 14 is di~ded ~ccordi~g to s~lch lo~:Lgitudl~al pla~e of ~mmètry to form the tw~o shell-halves, which ha~e a;~ elo~gated o~ive like-~hape,~he two blade~ 4 ~re inserted into the hub 14 each by wa~ o~ a ~lade shaft 16 rigid with .~t~ blade. ~n the end o~ each blade ~ha~t 16 inside the hub there i~ ~ayed a pla~etar;r bevel gear or p~:ion 17,10cE3~ed in~ide the hub 14 and en~;agirlg with the pinio~ 13 rigid with the dr~ ve shait 2 through the ~ eeve 5 on ~hich it i., fixed~.
~h~ t~o pl~etar.y pi~ons 17 oppose each other ~nd iace each other a~ially, the two ~hafts 16 bei~ held betwee~ the two ~hell~ 141 and 14" o~ th~ hub. ~o prevellt ~lack and keep the two opposing pinions 17 spaoed apart and aligned~ a spac~ng cyli~der 18 wlth an axial p~n 19 ~ idly mountad between the two pinions and in oontac~ therewith. ~he angle through which the blade~ can rotate rigid with the re~pec~ive pinLon~ iæ limited in order to de~ine the working inclinatio~
of the blade~ when the propeller rotates. In the e~ample o~ the dra~qing, the limitation on blade rotat~o~ i~
obtained by a .~top abutme~t which limit~ the rotation of the hub 14 relati~e to the ~eeve 5 rigid with th~ drive ~haft 2. ~he ~top abutme~t i~ formed in a~ annular cavity 20 provided on the marginal ed~e o~ the hu~ 14 which ~urround~
th0 ~lang~d ~leeve 5. An external ~top tooth ~1 pro3ecit~

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from the sleeve 5 and an in~ernal stop ~ooth projects from the hub 14. The two positions of engagement of the two teeth prevent further rotation of the hub relative to the drive shaft in one direction ~nd the other, and define the ; 5 two inclined posi~ions of the blades~ namely that Por forward running and that ~or reverse running, as will be explained hereinaPter.
The same stop condition could be obtained without s deviating from the invention by providing for example stop 10 blocks on the teeth of the pinions 17, at an angle correspon-ding to the required blade inclination~ However the design ~hown on the dra~nng offers the advantage of more easy setting of the optimum blade positions by making one of the stop teeth thicker or thinner, or by making one of the two teeth 15 insertable and fixable by screws so that it may be changed or moved. This design also has the advantage oP removing ~ the blade inclination gears from the action of the driveii~ torque, which is transmitted by the stop teeth directly to the hub. The feathering propeller assembly described operates ZO in the followin~ manner. When the boat or craPt is under sail with the engine at rest, the shaft 2 remains idle and, because of the dynamic resistance of the water, the blades are brought automatically into the eathered position, i.e.
the position of least resistance sho~m in Figures 1 and 2, 25 and there is no danger of them accidentally assuming another position because o~ the mutual gear engagement of the two ~, blades, there being therefore no need to provide or ~perate any control or clutch.
In the eathered position the te~th 21~'22 are sp~ced apart.
I at a certain moment the engine is started~ it rotates the dl~ive sha~t 2. The ~èathered propeller o~ers maximum resistance to rotation, and therefore does not immediately ~ ~ollow the sha~t, and the shaPt and sleeve there~ore rotate ;; relati~e to the hub, so that the drive pinion 13 drives the . !: J
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~082534 two planetary pinions 17 in such a manner that the two blades incline at the same angle o~ inclination to ~he plane normal to the axis. This ~lade rotation increases until the tooth 21 strikes against the stop tooth 22.
Relative movement between the hub and shaft then ceases ' because of this state of abutment, and the propeller i5 , driven by the sha$t at the inclination which it had attained ¦ at the moment in which the two teeth came into contact.
~ The arrangement is such that, starting $rom the $eathered ¦ 10 position which is considered the zero position, the abut-ment is encoun~ered by the tooth 21 a$ter an angle of rela-tive rotation corresponding to a precise predetermined angle o$ inclination of the blades~ As the shaft can rotate in two directions, there are two distinct angles o relative rotation before reaching the state of abutment, and consequently two possible distinct automatic angles of inclination of the blades. The3e angles are made to correspond to the normal angles o$ blade inclination or forward running and reverse running. The setting may be calculated in an obvious manner, starting $rom the two required angles o~ blade inclination and the ratio of the number of teeth on the drive pinion to the number o~ teeth on the planetary pinion, to give the theoretical angle of abutment in the two directions o$ rotation.
In a second improved embodiment o$ the invention shown in Figure 4, the sleeve 5, fixed on to the shaft 2 by the key 6~ and the cap 12 rigid with the pinion 13 are coupled by a straight toothed gear coupling.
~1 For this purpose, the sleeve comprises a ~lange 10 from which a collar or ring 101 projects, on the inner ~ .

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periphery of which there being provided straight tee~h 102. The cap 12 correspondingly carries on the outer periphery of its cylindrical surface 103 toothing 104 which engages with the toothing 102. The sleeve 5 is kept tight on the shat 2 by a nut 105 locked by a dowel 106. The cap 12 is kept engaged by its toothing 10~ in the toothing 102 by the two shells of the hub enclosure 14 which holds the whole assembly together and which contains in the groove 20 a stop abutment for a tooth on the sleeve 5. The enclosure 14 is at a fixed angular posi-Ition relative to the axis o the planetary gears 17.
¦The operatlon of the device is as follows.
To vary `the working pitch of the propeller, the twoshells o the hub enclosure 14 are removed, the cap 12 is disengaged while being held rigid with the blades 4 and the intermediate gears, and is re-engaged in a diferent angular position, compatible with the pitch of the toothing.
This gives only a rough setting, as it is not practical to make teeth o very small pitch, To obtain a finer setting, use is made oP the combination of this new modification and a Pundamental characteristic of the invention, namely plane-tary transmission~ To change the angular position of th2 blades relative to the shaft, the cap is withdrawn from its engagement in the sleeve 5, it is then disengaged from the planetary ge~rs 17 and, without moving these latter, is re-engaged therewith in a difPerent angular pOSitiOll, i.e.
oPset by one or more teeth. With different eombinations o~ the two relative engagement rotations described, a very Pine diPferential graduation may be obtained providing the number of teeth on the toothing 102 is different from the ..... ~ ` .

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numb~r of tee~h on the toothing 13. If or example there are 21 teeth on 102 and 20 teeth on the pinion 13, by dis-placing the coupling in the reverse direction by one tooth, the propeller control may be phase displaced by approximate-ly 18 - 17 = 1.
It is apparent tha~ by suitably choosing the number of teeth, adjustment may be made as gradual as required within the entire usable range of 0 to 9Q of inclination of the propeller blades.
The proposed object of avoiding controlled or possibly automated couplings with mechanical connections on the drive shaft ~or reversing the running o~ the propeller or for the feathering thereof, is very simply and immediately attained.
The efficiency o the propeller is very good, both in for~ard ; 15 and reverse running. The very simple compact constructi~n o~ the pinion device or automatically positioning the blades enables the dimensions of the hub to be reduced rela-tive to previous designs, and to give a very 1at propeller assembly with a further reduced hydrodynamic resistance, in accordance w1th the fundamental requirement ~or this type of propeller.
The improved device of the second described embodiment also enables the blades to assume any limit position through an arc of 360. Thus any pitch value may be obtained by a simple setting operation. The same propeller may be either right handed or left handed, and either pushing or pulling, thus giving complete universali~y.
In ordex to re~der smooth and ~afe th0 mo~ement between vax~ou~ compo~e~t part~ o~ the propelle~ and in order to remo~e any ha~rd o~ ~eiæure bu~he~ o~ synthe~i~
ant~friotlon materlal are prorided on the contacti~g ~urf~co~ o~ the~ component part~, per~orming a r~lati~e slid~n~ motion with respect to ea¢h other~ Fo~ example the . 1`~ ' . .

iO8ZS34 b~ade ~ha~ts 16, a~ well as the sleeve 5 and the ~pacer cylinder 18 mày be s.dvantageou~ly prov~ded with such bushe~. .
The materlal Ior ~uch bushe~ may be ~elected amo~g 5 different type~ o~ antifrictlon material.
Good results ha~ been o~tained with the u~e OL
acetalic re~ins having the following charaoteristics:
a) good elasticity allowing the bu~h to be expanded during the mounting o~ its seat and to return a~terwards ~o 1 10 it~ ori~inal ~hape. It i~ there~ore possible to con6truct I . the bu~h as a one piece sleme~t even ~n oase~ where other-t wi8e t~is would not be pos~ible;
b) low ~rictio~ coefficient;
c) high ~echanical ~trength~ especially h~gh compr~ssive ~- 15 ~t~ength~
. d) low moi~ture ab~orption, which make~ it po~sible to maintain practically unchanged in the long run, ~le phy~ical . and mechanical characteristics o~ the ~ush even i~ imme~ed : in water.
~he invention is ~u~ceptible to modi~ications o~
shape, particulars or details, without leaving its scope of protection as de~ined by the a~oregoing characteristics, and repeated in the claims given hereina~ter.
. While re~erence ha~ been made to sailing boat~ the propeller o~ the i~vention may be use~ully employed in any type o~ water vehicle.
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Claims (7)

The embodiments of the invention in which an exclusive property or privileges is claimed are defined as follows:

1. A feathering propeller especially for sailing boats, comprising an axially extending hub, a plurality of propeller blades journalled said hub on axes each in a plane radial to the hub to permit rotation of each blade to vary its pitch angle, with respect to the feathering position of the blades, a sleave member disposed coaxially within and journalled rotatably within limits by said hub for receiving therin an end portion of a power shaft and means for connecting said sleeve member with said power shaft, a bevel gear rotatable with each blade, a further bevel gear rotatable with said sleeve member and meshing in common with said blade gears and wherein said hub is formed of two shell-halves each internally of semi-cylindrical longitudinal configuration coextensive with the axis of the hub and screw means cooperating with each shell half for joining them together, said screw means extending transverse to the axis of the hub at a radial distance therefrom.

2. A propeller according to Claim 1, wherein said further bevel gear has a cylindrical extension having a spur gear toothing coaxial therewith and said sleeve member has an axial extension with a straight toothing coaxial with said spoor gear toothing and meshing therewith and wherein said hub has an inner annular recess facing the outer periphery of said sleeve member to define an annular cavity therebetween, a first stop formation freely projecting from said hub into said annular cavity and a second stop formation freely projecting from said sleeve into said cavity and arranged in the same circumferential plane as the first stop formation, thereby to allow a maximum relative angular movement in either direction between said sleeve member and said hub over an angle determined by the abutment positions of said first stop formation against said second stop formation, the common mesh between said bevel gear and said blade gears allowing in disassembled condition a first adjustment of the bevel gear relative to the blade gears in either directions and the mesh between said straight toothing and said spur gear allowing in disassembled condition a differential angular adjustment in either direction of said sleeve member relative to said blade gears.

3. A propeller according to Claim 2, wherein the number of teeth of said spur gear is different from the number of teeth of said further bevel gear and is not a multiple therof.

4. A propeller according to Claim 1, further comprising a spacer element between opposite said blade gears and in contact therewith.

5. A propeller according to Claim 1, wherein the blades are of the flat type and of low twist.

6. A propeller according to Claim 1, wherein at least one of surfaces in mutual sliding engagement has an anti-friction lining.

7. A propeller according to Claim 6, wherein said at least one surface is a cylindrical surface and wherein said lining has the shape of a bush of antifriction synthetic material.