IMPROVEMENTS IN OR RELATING TO A MARINE PROPULSION SYSTEM

Abstract

An outboard propulsion system comprising: a first portion for attachment to a boat comprising a stern, the first portion comprising an engine including a crankshaft; and a second portion comprising at least one propeller shaft having a longitudinal axis along the elongate length of the at least one propeller shaft, wherein the at least one propeller shaft is operably connected to the crankshaft via at least one drive shaft configured to transmit motive power therebetween, wherein the at least one drive shaft comprises a drop shaft and wherein the drop shaft is substantially perpendicular to the at least one propeller shaft, wherein the second portion is configured to pivot relative to the first portion about a steering axis, wherein the steering axis intersects the longitudinal axis of the at least one propeller shaft at an obtuse angle, wherein the first portion and second portion are configured to tilt together about a single axis of rotation substantially parallel to the stern of the boat, and wherein the first portion is fixed about a substantially vertical axis.

Claims

1. An outboard propulsion system comprising: a first portion for attachment to a boat comprising a stern, the first portion comprising an engine including a crankshaft; and a second portion comprising at least one propeller shaft having a longitudinal axis along the elongate length of the at least one propeller shaft, wherein the at least one propeller shaft is operably connected to the crankshaft via at least one drive shaft configured to transmit motive power therebetween, wherein the at least one drive shaft comprises a drop shaft and wherein the drop shaft is substantially perpendicular to the at least one propeller shaft, wherein the second portion is configured to pivot relative to the first portion about a steering axis, wherein the steering axis intersects the longitudinal axis of the at least one propeller shaft at an obtuse angle, wherein the first portion and second portion are configured to tilt together about a single axis of rotation substantially parallel to the stern of the boat, and wherein the first portion is fixed about a substantially vertical axis.

2. The outboard propulsion system according to claim 1, further comprising a fixing mechanism configured to attach the first portion to the stern of the boat, wherein the fixing mechanism is configured to permit only a single axis of rotation.

3. The outboard propulsion system according to claim 1, wherein the at least one drive shaft comprises a first intermediate shaft operably connected between the crankshaft and the drop shaft and wherein the first intermediate shaft is operably connected to the drop shaft via a first bevel gear.

4. The outboard propulsion system according to claim 3, wherein the first intermediate shaft is substantially parallel to the crankshaft longitudinal axis.

5. The outboard propulsion system according to claim 1, wherein the steering axis extends substantially parallel to the longitudinal axis of the crankshaft.

6. The outboard propulsion system according to claim 1, wherein the at least one drive shaft is operably connected to the at least one propeller shaft via a first bevel gear.

7. The outboard propulsion system according to claim 1, further comprising a transmission assembly configured to control the motive power provided to the at least one propeller shaft.

8. The outboard propulsion system according to claim 7, wherein the transmission assembly is located in the first portion.

9. The outboard propulsion system according to claim 7, wherein the transmission assembly further comprises an offset pair of gears configured to move the second portion closer to the fixing mechanism.

10. The outboard propulsion system according to claim 1, wherein the steering axis intersects the longitudinal axis of the at least one propeller shaft at an angle between 100 degrees and 140 degrees.

11. The outboard propulsion system according to claim 1, wherein the steering axis intersects the longitudinal axis of the at least one propeller shaft at an angle of about 120 degrees.

Description

[0086] The invention will now be further and more particularly described, by way of example only, and with reference to the accompanying drawings in which:

[0087] FIG. 1 is a schematic of the outboard propulsion system according to the present invention;

[0088] FIG. 2 shows an example transmission assembly of the present invention, as shown in FIG. 1;

[0089] FIG. 3 is a section through an example fixing mechanism for attaching the outboard propulsion system to a stern of a boat;

[0090] FIG. 4 shows an outboard propulsion system comprising an engine, an oil pan and an oil reservoir;

[0091] FIG. 5 shows an outboard transmission assembly comprising an oil transfer pump;

[0092] FIG. 6A shows the oil transfer pump when viewed from above;

[0093] FIG. 6B shows the top and side view of the oil transfer pump;

[0094] FIG. 6C shows the bottom and side view of the oil transfer pump.

[0095] FIG. 1 shows an embodiment of the outboard propulsion system 1 comprising a first portion 2 and second portion 5. The first portion 2 comprises an engine 3 including a crankshaft 4. The engine 3 is configured to produce and transfer motive power to the crankshaft 4. In some embodiments, the engine 3 may be a traditional four-stroke compression ignition diesel engine. However, any internal combustion engine may be used. In some embodiments, the engine is diesel, whereas in other embodiments the engine is petrol. In some embodiments, the engine is a hybrid and comprises at least one battery and at least one electric motor. In some embodiments, not shown, the outboard propulsion system is electric and comprises at least one electric motor and an output shaft instead of an engine and crankshaft.

[0096] The longitudinal axis 9 of the crankshaft 4 is parallel to the steering axis 8. The steering axis 8 and the longitudinal axis of the crankshaft 9 intersect a longitudinal axis of the boat 40 at an acute angle a of approximately 60 degrees. In some embodiments, not shown, the longitudinal axis of the crankshaft may intersect the longitudinal axis of the boat at an acute angle α between 0-90 degrees, 20-85 degrees, 40-80 degrees, 50-70 degrees, 55-55 degrees or at approximately 60 degrees. Furthermore, the second portion 5 comprises an outer propeller shaft 6 and an inner propeller shaft 106 having a longitudinal axis 7 along the elongate length of the shaft.

[0097] The crankshaft 4 is operably connected to a first intermediate shaft 12 via a spline joint. The first intermediate shaft 12 is operably connected to a transmission assembly 30. The transmission assembly 30 is operably connected to a second intermediate shaft 14 which is operably connected to a drop shaft 13 via a bevel gear 15. The first 12 and second 14 intermediate shafts are substantially parallel to the crankshaft 4. The drop shaft 13 is operably connected to the outer propeller shaft 6 via a first 90 degree bevel gear 17, hence completing the transfer of motive power between the crankshaft 4 and the outer propeller shaft 6. Furthermore, the drop shaft 13 is operably connected to the inner propeller shaft 106 via a second 90 degree bevel gear 117, hence completing the transfer of motive power between the crankshaft 4 and the inner propeller shaft 106.

[0098] Alternatively, in some embodiments (not shown), the first intermediate shaft 12 or second intermediate shaft 14 may be directly connected to the outer propeller shaft 6 via a first bevel gear configured to transmit motive power therebetween. The first intermediate shaft 12 or second intermediate shaft 14 may also be directly connected to the inner propeller shaft 106 via a second bevel gear configured to transmit motive power therebetween.

[0099] In some embodiments, not shown, there may be a single propeller shaft and the first intermediate shaft 12 or second intermediate shaft 14 may be directly connected to the propeller shaft via a bevel gear configured to transmit motive power therebetween.

[0100] Alternatively, in some embodiments (not shown), the crankshaft 4 may be directly connected to the at least one propeller shaft via a bevel gear configured to transmit motive power therebetween. For example, the crankshaft 4 may extend out of the engine 3, through the first portion 2, into the second portion 5 and connect to the at least one propeller shaft via at least one bevel gear.

[0101] As shown in FIG. 1, the plurality of drive shafts comprises a drop shaft 13, a first intermediate shaft 12 and a second intermediate shaft 14. The drop shaft 13 is substantially perpendicular to the outer 6 and inner 116 propeller shafts and is configured to transmit motive power from the crankshaft 4 to the inner 106 and outer 6 propeller shafts.

[0102] The second intermediate shaft 14 is operably connected between the first intermediate shaft 12 and the drop shaft 13. The second intermediate shaft 14 is substantially parallel to a longitudinal axis of the crankshaft 9 and is operably connected to the drop shaft 13 via a bevel gear 15.

[0103] The second portion 5 is configured to pivot relative to the first portion 2 about the steering axis 8. The steering axis 8 extends substantially parallel to the longitudinal axis of the crankshaft 9 and intersects the longitudinal axis of the propeller shafts 7 at an obtuse angle β between 100 degrees and 140 degrees. The axis 8′ is parallel to and offset from the steering axis in FIG. 1 and has been used to demonstrate the obtuse angle β for clarity. Preferably, the steering axis 8 (and offset axis 8′) intersect the longitudinal axis of the propeller shafts 7 at an angle β of about 120 degrees.

[0104] Furthermore, the outer propeller shaft 6 comprises a first propeller 16 configured to receive motive force from the outer propeller shaft 6 and generate thrust to drive the boat through a fluid, such as water, in use. The inner propeller shaft 106 comprises a second propeller 116 configured to receive motive force from the inner propeller shaft 106 and generate thrust to drive the boat through a fluid, such as water, in use.

[0105] In some embodiments, not shown, the inner and/or outer propeller shaft comprise a plurality of propellers.

[0106] The outboard propulsion system further comprises a transmission assembly 30 configured to control the motive power provided to the propeller shafts.

[0107] FIG. 2 shows a transmission assembly of the present invention. The transmission assembly 30 comprises a forward gear set 34 and a reversing gear 32 configured to control the speed and/or direction of motive power transferred to the propeller shafts. The transmission assembly also comprises a forward clutch 37 configured to enable the forward gear set 34 and a reversing clutch 36 configured to enable the reversing gears to be engaged interchangeably. The transmission assembly 30 is located in the first portion 2. However, in some embodiments (not shown), the transmission assembly may be located in the second portion 5.

[0108] Furthermore, the transmission assembly comprises an offset pair of offset gears 38 configured to move the second portion closer to the stern of the boat by a distance X. The distance X is approximately 105-110 mm, for example 107 mm. In some embodiments, not shown, X may be 0-1000 mm, 20-500 mm, 50-300 mm, 70-200 mm, 80-150 mm or 100-120 mm.

[0109] FIG. 3 shows a section through the fixing mechanism 11, wherein the section is taken through a plane parallel to the longitudinal axis of the boat 40 and approximately 5 to 250 mm from a side elevation of the fixing mechanism. The fixing mechanism 11 is configured to attach the first portion of the outboard propulsion system to the transom of a boat. Furthermore, the fixing mechanism is configured to tilt the first portion 2 and second portion 5 together about a single axis of rotation 10 substantially parallel to the stern of the boat.

[0110] The fixing mechanism 11 comprises a cradle 21 for attachment to the first portion 2 and a transom bracket 22 for attachment to the transom of the boat. The cradle 21 is fixed to the first portion 2 via a plurality of bolts configured to prevent relative movement therebetween. The cradle is bolted to the housing of the transmission assembly 30. The first portion is therefore fixed about a substantially vertical axis 42. In some embodiments, not shown, the first portion may be fixed about a substantially vertical plane.

[0111] The transom bracket 22 is configured to attach to the stern of the boat via a plurality of bolts, screws and/or clamps configured to pass through the transom bracket and the transom of the boat to couple the two components together. The cradle 21 and transom bracket 22 are operably connected via a rotatable joint 25 configured to permit the single axis of rotation 10 substantially parallel to the stern of the boat.

[0112] The rotatable joint 25 shown in the FIG. 3 section comprises a single rotatable joint. In some embodiments (not shown), the full fixing mechanism 11 may comprise at least two separate coaxial rotatable joints. Each rotatable joint comprises a spindle less than 500 mm long. More preferably, the spindle may be less than 400 mm, 300 mm or 200 mm long and most preferably the spindle is less than 100 mm long, for example 65 mm.

[0113] The fixing mechanism 11, as shown in the FIG. 3 section, further comprises a hydraulic arm 28 operably connected between the cradle 21 and transom bracket 22. The hydraulic arm 28 is configured to rotate the cradle relative to the transom bracket, hence rotating the outboard propulsion system 1 relative to the transom of the boat about the axis of rotation 10. This rotation may be used to trim and/or tilt the outboard propulsion system. In some embodiments (not shown), the full fixing mechanism may comprise a second hydraulic arm located on the opposing side of the fixing mechanism such that the fixing mechanism is symmetrical about a vertical axis. The second hydraulic arm may assist with trimming and/or tilting a heavy marine propulsion system and/or enabling two smaller hydraulic arms to replace one larger component. Furthermore, in some embodiments (not shown, the fixing mechanism may comprise a plurality of hydraulic arms, comprising up to, 2, 3, 4, 5, 8, 10 or more than 10 hydraulic arms.

[0114] The hydraulic arm(s) 28 is operably connected to an electronic control unit configured to expand and contract the hydraulic arm to control the movement of the cradle relative to the transom bracket. The control unit may be operated by a user, such as a captain, driver and/or crew member of the boat.

[0115] FIG. 4 shows the outboard propulsion system 1 including an engine 3 having a crankcase 60 comprising the crankshaft 4. The outboard propulsion system 1 further comprises an oil pan 65 and an oil reservoir 70. The engine 3 is configured to receive oil from the oil reservoir 70. In use, an oil transfer pump 80 pumps oil from the oil pan 65 into the oil reservoir 70 via at least one conduit. In addition, an oil supply pump, not shown in the accompanying drawings, pumps oil from the oil reservoir 70 into the engine 3 via at least one conduit. The oil supply pump is powered via a chain or belt operably connected to the crankshaft 4. Therefore, as the rotational speed of the crankshaft 4 increases, the oil supply pump receives more rotational energy, thus increasing the volume of oil supplied to the engine per unit of time. Alternatively, in some embodiments, the oil supply pump is operably connected to a pump shaft 82, thus receiving power therefrom.

[0116] Excess oil within the engine 3 is collected in the oil pan 65. The oil pan 65 is located substantially below the engine 3, in use. More specifically, the oil pan 65 is located substantially below the crankcase 60, in use. Consequently, oil within the engine and/or crankcase flows towards to oil pan under gravity. Oil within the oil pan 65 is then transferred into the oil reservoir 70 via the oil transfer pump 80, in use.

[0117] In some embodiments, the outboard propulsion system 1 further comprises an oil filter. The oil filter is positioned such that oil flowing from the oil reservoir 70 to the engine 3 passes through the filter. The filter is configured to remove contaminants, such as metal particles, from with the oil. This again increases the efficiency with which the engine can generate power. The outboard propulsion system 1 further comprises an oil cooler. The oil cooler is located between the oil reservoir 70 and the oil filter. More specifically, the oil cooler is located between the oil supply pump and the oil filter. Consequently, oil flowing from the reservoir 70 to the engine 3 is cooled and then filtered.

[0118] The oil reservoir 70 comprises an oil pick-up configured to receive oil and transfer it into the engine. The oil pick-up is in fluid communication with the engine 3 via at least one conduit. More specifically, the oil pick-up is in fluid communication with the engine 3 via the oil supply pump. Preferably, the oil pick-up is located towards the bottom of the oil reservoir 70. Locating the oil pick-up towards the bottom of the oil reservoir, in use, ensures that it remains submerged in oil, in use. This is particularly advantageous when the outboard propulsion system is rotated away from a horizontal plane, such as when turning a corner.

[0119] The oil reservoir 70 is located fore of the engine, as shown in FIG. 4. Therefore, in use, the oil reservoir 70 is located between the engine 3 and the boat. Alternatively, in some embodiments, the oil reservoir is located behind the engine or above the engine. Accordingly, the oil reservoir 70 may be located in any desirable position.

[0120] More specifically, the oil reservoir is located directly adjacent to the engine, as shown in FIG. 4. For example, the oil reservoir may be positioned in order to optimise the weight distribution of the outboard propulsion system and/or to improve the overall packaging of the system.

[0121] In some embodiments, the engine 3 comprises an internal wall 72 configured to separate the crankcase 60 from the oil reservoir 70. Consequently, a boundary of each of the crankcase 60 and the oil reservoir 70 is defined by the internal wall 72. The internal wall 72 further comprises an aperture 74 configured to balance pressure between the crankcase 60 and the oil reservoir 70. The aperture 74 is located towards the top of the oil reservoir 70, in use. Consequently, the aperture 72 and the oil pick-up are located at opposing ends of the oil reservoir 70.

[0122] FIG. 5 shows an outboard transmission assembly 30 comprising an oil transfer pump 80. The oil transfer pump 80 is configured to receive motive power, in the form of rotational energy, directly from the transmission assembly 30. More specifically, the engine 3 causes the crankshaft 4 to rotate about its longitudinal axis, which, in turn, causes the first intermediate shaft 12 and/or input shaft 12 to rotate. The oil transfer pump 80 comprises a pump shaft 82 which is coupled to the first intermediate shaft 12 and/or the input shaft. More specifically, the first intermediate shaft 12 and/or the input shaft is directly coupled to the reverse gear 32 and the reverse clutch 36, and the pump shaft 82 is directly coupled to the forward gear 34 and the forward clutch 37. Alternatively, in some embodiments, the pump shaft 82 is directly coupled to the first intermediate shaft 12 and/or the input shaft. However, in some embodiments, the pump shaft 82 is coupled to the first intermediate shaft 12 and/or the input shaft via at least one additional shaft.

[0123] The pump shaft 82 is configured to rotate constantly, in use. For example, the pump shaft is configured to rotate constantly when the engine 3 is turned on. More specifically, the pump shaft 82 is operably coupled to the crankshaft 4. Consequently, as the rotational speed of the crankshaft increases, the rotational speed of the pump shaft increases. However, there may be at least one gear configured to increases and/or decrease the rotational speed of the pump shaft 82 with respect to the crankshaft 4. Nevertheless, as the rotational speed of the crankshaft 4 increases, the pump shaft rotational speed increases, thus increasing the rate at which of oil is transferred from the oil pan 65 to the oil reservoir 70.

[0124] The engine, crankcase, oil pan, oil reservoir, turbocharger and conduits therebetween may comprise between 3 and 20 litres of oil in total. More specifically, the engine, crankcase, oil pan, oil reservoir, turbocharger and conduits therebetween may comprise between 5-15 litres of oil in total. Most specifically, the engine, crankcase, oil pan, oil reservoir, turbocharger and conduits therebetween may comprise between 7 and 11 litres of oil in total. For example, in some embodiments, the engine, crankcase, oil pan, oil reservoir, turbocharger and conduits therebetween comprises between 8 and 10 litres of oil in total.

[0125] In some embodiments, in use, the engine receives between 30 and 150 litres of oil per minute. More specifically, the engine receives between 35 and 60 litres of oil per minute. Most specifically, the engine receives between 40 and 45 litres of oil per minute. The oil supply pump is configured to deliver the aforementioned oil flow rates to the engine via a conduit. Alternatively, in some embodiments, the oil transfer pump 80 may pump up to 1,000 litres of fluid per minute from the oil pan to the oil reservoir. The fluid may comprise air and oil.

[0126] Alternatively, or in addition, the oil transfer pump 80 is configured to pump between 100 and 140 litres of oil per minute from the oil pan 65 to the oil reservoir 70. More specifically, the oil transfer pump 80 is configured to pump between 110 and 130 litres of oil per minute from the oil pan 65 to the oil reservoir 70. Most specifically, the oil transfer pump 80 is configured to pump between 115 and 125 litres of oil per minute from the oil pan 65 to the oil reservoir 70. Consequently, the oil transfer pump 80 may pull air from within the engine and deliver it to the oil reservoir 70. Consequently, the oil transfer pump 80 may be configured to generate a partial vacuum within the engine 3.

[0127] In some embodiments, the oil transfer pump 80 is configured to generate a partial vacuum within the crankcase 60. This ensures that substantially all of the oil within the crankcase is emptied into the oil reservoir 70 when engine 3 is turned off. The air pressure within the crankcase may be less than 1 bar, in use. More specifically, the air pressure within the crankcase may be less than 0.75 bar, in use. Most specifically, the air pressure within the crankcase may be less than 0.5 bar, in use. However, in some embodiments, the air pressure within the crankcase is less than 0.4 bar, in use.

[0128] The partial vacuum within the engine and/or crankcase reduces the air resistance on the crankshaft as it rotates, in use. Moreover, the partial vacuum within the crankcase also prevents excess oil within the crankcase from coming into contact with the crankshaft, in use. This may improve the efficiency of the engine by up to 3%.

[0129] FIG. 6A shows the oil transfer pump 80 when viewed from above; FIG. 6B shows the top and side view of the oil transfer pump 80; and FIG. 6C shows the bottom and side view of the oil transfer pump 80.

[0130] More specifically, the oil transfer pump 80 comprises a rotor 84 configured to transfers the oil from an inlet port to an outlet port within the transfer pump 80. The rotor 84 is a dual filled rotor.

[0131] Consequently, the oil transfer pump 80 comprises a first inlet 86 configured to receive oil from the oil pan 65. The first inlet 86 is located at a first end of the oil transfer pump 80. More specifically, the first inlet 86 is located at a first end of the rotor 84. For example, the first inlet 86 is located towards the top of the oil transfer pump 80, in use. The oil transfer pump 80 further comprises a second inlet 88 configured to receive oil from the turbocharger. The second inlet 88 is located at a second end of the oil transfer pump 80. More specifically, the second inlet 88 is located at a second end of the rotor 84. For example, the second inlet 88 is located towards the bottom of the oil transfer pump 80, in use. Accordingly, the first and second end of the oil transfer pump are opposing ends. More specifically, the first inlet 86 is positioned at the top on the oil transfer pump and the second inlet 88 is positioned at the bottom of the oil transfer pump. The oil transfer pump 80 further comprises an outlet position between the first inlet and the second inlet. The outlet is in fluid communication with the oil reservoir 70. Consequently, the turbocharger drain, oil pump inlet, oil pump outlet and corresponding oil conduits can be sized in order to optimise the engine performance.

[0132] The outboard propulsions system further comprises a seal 87 configured to provide a substantially fluid-tight seal between the transmission assembly and the engine. More specifically, the outboard propulsions system further comprises a seal 87 configured to provide a substantially fluid-tight seal between the transmission assembly and the engine 3. Most specifically, the outboard propulsions system further comprises a seal 87 configured to provide a substantially fluid-tight seal between the transmission assembly and the crankcase 60. The seal 87 is a lip seal. However, any suitable seal may be used.

[0133] Various further aspects and embodiments of the present invention will be apparent to those skilled in the art in view of the present disclosure.

[0134] “and/or” where used herein is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example, “A and/or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein.

[0135] Unless the context dictates otherwise, the descriptions and definitions of the features set out above are not limited to any particular aspect or embodiment of the invention and apply equally to all aspects and embodiments that are described.

[0136] It will further be appreciated by those skilled in the art that, although the invention has been described by way of example with reference to several embodiments, the invention is not limited to the disclosed embodiments and that alternative embodiments could be constructed without departing from the scope of the invention as defined in the appended claims.