EP1177127B1

EP1177127B1 - Bearing for a boat propeller driving shaft and method for its manufacturing and its fastening to the hull

Info

Publication number: EP1177127B1
Application number: EP99921142A
Authority: EP
Inventors: Fabio Buzzi
Original assignee: FB Design SRL
Current assignee: FB Design SRL
Priority date: 1999-05-13
Filing date: 1999-05-13
Publication date: 2006-06-28
Anticipated expiration: 2019-05-13
Also published as: WO2000069716A1; EP1177127A1; AU3847999A

Description

Field of the invention

The present invention relates to a universal bearing for the propeller driving shaft of a motor boat and a method for its production and attachment to the hull.

State of the art

Bearings provided for propeller driving shafts in power boats equipped with inboard motors are known, usually located in proximity to the same propeller, that allow propeller driving shafts of not excessively limited length to be employed without dangerous bending or misalignment of the same shaft developing in use. Such bearings usually comprise a bush, within which the propeller shaft rotates, integral with a body fixed rigidly to the same hull.
In particular, since the propeller shaft is subject to elevated dynamic loads and to strong vibrations during use, extreme precision is needed in the production of the aforementioned bearing and in its exact fixing to the hull to guarantee perfect alignment in order to prevent the shaft bending during rotation. In particular, in fast motorboats, such as speedboats for instance, in which the shaft of the propeller is considerably stressed, correct production of the bearing and its subsequent fixing to the hull are critical factors for the reliability of the boat itself.
Furthermore, the production and the fixing to the hull of such bearings generally require dedicated machining, because of the asymmetrical shape that the bearing frequently assumes. The shape is due, among other things, to the inclination of the shaft with respect to the surface of attachment of the device to the hull and to the extreme variety of hull geometries.
It is standard practice, therefore, to make individual bearings for each single boat based on the specific geometry of the same boat in order to guarantee precise mating of the propeller shaft with the bearing bush. In other words, the planning and the production of the bearing is on "ad hoc" activity that is undertaken separately for each boat.
In particular, such bearing devices are usually produced as castings and subsequently attached to the hull in a permanent way.
That involves the producer in elevated costs and long production times because of the impossibility of employing economies of scale, and, for the consumer, the difficulty of obtaining spare parts in a short time whenever the bearing breaks, because the piece normally needs to be produced from scratch again.
Furthermore, in the case of even small inaccuracies in the specificafiion of the plan, the adjustment of the bearing assembly to give optimum mating between shaft and bush is difficult - if not impossble - to achieve.
US-A-2,891,825 discloses a strut and bearing assembly for boat shafts comprising a mounting plate, a strut, a bearing housing having a bearing sleeve. The length of the strut assembly (vertical alignment) can be varied by the addition or subtraction of shims between the disc and the strut-flange. The vertical angularity of the bearing housing can be varied by means of moving the arcuate surface of the bearing housing relative to the complementary arcuate end portion of the strut. The adjusted position of the bearing housing is secured by a set-screw. The horizontal angularity of the bearing housing can be controlled by rotating the strut with the bearing housing relative to the mounting plate and adjusting disc. The extent of sidewise movement of the strut can be varied by changing the taper of adjusting disc or by utilising and rotating together two or more such discs between the mounting plate and the strut-flange.

Purposes of the Invention

One objective of the present invention is to resolve the aforementioned drawbacks of the known technique and produce a propeller shaft bearing for a boat that is adaptable to different types of motorboats.
Another objective of the present invention is to furnish a method for the production and assembly of a bearing for the propeller shaft of a boot that is particularly inexpensive and efficient.
A further objective of the present invention is to produce a propeller shaft bearing that doesn't require particularly complex and expensive machining or production technique.
Another objective of the present invention is to furnish a bearing for the propeller shaft that it is easy to adjust and replace.

Summary of the invention

These and other objectives are achieved by the propeller shaft bearing for a boat according to the first claim and the following dependent claims and by the method for the production and the attachment of a bearing for the propeller shaft of a boat according to the independent claim 11 and the following dependent claims.
The bearing for the propeller shaft of a boat according to the present invention comprises at least one element of attachment to the hull and at least one bearing arm for the propeller shaft. The element of attachment and the bearing arm are connectable together and can be reciprocally oriented or adjusted about at least one axis and can also be reciprocally locked in the final position selected.
In a particular form of embodiment, the bearing arm for the shaft can be orientated with respect to the element of attachment to the hull by rotating around at least a first axis and can be adjusted in translation, with respect to the same attachment element, along at least a second axis.
According to another aspect of the present invention, the element of attachment comprises a plate fixed to the hull and an intermediate shank connectable together and reciprocally orientatable or adjustable about at least one axis. The bearing arm for the shaft is then connected to the aforesaid intermediate shank.
According to a preferential embodiment of the present invention, the plate fixed to the hull comprises means for the attachment to the hull and means of hinging the intermediate shank along a longitudinal axis. In its turn, the intermediate shank comprises at least one partially hollow body and a through hole that transverses the same hollow.
According to a further aspect of the invention, the bearing arm can move and/or be adjusted about at least three respectively perpendicular axes.
Furthermore, the method for the production and the fixing of a bearing for the propeller shaft of a motor boat, of the type comprising at least one element of attachment and at least one bearing arm for the propeller shaft according to the present invention consists of : producing the element of attachment and the bearing arm in a such way that they can rotate reciprocally and/or can be adjusted about at least one axis; fitting the propeller shaft to the bearing arm, attaching the attachment element to the hull; orientating and fixing the bearing arm with respect to the element of attachment; fixing the arm to the element of attachment provisionally by means of means for temporary fixing; and finally fixing the arm irremovably to the bearing element when the desired position of the bearing arm with respect to the same bearing element is reached.

Brief description of the drawings

A device and a corresponding method of producing and of fixing the same to the hull, according to a preferential embodiment of the present invention, will now be illustrated by way of example and not limitation, with reference to the attached drawings, in which:

Figure 1 is a perspective view of a preferential embodiment of a propeller shaft bearing according to the invention fixed to a hull;
Figure 2 illustrates schematically a propeller shaft bearing in operational conditions
Figure 3 is an exploded view in perspective of the bearing shown in figure 1;
Figure 4 is a view in perspective of a propeller shaft bearing in a further embodiment.

Description of the preferential embodiments

With reference to Figures 1 and 2, the propeller shaft bearing of a motor boat is shown overall as 1, the hull of the boat as 2, the propeller shaft as 18 and the propeller, in this particular case of the immersed type, as 19.
The bearing 1 comprises a fixing plate 3 to the hull 2 of the boat, an intermediate shank 4 and a bearing arm 5 for the propeller shaft 18. The bearing arm 5 comprises a through cylindrical housing 6 within which turns the shaft 18 of the propeller 19. The plate 3, furthermore, presents holes 7 for means of attachment to the hull 2, for instance of the matching screw and female screw type, to connect irremovably the same plate 3 with the hull 2.
The plate 3, the shank 4 and the arm 5 are interconnected in a detachable way to allow the mutual orientatation and/or adjustment with respect to a varying number of axes, before their definitive locking once an optimum mutual position is reached, as will be illustrated below in the discussion of the method of production and fixing of the bearing to the hull. In the embodiment of figure 1, in particular, the bearing arm 5 is adjustable to slide along the normal axis B and it is also orientatable in rotation around the transverse axis C with respect to the intermediate shank 4. The intermediate shank 4, in turn, is orientatable with respect to the bearing 3 around the longitudinal axis A, being hinged longitudinally in correspondence of holes 8 of the same bearing 3.
The ability to adjust the distance from cylindrical housing 6 with respect to the fixing plate 3, indicated by the arrows "b," the possible rotation of the axis of cylindrical housing 6 around the longitudinal axis A and its possible oscillation around the transverse axis C, respectively indicated by the arrows "a" and "c", allow the bearing 1 to adapt to the different characteristics of inclination of the shaft 18 with respect to the hull 2, specific for each boat.
In particular, as shown in figure 3, the bearing arm 5 for the propeller shaft 18 is formed by a bush 14, whose through cylindrical housing 6 is sized to accept the shaft 18, and by a blade insert 15 endowed with a lengthened transverse opening 16. The blade insert 15 is shaped to fit, with a certain amount of play, into a slot 13 cut into the intermediate shank 4. The intermediate shank 4 comprises, in its turn, a body 11, occupied at least partially by the slot 13, integral with a bush 10 matching the holes 8 of the plate 3. The body 11 is furthermore crossed by a through hole 9 that is arranged transversely with respect to the extension of the slot 13 and is apt to lodge a hinge pin or pivot, 12.
The bearing 1 is assembled by introducing the blade insert 15 of the arm 5 into the slot 13 of the shank 4 and linking such parts by the insertion of the pivot 12 into the hole 9 and into the through opening 16. Finally, the connection between the shank 4 and the plate 3 is obtained by mating the bush 10 of the shank 4 with the holes 8 of the bearing 3 by means of a hinge pin, not shown.
The lengthened hole 16 allows the insert 15 to slide in the slot 13 along the same axis of the slot 13, the B axis of figure 1. Furthermore, the dimensions and the shape of the blade insert 15 is such to allow the angular oscillation of the insert 15 around the axis of the pivot 12, corresponding to the C axis of figure 1, within the hollow 14. Finally, the intermediate shank 4 is fitted in an oscillating way around the pin through the bush 10 and the holes 8, corresponding to the axis A of figure 1.
Advantageously, due to the peculiar shape and arrangement of the parts, the bearing arm 5, and therefore the bush 14 within which the propeller shaft 18 rotates, can be orientated and adjusted around three reciprocally perpendicular axes. This allows the bearing 1 to be adapted to boats with different characteristics, with consequent reductions in production and planning times and in cost; the maintaining of stocks of such bearings as spare parts becomes a possibility.
Figure 4 illustrates a further form of embodiment of a bearing for the propeller shaft according to the present invention. In such form of embodiment, simplified compared to that of figure 2 or 3, the bearing 20 comprises only two parts: the bearing arm 21 for the propeller shaft and an element of attachment 22 for the attachment of the same bearing 20 to the hull.
In a similar way to the bearing 1 of figure 3, the arm 21 is connected to the element of attachment 22 by means of an insert endowed with a lengthened transverse opening (not shown) that allows the same insert to oscillate and slide in a hollow present in the body 26 of the element 22. The element 22, in turn, comprises a hull fixing plate integral with the body 26, equipped with holes 25. The body 26, similar to the body of the shank 4 in figure 3, of the present invention presents at least a partial hollow within which the aforementioned insert of the arm 21 engages. The body 26 presents furthermore, to allow the insertion of a pivot, a transverse hole through the hollow, corresponding to the hole 9 of the bearing 1 of figure 3.
This embodiment, that allows the bearing arm 21 to be orientated and adjusted with respect to the element of attachment 22 only about two perpendicular axes, is structurally stronger and easier to produce compared to the embodiment of Figures 2 and 3.
The bearing for the propeller shaft of a boat, according to the present invention, can also be produced by mating the bearing arm of the shaft (having a connection body in this embodiment) and the element of attachment to the hull. The body of connection, corresponding to the shank 4 of figure 3, is produced integrally with the bearing arm and comprises adjustable means of connection to the element of attachment to the hull.
The method for the production and the fixing to the hull of a bearing according to the invention will be illustrated below taking the bearing 1 illustrated in figure 3 as a model, but is understood that this method is equally applicable to the bearing 20 of figure 4 and evidently is not limited to any particular form of embodiment of the bearing. This method, according to a preferential embodiment of the invention, thus includes a phase of production and connection of the parts, reciprocally orientatable and/or adjustable, forming the bearing 1, as above described for instance for the bearing of figure 3. Preferably, the constituent parts of the bearing 1 are produced by die-casting, or precision casting, of stainless-steel or of titanium or its alloys.
The method foresees the insertion of the propeller shaft 18 within the bush 14 of the bearing arm 5 and the fixing of the bearing 3, or one other element of attachment, to the hull 2.
Subsequently, there follows a phase of orientatation and adjustment of the arm 5 with respect to the bearing 3, by means of the oscillation of the same arm about the axes A and C of figure 2 and by sliding the same arm with respect to the B axis, as illustrated above. This and the preceding phase - that need not necessarily be performed in the order in which they are described - allow a precise mating of the shaft 18 with the bush 14.
Below is provided a phase in which the bearing arm 5 is fixed in a temporary way to the intermediate shank 4, and the latter to the plate 3. In particular, the provisional fixing of the arm 5 to the shank 4 could be achieved by bolting the parts together, for instance by means of tightening a bolt extending through the hole 9 and the opening 16. Similarly, the fixing of the shank 4 to the plate 3 could be achieved by tightening a bolt, employing where necessary a link 17 between the head of the bolt and the corresponding holes on the plate 3, extending through the housing defined by the holes 8 and the bush 10.
Following the phase of temporary fixing of the parts, and when the optimum position of the bearing arm 5 with respect to the plate 3 has been reached, the method provides for the definitive or irremovable fixing of the whole bearing 1, or of the arm 5 to the shank 4 and of the latter to the plate 3, preferably by welding.
After the definitive fixing, the bolts could be removed from their seats and be replaced by plugs or fixed by means of welding.
According to a particularly advantageous embodiment of the method illustrated, it is possible to produce the intermediate shank 4, that preferably has a hydrodynamic shape, particularly extended in length along the sliding axis B of the insert 15, and subsequently cut it, transversely to this axis but not necessarily perpendicular to it, to adapt it with precision to the specific requirements of the boat for which the bearing is destined. By selective cutting of the intermediate shank 4, it is possible to produce a precise joint between the arm 5 and the shank 4 such that, in the required layout of the parts, the bush 14 is substantially in line with the lower edge of the hollow 13 of the shank 4, thus facilitating and making more effective the operation of welding the same shank 4 to the bearing arm 5.
It is evident, in the light of what has been described above, that the bearing and the method for the production and the fixing to the hull, according to the present invention, involve a reduction of the production costs of such bearings for the propeller shaft of a motor boat, in that they render unnecessary dedicated planning and production of this bearing for each boat.
Furthermore, the flexibility of use of the bearing and of the method claimed, allow extremely precise adjustment of the joints between the propeller shaft and the bush of the same bearing, even in the light of small production inaccuracies compared to the specified plan.
Again, the symmetry possible in the components of the bearing according to the present invention allows the simplification of the machining necessary for the installation of the same bearing.
Finally, given the modularity and adaptability of the bearing to different boats, the present invention allows stocks of this bearing to be created and maintained as spare parts.

Claims

A bearing for the propeller driving shaft (18) of a motor boat, formed from at least one element (3,4) of attachment to the hull (2) comprising a fixing plate (3) and an intermediate shank (4), and from at least one bearing arm (5) for the shaft (18), which are connected together and which can be relatively oriented and/or adjusted about three perpendicular axes (A, B, C), as well as relatively locked in the selected final position, characterised in that said fixing plate (3) comprises means (8) of hinging along a longitudinal axis (A) to said intermediate shank (4).
A bearing according to Claim 1, characterised in that said bearing arm (5) is orientatable with respect to said element (3, 4) of attachment to the hull (2) by rotating around at least a first axis (C) and it is adjustable for translation along at least a second axis (B).
A bearing according to Claim 1 or 2, characterised in that said element of attachment (3,4) can be connected together and relatively orientated and/or adjusted about at least one axis (A), said bearing arm (5) being connectable to said intermediate shank (4).
A bearing according to Claim 3, characterised in that said plate (3) comprises means (7) for the attachment to the hull and said intermediate shank in turn comprising a body at least partially endowed with a hollow (13), and a through hole (9) that intersects said hollow transversely.
A bearing according to Claim 4, characterised in that said bearing arm comprises a bush (6) within which is engaged said propeller driving shaft (18), and an insert (15) so-shaped to slide and oscillate within said hollow (13) of the intermediate shank (4), said insert presenting a lengthened transverse opening (16) for adjustable joining to said through hole (9) by means of a pivot element (12).
A bearing according to one of the preceding Claims, characterised in that it comprises means for the temporary fixing and means for the mutual irremovable fixing of said element of attachment and of said bearing arm or of components of said element of attachment and of said bearing arm respectively.
A bearing according to Claim 6, characterised in that said means of temporary fixing are of the threaded parts fit type.
A bearing according to anyone of the preceding Claims characterised in that it is produced in stainless-steel or in titanium or its alloys.
Method for fixing a bearing for the propeller driving shaft of a motor boat according to anyone of the preceding claims to the hull (2) of said boat, characterised in that it comprises the following phases:
a) engaging said propeller driving shaft (18) with the bearing arm (5);

b) attaching the element of attachment (3, 4) to said hull (2), comprising a fixing plate (3) and an intermediate shank (4), wherein said fixing plate (3) comprises means (8) of hinging along a longitudinal axis (A) to said intermediate shank (4);

c) orientating and/or adjusting said bearing arm (5) with respect to said element of attachment (3, 4) about three perpendicular axes (A, B, C), as well as orienting and/or adjusting said intermediate shank (4) with respect to said fixing plate (3) through said means (8) of hinging;

d) fixing provisionally, by using means for temporary fixing, said arm (5) with respect to said element of attachment (3, 4);

e) fixing irremovably said bearing arm (5) with respect to said element of attachment (3, 4), when the desired position of said bearing arm (5) with respect to said element of attachment (3, 4) has been reached.
Method according to Claim 9, in which said element of attachment (3,4) can be relatively oriented and/or adjusted about at least one axis, said intermediate shank (4) being connected to said bearing arm (5) such a way this latter can be oriented with respect to said intermediate shank (4) by rotating around at least a first axis (C) and it can be adjusted for translation along at least a second axis (B).
Method according to one of Claims 9 or 10, characterised in that said phase of provisional fixing is achieved by bolting.
Method according to anyone of Claims from 9 to 11, characterised in that said phase of definitive fixing is achieved by welding.
Method according to anyone of Claims from 10 to 12, characterised in that it comprises the phase of cutting said intermediate shank (4) to obtain a correctly sized bearing.