GB2098562A - Propulsion unit for a water- borne vessel - Google Patents

Abstract

In order to offer the advantages of an inboard motor with the improved steering of an outboard motor, a propulsion unit for a water-borne vessel has a propeller housing 10 at the lower end of a depending leg 9, and which can be rotated about the axis of the leg 9 for steering the vessel. There are two input coaxial shafts, namely a horizontal drive shaft 31 and a steering shaft 20 for rotating the propeller housing 10 about the axis of the leg 9. This avoids external steering controls extending to the leg 9. The leg 9 can be swung up about pivot pins 12, automatically disengaging the drive and the steering due to the incorporation of dog clutch members 37, 24. After swinging up, the leg 9 can be lifted off completely by withdrawing the pins 12 from their inclined slots 13. <IMAGE>

Description

SPECIFICATION Propulsion unit for a water-borne vessel The Invention According to the present invention, there is provided a propulsion unit for a water-borne vessel, the unit comprising: a depending leg; a propeller housing supported on the lower end portion of the leg, the propeller housing being rotatable generally about the axis of the leg for steering the vessel; and a drive transmission assembly having two concentric input shafts, a first, drive shaft for driving the propeller and a second, steering shaft for rotating the propeller housing generally about the axis of the leg.

The invention also provides such a propulsion unit in which the leg is mounted on the drive transmission assembly for pivoting about a substantially horizontal axis, so that the leg can be swung up about the pivot on striking an obstruction, there being disengageable clutch means between the drive transmission assembly and the leg, below the level of the pivot, so that the drive is disengaged when the leg is swung up.

In this unit, it is not essential that the input shafts should be concentric, though it is desirable as it avoids external steering controls extending to the leg and also permits the unit to be swung without difficulty about the axis of the input shafts.

The propulsion unit can be used for any suitable water-borne vessel, such as boats in general, barges, scows, yachts or dinghies. The propulsion unit can be mounted on the transom of the vessel.

Alternatively, particularly in the case of a yacht, the propulsion unit can be mounted towards the aft end, the leg passing through the bottom of the hull with a suitable waterproof seal. It is known to position drives in this manner in yachts, but in such arrangements, steering was achieved by means of a rudder.

Using the propulsion unit of the invention, the vessel can be steered even when it is stationary. In addition, a compact unit can be provided, and various safety features can be incorporated.

Description of Preferred Embodiments The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an isometric view of a water-borne vessel fitted with an inboard motor and a propulsion unit in accordance with the invention; Figure 2 is a vertical section, on a larger scale, through a similar propulsion unit; Figure 3 is an isometric projection of part of Figure 1, on a yet larger scale; Figure 4 is a part vertical section through part of a different propulsion unit; and Figure 5 is a view looking in the direction of the arrow V in Figure 4, with the leg removed.

First Embodiment of the Invention Figure 1 illustrates a dinghy 1, but it will be appreciated that the propulsion unit of the invention can be applied to any suitable waterborne vessel. The dinghy 1 has a suitable inboard engine 2 in a housing 3, a tiller 4, and a propulsion unit 5 mounted on the transom 6.

The propulsion unit 5 is shown in more detail in Figures 2 and 3. In general terms, the propulsion unit 5 has a drive transmission assembly 7 mounted by suitable mounting means on the transom 6. In this case, the assembly 7 is inserted through an aperture in the transom 6, with an interposed collar seal 8: the seal 8 is held in position by any suitable fixing means (not shown), e.g. by bolting the lip of the seal 8 to the transom 6. There is a depending leg 9 whose lower end supports a propeller housing 10 on which is rotatably mounted a propeller 11.

The leg 9 is mounted on the drive transmission assembly 7 by mounting means comprising a substantially horizontal athwartships axis pivot connection including two pivot pins 12 (shown cut off in Figure 3). In this way, the leg 9 can be swung up about the pivot connection on striking an obstruction.

The pivot pins 1 2 are received in respective inclined slots 13 in tubular side members 14 fixed to the drive transmission assembly 7. The side members 14 house the depending limbs of locking means in the form of an inverted-U shaped locking member 15. The locking member 1 5 has projecting abutments 1 6 which engage behind the pivot pins 1 2 and prevent accidential release by closing the mouths of the inclined slots 1 3. For deliberate release, the locking member 1 5 (whose upper bar forms a handle) must be raised against the downward biassing of two tension springs 1 7 (see Figure 3). In this way, the leg 9 and associated parts can be readily removed to prevent tampering or theft.The engine 2 can also be arranged to be readily removed from its housing 3, leaving only the drive transmission assembly 7 and associated parts in the vessel.

Once it is suspended from its pivot pins 12, the leg 9 can rest in position by gravity and due to the propulsion force of the propeller 11. However, it is preferred to have some detent mechanism. As shown in Figures 2 and 3, the leg has two detent pins 18 (shown cut off in Figure 3). As the leg 9 is lowered, the detent pins 1 8 engage and lift respective detent rollers 1 9 mounted on the locking member 15, which moves slightly upwards against the biassing of the springs 1 7. If an obstruction is struck, the detent pins 1 8 will push up the detent rollers 19 and allow the leg 9 to swing up.

The drive transmission assembly 7 includes a generally horizontal input steering shaft (or tube) 20. The steering shaft 20 may be connected by any suitable linkage to a steering wheel; such a construction can be devised without difficulty, and is particularly useful for instance for cruisers or even for inflatable dinghies. Alternatively, as shown in Figure 1, the tiller 4 is directly pivoted to the steering shaft 20. If the steering shaft 20 is turned through 1 800 (see below), the tiller 4 can be pivoted through 1800 about the transverse pivot axis through which it is connected to the steering shaft 20. The forward end of the steering shaft 20 can be carried in a glass-reinforced plastics material bush 21 fixed e.g. to the engine housing 3. The aft end portion of the steering shaft 20 carries a cam 22 whose function is described below.The aft end of the steering shaft 20 is locked to a clutch ring 23 which carries a number of spring-loaded pins or dogs 24. These dogs 24 engage in bores in an outer bevel gear 25 which forms part of steering transmission means connecting the propeller housing 10 to the steering shaft 20. The remainder of the steering transmission means is formed by a second outer bevel gear 26, a tubular shaft 27 and screws 28.

The propeller housing 10 has its weight supported by the tubular shaft 27, but it can rotate about the axis of the leg 9, thereby steering the vessel without the use of a rudder. The dogs 24 form disengageable clutch means between the drive transmission assembly 7 and the leg 9, below the level of the pivot pins 12. Thus the dogs 24 are disengaged when the leg 9 is swung up. They can be reengaged by lowering the leg 9 and then rotating the steering shaft 20 until they move into their respective bores.

It is possible to rotate the propeller housing 10 through substantially more than 1 800, in this case right through 3600. Thus the vessel may go astern without changing the direction of rotation of the propeller 11. In order to prevent the leg 9 swinging up when the vessel is being reversed, a locking means can be provided to prevent the locking member 1 5 lifting. In this case, there is automatic locking means actuated by the cam 22.

The cam 22 engages a cam follower in the form of a forwardly-spring-biassed, horizontally-siiding bar 29 whose aft end carries a horizontal locking bar 30 (best seen in Figures 3). When the bar 29 is pushed aft by the cam 22 (propeller housing 10 turned through 1 800), the locking bar 30 engages in slots in the locking member 15, thereby preventing the locking member 1 5 being pushed upwards and hence firmly locking the leg 9.

The drive transmission assembly 7 also includes a generally horizontal input drive shaft 31 coaxially within the steering shaft 20. Any suitable construction can be provided for connecting the drive shaft 31 to the engine 2. However, Figure 2 shows the drive shaft 31 sliding telescopically over a drive shaft 32 which can engage a drive output of the engine 2 by way of a dog clutch (not shown). The shaft 31 is rotationally fixed to the shaft 32 by cross-pins 33 but is axially slidable and is biassed rearwardly by a compression spring 34 engaging a further cross-pin 35. At its aft end, the drive shaft 31 is pinned to a short shaft 36 which carries a cross-key 37. The cross-key 37 engages in a cross-slot in a shaft 38 carrying an inner bevel gear 39.The shaft 38 and the inner bevel gear 39 form part of drive transmission means connecting the propeller 11 to the drive shaft 31; the remainder of the drive transmission means is formed by a second inner bevel gear 40, a generally vertical connecting shaft 41, further bevel gears 42, 43, a stub shaft 44 and a friction clutch. The friction clutch is formed by two drive members fixed to the stub shaft 44, namely a drive disc 45 and a nose piece 46. The drive members sandwich between then the hub 47 of the propeller 11 and O-rings 48 are carried in annular grooves and are compressed between the respective drive members and the hub 47. The O-rings 48 act as sealing rings, and prevent the ingress of water, and their compression can be adjusted by means of a lock-nut (not shown) securing the nose piece 46 in position.The friction clutch prevents damage if the propeller 1 1 is snagged, for instance by being caught up in a rope. Having the friction clutch close to the propeller 11 keeps low the inertia of the parts which are stopped if the propeller 11 is snagged.

The input shaft 31 and the drive transmission means form a generally Z-shaped configuration; the input shaft 31 is roughly parallel to but spaced above the propeller axis, the connecting shaft 41 forming the cross-bar of the Z.

If the leg 9 swings up, the dog clutch cross-key 37 is disengaged. It is preferred to stop the engine 2 before re-engaging the clutch. This can be done by lowering the leg 9 and restarting the engine 2 so that the cross-key 37 reengages in its crossslot at relatively low speed.

The drive transmission assembly 7 together with the leg 9 and associated parts can be swung generally about a horizontal fore-and-aft axis, the assembly 7 turning in the seal 8. This enables the depth of the propeller 11 beneath the water to be adjusted so as to permit passage through shallow waters. Doing this will give rise to a steering moment, but this can normally be allowed for. If there are two propulsion units, these two steering moments can balance; in such an arrangement, the vessel could be steering either by varying the relative speeds, of the two propulsion units, or by using the individual steering shafts 20 and associated mechanisms. Another advantage of being able to swing the leg 9 about the fore-andaft axis can be obtained if the amount of swinging is very substantial and enables the propeller 11 to be brought above the water level. In this case, the propeller 11 can be inspected and also, for instance, ropes or lines can be disentangled from the propeller 11.

In Figure 2, there is indicated a worm drive 48 which engages a bull ring on the drive transmission assembly 7 for swinging the leg 9 about the fore-and aft-axis, the assembly 7 rotating in the seal 8. Such an arrangement would not be appropriate for the dinghy 1 which is shown, but could be used for instance in a cruiser.

In such a case, the worm drive 48 would be driven by a suitable electric motor. In a similar manner, the transom 6 is shown as being vertical in Figure 2, though it is shown as sloping slightly in Figure 1, the assembly 7 being suitably profiled.

Bearings and seals are provided in the normal way, but these are not described in detail. Any suitable method can be provided for lubricating the bearings, and the lubrication is not shown. For instance, the propeller housing 10 may be filled with oil and provided with a pump, driven by the shaft 41, to provide circulation for lubricating the upper end of the leg 9; thus, the shaft 41 can be formed as a tube and provided with an impeller to force a lubricant up the centre of the shaft 41 , the oil return being achieved under gravity. Likewise, a re-circulating lubrication system can be provided for the input drive shaft 31 and associated parts.

Parts such as the casing s of the assembly 7, propeller housing 10 and the casing at the top end of the leg 9 can be formed of any suitable material, such as glass-reinforced plastics material.

Second Embodiment of the Invention The second embodiment corresponds closely to the first embodiment, and similar parts are indicated with the same references and will not be described in detail.

In this case, the leg 9 is intended to be more permanently fixed to the drive transmission assembly 7, by means of screw pivots 49. The leg 9 is detailed in its fully extended position by athwartships-sliding detent pins 50 which are sprung outwards. The heads of the pins 50 are chamfered, and engaged in holes in the side members 14. The detent pins slide in cross-bores in the aft part of the drive transmission assembly 7. In this way, the leg 9 can click home into its fully extended position, but can be released if an obstruction is struck. However, in order to lock the leg 9 when going astern under power, the sliding bar 29 is pushed aft by the cam 22 and passes between the inner ends of the detent pins 50, preventing their release.

In this embodiment, the sliding bar 29 is arranged below the level of the coaxial shafts 20,31.

Claims (12)

1. A propulsion unit for a water-borne vessel, the unit comprising: a depending leg; a propeller housing supported on the lower end portion of the leg, the propeller housing being rotatable generally about the axis of the leg for steering the vessel; and a drive transmission assembly having two concentric input shafts, namely a generally horizontal drive shaft for connection to an inboard engine for driving the propeller and a steering shaft for rotating the propeller housing generally about the axis of the leg.

2. The propulsion unit of Claim 1, wherein the leg is mounted on the drive transmission assembly by mounting means comprising a substantially horizontal athwartships axis pivot connection, whereby the leg can be swung up about the pivot connection on striking an obstruction.

3. The propulsion unit of Claim 2, wherein the input drive shaft is connected to the propeller by way of a disengageable clutch below the level of said pivot connection, arranged such that the drive transmission is disengaged when the leg is swung up.

4. The propulsion of Claim 3, wherein the input steering shaft is connected to the propeller housing by way of a disengageable clutch below the level of said pivot connection, arranged such that the disengageable clutch is disengaged when the leg is swung up.

5. The propulsion unit of Claim 4, wherein the drive disengageable clutch and the steering disengageable clutch are in the form of a coaxial respective dog clutches, comprising axiallymovable spring-loaded members which engage in corresponding cut-outs.

6. The propulsion unit of any one of the preceding Claims, wherein the leg is completely disengageable from the drive transmission assembly.

7. The propulsion unit of any one of Claims 2 to 5, wherein the leg is completely disengageable from the drive transmission assembly, said pivot connection comprising at least one substantially horizontal athwartships axis pivot pin, at least one inclined slot for receiving the pin, and displaceable locking means for substantially closing the mouth of the slot.

8. The propulsion unit of any one of Claims 2 to 5 and 7, wherein the propeller housing is rotatable through substantially more than 1800 so as to enable the vessel to go astern without changing the direction df rotation of the propeller, the propulsion unit further including automatic locking means for locking the leg in its fully extended position when the propeller housing is rotated through at least 900 from its direct forward position.

9. The propulsion unit of Claim 8, wherein the automatic locking means comprises a cam associated with the steering shaft, a cam follower which follows the cam, and a locking member actuated by the cam follower to prevent the leg swinging up about the pivot connection.

10. The propulsion unit of any one of the preceding Claims, and including mounting means for mounting the drive transmission assembly on the vessel, the mounting means permitting the drive transmission assembly and the leg to swing about a generally horizontal fore-and-aft axis.

11. The propulsion unit of any one of the preceding Claims, wherein the propeller is driven by a friction clutch comprising a stub shaft, a hub of the propller mounted on the stub shaft and able to rotate with respect thereto, first and second drive members rotationally fixed to the stub shaft on either side of the propeller hub, and sealing rings compressed between the propeller hub and the respective first and second drive members.

12. A propulsion unit for a water-borne vessel, substantially as herein described with reference to, or as shown in, Figures 1 to 3 or Figures 4 and 5 of the accompanying drawings.

1 3. A water-borne vessel fitted with the propulsion unit of any one of the preceding Claims.