GB2028746A

GB2028746A - Drive for watercraft comprising a surface propeller

Info

Publication number: GB2028746A
Application number: GB7925004A
Authority: GB
Original assignee: Hurth Verwaltungs GmbH
Current assignee: Hurth Verwaltungs GmbH
Priority date: 1978-07-18
Filing date: 1979-07-18
Publication date: 1980-03-12
Also published as: ES482561A1; SE7903077L; AR216012A1; FR2431424A1; GB2028746B; BR7904553A

Abstract

A drive for a watercraft comprises a surface propeller 8 which is driven by an inboard motor by way of a shaft assembly which extends through the transom 28 and is jointed at least in the region of the transom; the outboard propeller shaft is journalled in a support arm 2 with a forward flange plate 27, fitted to the transom on the outboard side, such that the propeller thrust is transferred directly from a propeller thrust bearing in the support arm to the watercraft. The support arm 2 is a one-piece structure in the form of box sections 3, 4 which in addition to the propeller shaft bearings also house connections for cooling water lines, the exhaust gas duct, and operating elements for a steering rudder 31 fitted aft of the propeller, and also carries a trimming rudder 38 which can be swivelled about a horizontal axis. A change-over and/or reversing gear can be provided inside the watercraft, or between the transom and support arm, or inside the support arm. <IMAGE>

Description

SPECIFICATION Drive for a watercraft comprising a surface propeller This invention relates to a drive for a watercraft comprising a surface propeller, which is rotated by an inboard motor by way of shafting.

In the case of a surface propeller the whole propeller is not immersed in the water, but the propeller projects increasingly out of the water as the speed of travel increases, and at maximum speed, about half the propeller projects above the water.

A drive comprising a surface propeller is known, in which the inboard motor and shaft assembly leading to the propeller are disposed on a common support, which is swivel-mounted to the rear of the watercraft in the vicinity of the transom, optionally by way of a damping element, there being provided devices for varying the angle of inclination of the support, and thus varying the depth of immersion of the propeller.

Such a drive, which is intended to overcome the many drawbacks of the well-known Z drive, gives very good results in practical use, in particular in the case of racing boats. However, because of the considerable weight of the drive motor, which in most cases is a diesel engine, this drive is less suitable for leisure boats.

A drive comprising a surface propeller is known from U. S. Patent 3,933,116, in which the motor is fixed inside the watercraft and the shaft which supports the propeller is connect to the motor by means of a universal coupling. The propeller shaft is supported in an arm provided with a cavitation plate, and which is so mounted on the stern of the watercraft that it can swivel about a horizontal axis in order to vary its depth of immersion, and also about a vertical axis so that the craft can be steered. A drawback is that the propeller thrust is taken up by the various pivot pins. A further drawback is that because of the weight of the movable arm, the hydraulic devices for lifting and lowering it have to be correspondingly large.

The latter drawback is overcome if the arm carrying the propeller is rigidly fixed to the watercraft, and the depth of immersion of the propeller is determined by a trimming rudder which swivels about a horizontal axis and is connected to the cavitation plate. Such a device is known from U. S.

Patent 4,031,846. In order to be able to dispose the propeller thrust bearing inside the watercraft, so that the propeller shaft is supported partly in the craft and partly in the arm, this arm is not in the form of a single unit, and therefore assembly and dismantling are difficult. This means that the necessary devices for operating the rudder for steering the craft are freely mounted on the arm, so that they are easily damaged and are in contrast to the enclosed appearance required in present-day leisure boats.

An object of the present invention is to provide a drive for a watercaft comprising a surface propeller, wherein the propeller and the propeller-supporting arm form a complete structural unit, which can be fitted as a unit, without any problems, to the watercraft, and with which the propeller thrust is transferred directly to the craft without being diverted through other units. The drive is to be of enclosed appearance, and simple and inexpensive to construct.

The invention provides a drive assembly for a watercraft comprising a support arm provided with a flange plate at its forward end for fixing the support arm rigidly to the stern of the watercraft, a propeller shaft journalled in the support arm, a propeller thrust bearing being mounted in the region of the flange plate, in such a manner that propeller thrust will be transmitted to the flange plate only by way of rigid parts, drive coupling means at the forward end of the propeller shaft in the region of the flange plate, for coupling to an inboard drive, and a surface propeller on the propeller shaft at the after end of the support arm.

Thus, the propeller-supporting part of the shafting is supported externally to the watercraft in the support arm, fixed rigidly by means of the flange plate to the craft; the propeller thrust bearing is fitted inside the support arm so that the propeller thrust is transferred to the watercraft only by way of rigid parts and onto a large surface area.

Preferably the support arm is constructed in one piece, preferably of cast iron, and consists of a box-shaped lower part extending in a longitudinal direction and comprising coaxial holding bores for the bearing arrangement of the propeller shaft, and a likewise longitudinally extending superposed boxshaped upper part shaped in the form of a cavitation plate and projecting at its rear end beyond the lower part, wherein the upper and lower parts are joined together by means of a longitudinally extending rib or the like, and, at their front end, by means of the flange plate.

This construction is very reliable operationally.

The one-piece box form of the support arm ensures high rigidity and also gives sufficient scope for giving a stylish form to the unit. In many cases, an inclined propeller shaft is preferred in order to improve efficiency; to provide this the box-shaped upper part and the box-shaped lower part converge towards the flange plate at an acute angle, with the upper part being substantially horizontal and the lower part being inclined thereto, and both parts comprising a common separation wall where the vertical rib is partly lacking. If the propeller shaft thrust bearing is arranged in a journal box, the propeller thrust is kept remote from the motor, and is led to the stern of the watercraft by the shortest way.In a preferred arrangement, a journal box containing roller bearings, in which the propeller shaft is radially supported and which take up the propeller thrust, is disposed in that end of the support arm facing the transom, the journal box being closed outwardly by means of a cover. For lubricating the roller bearings the journal box is preferably at least partly filled with oil, and the cover is provided with a chamber forming an oil reservoir, which is connected to the inner compartment of the journal box and is closed outwardly by means of a closing screw or the like, possibly carrying an oil-measuring dip-stick. With roller bearings running in the oil bath, the life is increased with respect to grease-lubricated bearings, and this is particularly important for the thrust bearing.

In contrast to a splined spigot ad socket connection, a flange connection between the propeller shaft and that part of the shafting situated inside the watercraft not only gives easy assembly and dismantling, but also makes it possible to include a flexible coupling for compensating angular deflections and alignment errors. A swivel-mounted rudder can be disposed behind the propeller on the upper part of the support arm for steering the watercraft. Fluid flow lines and actuating rods can be laid in the box profiles, so that they do not hinder flow and are protected from damage.In a preferred arrangement the upper part of the support arm is divided by means of a partition wall into two longitudinally extending chambers, and a rod for swivelling the rudder is led through one of the chambers, and the other chamber contains the exhaust gas line for the drive motor and possibly a silencer. Connetions for the feed and/or discharge cooling water lines of the drive motor can be provided in the lower part of the support arm or in the flange plate. The support arm may carry a trimming rudder at the rear end of the upper part, which rudder can be swivelled about a horizontal axis. The trimming rudder may comprise a recess which allows the trimming rudder to extend to the rear of the steering rudder on both sides of the latter, without the swivel movement of the latter being hindered.Preferably, the trimming rudder is operated by hydraulic cylinders disposed on the side of the upper part of the support arm and which act by means of their piston rods on a rod connected to the trimming rudder and have their feed lines laid within one of the chambers in the support arm, preferably within the chamber containing the steering rudder rod. Water guide surfaces may be provided extending rearwards in an inclined direction from the lower part to the upper part of the support arm, on both sides of the longitudinally extending vertical rib joining the lower part to the upper part, and are connected to this rib, and are curved both outwards towards the sides and in their longitudinal direction.

The field of application of the drive can be further widened if it is combined with a change-over and/or reversing gear.

For manoeuvring watercraft fitted with a surface propeller drive, it has previously been usual to provide a reversible motor. However, such motors are not obtainable from all manufacturers. A simple arrangement of the gear is obtained if an inboard change-over and/or reversing gear is disposed in front of the flange plate, its input shaft being connected to the inboard part of the shafting and its drive shaft being connected to the propeller shaft.

However, the necessary room for the gear is not always available, and the fact that the motor thus becomes disposed more towards the middle of the craft may lead to trimming difficulties. It can therefore be of great advantage to dispose the gear outside the watercraft. In one possible arrangement a change-over and/or reversing gear is disposed between the transom and support arm in such a manner that its casing is flanged by one of its end faces to the transom and by its opposite end face to the support arm, and its input shaft is connected to the inboard shafting which is divided in the region of the transom, and its output shaft is connected to the propeller shaft.If in this case the connection between the output shaft of the gear and the propeller shaft is in the form of a socket-type coupling, then the support arm can be used without modification both in constructions using the gear and in constructions without the gear. In these constructional cases in which due to the gear the length of the drive unit becomes too large, the gear may be fitted inside the support arm. In this case it is advantageous if the gear is made interchangeable with a journal box containing the propeller th rust bearing, which would be provided in the case of an embodiment in which the said gear is not present. In ail cases, an inexpensive and easily assembled embodiment is attained if the drive shaft of the gear is made in one piece with the propeller shaft, and a bearing for this shaft is in the form of a propeller thrust bearing.

The invention is further described hereinafter with reference to several embodiments illustrated in the accompanying drawings in which: Figure 1 is a diagrammatic illustration of a drive assembly according to the invention fitted on a watercraft, Figure2 is a diagrammatic illustration of another drive assembly according to the invention fitted on a watercraft, Figure 3 is a side view of a drive assembly according to the invention, Figure 4 is a cross-section on the line IV-IV of Figure 3, Figure 5 is a part section through the after end of the upper part of the drive assembly, comprising the rudder bearing, Figure 6 is a perspective view of the drive assembly mounted on a watercraft, Figure 7 is a longitudinal section through the support arm, Figure 8 is a longitudinal section through the propeller shaft bearing assembly in a journal box, Figure 9 is a cross-section through the cover of the journal box, comprising an oil reservoir, Figure 10 is a diagrammatic arrangement of a gear in a further embodiment of a drive according to the invention, Figure 11 is a simplified representation of the arrangement of a reversing gear on the stern of a watercraft, connected to the drive assembly, and Figure 12 is a simplified representation of the arrangement of a gear inside the support arm of a drive assembly according to the invention.

Figure lisa diagrammatic view of a drive assembly according to the invention. A drive motor 52 is fitted in a watercraft 51, which is only dagrammatically illustrated, and drives the drive assembly 1, fixed externaily on the transom 28, by way of a shaft assembly 53 which passes through an opening 54 in the transom 28. This drive assembly consists substantially of a support arm 2 which supports a propeller shaft 7 which carries at its free after end a propeller 8 which dips into the water. The propeller is covered by a cavitation plate 9, on which a rudder 31 is swivel-mounted to the rear of the propeller for steering the watercraft 51.

The support arm 2 is formed in one piece from two hollow box sections, namely the lower part 3 and upper part 4, which are joined together by a longitudinal vertical rib 10 (Figures 3 and 4). The support arm 2 is provided at its forward end with a flange 27 for fixing it to the watercraft 1, preferably on the transom 28, this flange being so dimensioned that the drive assembly can be made as universally mountable as possible on the various types of boat.

Lateral water guide surfaces 11 are disposed on the rib 10, and are inclined rearwardly upwards from the lower part 3 upwards to the upper part 4, being so curved longitudinally and laterally that they partly form a dome, open at the rear, concave to the propeller 8.

The bearing arrangement for the propeller shaft 7 housed in the lower part 3 will be described in detail hereinafter. The lower part 3 or flange 27 can be fitted with connections for the cooling water feed and/or discharge lines of the drive motor 52. Such a connection is indicated in Figure 3 at 29. The upper part 4 is divided by a longitudinal vertical partition wall 35 into two chambers 36,37, one of which, 37, houses the exhaust duct for the drive motor 52. A silencer can also be incorporated here. The rod 30 for controlling the rudder 31 passes through the other chamber 36. This rudder is supported by means of a shaft 59 in bearing bushes 32 (Figure 5), disposed in the rear part of the upper part 4 or chamber 36. The rod 30 is hinged to a lever 60 which is fixed to the shaft 59 by means which are known, and therefore not illustrated or described.A cover 33 is fixed by screws 34 on the upper part 4 over the shaft 59. In addition, a trimming rudder 38 is fitted on the upper part 4. It is rotatable about a horizontal axis forward of the rudder 31, by hydraulic cylinders 42 mounted on the sides of the upper part 4, which act by means of their piston rods 41 on arms 40 fixed to the trimming rudder. In order not to impair the range of swivel of the rudder 31, the trimming rudder 38 is provided with a recess 43 (Figure 6), through which the rudder 31 passes, and the trimming rudder extends aftwards on both sides of the rudder 31.

The upper part 4 and lower part 3 can be disposed so that they are substantially parallel as shown in Figure 1 or so that they form an acute angle with each other; this latter construction is shown diagrammatically in Figure 3, which also represents an example of the direct connection of the drive motor 52 to the propeller shaft 7 by a coupling flange 16. In this case the parts 3, 4 possess a common separation well 55 (Figure 7) over the forward part of their length, the rib 10 then being correspondingly shorter. The description given hereinafter relative to the propeller shaft and its bearing arrangement is valid for both embodiments of the support arm.

As shown in Figure 7, the lower part 3 of the support arm 2 is provided with coaxial holding bores 5, 6, in which the bearings for the propeller shaft 7 are mounted. Directly forward of the propeller 8, which is fixed onto the after end of the propeller shaft 7 by known means, not shown, the bore 5 comprises a bearing 17 (Figures 10 and 11), which can for example be a friction bearing. However, ball or roller bearings can obviously also be used, if sealed against water entry. At the forward end, facing the transom 28, the larger bore 6 is sized to take a journal box 12 (Figure 8). Roller bearings 14, 15 housed in this journal box form a second support bearing for the propeller shaft 7, and the bearing 15 takes up the propeller thrust, which is transmitted via the flange plate 37 to the transom.

In the illustrated embodiment, a flange 16 with a fitting key 18 is tightly mounted on the forward end of the propeller shaft 7, and is axially retained by means of a nut 19 and washer 20. The journal box 12 is closed to the exterior means of a cover 21. This complete unit, consisting of the journal box 12, roller bearings 14,15, flange 16 and its fixing elements, propeller shaft 7 and cover 21 can be previously assembled outside the support arm 2, and inserted as a complete unit into the latter. The screws necessary for fixing the previously assembled unit in the arm 2 are only diagrammatically illustrated, with the reference numeral 61.

The roller bearings 14,15 run in an oil bath in order to give better heat dissipation and to increase their life. For this purpose, the inner space 22 of the journal box 12 is filled with oil, and suitable sealing elements such as radial shaft sealing rings and 0 rings are provided at all separation planes and at the shaft penetration points. In order to increase the oil volume, the cover 21 is provided with a lateral chamber 23 (Figure 9) which serves as an oil reservoir and is connected to the space 22 by way of bores 24, 25. A check on the oil can be made by means of a closure screw 26, in which an oil dip-stick 26' can be fitted. The drive connection to the drive motor 52 is made by means of the coupling flange 16, possibly by way of an intermediate shaft assembly 53 (Figure 1).For this purpose, screws 62 or other suitable connection elements are provided.

An inboard change-over gear and/or reversing gear 56 can be disposed between the motor 52 and drive assembly 1 (Figure 10). Its input shaft can be connected to an intermediate shaft assembly 53, or, as illustrated, it can be flanged directly to the motor 52. Its output shaft 58 is connected to the flange 16 of the propeller shaft 7.

In order to balance angular deflections and axial misalignments, a flexible coupling 57 or the like can be used between the flange 16 and shaft assembly 53 or shaft 58.

Figure 11 shows a drive assembly with a reversing gear 70 shown in a simplified manner and not to scale, disposed outside the watercraft. The inboard drive motor 52 drives the gear 70 by way of a shaft assembly 53 which passes through an opening 54 in the transom 28; this gear 70 has a casing 75 fixed at its forward end face to the outside of the transom 28 by known means, not shown. The shaft assembly 53 is connected by way of a flexible coupling 72 or other suitable connection to the input shaft 71 of the gear.

The output shaft 73 is connected in a suitable manner, e.g. by means of splined socket coupling 74, to the propeller shaft 7. The propeller shaft is supported in the support arm 2, which is flange connected to the after end face of the gear casing 75 by known means, not shown. At its free after end, the propeller shaft carries the surface propeller 8 which dips into the water. This propeller is covered by the cavitation plate 9, in which the steering rudder 31 is swivel-mounted after of the propelier. The devices for operating the rudder are as already described, and are therefore not illustrated.

The gear 70 is not iimited to the described construction. It can be a pure step-up gear, or a multi-stage change speed gear, or, as illustrated, a reversing gear: the drive is transmitted to the drive shaft 73 by way of a double disc clutch 76 either through spur gears 77, 77' which reverse the rotational direction or through spur gears 78,78', 28" which do not reverse the rotation. No description need be given of the equipment for operating the reversing clutch 76, as it is well known and is not important for the purposes of the present invention.

The propeller thust is transmitted from the thrust bearing 15 directly to the transom 28 and thus to the watercraft by way of the flange plate 27 and the gear casing 75.

Afurther embodiment of a drive device according to the invention is illustrated in section in Figure 12, again simplified and not to scale. The drive motor 52 rotates a gear 70 by way of shaft assembly 53 which passes through opening 54 in the transom 28, and a flexible coupling 72 or other suitable connection.

This gear 70 is fitted inside the support arm 2, preferably in a suitable casing 75'. The construction of the gear 70 is similar to that previously described in relation to Figure 11. Its output shaft 73 is connected in a suitable manner to the propeller shaft 7, which at its free after end carries the surface propeller 8.

At the rear end of the support arm 2, the holding bore 5 contains a bearing 17 for the radial support of the propeller shaft 7. At its front end, the propeller shaft 7 can be supported either in or on the output shaft 73 of the gear. Alternatively the output shaft 73 and propeller shaft 7 can be made in one piece, as shown; a bearing 79 for the gear shaft 73 then also acts as the propeller thrust bearing. Such an embodiment is also possible in the case of the embodiment shown in Figure 11, and the bearings 14, 15 and journal box 12 can then be dispensed with. The propeller thrust is then transmitted from the gear casing directly to the transom 28 or to the watercraft 51. The gear casing 75' in Figure 12 is centred in a forward holding bore 6 in the support arm 2. If the gear casing 75' is suitably shaped, then this holding bore can be so made that the support arm 2 is suitable, without any modification both for the application in which the gear 70 is incorporated as shown in Figure 12, and for the application comprising the intermediately mounted gear shown in Figure 11, and also for the application without an outboard gear, as shown in Figures 2 and 8, the bore 6 then accommodating the journal box of the propeller thrust bearing instead of the internal gear casing 75'.

Claims

1. A drive assembly for a watercraft comprising a support arm provided with a flange plate at its forward end for fixing the support arm rigidly to the stern of the watercraft, a propeller shaft journalled in the support arm, a propeller thrust bearing being mounted in the region of the flange plate, in such a manner that propeller thrust will be transmitted to the flange plate only by way of rigid parts, drive coupling means at the forward end of the propeller shaft in the region of the flange plate, for coupling to an inboard drive, and a surface propeller on the propeller shaft at the after end of the support arm.

2. A drive assembly as claimed in Claim 1, in which the support arm is constructed in one piece and consists of a longitudinal box shaped lower part comprising coaxial holding bores for propeller shaft bearings, and a superposed longitudinal box-shaped upper part shaped in the form of a cavitation plate and projecting at its after end beyond the lower part, and the upper and lower parts are joined together by means of a longitudinally extending rib or the like, and, at their forward ends, by means of the flange plate.

3. A drive assembly as claimed in Claim 2, in which the box-shaped upper part and the boxshaped lower part converge towards the flange plate at an acute angle, the said upper part being substantially horizontal and the said lower part being inclined thereto, the two said parts having in their forward end regions a common wall where the vertical rib is lacking.

4. A drive assembly as claimed in Claim 2 or 3, in which a journal box, containing roller bearings in which the propeller shaft is radially supported and which take up the propeller thrust, is disposed in the forward end of the support arm, the journal box being closed outwardly by means of a cover.

5. A drive assembly as claimed in Claim 4, in which the journal box forms an oil bath for lubricating the roller bearings, and the cover is provided with a chamber forming an oil reservoir, which chamber is connected to the interior of the journal box and is closed to the exterior by means of a closing screw or the like.

6. A drive assembly as claimed in Claim 2, 3, 4 or 5 in which a rudder which can be swivelled about a substantially vertical axis is disposed aft of the propeller in that portion of the said upper part which projects beyond the said lower part.

7. A drive assembly as claimed in Claim 6 in which the uppr part of the support arm is divided by means of an internal partition well into two longitudinal chambers, a rod for swivelling the rudder extends through one of the chambers, and the other chamber contains an exhaust gas line for a drive motor of the watercraft.

8. A drive assembly as claimed in any of Claims 2 to 7 in which the support arm carries a trimming rudder at the after end of the said upper part, which trimming rudder can be swivelled about a horizontal axis.

9. A drive assembly as claimed in Claim 8 when dependent on Claim 6 or 7, in which the trimming rudder extends on both sides of the first-mentioned rudder and comprises a recess which allows the first-mentioned rudder to swivel.

10. A drive assembly as claimed in Claim 9 in which the trimming rudder extends aft of the first-mentioned rudder.

11. A drive assembly as claimed in Claim 8,9, or 10 when dependent on Claim 7 in which the trimming rudder is operated by hydraulic cylinders disposed on the sides of the said upper part and which act by means of their piston rods on the trimming rudder and have their hydraulic feed lines laid within one of the said chambers in the upper part of the support arm.

12. A drive assembly as claimed in any of Claims 2 to 11 in which water guide surfaces extend aft in an upwardly inclined direction from the said lower part to the upper part of the support arm on both sides of the longitudinally extending rib joining the lower part to the upper part, and are connected to this rib, and are curved both outwards towards the sides and in their longitudinal direction.

13. A drive assembly as claimed in any of Claims 2 to 12 in which connections for feed and/or discharge cooling water lines of a drive motor of the watercraft are provided in the lower part of the support arm or in the flange plate.

14. A drive assembly as claimed in any of Claims 1 to 13 in which the propeller shaft carries a coupling flange at its forward end, by means of which it is joined to an inboard drive shaft.

15. A drive assembly as claimed in any of Claims 1 to 13 in which a change-over and/or reversing gear, is disposed forward of the flange plate and has an input shaft adapted to be connected to an inboard drive shaft, and an output shaft connected to the propeller shaft.

16. A drive assembly as claimed in any of Claims 1 to 13 in which a change-over and/or reversing gear is disposed forward of the support arm and has a casing with one end face adapted to be fixed to the transom of the watercraft and an opposite end face fixed to the support arm, an input shaft adapted to be connected to an inboard drive shaft in the region of the transom, and an output shaft connected to the propeller shaft.

17. A drive assembly as claimed in any of Claims 1 to 13 in which a change-over and/or reversing gear is disposed in the support arm.

18. A drive assembly as claimed in Claim 17 in which the gear is made interchangeable with the journal box which contains the propellerthrust bearing and which would be provided in the case of the embodiment in which the said gear is not included.

19. A drive assembly as claimed in anyone of Claims 16 to 18 in which the output shaft of the gear is made in one piece with the propeller shaft, and one bearing for this shaft is a propeller thrust bearing.

20. A drive assembly for a watercraft, comprising a surface propeller rotated by an inboard motor by way of a shaft assembly passing through the transom of the watercraft which shaft assembly comprises shaft portions with a joint in the region of the transom, the outboard shaft portion which supports the propeller being journalled in a support arm which is fixed by a flange plate rigidly to the watercraft or to its transom, a propeller thrust bearing being disposed in the region of the fiange plate in such a manner that the propeller thrust is transferred to the flange plate and thus to the watercraft only by way of rigid parts.