Inboard Outboard Drive

This application is related to the following applications entitled: INBOARD OUTBOARD DRIVE AND MOUNTING SHIELD THEREFOR; U.S. Ser. No. 461,876 and INBOARD OUTBOARD DRIVE AND MOUNTING THEREFOR U.S. Ser. No. 461,962 both filed on Jan. 28,1983.

This invention relates to inboard outboard drives of the type where the propeller leg extends through an opening in the bottom of the hull of the boat, and particularly to an improved mounting of the propeller leg for side steering and stress relieving and vibration damping purposes, and to an improved modular housing arrangement of the propeller leg assembly.

Inboard outboard drives as shown in FIG. 1 are known in the prior art having an engine part with an output shaft located inboard and a propeller leg or lower unit which has an inboard located upper end portion for attachment to the engine part adjacent the output shaft, an intermediate portion extending vertically downwardly via an opening in the bottom of the hull surface of a boat, and an outboard propeller portion at the lower end on which a propeller is mounted. The horizontal output shaft is by an upper angular gear box in the upper portion, a vertical power transmission shaft in the intermediate portion, a lower angular gear box and a horizontal propeller shaft drive-connected to the propeller on the propeller portion. The propeller leg assembly includes thus shafting and a lower angular gear box in the propeller housing portion for the transmission of torque from the engine part to a propeller mounted on the propeller housing.

The large propeller thrust and the long lever arm between the propeller shaft and engine output shaft produce a large bending moment, e.g. in the order of 300 to 500 kilopounds, causing stress at the connection of the propeller leg to the engine part, which connection is located in the region where the horizontally extending engine output shaft projects from the engine part. The propeller leg, where it extends through the opening in the hull, does not engage the hull in a rigid manner, because vibration causing noise and stress would be transferred to and magnified by the hull. Thus the propeller leg does not positively or rigidly engage the hull to provide a reaction for the propeller thrust bending moment.

Inboard outboard drives of this type, where the propeller leg extends through an opening in the bottom of the boat hull, have been used as auxiliary motors for sailing boats and are therefore often called S-drives. Although an S-drive generally includes an upper angular gear box between the horizontal output shaft of the engine part and the transmission shaft in the propeller leg assembly, the output shaft of the engine part may also be aligned with this transmission shaft, e.g. by the engine extending vertically, and then an upper angular gear box is not needed.

Other inboard outboard drives where the propeller leg is mounted on the transom and located completely outboard are called Z-drives and may be pivoted for side steering. In S-drives the propeller leg has been in general non-pivotally attached to other parts of the drive and side steering of the boat has been effected by a rudder blade of that boat in the same manner as in sailing boats without a motor and in motor boats with an inboard motor. This type of steering a boat driven by an S-drive often provides poor maneuverability at low velocities because the flow forces on the rudder blade are small.

An object of the present invention is to provide an improved inboard outboard drive of the S-type described above including a propeller leg extending through an opening in the bottom of the hull of a boat and having an outboard propeller housing portion which is pivotally mounted for side steering. Such a driving system provides proper maneuvering power because the transverse force for side steering is then a component of the thrust of the propeller.

The propeller leg comprises an upper inboard portion, an intermediate portion at said opening in the hull and an outboard propeller mounting portion. The propeller leg has power shaft means having an inboard upper angular gear box and an outboard lower angular gear box connected by power transmission shafting. The power transmission shafting between the engine and the upper angular gear box includes a universal joint. The propeller leg assembly is pivotally mounted by bearing means on the boat hull or on a bracket fixedly attached to the engine part for pivotal movement about the bearing axis or side steering axis which passes through the universal joint and the upper part of which is inclined forward relative to the power transmission shafting extending in the propeller leg between the upper and lower angular gear boxes. This forward inclination of the upper part of the steering axis improves appreciably the steering qualities of the boat, and in particular reduces the necessary steering effort in comparison to all hitherto known motor-driven sailing boats. The lower angular gear box, generally a 90.degree. gear box, can drive either a single propeller or a dual propeller assembly.

A cooling water system has an inlet or orifice opening located at the forward end of an outboard portion of the propeller leg and connected to a cooling water pipe mounted concentrically with the inclined steering axis to draw cooling water for the engine. The inlet has a self cleaning anticlogging device employing a grill and a cleaning comb on the hull having relative movement in response to steering movement. The lower outboard or propeller housing portion of the propeller leg may be made symmetrical for attachment in two rotational positions, one for driving at least one pusher propeller and the other for driving at least one traction propeller.

Another object of the present invention is to provide an inboard outboard drive construction and arrangement for mounting in the hull of a boat to reduce said stress and to obtain a lower level of vibration and noise transmitted to the hull and thus a quieter hull.

The inboard outboard drive has, as already stated, an engine part with a horizontal output shaft, a propeller leg with an upper portion with an upper gear aligned with and driven by the engine output shaft, an intermediate portion extending through an opening in the hull and an outboard propeller portion with a lower gear box driven by a vertical shaft connected to the upper gear box and driving a horizontal propeller shaft and propeller. The engine part is supported at a lower portion, near one end of the engine part, by first resilient vibration damping means. The output shaft projects from the other end of the engine. A mounting bracket is fixed on the engine part and also projects from the other end of the engine part below the output shaft. The propeller leg is mounted by the bracket on the engine part so that the engine part and the propulsion leg or system function as a single, large mass of inertia so that rather hard and effective vibration dampers or insulators may be used. The propeller leg is mounted on the bracket in a place located below the upper gear box and spaced below the output shaft. The mounting bracket is supported, particularly at its free end, by second resilient vibration damping means.

A further object of the invention is to provide an improved inboard outboard drive of the type described above wherein the propeller housing portion and/or the upper portion of the propeller leg assembly may readily be dismantled for repair or modification purposes without the boat becoming unable to float on that account, and in the case of the upper portion of the propeller leg assembly, even without the need to take the boat out of the water.

The propeller leg assembly or lower unit is constructed according to module construction principles so a further advantage is obtained, viz. that different drives may readily be assembled from several basic components. In particular a preferred embodiment with an intermediate module permits many variations in the construction of the drive, without the need to make any structural changes on the hull and/or on the engine part. The invention permits the alternate use of spare part modules, and makes it further possible to produce larger series of certain basic components, e.g. the inboard module. Engine parts of different types can be easily adapted to fit the module-constructed propeller leg part or lower unit.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic side view with parts in section of a prior art S-drive relating to the invention shown in FIGS. 2 to 25;

FIG. 2 is a schematic side view with parts in section of a first embodiment of a steering inboard outboard drive according to the invention;

FIG. 3 is a diagramatic view showing the relation between the steering axis and the power transmission axis;

FIG. 4 is a schematic side view with parts in section of a second embodiment;

FIG. 5 is an enlarged axial cross sectional view of a modification of the bearing means 133 of FIGS. 2 and 4;

FIG. 6 is an enlarged axial cross sectional view of another modification of bearing means 133;

FIG. 7 is a partial side view of a preferred embodiment of a outboard propeller portion of the lower unit with the propeller omitted;

FIG. 8 is a reduced axial cross sectional view of a cooperating intermediate portion of the lower unit;

FIG. 9 is a partial side view of the mounting of a dual traction propeller unit;

FIG. 10 is a partial side view of the mounting of a dual pusher propeller unit;

FIG. 11 is a partial side view with parts in section of an S-drive according to the invention;

FIG. 12 is a schematic side view with parts in section of an embodiment with a support bracket;

FIG. 13 is a schematic side view with parts in section of another embodiment with a support bracket;

FIG. 14 is a schematic side view of a further embodiment;

FIG. 15 is a partial perspective view of a modified bracket;

FIGS. 16, 17 and 18 are schematic partial side views with parts in section and in disassembled condition respectively of first, second and third principal embodiments of a modular housing arrangement;

FIG. 19 is a schematic side view with parts in section and in disassembled condition of a modification of FIG. 18;

FIG. 20 is an enlarged cross-sectional view on the line 20--20 of coupling 51a and shaft 50 of FIG. 19;

FIG. 21 is an enlarged axial cross-sectional view of a modification of the intermediate module 31 in the embodiments of FIGS. 18, 19 and 23;

FIG. 22 is a diagramatic side view with parts in section of an inboard outboard drive according to the invention with a not exactly vertically extending lower unit;

FIG. 23 is a diagramatic side view with parts in section and in disassembled condition of a modification of the drive of FIG. 18;

FIG. 24 is a diagramatic partial sectional view of a modified drive employing a magnetic coupling for the transmission of torque between separate portions of the shaft; and

FIG. 25 is a perspective view of a modified inboard outboard drive according to the invention.

Structural parts having basically the same function are in all the drawing figures designed by identical or analogous reference numerals and reference is made to the description of other figures.

According to FIG. 1, which shows related prior art, an inboard outboard drive of the so-called S-type has an engine part 1 with a flywheel housing 1a which is terminated by a cap 1a' to which the upper end of a propeller leg assembly or lower unit is attached, e.g. riveted. The output shaft 1b of engine part 1 enters propeller leg assembly 2 and is connected to upper angular gear box 1c to drive power transmission shaft 5 in propeller leg 2. At the bottom or lower end of propeller leg 2 is a propeller housing portion 3 having therein a lower angular gear box 3c drive-connecting power transmission shaft 5 to propeller shaft 3c which extends through propeller housing 3 and on which propeller 4 is mounted. Propeller leg 2 passes through an opening 12 in the bottom 10 of the shell 10s of hull 10h. Opening 12 is somewhat larger than the outer circumference of propeller leg 2 and the intermediate space between propeller leg 2 and bottom 10 is sealed by a resilient sealing membrane 12a. The propeller leg 2 provides a watertight enclosure which is sealed to the bottom 10 by membrane 12a to provide a watertight hull 10h with an inboard outboard drive.

The engine 1 rests on three damper blocks of resilient material, of which the forward ones or pair 1d (only one can be seen in the drawings) lie side by side or are spaced transversely, and the third one, 1f, centrally supports the flywheel housing 1a. The thrust of the propeller acts horizontally forward in the sense of arrow R and has a lever arm H causing a bending moment which acts on the engine part 1 at the cap 1a' of the flywheel housing 1a, in the region where the output shaft 1b protrudes or extends.

Engine part 1 is horizontally mounted on a resilient vibration absorbing support means, provided by rubber blocks 1d, inboard to bottom shell 10s of boat hull 10h and has horizontal output shaft 1b extending from flywheel housing 1a.

According to the present invention, as illustrated in FIG. 2, the propeller leg (lower unit) 2 is in the exemplified embodiment an assembly of modules, and is pivotally mounted by a pivotal bearing 133 which is secured and mounted in an inclined position on the bottom shell 10s of boat hull 10h. Propeller leg 2 has at its lower end a propeller housing portion 3 having therein a 90.degree. lower angular gear box connected to drive a pusher propeller 4 rotatably mounted thereon. A power transmission shaft 5 extends vertically inside propeller leg 2 to provide a drive connection between upper angular gear box 1c and lower angular gear box 3c. Propeller shaft 3b on which propeller 4 is mounted is driven by lower angular gear box 3c wherefrom it extends. These gear boxes and shafts provide power transmission means mounted in propeller leg 2 for drive-connecting engine 1 to drive propeller 4. The propeller leg 2 passes or extends through opening 12 in bottom shell 10s. Opening 12 is larger than the outer circumference of propeller leg 2 and is sealed by a membrane 12a to prevent the entry of water in which the boat floats into the hull 10h.

A side-steering device or actuator, not shown, e.g. a steering cable, is attached to one or two oppositely disposed steering arms 26 which are attached to and project from the side of propeller leg 2. The side steering device is operated from the drivers's place to rotate or pivot propeller leg 2 in one or the other sense about the steering axis G.

A universal joint 1d is arranged inboard between output shaft 1b and stub shaft 1b', i.e. between engine part 1 and the housing or upper module unit 32 in which upper gear box 1c is located. The pivotal bearing 133 is inclined relative to power transmission shaft 5 with such an angle .alpha. that the steering axis G passes through universal joint 1d.

Propeller leg 2 comprises three portions, more precisely, in the exemplary embodiment shown, three module units, viz. an upper gear box housing or upper inboard module 32, an intermediate housing or module unit 31 and a lower outboard underwater housing or module unit 30 which comprises propeller housing portion 3. The intermediate module 31 is attached to upper module 32 and lower module 30 is firmly attached at K to intermediate module 31 to form a watertight propeller leg assembly 2. Intermediate unit 31 has a convex conic envelope surface providing an upper bearing surface fitting into a lower concave conic surface in pivotal bearing 133 to pivotally mount propeller leg 2 on hull 10h for pivotal movement about the bearing axis which coincides with steering axis G. The conic bearing surfaces have the smaller diameter portions at the lower end, so that pivotal bearing 133 supports propeller leg 2 and the propeller leg 2 can be inserted from above into pivotal bearing 133 and opening 12. It will be appreciated that the convex conic surface also may be, with appropriate inclination, provided on or attached to e.g. a cylindrical propeller leg which in such a case may be manufactured in one piece, and from above inserted into the concave conic surface of the bearing. An attachable part with a convex conic surface is shown in FIGS. 5 and 6.

FIG. 3 is a schematic diagramatic view of an S-drive arrangement with dual propeller shafts 3b, 3b' for a dual propeller assembly 4, 4' as shown in FIG. 10. The lower angular gear box 3cc is arranged for driving propeller shafts 3b, 3b' in opposite directions. The propeller leg 2 is mounted in the inclined bearing 133. The least possible inclination (angle .alpha.) between axis G and shaft 5 is defined by the structural requirements for strength which determine the diameter D of the lower end of intermediate portion 31, which diameter in its turn depends on the wall thickness of the housing material and the diamter d of power transmission shaft 5.

According to FIG. 4 a straight console or bracket 27 is rigidly attached to engine part 1, e.g. by riveting 27a, and the pivotal bearing 133 is mounted on bracket 27. The opening 12 in the bottom 10 of hull 10h is sealed by the membrane 12a which is sealed to hull 10h and around propeller leg 2 and is inboard surrounded by an annular resilient means 40 which supports and possibly also seals the rear terminal portion of bracket 27 where the bearing 133 for the propeller leg 2 is mounted and by which also the rear portion of the engine part 1 is supported, because the rear rubber block 1d (FIG. 1) is omitted. Annular means 40 is therefore constantly compressed by a part of the weight of engine part 1 and the whole weight of propeller leg 2 (minus buoyancy of its immersed portion).

According to FIGS. 5 and 6, in both embodiments, the pivotal bearing 133 comprises a conic or funnel shaped receiving portion 133a for propeller leg 2. Receiver portion 133a is pivotally mounted in bearings on a conic bearing bed 133b which is mounted with the necessary inclination in hull 10h of the boat. FIG. 5 shows the steering axis G and the pivotal bearing 133 having rolling elements such as ball-bearings balls 133c, complemented by a sealing packing 133d. The FIG. 6 embodiment of bearing 133 has self-sealing slide or surface bearing means 133e.

The construction FIG. 4 in which the propeller leg 2 pivotally protrudes from bottom 10 of the hull, permits a special arrangement of the cooling water inlet and enables to provide an automatic cleaning means 28m having comb 28 and grill 29a for the orifice opening 29 of a cooling water pipe 129. Said cleaning means 28m is shown in greater detail in FIGS. 7 and 11. According to FIG. 7 an inlet or orifice portion 29 of a cooling water intake pipe 129 (FIGS. 4 and 8) is provided in the outboard module 30. The water inlet port or orifice opening 29 itself is covered by a grill 29a which has transversal slots 29a' and which is detachably fixed on outboard module 30 with the aid of mounting screws 229. A cleaning comb 28 has mounting means for mounting outside on the bottom 10 of the hull, or on another non pivotal part on hull 10h. Cleaning comb 28 has comb teeth 28' which fit into the slots 29a of the grill. The comb teeth 28' scrape clean the slots 29 a' upon each side-steering movement of propeller leg 2, whereby clogging of the cooling water inlet or orifice opening 29 by deposition of water plants, trash, etc. is hindered or prevented. It will be readily appreciated that the described automatic cleaning means may be equally well applied with the embodiment of FIG. 2.

FIG. 8 shows in a cross-section on a smaller scale through an intermediate module 31, an embodiment of the cooling water intake pipe 129 that has a bend so the upper portion of the pipe may extend concentrically with the steering axis G while in the lower portion 129, this concentric relation does not exist. It will be recognized that the cooling water intake pipe 129 at the same time cools lubricating oil in a space 31K inside the intermediate module 31, where the oil is fed-in through a channel 129a between the outboard module 30 (FIGS. 2, 4 or 7) and the intermediate module 31.

The outboard module 30 is, in its attachment portion to the inboard module 31, i.e. in the uppermost portion, e.g. above the plane L in FIG. 7, preferably symmetrically shaped so that it may be mounted for pusher propellers FIG. 10 or traction propellers FIG. 9, as desired or needed. Outboard module 30 may then with the aid of a flange 30A be connected to the intermediate module 31 either in the position with attachment portion 3P and propeller shaft 3b facing aft at the aft edge as shown in the drawing, or mirror-inverted, i.e. with the attachment portion 3P and propeller shaft 3b for propeller 4 turned in the opposite direction facing fore at the fore edge. The inlet portion of the cooling water intake pipe is then doubled to provide 2 inlet portions, with one inlet portion 29 in a left position, and another inlet portion 29' in a right position.

A stabilizing fin (lateral face) 128, known per se, is preferably provided and in such a manner that its attachment portion 128a to the propeller leg 2 has the shape of a closing cap for the one of the water pipe inlet or orifice portions 29, 29' which is not in use, i.e. essentially is imperforate, has the same shape as the grill, and is provided with identically located fixing means like grill 29a, such as mounting screws 228. Thus when the outboard module 30 is mounted in reverse position, grill 29a and fin 128 readily may change place one with another, so that the grill again is located fore and the fin aft in regard to the driving direction, arrow M (FIGS. 7, 9 and 10).

FIGS. 9 and 10 respectively show a traction drive and a pusher drive dual propeller assembly. The propeller housing portion 3 of propeller leg or lower unit 2 is for hydrodynamic reasons complemented with differently shaped closing caps 3e, 3f depending on whether a closing cap is needed in fore position or in aft position. Cap 3f may preferably be shaped so as to also be able to close an exhaust gas discharge portion 4G in the hub of the propeller, as shown in FIG. 9.

FIG. 11 shows an S-drive according to the invention mounted on an inclined bed 11C provided in the bottom 10 of the hull 10h. The cleaning comb 28 passes through opening 12 in bottom 10 and is attached to a stationary (not rotary or side-steerable) part 28S.

The power transmission means connecting engine part 1 (FIG. 2) to propeller 4 includes a vertically extending power transmission shaft divided into three parts, lower part 50, intermediate part 51 and upper part 52 connected one with another by spline connections when the module units 30, 31 and 32 are assembled forming propeller leg 2.

Between the inclined bed 11C and the bearing bed 133b a resilient means 40 is provided having the same sealing and damping functions as resilient means 40 in FIG. 4. The opening 12 is otherwise not particularly sealed, and the space 120 is filled with water, fairing member 120a providing principally a hydrodynamic fairing function, without sealing. Other parts are similar to the above described FIGS. 2 to 10.

The steering means 26, FIG. 2, on pivotal propeller leg 2 may, if desired, be mechanically connected to a conventional rudder blade (not shown) of the boat for common rotation in a selected transmission ratio.

The side steering inboard outboard drive according to this invention is, as already stated, advantageous for sailing boats. It is, however, also particularly suited for planing boats (hydroplanes), because such boats slide a little transversely off course when driving along a curved course, and a drive unit with a deflected rudder blade may make it difficult to drive in a curved course, in contrast to a drive with a pivotal propeller housing according to the present invention which makes it easier to drive a curved course.

According to FIG. 12, in a modification of the embodiment of FIG. 4, a supporting console or bracket 20 is an angular type bracket and has a vertical leg 20a fixed to the flywheel housing 1a and a horizontal leg 20b for supporting the propeller leg 2. The propeller leg is rigidly but pivotally mounted in rotary bearing 21 in horizontal leg 20b of bracket 20 so the propeller leg 2 and engine part 1 act as a unitary inertial mass with regard to stress and vibration. In order to further aid in fixing propeller leg 2 to engine part 1, the upper end of propeller leg 2 also axially engages an axial bearing portion 21a of bearing 21 on housing 1c' for upper angular gear box 1c. The housing 1c' is firmly connected by rods 20' to bracket 20 and thus fixed on engine part 1. The upper angular gear box 1c is aligned with and driven by horizontal engine output shaft 1b. Upper gear box 1c drives vertical power transmission shaft 5 extending vertically downwardly in propeller leg 2 to lower angular gear box 3c which drives horizontal propeller shaft 3b and propeller 4 mounted on propeller housing portion 3 of propeller leg 2. The upper gear box 1c and output shaft 1b are located a spaced distance above the place of attachment of propeller leg 2 to mounting bracket 20. The bending moment is transferred from propeller leg 2 to engine part 1 at this place of attachment, whereby the engine part is relieved in the region, cap 1a' of housing 1a, where output shaft 1b extends out of engine part 1. The propeller leg 2 is connected to a rudder lever 26' or other side steering device to pivot propeller leg 2 to one side or the other about the vertical axis of bearing 21 for side steering. In this embodiment, the steering axis coincides with the power transmission shaft 5.

The engine part 1 rests at or near its forward portion in a conventional manner on two side by side located or laterally spaced vibration dampening blocks 1d of which only one is seen in the FIG. 12 side view. Supporting bracket 20 rests at its free end on a resilient vibration damping annular element 40 which surrounds opening 12 and propeller leg 2. The whole inboard outboard drive, i.e. engine part 1, propeller leg 2 and housing 1c' provide a unitary mass of inertia resting at the forward end of engine part 1 and at the rear or propeller leg end on vibration damping means mounted in hull 10h. A thin sealing membrane 12a is provided in the opening 12 and sealed to hull 10h and around propeller leg 2. The bearing 21 may also be sealed and then annular element 40 would also seal opening 12.

According to FIG. 13 a straight support bracket 27 has a pair of arms 27a one on each side of engine part 1, each secured, e.g. by rivets 27', to the front and rear of the lower portion of engine part 1, and a base or platform 27b at the rear of the engine part below engine output shaft 1b. The propeller leg 2 extends through hole 27c in base 27b and is secured and sealed thereto by bolts 2b. The resilient annular element 40 between bracket base 27b and hull 10h provides sealing, so a separate sealing membrane may, if desired, be omitted. The drive means between the horizontal engine output shaft 1b and horizontal propeller shaft 3b is the same as described above.

In the modification FIG. 14 engine part 1 is mounted near the forward end on a pair of damper blocks 1d and has at the rear end flywheel housing 1a with cap 1a' from which engine output shaft 1b projects. The support bracket 20" has a partial tubular shape with a front vertical portion secured to flywheel cap 1a' and slopes angularly downward and rearward and rests with its lower end secured on a socket part 2e which is mounted on a support 33. The propeller leg 2 has upper module 32, an intermediate module 31 and a lower or propeller module 30 with propeller housing 3 secured together as a unit. The engine shaft 1b is connected by a universal joint 1d to stub shaft 1b' and upper gear box 1c in housing 1c' of upper module 32 which drives vertical power transmission shaft 5. The shaft 5 drives lower gear box 3c, horizontal propeller shaft means 3b and one or dual propellers 4, 4'. The propeller leg 2 is fixedly and rotatably supported by bearing 133 having an inner bearing part on intermediate module 31 and an outer bearing part on socket part 2e. The socket part 2e on which bracket 20" and bearing 133 rest is mounted and sealed on an annular resilient vibration damping member 40 as shown in FIG. 11 which is mounted and sealed in an annular bedding 11C provided in the bottom 10 of hull. Thus socket part 2e and damping member 40 provide support 33 supporting through bracket 20" the rear end of engine part 1 and propeller leg 2 resiliently on hull 10h. The pivotal axis of bearing 133 and thus the side steering axis S is inclined forwardly at an acute angle .alpha. with the axis D of power transmission shaft 5.

Another embodiment of a support bracket 20'" is shown in FIG. 15 and similarly fixed to cap 1a' of flywheel housing 1a of engine 1. Support bracket 20"' like the other support brackets projects from cap 1a' toward the rear like engine output shaft 1b, and has, like bracket 20" in FIG. 14, a vertical portion 20"'a attached to cap 1a', a rearwardly extending portion 20"'b and a downwardly extending portion 20"'c, rather than the rearwardly and downwardly sloping portion of bracket 20" FIG. 14. The bottom of the downwardly extending portion 20"'c is secured by screws 2c to propeller leg 2 (lower housing) directly or through a socket part 2e.

The arrangement according to the invention is used in drives having one propeller, FIGS. 12 and 13, or dual propellers, FIG. 14, or propellers of the pusher type FIG. 10, or of the traction type, FIG. 9. The support bracket may protrude with respect to the engine part in a rearward or aft direction or in the reverse direction, i.e. forward in the direction of driving M, FIGS. 7, 8, 9, 10, if such location of engine part 1 and propeller leg 2 is desired.

The support bracket is fixed to the propeller leg 2 between the engine output shaft 1b and propeller shaft 3b, essentially centrally between these shafts, i.e. below the output shaft 1b and upper gear box 1c, and preferably at the bottom of engine part 1 near the bottom 10 of hull 10h. The first resilient means for supporting engine part 1, and the second resilient means for supporting the bracket and the attachment of propeller leg 2 to the bracket are substantially in horizontal alignment. Thus the lever arm H', FIGS. 12, 13 and 14, of the bending moment generated by propeller thrust R has a reduced value as compared to the lever arm H FIG. 1 of a prior art drive otherwise having similar dimension values. Since the bending moment is the product of the lever arm and thrust (M=H.times.R), the bending moment (H'.times.R) is reduced. Thus the stress on the attachment of the propeller leg to the engine part is also reduced and the vibration forces are reduced, and more easily damped by the large unitary mass of the engine and propeller leg mounted on damper means nearby aligned with the place of attachment. This improved construction with a reduced lever arm is obtained without direct contact of the propeller leg to the hull at opening 12 which would directly transmit vibration and noise to the hull 10.

FIGS. 16 to 18 schematically show three different embodiments of a modular housing arrangement, each making use of some principles of the present invention.

In FIG. 16 the propeller leg assembly 2 comprises an outboard module 30 which has a propeller housing part 3 with power transmission drive means mounted therein and including the power transmission shaft 50, the lower angular gear box 3C, which is a 90.degree. angular gear, and propeller shaft 3b for supporting and driving propeller 4. The outboard module 30 provides a watertight enclosure with an open upper end which receives shaft 50 and is aligned with opening 12 and is attached and sealed by attaching means 10a, e.g. by welding etc. not shown in detail, around opening 12 to bottom 10 of hull 10h. An inboard module 32 has power transmission means including the upper angular (90.degree.) gear box 1c, drive or power transmission shaft 52 and stub shaft 1b' connected by connectional coupling 5a, 5b to engine shaft 1b. Inboard module 32 has an open lower end positioned over opening 12 in bottom 10 and a lower connecting flange 32a which is attached and around opening 12 to bottom 10 by retaining screws 30a". The inboard module 32 also has an upper or another connecting flange 32b at the upper end for similarly securing inboard module 30 to engine part 1.

The respective outboard and inboard modules 30 and 32 each has its shaft portion respectively 50 and 52 having at their adjacent free ends its coupling part 50a and 52a of a detachable coupling 50a, 52a. Upper gear box 1c drives shaft portion 52, coupling 50a, 52a and shaft portion 50 providing detachable power transmission shaft means which extends through inboard module 32, its open lower end, opening 12 and open upper end of outboard module 30 and in outboard module 30 to drive gear box 3c, shaft 3b and propeller 4. In practice these parts of a coupling will be defined by a spline joint with outward grooves, e.g. 50a on the shaft portions, e.g. 50, and inward grooves in a connecting sleeve, e.g. 51a which is slidable on the shaft portions, as shown in FIGS. 19 and 20. Stub shaft 1b' and conventional coupling 5a, 5b are provided for detachably drive-connecting output shaft 1b of engine part 1 to upper angular gear box 1c. It will be recognized that both inboard and outboard modules 30, 32 function together as a propeller leg assembly 2 and that for repair or replacement of the inboard module 32 it may be removed by detaching lower and upper connecting flanges 32a and 32b, coupling 50a, 50b and coupling 5a, 5b without causing any leakage through opening 12 into hull 10h and without need for an extra sealing element or membrane in opening 12, since the outboard module 30 continues to seal opening 12.

In the following descriptions of various embodiments and modifications of the invention the modified structure is described and reference is made to the prior description of similar parts in other embodiments or modifications.

In the embodiment of FIG. 17, the inboard module 32 is attached by attaching means 10b to the bottom 10 of the hull 10h and the outboard module 30 is provided with a connection flange 30a secured by retaining screws (not shown for clarity). In the opening 12 is a sealing membrane 12a sealed to bottom 10 and through which sealingly passes the shaft portion 52 whose coupling element 52 is located on the outboard side of the membrane 12a for connection with the coupling element 50a on shaft portion 50.

In the preferred embodiment of FIG. 18, a third module unit, an intermediate module 31, is fixedly mounted to the bottom 10 of the hull 10h. The intermediate module 31 is on the one hand provided with a lower connection flange 31a for attachment to the connection flange 30a of the outboard module 30, and on the other hand with an upper connection flange 31aa for attachment to the lower connection flange 32a of the inboard module 32. In the intermediate module 32 is a sealing membrane 12a and a transmission shaft portion 51. The shaft portion 51 passes sealingly through the membrane 12a and is at both ends provided with a coupling part 51a, 51aa for connection to corresponding coupling parts 50a and 52a on the shaft portions 50 and 52. Inboard module 32 is as shown in FIG. 16, and outboard module 30 is as shown in FIG. 17 and described above.

In this preferred embodiment FIG. 18, the boat remains sealed irrespective of which of the modules 30 and 32 is removed, and it is easy to dismount as well from beneath (i.e. from the outboard side) the outboard module 30 from the intermediate module 31, as from above (i.e. from the inboard side) the inboard module 32 from the intermediate module 31, if the one or the other is needed, e.g. for repair modification purposes.

In FIGS. 19 and 21 is shown a further embodiment where the intermediate module 31 is mounted in a support 33 which in its turn is fixedly mounted in opening 12 in bottom 10 of hull 10h. The intermediate module 31 has a flat collar 31b with which it will rest on a sealing packing 33a, e.g. of rubber, on the support 33. Inside the intermediate module 31, the shaft portion 51 passes sealingly through said sealing packing 12a. The outboard module 30 is instead of a connection flange, provided with separate recesses 30a' adjacent openings 30b through which retaining screws 30" pass towards threaded holes (not shown) in the connection flange 31a of intermediate module 31. Inboard module 32 has flange 32a secured by screws to flange 31aa of intermediate module 31 as in FIG. 18.

In FIG. 20 coupling parts 50a and 51a are shown. They are defined by outer splines 50a on shaft 50 and by sleeves 51a having inner splines fixed to the respective shaft portion 51. The other coupling parts 51aa and 52a are similar. As is well known, a spline joint may be readily assembled by axially inserting one part into the other, and moreover has a telescopic effect, i.e. it allows to some extent axial movement even under operation.

The intermediate module 31 of FIG. 21 may even be rotatably mounted in its support, e.g. with the aid of rolling or ball bearings 33b whereby a side-steerable inboard outboard drive as e.g. in FIG. 12 is obtained. The shaft portion 51 is sealed by two packings 12a' and the intermediate module is sealed in regard of its support 33 by a further packing 12a".

In FIG. 2 has already been shown another embodiment of of a propeller leg or lower unit built up of three module units, where the engine part 1 is provided with a flywheel housing 1a and on the bottom 10 of the hull 10h is a pivotal bearing 133, shown on a larger scale in FIG. 5, mounted in an inclined position. Propeller leg 2, composed of the module units 30, 31 and 32, is pivotally mounted in the pivotal bearing 133 for rotating about steer axis G.

The intermediate module 31 has conical outer envelope surface which fits into and is supported on the pivotal bearing 133 and the axis of which coincides with, or more precisely, defines, the side-steering axis G. The intermediate module 31 is at K, i.e. at the narrowest place of the conical surface, attached to the outboard module 30, whereby insertion of the lower unit into the conical pivotal bearing 133 is enabled. The conical envelope surface defines a receiving surface for the lower unit and it can be arranged on a separate part around the module, as has been shown in FIGS. 5 and 6, instead of being provided immediately on the module itself.

In another three module embodiment according to FIG. 4, straight console or bracket 27 is attached to the engine part 1 and the pivotal bearing 133 is mounted on the bracket. The opening 12 in the bottom 10 of hull 10h is sealed by the membrane 12a and is inboard surrounded by an annular resilient means 40 which supports the rear terminal portion of bracket 27 where the bearing 133 for the propeller leg assembly 2 is mounted.

The propeller leg assembly or lower unit 2 composed of the modules 30 and 32, or 30, 31 and 32 need not necessarily extend exactly vertically. In FIG. 22 is shown an inclined transom 11A attached to bottom 10 of hull 10h, having adjacent bottom 10 an opening 12T in which support 33 is mounted. The intermediate module 31 passes with its axis, defined by shaft 51', essentially at right angles through transom 11A and modules 30 and 32 are attached to intermediate module 31 with their axes, defined by shafts 50' and 52', subtending angles .beta. and .gamma., which are other than 90.degree. and 180.degree., with shaft 51'. In the example shown, .beta. is appr. 150.degree., and .gamma. is appr. 135.degree., so that shafts 50' and 52' subtend together an angle .delta., appr. 105.degree. which is not too different from 90.degree. as shown in the other exemplary embodiments. The outboard module 30 has in addition to lower angular gear box 3c', another intermediate angular gear box 3d, and both these angular gear boxes, as well as the upper angular gear box 1c' arranged in the inboard module 32, differ from the angular gear boxes described hitherto in that they are more than 90.degree. angular gear boxes. Inboard module 32 carries a gear lever 19 for gear box 1c.

An inboard outboard drive may even have, as stated earlier, an engine part with a vertical output shaft. In FIG. 23 is shown such a solution in connection with the present invention. The inboard module is there provided with a second connection flange 32aa to which an engine part 1' with a vertical output shaft 1b" is attached with the aid of a corresponding connection flange 1aa. Otherwise this drive is like FIG. 18.

The coupling parts which connect the shaft portions of the separate modules may according to FIG. 24 also be defined by parts 50a' and 52a' of a magnetic coupling, which are separated by a sealing membrane 12a of non-magnetic material. It will be observed that in this case the intermediate module 31 does not need to have any shaft portion of its own, but merely a membrane 12a.

FIG. 25 shows in perspective an inboard outboard drive according to the invention, assembled outside a boat hull. The engine part 1 is provided with holders 1d' to be fixed to rests 1d (FIG. 1) and with a fork-shaped guide 1g attached to the cap 1a' of the flywheel housing 1a and from which the housing 1c' of the angular gear box of the inboard module 32 protrudes. The connection flange 32a of inboard module 32 is attached by screws 32a' to the intermediate module 31. Intermediate module 31 may rest on an annular resilient means 40 of FIG. 12 and guide 1g may at the same time fill the function of rods 20' and bracket 20.

While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.

With reference to FIG. 22 it will be noted that a propeller leg extends essentially vertically in the sense of the present specification if at least the outboard portion thereof subtends an angle of 90.degree.-120.degree. with a horizontal part, such as a horizontal output shaft, of the drive.