Outboard motor

Abstract

An outboard motor (10) comprising an internal combustion engine (11), a crankshaft (18) of the internal combustion engine, an electric motor (26), a motor shaft (27) of the electric motor, a torque transfer assembly (19), a gearbox input shaft (20), a gearbox (17), a gearbox output shaft (21), an endless loop flexible drive coupling (22) and a propeller shaft (12), wherein the crankshaft (18) is connected to the gearbox input shaft (20) through the torque transfer assembly (19), and wherein the gearbox output shaft (21) is connected to the propeller shaft (12) through the endless loop flexible drive coupling (22), wherein the motor shaft (27) of the electric motor (26) is connected to the torque transfer assembly (19). Disclosed is an outboard motor comprising a plurality of electric motors.

Description

[0001] OUTBOARD MOTOR

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an outboard motor. More specifically, the present invention relates to an outboard motor comprising an internal combustion engine, a crankshaft, an electric motor with a motor shaft, a torque transfer assembly, a gearbox input shaft, a gearbox, a gearbox output shaft, an endless loop flexible drive coupling and a propeller shaft, wherein the crankshaft is connected to the gearbox input shaft through the torque transfer assembly, and wherein the gearbox output shaft is connected to the propeller shaft through the endless loop flexible drive coupling.

[0004] Outboard motors are self-contained propulsion and steering devices for watercrafts, such as boats, and are arranged to be fastened to the transom of a boat. One type of such watercrafts is boats that are designed to plane during operation, wherein the propeller shaft is arranged substantially horizontally and below a hull of the watercraft during operation. This type of outboard motors can be used for driving a single propeller or dual counterrotating propellers.

[0005] PRIOR ART

[0006] Outboard motors are common for propulsion of watercrafts, such as boats. They have a powerhead with an engine, such as an internal combustion engine, a midsection and a lower unit with a propeller shaft for driving a propeller connected to the propeller shaft. A power transfer arrangement is arranged for transferring output power from the engine to the propeller shaft.

[0007] A plurality of outboard motors is disclosed in the prior art. One prior art outboard motor is disclosed in W02009 / 075623, wherein a diesel engine crankshaft is connected to a gearbox through a belt or chain drive, and wherein the gearbox is connected to the propeller shaft through another belt or chain drive. This prior art outboard motor has proven to be strong, efficient and reduces fuel consumption. However, it is desirable to further improve such outboard motors when it comes to power, efficiency and flexibility. BRIEF DESCRIPTION OF THE INVENTION

[0008] One object of the present invention is to provide an efficient and reliable outboard motor with increased power capacity and flexibility. An outboard motor according to the invention can operate in an efficient and flexible manner in different environments to obtain faster acceleration and a favourable energy consumption.

[0009] The present invention relates to an outboard motor comprising an internal combustion engine, a crankshaft of the internal combustion engine, an electric motor, a motor shaft of the electric motor, a torque transfer assembly, a gearbox input shaft, a gearbox, a gearbox output shaft, an endless loop flexible drive coupling and a propeller shaft, wherein the crankshaft is connected to the gearbox input shaft through the torque transfer assembly, and wherein the gearbox output shaft is connected to the propeller shaft through the endless loop flexible drive coupling, characterised in that the motor shaft of the electric motor is connected to the torque transfer assembly. The combination of the torque transfer assembly between the crankshaft and the gearbox together with the electric motor connected to the torque transfer assembly results in an efficient and reliable outboard motor with favourable power capacity and flexible driving modes as well as the possibility to save fuel. For example, the electric motor may also function as a generator. The electric motor can be arranged on the torque transfer assembly. The electric motor can be arranged to provide rotational power to the torque transfer assembly.

[0010] The motor shaft of the electric motor can be concentric with the crankshaft. Hence, the electric motor can easily be provided, e.g. also in the form of a retrofit solution. The crankshaft can be selectively in driving connection with one side of the torque transfer assembly through a clutch, wherein the electric motor is connected to an opposite side of the torque transfer assembly. Hence, the electric motor can be arranged in a favourable position for power output and easy connection and accessibility. For example, an upper gear, sprocket or timing pulley of the torque transfer assembly is connected to the motor shaft of the electric motor and, through the clutch, to the crankshaft. Hence, the upper gear, sprocket or timing pulley of the torque transfer assembly can be arranged between the crankshaft and the electric motor to provide an efficient and powerful structure. The upper gear, sprocket or timing pulley of the torque transfer assembly can be aligned with the motor shaft of the electric motor and with the crankshaft, hence forming a straight and simple structure for efficient power transfer and facilitated installation.

[0011] The electric motor can be a first electric motor having a first motor shaft, and the outboard motor can also comprise a second electric motor having a second motor shaft, wherein the second electric motor is connected to the gearbox input shaft or the gearbox output shaft. Hence, an efficient and powerful outboard motor with flexible drive modes and reduced fuel consumption can be achieved. The first electric motor can be bigger than the second electric motor, which provides flexibility and power but may also provide a hydrodynamic outboard motor. Hence, the second electric motor can be smaller in size, i.e. volume, than the first electric motor.

[0012] A first control system may be connected to the first electric motor and a second control system may be connected to the second electric motor, wherein the first and second electric motors are individually controllable by means of the first and second control systems. Hence, the first and second electric motors can be individually controlled for efficient and flexible power usage and also power uptake as one or both of the electric motors may function as a generator for charging a battery or power output for other functions.

[0013] The electric motor may be cooled by a closed cooling circuit operating by means of a pump for pumping cooling liquid to a housing or a chamber within said housing for cooling the electric motor and optionally also for cooling other components, such as the torque transfer assembly.

[0014] The outboard motor of the present invention is used for a watercraft, such as a boat, comprising a hull. The watercraft can be a planing boat. The outboard motor is arranged for both propelling and steering the watercraft. One or more batteries for supplying power to the electric motors or being charges by the electric motors functioning as generators can be arranged within the hull of the watercraft.

[0015] Further characteristics and advantages of the present invention will become apparent from the description of the embodiments below, the appended drawings and the dependent claims.

[0016] SHORT DESCRIPTION OF THE DRAWINGS

[0017] The invention will now be described in more detail with the aid of exemplary embodiments and with reference to the accompanying drawings, in which

[0018] Fig. 1 is a schematic and partial section view of an outboard motor according to one embodiment, wherein a cowling has been removed for illustration purposes,

[0019] Fig. 2 is a schematic side view of the outboard motor similar to Fig. 1 but with dual propellers,

[0020] Fig. 3 is a schematic and partial section view of an outboard motor according to another embodiment,

[0021] Fig. 4 is a schematic and partial section view of an outboard motor according to yet another embodiment, and

[0022] Fig. 5 is a schematic side view of a part of an outboard motor according to a further embodiment.

[0023] THE INVENTION

[0024] With reference to Fig. 1 an outboard motor 10 for a watercraft, such as a boat, is illustrated according to one embodiment of the invention. The outboard motor 10 is a self-contained marine propulsion and steering device for propulsion and steering of the watercraft. Such watercrafts comprise a hull and a transom. The outboard motor 10 can be used for different types of watercrafts. For example, the watercraft is arranged to plane during operation at higher speed, wherein the hull is arranged with a planing hull form. The outboard motor 10 comprises an internal combustion engine 11 , such as a diesel engine. The engine 11 is arranged in a power head of the outboard motor 10. The power head also includes an engine housing, such as a cowling (not illustrated in the drawings). The outboard motor 10 also includes a lower unit having a propeller shaft 12, and a midsection connecting the powerhead and the lower unit. The lower unit includes the propeller shaft 12, a torpedo-shaped housing for the propeller shaft 12 and optionally a conventional skeg and optionally the propeller 13. The midsection is formed as a leg connecting the power head and the lower unit. The propeller shaft 12 is provided with a propeller 13, which may be detachable. The outboard motor 10 is arranged to be connected to the hull of the watercraft, e.g. so that the outboard motor 10, or at least a major part thereof, is arranged outside the hull. The midsection is arranged outside the transom and the lower unit with the propeller shaft 12 is arranged outside and below the hull. When the outboard motor 10 is operated the propeller shaft 12 is arranged below the water line and also below the hull. For example, the lower unit is arranged below the hull during normal operation of the outboard motor 10. Hence, the outboard motor 10 is arranged to project a distance into the water when operated, so that the propeller 13, the lower unit and optionally a part of the midsection are immersed in the water, so that the water line is arranged above the propeller 13 and above the lower unit. Hence, the lower unit is formed for efficient hydrodynamics.

[0025] For example, the outboard motor 10 comprises conventional fastening means for fastening the outboard motor 10 to the stem of the hull, such as the transom. The fastening means is, for example, arranged as a conventional mounting bracket 14. For example, the mounting bracket 14 comprises or is provided with a trim / tilt system, such as a hydraulic or electric trim / tilt system. For example, the trim / tilt system is conventional. Hence, the outboard motor 10 comprises a laterally extending trim axis 15, such as a horizontal trim axis. The outboard motor 10 comprises a steering axis 16, such as a vertical or substantially vertical steering axis (depending on trim). The entire outboard motor 10, except for the mounting bracket 14, is turned around the steering axis 16 for steering the watercraft. Hence, the power head, the midsection and the lower unit are pivotable around the steering axis 16. For example, the power head, the midsection and the lower unit are arranged in fixed positions in relation to each other and are turned as one unit around the steering axis 16.

[0026] The outboard motor 10 comprises a gearbox 17 having gears for driving the propeller 13 in forward and in reverse. For example, the gearbox 17 is conventional and may comprise a forward gear, a reverse gear and a neutral position. A crankshaft 18 of the engine 11 is connected to the gearbox 17 through a torque transfer assembly 19 for transferring rotational power, also called torque, from the crankshaft 18 to an input shaft 20 of the gearbox 17. For example, the torque transfer assembly 19 is a chain drive or a belt drive assembly comprising sprockets and a chain or timing pulleys and a belt. Alternatively, the torque transfer assembly 19 comprises gears. The gearbox 17 comprises a gearbox output shaft 21 . For example, the gearbox 17 is located below the engine 11 , between the crankshaft 18 and the propeller shaft 12, wherein the gearbox input shaft 20 and the gearbox output shaft 21 are arranged in parallel with the crankshaft 18 and the propeller shaft 12. The gearbox output shaft 21 is connected to the propeller shaft 12 through an endless loop flexible drive coupling 22, such as a chain drive or a belt drive.

[0027] In the illustrated embodiment, the outboard motor 10 comprises a clutch 23, such as a cam clutch, which e.g. is hydraulically or electrically operated. The clutch 23 is arranged on or connected to the crankshaft 18 for transferring torque from the crankshaft to the torque transfer assembly 19 when the clutch 23 is engaged, wherein no torque is transferred from the crankshaft 18 to the torque transfer assembly 19 when the clutch 23 is fully disengaged. For example, the crankshaft 18 has one end connected to a flywheel 24, wherein the clutch 23 is arranged between the flywheel 24 and the torque transfer assembly 19. The clutch 23 is connected to a drive shaft 25, wherein the crankshaft 18 selectively drives the drive shaft 25 through the clutch 23. The drive shaft 25 is, e.g. coaxial with the crankshaft 18. The drive shaft 25 drives the torque transfer assembly 19. For example, an upper sprocket or timing pulley of the torque transfer assembly 19 is arranged on the drive shaft 25. For example, the upper sprocket or timing pulley of the torque transfer assembly 19 is fixed on the drive shaft 25 and rotates with the drive shaft 25.

[0028] The outboard motor 10 comprises at least one electric motor 26. The electric motor 26 is connected to one of the drive shaft 25 and gearbox input shaft 20. Hence, the electric motor 26 is connected to the torque transfer assembly 19 for driving thereof, e.g. together with the engine 11 , so that the torque transfer assembly 19 is driven by the engine 11 and / or the electric motor 26, e.g. selectively one or both of the engine 11 and the electric motor 26. The electric motor 26 comprises a motor shaft 27. The motor shaft 27 may be fixed to the drive shaft 25 or connected to the drive shaft 25 through a clutch.

[0029] In the embodiment of Fig. 1 , the outboard motor 10 comprises a first electric motor 26a and a second electric motor 26b. The first electric motor 23a is driving the torque transfer assembly 19, e.g. through the drive shaft 25 or the gearbox input shaft 20. A motor shaft 27a of the first electric motor 26a is, e.g. coaxial with the drive shaft 25 or the gearbox input shaft 20. In the illustrated embodiment, the first electric motor 26a is connected to the drive shaft 25 for driving the upper sprocket or upper timing pulley of the torque transfer device 19. For example, the upper sprocket or timing pulley of the torque transfer assembly 19 is arranged between the engine 11 and the first electric motor 26a. Hence, the first electric motor 26a and the engine are arranged on opposite sides of the upper sprocket or timing pulley of the torque transfer assembly 19. For example, the clutch 23 and the flywheel 24 are arranged between the engine 11 and the first electric motor 26a in a travel direction. For example, the first electric motor 26a is arranged in an aft direction.

[0030] The second electric motor 26b is connected to the gearbox output shaft 21 for selectively driving thereof with or without additional torque from the engine 11 . For example, the motor shaft 27b of the second electric motor 26b is coaxial with the gearbox output shaft 21 . The second electric motor 26b is, e.g. arranged in an aft direction below the first electric motor 26a and, e.g. generally above a waterline during operation. Hence, the propeller shaft 12 can be selectively driven by one or more of the engine 11 , the first electric motor 26a and the second electric motor 26b. According to one embodiment, the first electric motor 26a is larger and / or more powerful than the second electric motor 26b.

[0031] The electric motors 26a, 26b comprise the motor shafts 27a, 27b for output power in the form of rotational power, also called torque herein. The motor shafts 27a of the first electric motor 26a may be fixed to the drive shaft 25 or connected to it through a clutch (not illustrated), wherein the motor shaft 27b of the second electric motor 26b may be fixed to the gearbox output shaft 21 o may be connected to it through a clutch.

[0032] For example, the electric motors 26a, 26b comprise a stator and a rotor. For example, the electric motors 26a, 26b are AC electric motors, such as asynchronous motors. For example, the electric motors 26a, 26b are induction motors. Alternatively, the electric motors 26a, 26b are DC motors, such as brushed DC electric motors, permanent magnet DC motors, or brushless DC motors. According to one embodiment, the electric motors 26a, 26b are axial flux motors. For example, each of the electric motors 26a, 26b is able to develop at least 50 kW or at least 75 kW, such as 100 kW, 200kW or 300kW. For example, the first electric motor 26a is able to develop at least 200kW or at least 300kW, wherein the second electric motor 26b is able to develop maximum 200 kw, maximum 150 kW, maximum 100kW or maximum 50kW. For example, the electric motors 26a, 26b are conventional industrially produced electric motors, such as mass produced in series of at least thousands. The electric motors 26a, 26b can be replaceable and / or retrofit, i.e. add-ons to a previously assembled outboard motor having only the internal combustion engine 11 . The electric motor 26 or electric motors 26a, 26b is / are connected to or connectable to a battery or a plurality of batteries arranged on board the watercraft (not illustrated). For example, the electric motors 26a, 26b are reversible, so that the motor shafts 27a, 27b can be driven in any rotational direction. For example, the speed of the electric motors 26a, 26b is adjustable, so that the motor shafts 27a, 27b can be driven in a selectable rotational speed. For example, the speed and rotational direction of the electric motors 26a, 26b are controlled by a conventional control system, which are not illustrated in the drawings. According to one embodiment, the first electric motor 26a and / or the second electric motor 26b is / are arranged to function as a generator.

[0033] With reference also to Fig. 2, the outboard motor 10 is illustrated according to another embodiment. The embodiment of Fig. 2 is similar to Fig. 1 in the arrangement of the first electric motors 26a on the drive shaft 25 and the arrangement of the second electric motor 26b on the gearbox output shaft 21 . In the embodiment of Fig. 2 the outboard motor 10 comprises a first propeller 13a and a second propeller 13b. The propellers 13a, 13b are arranged for counter-rotating, wherein the propellers 13a, 13b are arranged to rotate in opposite directions in relation to each other for propelling the watercraft. Hence, one of the first and second propellers 13a, 13b is a right- handed propeller, which rotates clockwise as viewed from the stern when propelling the watercraft forward, wherein the other is a left-handed propeller, which rotates counter-clockwise as viewed from the stem when propelling the watercraft forward. The outboard motor 10 comprises a first propeller shaft 12a and a second propeller shaft 12b. The first propeller shaft 12a is arranged for driving the first propeller 13a. Hence, the first propeller 13a is connected to or connectable to the first propeller shaft 12a. The second propeller shaft 12b is arranged for driving the second propeller 13b. Hence, the second propeller 13b is connected to or connectable to the second propeller shaft 12b. The first and second propeller shafts 12a, 12b are arranged in the form of dual propeller shafts. The first and second propeller shafts 12a, 12b are concentric and arranged to rotate in opposite directions to rotate the first and second propellers 13a, 13b in opposite directions. For example, the first propeller shaft 12a extends through the second propeller shaft 12b and through the second propeller 13b to the first propeller 12a. Hence, the first propeller shaft 12a is arranged with smaller diameter than the second propeller shaft 12b. Further, the first propeller shaft 12a is longer than the second propeller shaft 12b. The propeller shafts 12a, 12b are arranged in the torpedo-shaped housing of the lower unit. The propeller shafts 12a, 12b are arranged in parallel to the crankshaft 18. With reference to Fig. 3, the outboard motor 10 is illustrated according to yet another embodiment, wherein the outboard motor 10 comprises a single electric motor 26. In the embodiment of Fig. 3, the electric motor 26 is arranged on the drive shaft 25 for driving the upper sprocket or timing pulley of the torque transfer assembly 19. The electric motor 26 is arranged with its motor shaft 27 coaxial with the crankshaft 18 and on the opposite side of the upper sprocket or timing pulley as the clutch 23.

[0034] As can be seen in Fig. 3 the upper sprocket or timing pulley 28 is connected to or arranged on the drive shaft 25 and drives a chain or belt 29 connected to the gearbox input shaft 20 through a lower sprocket or timing pulley 30. Hence, the torque transfer assembly 19 comprises the upper sprocket or timing pulley 28, the chain or belt 29 and the lower sprocket or timing pulley 30. The torque transfer assembly 19 may have this configuration in all embodiments. Similarly, the endless loop flexible drive coupling 22 may comprise an upper sprocket or timing pulley 31 , a chain or belt 32 and a lower sprocket or timing pulley 33, wherein the upper sprocket or timing pulley 31 is arranged on the gearbox output shaft 21 and the lower sprocket or timing pulley 33 is arranged on the propeller shaft 12, so that the propeller shaft 12 is driven by the chain or belt 32. The endless loop flexible drive coupling 22 may have this configuration in all embodiments.

[0035] With reference to Fig. 4, the outboard motor 10 is illustrated according to a further embodiment, wherein the outboard motor 10 comprises the first electric motor 26a and the second electric motor 26b as described with reference to Fig. 1 and, in addition, a third electric motor 26c. The third electric motor 26c is arranged for driving a lower sprocket or timing pulley of the torque transfer assembly 19. The third electric motor 26c is, e.g. arranged with its motor shaft 27c coaxial with the gearbox input shaft 20. For example, the electric motors 26a-c are arranged to be selectively driven separately or in combination with each other and / or the engine 11 , such as by means of a conventional control system. For example, the third electric motor 26c is larger than the second electric motor 26b. For example, the first and third electric motors 26a, 26c are similar, wherein the second electric motor 26b is smaller. With reference to Fig. 5 a part of the outboard motor according to an embodiment similar to Fig. 3. In Fig. 5 the engine 11 is not illustrated. In the embodiment of Fig. 5 a single electric motor 26 driving the upper sprocket or timing pulley of the torque transfer assembly 19 similar to Fig 3 is illustrated but the engine 11 and further electric motors 26b, 26c may be included as described above. As can be seen in Fig. 5 the torque transfer assembly 19 comprises a housing 34 enclosing the upper sprocket or timing pulley 28, the chain or belt and the lower sprocket or timing pulley 30 as described above. The housing 34 comprises an inlet and an outlet for cooling liquid, wherein cooling liquid can be circulated through the housing 34 by means of a pump (not illustrated). For example, the inlet is connected to a source of cooling liquid forming a closed cooling circuit for cooling the torque transfer assembly. For example, the compartment for cooling liquid is separated from a compartment containing the chain or belt 29. According to one embodiment, the compartment for cooling liquid is arranged adjacent the electric motor 26 for cooling thereof as well as the torque transfer assembly 19. Alternatively, a separate cooling circuit, which may be closed and may comprise its own dedicated pump, is arranged for cooling the electric motor.

[0036] All embodiments disclose an outboard motor 10. Hence, the engine 11 , crankshaft 18, electric motor(s) 26a-c, motor shaft(s) 27a-c, drive shaft 25, gearbox input shaft 20, gearbox output shaft 21 and the propeller shaft(s) 12a, 12b are in a fixed configuration in relation to each other.

Claims

CLAIMS1. An outboard motor (10) comprising an internal combustion engine (11 ), a crankshaft (18) of the internal combustion engine, an electric motor (26), a motor shaft (27) of the electric motor, a torque transfer assembly (19), a gearbox input shaft (20), a gearbox (17), a gearbox output shaft (21 ), an endless loop flexible drive coupling (22) and a propeller shaft (12), wherein the crankshaft (18) is connected to the gearbox input shaft (20) through the torque transfer assembly (19), and wherein the gearbox output shaft (21 ) is connected to the propeller shaft (12) through the endless loop flexible drive coupling (22), c h a r a c t e ri s e d in that the motor shaft (27) of the electric motor (26) is connected to the torque transfer assembly (19).

2. The outboard motor of claim 1 , wherein the motor shaft (27) of the electric motor (26) is concentric with the crankshaft (18).

3. The outboard motor of claim 1 or 2, wherein the crankshaft (18) is selectively in driving connection with one side of the torque transfer assembly (19) through a clutch (23) and wherein the electric motor (26) is connected to an opposite side of the torque transfer assembly (19).

4. The outboard motor of claim 3, wherein an upper gear, sprocket or timing pulley (28) of the torque transfer assembly (19) is connected to the motor shaft (27) of the electric motor (26) and, through the clutch (23), to the crankshaft (18).

5. The outboard motor of claim 4, wherein the upper gear, sprocket or timing pulley (28) of the torque transfer assembly (19) is aligned with the motor shaft (27) of the electric motor (26) and with the crankshaft (18).

6. The outboard motor of claim 4 or 5, wherein the torque transfer assembly (19) comprises a chain or a belt (29) connected to the upper sprocket or tim-ing pulley (28) and a lower sprocket or timing pulley (30), and wherein the lower sprocket or timing pulley (30) is arranged on the gearbox input shaft (20).

7. The outboard motor of any of the preceding claims, wherein the electric motor (26) is a first electric motor (26a) having a first motor shaft (27a), and wherein the outboard motor also comprises a second electric motor (26b) having a second motor shaft (27b), wherein the second electric motor (26b) is connected to the gearbox input shaft (20) or the gearbox output shaft (21 ).

8. The outboard motor of claim 7, wherein the second motor shaft (27b) is concentric with the gearbox input shaft (20) or the gearbox output shaft (21 ).

9. The outboard motor of claim 7 or 8, wherein the first electric motor (26a) is bigger than the second electric motor (26b).

10. The outboard motor of any of claims 7 to 9, wherein a first control system is connected to the first electric motor (26a) and a second control system is connected to the second electric motor (26b), wherein the first and second electric motors (26a, 26b) are individually controllable by means of the first and second control systems.

12. The outboard motor of any of the preceding claims, wherein the electric motor (26) is an axial flux motor.

13. The outboard motor of any of the preceding claims, wherein the electric motor (26) is arranged to provide at least 50kW, such as at least 100kW or at least 200kW.

14. The outboard motor of any of the preceding claims, wherein the crankshaft (18) is arranged in parallel to the propeller shaft (12), wherein a position of the crankshaft is fixed in relation to a position of the propeller shaft andwherein the gearbox (17) is arranged in a position below the internal combustion engine (11 ).

15. The outboard motor of any of the preceding claims, wherein the endless loop flexible drive coupling (22) is a belt or a chain drive.

16. The outboard motor of any of the preceding claims, wherein the torque transfer assembly (19) comprises a chain and sprockets.

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