The invention relates to an interchangeable propeller unit for supplementing internal combustion engines of a watercraft with an electric drive, by replacing the propeller unit with an interchangeable propeller unit. The engine consists of an internal combustion driving mechanism arranged in the engine housing, a hollow part with an upper flange, a propeller housing consisting of a cylindrical part and a skeg, and, advantageously a connecting housing inserted between the engine housing and the propeller housing. A propeller unit is located in the cylindrical part of the propeller housing. The end of the cylindrical part opposite to the propeller is closed. The propeller unit consists of a shaft coupling structure formed on the shaft and a propeller attached to the end of the shaft of the shaft coupling structure. A shaft coupling structure and a reverser switch are inserted between the driving mechanism and the shaft coupling structure. The upper flange of the hollow part of the propeller housing is attached to the engine with a releasable connection. The motor is equipped with a control panel. The propeller housing is designed in such a way that a nest having a cross-section corresponding to the cross-section of the cylindrical part and shaped as a body of rotation is provided at the end of the cylindrical part opposite the propeller. An electric motor is placed in the nest, which is connected to a power supply.

Environmental protection and awareness of environmental protection are becoming more and more prevalent in shipping as well. Thanks to this, electric boat motors are gaining more and more space. At the same time, even with the current state of the art, the range of electric boat motors does not reach the desired level. Furthermore, there are many waters on which watercraft equipped with internal combustion engines using fossil energy are not allowed. Furthermore, it is not beneficial to use loud, polluting engines when fishing or for maneuvering in ports. At the same time, it may be necessary to use gasoline or diesel engines to get to the planned place of fishing or to the port. This is usually solved by using an electric drive motor in addition to the fossil-fueled motors.

The most general design of the propeller unit of traditional watercraft engines can be found in the film on the Internet https://www. youtube. com/watch?v=S_A5OXC8p4s&t=644s.

Patent application US 3,703,642 discloses an outboard motor for use in small boats. The outboard motor unit according to the invention consists of a conventional either two-stroke or four-stroke outboard motor, and can be powered by any desired fuel, such as gasoline or diesel. The engine includes a primary propulsion engine with throttle control for adjusting engine speed, a propeller, and a propeller shaft. It also includes a drive shaft, gear mechanism, cardan shaft and clutch. The engine is connected to the cardan shaft on which the propeller is mounted through a clutch arrangement. The cardan shaft extends beyond the standard final drive bearing and is connected directly to an electric motor. The rotor of the electric motor is in line with the cardan shaft and operatively permanently connected to it and is arranged to rotate when the propeller shaft rotates and to rotate the propeller shaft when the rotor shaft rotates. It further includes an electrical power connection for said electric motor connected to a switching mechanism for switching the power connection. It includes a means operatively connecting the throttle control and the switch mechanism, arranged to close or open the switch mechanism at selected values of the throttle settings. Thus, the electric motor is connected to the battery via a cam-operated switch that closes the circuit only when the motor throttle is at or beyond a selected fraction of its fully engaged position, for example at three-quarter throttle. When the engine is operating at or beyond the selected position, with the clutch engaged, the electric motor is rotated by the cardan shaft. The rotation speed of the cardan shaft will be high enough for the electric motor to act as a generator to charge the battery. At lower engine speeds, the cam operated switch will be open and the electric motor will not produce any output. When the engine is not running, turning the engine throttle to or beyond the selected position the electric motor is connected to the battery, which rotates the cardan shaft. The engine clutch is then in the disengaged position, so the electric motor does not have to turn the engine as well.

This solution is closest to the present invention however, it differs from it in several points. At the same time, this is a solution that must be taken into account already during the production of the engine. That is, from the engine housing to the propeller housing, the engine must be built purposefully. A complicated construction of the mechanical switching system is necessary in order for the electric motor to function properly in generator operation. In generator mode, the electric motor cannot be operated in the full speed range of the internal combustion engine. At the same time, it increases the load on the internal combustion engine, because the electric motor must be rotated in all cases when it is not operating as an electric motor, but as a generator. For this reason, it does not generate electricity in a significant part of the speed range, but increases the load on the shaft of the propeller. In addition, the load increases further when the electric motor enters charging mode, because the energy required to rotate the propeller shaft increases. The electric motor draws more energy from the internal combustion engine in generator mode than it produces into the energy storages. The solution according to the referenced invention can only be implemented if a mechanical connection can be established between the throttle lever and the switching element of the electric motor. Finally, the applicability of the described solution can be questioned in the case of the internal combustion engines, since on today's outboard engines, the reversing switch moves the clutch with the piston shaft at the end of the propeller shaft opposite the propeller. This cannot be used in the described solution. The document does not explain how this problem is solved. In addition to the above, it is also not advantageous that the propeller cannot be put into a free- running position in any way (for example during installation), because the shaft of the electric motor is always connected to the propeller. Furthermore, due to the generator operation, manual rotation of the propeller generates current unnecessarily, or may cause damage. The patent application US 3703642 does not even tangentially describe the design or modification of the reverser.

In the case of the hybrid drive according to the present invention, only the propeller housing of the ready-made marine engine needs to be replaced, regardless of the age of the engine, and the electrical cables must be routed from the propeller housing to the engine. For this operation, the electrical wires can be routed up in the already existing cavities in the propeller housing, in the connecting housing, and in the engine housing, and connected from the engine housing to the control panel. Furthermore, the problem that the reversing still works in the usual way in the case of conventional motor drive is solved. The solution of the present invention can be used for all engines that are made or were made with a propeller housing. This is true even for inboard engines the connecting housing of which is attached to the bottom of the boat and the propeller housing is fixed to the connecting element.

Patent application US 9,533,747 describes a hybrid marine propulsion system. The essence of the invention is that in charging mode, the excessively discharged battery is disconnected from the electric motor. Furthermore, the controller calculates a cumulative charge limit for the batteries by summing up the limited current amounts of the batteries. According to this result, it controls the operation of the system in charging mode so that the cumulative charging limit is not exceeded. This prevents the other batteries from draining too much.

Patent application US 5616056 describes an auxiliary propulsion system for seagoing ships, where a diesel engine acting as the main engine drives the propeller through a shaft system.

Patent application US 8682516 describes a hybrid marine propulsion system for marine vessels. The solution describes an engine mode in which the engine alone drives the marine vessel, an electric mode in which the engine alone drives the marine vessel, and a boost mode in which the engine and electric motor drive the marine vessel together.

WO 2009076659 A1 describes a hybrid propulsion and power management system for use in marine vessels that dynamically monitors and utilizes energy from a variety of energy sources to operate in multiple modes and provide efficient power supply across the full range of propulsion needs.

These solutions are robust propulsion systems used in marine vessels, with completely different goals and implementation methods than the problem solved according to the present invention. They are not suitable for use on the ships for which the present solution was created. Patent application US2019300136A1 discloses a vessel propulsion apparatus which includes an engine and an electric motor located independently of the engine, a propeller shaft, a first gear that defines a first transmission path extending from the engine to the propeller shaft, and transmits the power of the engine to the propeller shaft, and a second transmission path that is a different from the first transmission path. It extends from the electric motor to the propeller shaft to transmit the power of the electric motor along the second transmission path to the propeller shaft.

This solution is significantly more complicated than the solution according to the present invention, it involves significant additional mechanical work, and it is also not suitable for adding an electric drive to watercraft previously made exclusively with an internal combustion engine. Furthermore, the power transmission and the operation of the double clutch solution require significant additional energy.

Patent application US5580287A describes the known electric boat motor.

The aim of the present invention is to develop a hybrid drive system which is suitable for subsequently adding an electric motor to engines of boats with outboard or built-in engines without having to change any other part of the engine apart from the propeller housing.

It has been realized that by designing the propeller housing in the same way as the original housing, with the difference that the depth of the cylindrical part is increased at the end of the propeller housing opposite the propeller forming a nest in it for the electric motor, and the end of the reverser does not control the end of the piston shaft, but the control element arranged on the piston shaft, then both the electric motor and the explosive motor can work according to the aim.

Accordingly, the invention is an exchangeable propeller unit for supplementing internal combustion watercraft engines with an electric drive, by replacing the propeller unit with an exchangeable propeller unit. The engine consists of an internal combustion driving mechanism arranged in the engine housing, a propeller unit and, preferably, a connecting housing installed between the engine and the propeller unit. The propeller unit consists of a hollow part having an upper flange, a cylindrical part and a skeg, as well as a propeller driving unit provided in the cylindrical part. The end of the cylindrical part opposite to the propeller is closed. The propeller driving unit consists of a shaft coupling structure formed on the external shaft and a propeller attached to the end of the shaft of the shaft coupling structure. A driving element is installed between the driving mechanism and the shaft coupling structure. The direction of rotation of the shaft is set with a reverser inserted to the internal shaft located inside the external shaft. The upper flange of the hollow part is releasably connected to the engine housing, preferably, to the connecting housing. The motor is equipped with a control panel. The cylindrical part is designed in such a way that at its end opposite the propeller, there is a nest having the shape of a body of rotation with a cross-section matching the cross-section of the cylindrical part. In the nest an electric motor is placed, which is connected to a power supply. The electric motor is connected uniaxially to the internal shaft by means of a shaft coupling element. The electric motor is connected to the control panel through the interposition of disconnecting switch(es) sensing the position of the polarity changing switch and the reverser. The control element controlled by the reverser is attached to the shaft. Advantageously, the shaft coupling element is formed with clutch discs, namely a first clutch disc and a second clutch disc, where the first clutch disc is attached to the end of the internal shaft opposite to the propeller, the second clutch disc is attached to the end of the shaft of the electric motor towards the shaft coupling structure.

The invention will be described with reference to the accompanying drawings.

Figure 1 is a schematic representation of the propeller driving unit and the electric drive arranged uniaxially, in side view, partially in section.

Figure 2 schematically shows the side view of the portion marked II of Figure 1 , where the shaft coupling element is designed with an electromagnetic switch, in disconnected position, partially in section.

Fig. 3 shows the side view of an embodiment of Figure 1 , where the shaft coupling element is designed with an electromagnetic switch, in connected position, partially in section.

Figure 4 is a side view of the internal shaft with the control element and the first pressure plate. Figure 5 is the internal shaft with the bearing-mounted control element and the first pressure plate, in side view, partially in section.

Figure 6 is the front view of the internal shaft of Figure 4 or Figure 5.

Figure 7 shows the connection of the propeller mounted on the external shaft and the driving element with the shaft coupling structure, and the connection of the external shaft with the internal shaft in side view, partially in section.

Figure 8 shows the engagement of the external shaft with the internal shaft in side view, partially in section.

Figure 9 is an embodiment of Figure 1 in which the shaft coupling element is designed with an electromagnetic switch and the reverser is in forward/reverse gear and the shaft coupling element is in disconnected position, shown in side view, partially in section.

Figure 10 is the side view, partially in section of an embodiment of Figure 1 , where the shaft coupling element is formed with an electromagnetic switch, and the reverser is in reverse/forward gear and the shaft coupling element is in disconnected position.

Figure 11 shows the side view of the shaft coupling realized with switch bars, in the position when the engine is idling and the external shaft is connected to the internal shaft of the electric motor, partially in section. Figure 11a schematically shows the dimensioning and design of the end of the reversing switch.

Figure 11 b schematically shows a different design and dimensioning of the end of the reversing switch.

Figure 12 shows the side view of the shaft coupling realized with switch bars, in the position when the engine is in forward or reverse gear, and the external shaft and the internal shaft of the electric motor are disconnected with the switch bars, partially in section.

Figure 13 shows the side view of the shaft coupling realized with switch bars in the position when the engine is in reverse or forward gear, and the external shaft and the internal shaft of the electric motor are disconnected, partially in section.

Figure 14 shows the sectional side view of the electric motor and the electromagnetic switch, as well as the electric motor shaft and the shaft coupling element.

Figure 15 shows the design of the propeller unit, partially in section.

Figure 16 shows the embodiment of the propeller unit, partially in section, in the case of a built- in engine.

Figure 17 shows the embodiment of the propeller unit, partially in section, in the case of an outboard motor.

Figure 18 schematically shows a possible embodiment for mechanical and electronic control of the propeller unit supplemented with an electric motor, where the propeller unit is shown partially in section.

The present invention relates to a interchangeable propeller unit 8, which is suitable for supplementing traditional internal combustion watercraft engines with an electric drive. This is illustrated in Figures 15 - 18. The engine 2 consists of an internal combustion driving mechanism 4 arranged in the engine housing 3, a propeller unit 8, and in the case of an outboard engine, a connecting housing 9 installed between the engine 2 and the propeller unit 8. In the case of built-in watercraft engines, the connecting housing 9 is not used in all cases, and even the engine housing 3 is not usually necessary, if the driving mechanism 4 is located below the deck. The propeller unit 8 (Figures 15 - 18) is designed so that the internal combustion watercraft engine can be interchangeably fixed to the place of the previous propeller unit, without having to change the connections of the driving mechanism 4 and the previous propeller unit. These are typically the engagement and/or connection methods of the driving element 15 and the reverser 16 formed at the end of the operating shaft 33 forming the reverser structure to the former propeller unit.

The propeller unit 8 consists of the hollow part 1 with the upper flange 6, the cylindrical part 7 and the skeg 5 (Figures 16 and 17). The propeller driving unit 10 is located in the cylindrical part 7. The end of the cylindrical part 7 opposite to the propeller 11 is closed. The propeller driving unit 10 consists of the shaft coupling structure 14 formed on the external shaft 12 (Figure 8) and the propeller 11 fixed to the end of the external shaft 12 (Figures 1 , 7), according to the traditional design. The driving element 15 is installed between the driving mechanism 4 and the shaft coupling structure 14 (Figure 17). The direction of rotation of the external shaft

12 is determined by the reverser 16 (Figures 3, 9, 10, 11 , 12, 13) attached to the internal shaft

13 (Figures 4, 5) located inside the external shaft 12.

The propeller unit 8 is releasably attached to the engine 2, which enables the replacement of certain wearing parts, such as the water wheel that ensures the flow of cooling water or the repair of the shaft coupling structure 14 and the gears in it. For this purpose, an upper rim 6 is formed on the hollow part 1 , with which the propeller unit 8 is releasably attached directly to the engine housing 3 or to the connecting housing 9 (Figure 15).

The direction of rotation (forward - backward - stationary position) and speed of the traditional internal combustion watercraft engines were controlled by the operating apparatus 31 (Figure 18), which actuates the reverser 16 and determines the amount of throttle, i.e. the speed of the driving element 15, in a known manner. The engine 2 according to the present invention, supplemented with electric motor 19, are also equipped with a control panel 17, which ensures that only one drive mode can operate at the same time (Figure 18). That is, either the internal combustion engine 2 or the electric motor 19.

The cylindrical part 7 is designed so that it contains the electric motor 19 and the shaft coupling element 21. Therefore, a nest 18 shaped as a body of rotation having a cross-section corresponding to the cross-section of the cylindrical part 7 is provided at the end of the cylindrical part 7 opposite the propeller 11 (Figures 15, 16, 17). In the nest 18, the electric motor 19 and a portion or the whole of the shaft coupling element 21 are placed. The wires required for the power supply 20 and operation of the electric motor 19 are introduced into the motor housing 3 through the hollow parts of the propeller unit 8 and the connecting housing 9. Here, or guided further from here, they are connected to the power supply 20 (Figure 18).

In order to realize the operation according to the present invention, the electric motor 19 is uniaxially connected to the internal shaft 13 by insertion of the shaft coupling element 21 (Figures 2, 3, 9, 10, 12, 13, 14). Furthermore, the control element 24 controlled by the reverser 16 is attached to the internal shaft 13 (the control element 24 is shown in all Figures). The control element 24 is the disc attached to the internal shaft 13. Such a design of the control element 24 is necessary because of the connection of the electric motor 19 and the internal shaft 13. That is, the reverser of the traditional internal combustion watercraft engines was connected directly to the end of the internal shaft and moved the internal shaft through the shaft end. With the known design, the reverser would have been in the way, or more precisely, it would have prevented the connection according to the invention between the internal shaft 13 and the shaft 26 of the electric motor 19. In order to safely separate the possibility of operating the internal combustion engine 2 and the electric motor 19, disconnecting switch(es) 23 detecting the position of the reverser 16 (a single-circuit switch is shown in the drawing) is placed between the operating apparatus 31 and the speed control device 32 of the control panel 17. If the internal combustion engine 2 is in gear and/or working, the disconnecting switch 23 prohibits the operation of the electric motor 19. The control panel 17 also houses the speed control device 32, which adjusts the direction of rotation of the electric motor 19 via the polarity changing switch 22 (Figure 18).

In the solution according to the present invention, a coupling solution known from vehicle technology is used. According to this, the connecting part of the shaft coupling element 21 is formed from pressure plates 25, 27 (Figure 6) designed similarly to each other, namely the first pressure plate 25 and the second pressure plate 27. The first pressure plate 25 is attached to the end of the internal shaft 13 opposite to the propeller 11 (Figures 7, 8), and the second pressure plate 27 is attached to the end of the shaft 26 of the electric motor 19 towards the shaft coupling structure 14 (Figure 1 and partly Figure 2). The clutch disc 30 is placed between the two pressure plates 25, 27 (Figures 2, 3, 9 - 14). In order for the second pressure plate 27 at the end of the shaft 26 of the electric motor 19 to close with the clutch disc 30 and thus to the first pressure plate 25, several solutions are possible. In the case of a possible design, the shaft 26 of the electric motor 19 is designed as part of the electric motor 19 so that it is made capable of axial movement (Figures 2, 3, 9 - 14). The coupling element 21 can be, for example, the electromagnetic switch 28 (Figures 2, 3, 9, 10). The shaft 26 of the electric motor 19 can also be formed from two parts. Then the shaft of the electric motor 19 is connected to the electromagnetic switch 28 in the shaft coupling element 21 in a form-locking manner in the direction of rotation, while it is connected movably in the axial direction. In this case, when the shaft coupling element 21 is connected, the electric motor 19 will rotate the propeller 11 , of course, if the shaft coupling structure 14 is disconnected. This solution is not shown, as it is well within the knowledge of a person skilled in the art.

For example, the shaft coupling element 21 can also be the switch bar 29. The dimensioning of the switch bar 29 (Fig. 11 , 12, 13) is such that when the reverser 16 (Fig. 11a) is fully depressed, for example the propeller 11 rotates in accordance with reverse gear, then the internal shaft 13 is pushed forward in a position of size a. Then the first pressure plate 25 moves away from the clutch disc 30, and the shaft coupling element 21 is disconnected (Figure 13). If the reverser 16 is in the middle position, then the propeller 11 essentially stops, i.e. the driving element 15 does not rotate the propeller 11 . The internal shaft 13 moves backwards by an amount a to the position p and the first pressure plate 25, the clutch disc 30 and the second pressure plate 27 connect with each other. Then the electric motor 19 can operate the propeller 11 according to the setting on the control panel 17 (Figure 11). When the reverser 16 is fully pulled up, for example, the propeller 11 rotates in accordance with forward motion, the internal shaft 13 is fully pushed back with an extent of a + p to the place of size y. Then the second pressure plate 27 is removed from the clutch disc 30 by the switch bar 29, and the shaft coupling element 21 is disconnected (Figure 12). It also follows from the above that the size of the actuator of the switch bar 29 is such that in the middle position of the reverser 16 (the engine 2 is idling), the shaft coupling element 21 is in the closed state. At the same time, when the reverser 16 is in the upper position — then the internal shaft 13 is closest to the electric motor 19 — i.e. the control element 24 is in the position of y dimension, then the switch bar 29 moves the second pressure plate 27 away from the clutch disc 30 (Fig. 12). This is achieved by choosing the size y larger than size p. Of course, these dimensional differences are very small, but they are sufficient for proper operation.

It is noted that the definitions used in the description forward - backward - stationary position/empty are occasional and depend on the direction of rotation of the driving element

15 and the design of the propeller 11 (left directed or right directed). Furthermore, the reverser

16 can be designed not only stepped. If the operating shaft 33 of the reverser 16 does not move up and down, but for example it is a rotating rod, then the reverser 16 can be a cylindrical element on the operating shaft 33 with sides designed in varying measures, namely a; P; y (Figure 11 b). In this case, a < p < y.

The operation of the propeller unit 8 according to the present invention is already clear from what has been described so far. During supplementing the traditional internal combustion watercraft engines with electric drive, the former propeller unit is replaced by the propeller unit 8 according to the present invention. The propeller unit 8 according to the invention is formed in such a way that the cylindrical part 7 is supplemented with the nest 18 as described above. After that, the previously described components are assembled on the external shaft 12 and the internal shaft 13, and they are inserted from the direction of the propeller 11 into the cylindrical part 7 and its nest part 18. The end of the cylindrical part 7 towards the propeller 11 typically closes the cylindrical part 7 with a screwed connection. When assembling the interchangeable propeller unit 8, the electric wires of the electric motor 19 and the electromagnetic switch 28 are guided out on the upper flange 6 of the hollow part 1. The electrical wires of the electric motor 19 and the electromagnetic switch 28 are then guided, if necessary, through the connecting housing 9 or directly into the motor housing 3. Depending on the location of the control panel 17, the electric wires of the electric motor 19 and the electromagnetic switch 28 are connected to the control panel 17 either in the motor housing 3 or outside the motor housing 3 (Figure 18). If in the solution switch bar 29 is used, obviously, only the electric motor 19 has electric wires. These wires are guided out as described above.

The advantage of the present invention is that a hybrid drive system has been developed that is suitable for supplementing the outboard or built-in engines of boats with an electric motor without having to change any other parts of the engine apart from the propeller housing. Furthermore, the solution of the shaft coupling is simpler than any previously known solution, i.e. by minimally modifying the already known reverser rods, it is ensured that the engine controls on the operating surface is not changed, i.e. the watercraft could be driven in the usual way. With the traditional reverser rods shown in the present invention, it is ensured that the internal combustion engine and the electric motor are able to connect the ship's engine to the propeller only independently of each other.