Improved drive device for a watercraft

Abstract

The invention relates to a drive device (10) for a watercraft (3), which is capable of being mounted on a watercraft (3) around a linking member (12) that allows at least two rotations in independent directions, including a yaw direction (Z) of the watercraft. The drive device comprises - a power supply module (14) capable of housing at least one battery; - a motor unit (16) comprising at least one electric motor electrically connected to the power supply module; and - a bar-shaped member (20) having a proximal portion located near the linking member (12) and attached to the power supply module (14), and a distal portion located away from the pivot link (12), which supports the motor unit (16) such that the motor unit is arranged at a distance from the power supply module (14); wherein the motor unit (16) comprises an output shaft to which at least one propeller (18) is rigidly attached.

Description

[0001] DESCRIPTION

[0002] TITLE: Improved boat motorization device

[0003] 1. Field of the invention

[0004] The invention relates to the field of boat motorization, and more particularly relates to an improved boat motorization device. This device is designed in particular to equip small and medium-sized boats: pirogue, rowboat, rigid or inflatable canoe, etc.

[0005] 2. Prior art

[0006] For this type of boat, there are two main families of removable motorization: outboard type motorizations (hereinafter called "outboard"), and "long-tail" type motorizations (hereinafter called "long-tail", their generic name in English).

[0007] The outboard motor consists of a unit consisting of a motor driving a propeller, the unit being attached to the rear of a boat, partly outside the hull. Although the outboard motor has a small footprint, its proper operation requires a significant draft, at least 50 cm. This makes the outboard inefficient in shallow waterways, or where there are shoals. In addition, outboard motors are mostly thermal, and therefore polluting and noisy (80 to 100 dB). This is especially true since the standards for thermal engines in the automotive industry do not apply to outboard motors. Finally, outboards can only be attached to the rear of a boat, and are therefore not compatible with all boats, particularly boats typical of Southeast Asia.

[0008] We certainly know of outboards with electric motors, but these do not solve the problem of the need for draft, nor that of necessarily fixing at the rear of the boat. Outboards are distinguished by a column at the end of which is mounted a propeller whose axis forms a 90° angle with the column. The outboard engine is generally arranged at the top of the column, on the boat side. To propel the boat, the outboard is lowered until the propeller is submerged, the column plunging vertically into the water perpendicular to its surface, which means the propeller axis is horizontal, maximizing the effect of the thrust. Outboards generally only allow a single rotation, around the yaw axis (i.e. around the central column or parallel to it), and a translation along this same yaw axis to raise and lower the outboard.Thus, while sailing, the outboard can only be maneuvered by pivoting it around the yaw axis, and it must be raised until the propeller is fully exposed to avoid debris.

[0009] To avoid collision between an outboard and debris, outboards are known whose central column is mounted on a pivot connection around the pitch axis. The propeller of such outboards can thus be tilted out of the water or flush with the water surface in the presence of debris or shoals, by pivoting around the pitch axis. However, pivoting along the pitch axis of an outboard so that the propeller is flush induces a vertical or nearly vertical positioning of the propeller axis, whereby the horizontal thrust of the propeller is minimal or non-existent. These outboards therefore remain very inefficient and unsuitable for navigation in shallow waters.

[0010] It is for this reason in particular that long-tail motors have been developed, particularly suitable for areas of shallow water or low draft. The invention relates more specifically to these long-tail motors.

[0011] Figure 1 illustrates the operating principle of long-tail motors. This type of motor consists of a turret 1 mounted via a double pivot 2 on a boat 3 and carrying a thermal engine 4 arranged at the top of the turret 1. The double pivot 2 allows the rotation of the long-tail motor 1 along at least two independent axes of rotation, including at least the yaw direction of the boat. The turret further comprises a boom 5 — hence the name long tail — at the end of which is mounted a propeller 6. The propeller is driven directly by the thermal engine 4 via a shaft housed in the boom 5 or forming said boom 5, without any additional transmission member or gear. When the thermal engine 4 is in operation, the propeller 6 propels the boat, the direction adjustment being carried out by a user 7 by pivoting the turret 1.Due to its simple design, the thermal engine of the long-tails has no gearbox, and the modulation of the propulsion force and therefore the speed of the boat is done using a carburetor lever.

[0012] Long-tail motorization is a very popular solution, particularly in Southeast Asia. This popularity is explained by its simple design, its adaptability to a wide variety of boats, especially those on which it is not possible to attach an outboard motor, and the low draft required to use the motorization, very useful in shallow waterways.

[0013] However, despite its undeniable advantages, the long-tail motor is not without its drawbacks. The thermal engine 4 of the long-tail must be out of the water and on the boat 3, to act as a counterweight and minimize the moment of inertia, thus allowing easy maneuvering of the pole 5 and the propeller 6. This thermal engine 4 is thus mounted on the turret 1 close to the user, with all the pollution and acoustic disadvantages that this implies, especially close to the navigator steering the boat.

[0014] This assembly, combined with a very long pole—at least two meters—is essential to obtain satisfactory horizontal thrust, especially since the propeller rotates in the same direction as the engine axis due to the direct transmission. This pole length makes long-tail engines extremely cumbersome, especially when parking a boat, and complicates maneuvering the boat during tight turns. Due to the lack of a gearbox at the output of the thermal engine, it is not possible to reverse with a long-tail engine.

[0015] Furthermore, since the propeller axis is not horizontal once the propeller is submerged and therefore forms an angle a with the water surface (see figure 1), this results in a loss of thrust - since it is not entirely horizontal - and therefore poor efficiency. This efficiency is also impaired by friction between the water and the submerged pole, the length of the submerged pole being all the greater as the pole is extended when the propeller is submerged. The non-horizontality of the propeller axis and the immersion length of the pole are opposed, so that improving one of the two parameters necessarily harms the other, limiting the theoretical efficiency of long-tail engines. A toothed wheel or universal joint type transmission could be considered so that the propeller is not in the extension of the pole.However, this approach has not been satisfactory, due to the loss of efficiency associated with an additional transmission, the additional noise pollution and the sealing constraints for a submerged transmission.

[0016] Finally, long-tail engines do not allow reversing, since their thermal engine does not have a gearbox, and their engine has the same drawbacks as the thermal engines of the outboards presented above.

[0017] The invention improves the situation by proposing a device which does not have all or part of the aforementioned drawbacks.

[0018] 3. Statement of the invention

[0019] To this end, the technique of the invention proposes a device of a new type, overcoming the drawbacks of conventional motorizations. This motorization device for a boat is capable of being mounted on a boat around a connecting member allowing at least two rotations in independent directions including a yaw direction of the boat. This motorization device comprises: a power module, capable of housing at least one battery; a motor unit comprising at least one electric motor electrically connected to said power module; and a bar-forming member, of elongated shape, having a proximal portion, close to the connecting member, fixed to the power module, and a distal portion, at a distance from the pivot connection, carrying the motor unit so that the motor unit is arranged at a distance from the power module; the motor unit comprising an output shaft on which at least one propeller is secured.

[0020] Thanks to this particular arrangement of the electric motor near the propeller, intended to be submerged, not only is the noise and atmospheric pollution of this motorization device drastically reduced compared to a long-tail motorization, but in addition its efficiency is improved, as is its maneuverability.

[0021] This motorization device can therefore be used even with a very low draft and can be installed on any type of boat, the propulsion force being modulated by modulating the electric supply current. This radically differentiates this motorization device from outboards. Since it is an electric motor, it is possible to reverse the polarity of the current supplying it so as to make the electric motor rotate in the opposite direction and reverse the boat, thus improving maneuverability.

[0022] This specific arrangement of the engine unit near the propeller has many advantages: The engine unit / propeller transmission is direct, thus ensuring optimal transmission efficiency. The device is thus relieved of a large, torsion-prone, heavy, and high-inertia drive shaft. The engine unit gains in maneuverability and responsiveness.

[0023] The power unit and propeller are at the end of the tiller and in direct drive. This allows the power unit and propeller to be connected so that the propeller axis is oriented horizontally when the propeller is fully submerged. This eliminates losses associated with a non-horizontal propeller without the need for additional transmission.

[0024] Since the motor unit is at least partially submerged during operation, its cooling is ensured by the water in which it is immersed. This cooling allows for a considerable reduction in the weight of the electric motor, which no longer needs to be equipped with heavy radiators (typically more than fifteen kilograms). This reduces manufacturing costs, improves handling, and avoids the pollution caused by the manufacture of a heavy metal radiator.

[0025] The layout of the power module, which houses the battery, acts as a counterweight to the motor unit, further improving the maneuverability of the device. This also facilitates access to the battery for recharging or to prevent theft when the boat is docked.

[0026] The motorization device thus offers improved efficiency, a reduction in induced pollution, increased maneuverability and ease of use compared to all known solutions.

[0027] According to a particular aspect, the bar-forming member comprises a so-called oblique section, arranged between the two distal and proximal portions, extending in a longitudinal direction forming an angle of at least 30° with the axis of the propeller.

[0028] Thus, thanks to the oblique section, the size of the motorization device is drastically reduced. This geometry allows the motor unit and the propeller to be submerged much closer to the boat than in the case of a long-tail motorization with a straight pole. It is thus possible to take tight turns in narrow waterways with low draft.

[0029] In addition, this simplifies the storage of the motorization device when the boat is stopped, since it is shorter, by pivoting it to house the electric motor, the propeller and the steering component entirely in a small boat. Once stored, the motorization device no longer protrudes, or only marginally, unlike a classic long-tail motorization.

[0030] In addition to reducing the overall dimensions, this obliqueness allows the tiller to enter the water at a much greater angle when the propeller is fully submerged than for a conventional long-tail motor. This angle of entry into the water limits the length of the submerged tiller and therefore the friction when the boat is propelled.

[0031] Thanks to an oblicity of at least 30° between the propeller axis and the longitudinal direction of the oblique section, the gain in compactness is more than 50% in length reduction, and reaches 65% length reduction for an angle of approximately 60° (approximately 1.15 m in length compared to 3.40 m for a classic long-tail engine).

[0032] According to a particular aspect, the bar-forming member comprises a so-called oblique section, arranged between the two distal and proximal portions, extending in a longitudinal direction forming an angle of at most 60° with the axis of the helix.

[0033] Limiting the angle of obliquity to 60° or less makes it possible to limit the effect of an impact of the submerged part of the motorization device with an obstacle. Indeed, in the event of contact with an obstacle (for example a shoal or a floating object), a vertical (90°) or insufficiently oblique (for example 70°) section would be equivalent to a quasi-frontal impact of the obstacle on the distal portion of the tiller-forming member and the propeller. On the other hand, an obliquity of less than 60° makes it possible to deflect the impact. Furthermore, an angle of less than 60° makes it possible to obtain sufficient leverage to pivot the motorization device in the pitching direction with reduced movement on the part of the operator, in particular to bring the propeller out of the water without part of the motorization device coming into contact with the boat.This reduction in stroke for good maneuvering of the device thus allows the compatibility of the motorization device with a large number of boats.

[0034] The bar-forming member may have at least over part of its length a cross-section whose thickness transversely to the helix axis is at least three times smaller than the width.

[0035] Thanks to this refined section of the bar-forming member, it generates considerably less friction once immersed, improving the efficiency and discretion of the motorization device.

[0036] Furthermore, thanks to this particular geometry, the tiller member can act as a rudder for the boat. The motorization device thus plays a dual role for the boat. With this rudder function, the motorization device allows the boat to be maneuvered even with a stationary electric motor, so that it can turn or brake completely silently.

[0037] The bar-forming member may have a hydrodynamic profile.

[0038] Thanks to this hydrodynamic profile, also called a hydrofoil profile, the friction of the submerged part of the device is considerably reduced, improving performance. It should be noted that the hydrodynamic profile can be combined with the thickness / width ratio described above to further improve performance and maneuverability.

[0039] The motorization device may further comprise at least one attitude stabilizer secured to the distal portion, close to the propeller.

[0040] The trim stabilizer improves the handling and stability of the motorization device, and in particular allows the propeller to be kept horizontal when it propels the boat. This trim stabilizer may, for example, include one or more lateral fins.

[0041] The motorization device may further comprise a protective member arranged under the propeller.

[0042] The protective member protects the propeller from impact with a shoal or debris. This protective member may, for example, comprise a lower fin secured or integral with the bar-forming member, and extending at least partly under the propeller.

[0043] The motorization device may further comprise a drawbar, fixed to the power module or to the proximal portion of the bar-forming member, the drawbar being bent and / or retractable.

[0044] This tiller allows for easy maneuvering of the motorization device. Its retractable nature makes it easier to store the motorization device. Its elbow provides a better angular travel of the motorization device.

[0045] The bar member can be made of stainless steel or aluminum.

[0046] The bar-forming member thus acts as a heat sink, thanks to the properties of aluminum. It is thus possible to connect this bar-forming member with a thermally conductive material (for example thermal paste) to parts likely to release heat, for example a power module controller. The member, thanks to its large size, thus maintains a relatively low touch temperature, limiting the risk of burns.

[0047] The at least one battery that can be housed in the power module can be removable. This simplifies the transport of the device, as well as its recharging, the battery being able to represent between a quarter and three quarters of the mass of the entire motorization device.

[0048] According to a particular aspect of the invention, the propeller is axially distant from the motor, this distance being between 8 and 20 cm, and preferably 10 cm.

[0049] This further increases efficiency at high speeds, as the propeller bites more into the water.

[0050] According to an even more particular aspect of the invention, the propeller shaft is surrounded by a flow guide. This flow guide can taper towards the propeller. This flow guide limits turbulence between the engine unit and the propeller, and therefore improves efficiency.

[0051] According to a particular aspect of the invention, the axis of the propeller is substantially directed towards the pitch axis (i.e. less than 5°).

[0052] This particular geometry makes it possible to significantly limit the nose-up / dive torque induced by the propeller thrust.

[0053] In another particular aspect, the propeller axis points slightly above the pitch axis of the connecting member. This angle is preferably between 1 and 5°, and more preferably around 2°. This makes it possible to reproduce a nose-up torque effect that is very popular with canoeists using long-tail engines.

[0054] 4. List of Figures

[0055] The proposed technique, as well as the various advantages it presents, will be more easily understood, in the light of the following description of illustrative and non-limiting embodiments thereof, and the appended drawings among which:

[0056] [Fig. 1] represents a classic long-tail engine;

[0057] [Fig. 2] represents a schematic diagram of an example of a motorization device according to the invention;

[0058] [Fig. 3] represents a detailed view of the device of Figure 2, seen from the side;

[0059] [Fig. 4] represents a top view of the device of Figure 3;

[0060] [Fig. 5] represents a perspective view of a prototype of the device of Figure 3;

[0061] [Fig. 6] represents a perspective view from above of the device of Figure 5;

[0062] [Fig. 7] represents a perspective view of the profile of the device of Figure 5;

[0063] [Fig. 8] represents a perspective view of the propulsion group of the device of figure 5, seen from the rear;

[0064] [Fig. 9] represents a perspective view of the propulsion group of figure 8, seen from three-quarters;

[0065] [Fig. 10] represents a perspective view of the device of Figure 5 mounted on a boat;

[0066] [Fig. 11] represents a view of the front face of the power supply module of the device of Figure 5;

[0067] [Fig. 12] represents a first variant of the device of figure 3;

[0068] [Fig. 13] represents a second variant of the device of figure 3;

[0069] [Fig. 14] represents a third variant of the device of figure 3;

[0070] [Fig. 15] represents a fourth variant of the device of figure 3, with an elongated and exposed propeller axis;

[0071] [Fig. 16] represents the variant of Fig. 15, once assembled; and

[0072] [Fig. 17] shows an overview of a variant of the device of Figure 15.

[0073] 5. Detailed description of the invention

[0074] We then illustrate various embodiments of the proposed technique, treated as simple illustrative, and non-limiting, examples, with the support of figures 2 to 14.

[0075] 5.1. General principle

[0076] The starting point of the invention is a long-tail motorization as described above. From this basis, the general principle of the invention is to radically modify the arrangement of its constituent elements. Thus, on the one hand the motor unit comprises an electric motor and not a thermal engine. On the other hand, the motor unit is offset at the end of the pole, the propeller being at the direct output of the motor unit.

[0077] The direct proximity between the engine and the propeller, at the end of the pole, has many advantages. The engine is submerged when the propeller propels the boat. The water, especially when it is moving relative to the engine, therefore cools the engine completely passively. The design of the engine is simplified and lightened, because there is no longer any need to install heavy radiators to dissipate the heat that the engine produces during operation.

[0078] Furthermore, since the propeller is a direct output from the engine group, the transmission is radically lightened, since there is no longer any need for an elongated shaft, housed in a pole or forming it. Efficiency is improved. But, in addition to the gain in efficiency, this removes all the constraints of pole geometry of conventional long-tail engines, as will be seen below. Indeed, the propeller being a direct output from the engine group, it forms with said engine group a solid propulsion group whose arrangement, in particular the orientation, are much more modular than for a conventional long-tail engine, while being of simpler design.

[0079] Other advantages of this new type of arrangement of the constituent elements of the motorization device according to the invention will be developed below.

[0080] Reference is made to Figures 2 to 11. The boat 3 defines an orthogonal reference frame formed by a roll direction X, a pitch direction Y and a yaw direction Z.

[0081] The motorization device according to the invention, hereinafter referred to as device 10, is capable of being mounted on a boat 3. The mounting is done by a connecting member 12 allowing at least two rotations in two independent directions, at least one of which is the direction z coinciding with the yaw direction of the boat Z. The connecting member 12 can be synthesized in the form of a ball joint with finger when the connecting member only allows two rotations, as shown diagrammatically in Figure 2.

[0082] The device 10 comprises a power module 14, a motor unit 16, a propeller 18 and a bar 20. The power module 14 is capable of receiving a battery to power the device 10.

[0083] In the illustrated example, the power supply module 14 receives the battery 140 in an open housing. The power supply module 14 may further comprise a controller 142, arranged to electrically control the motor group 16.

[0084] The controller 142 may further comprise an on / off switch 1420, a display screen 1422, a power-on indicator light 1424, a circuit breaker and / or associated connectors 1426, as can be seen in the example illustrated in FIG. 11. The connectors 1426 make it possible to electrically connect the battery 140 to the controller 142. Here, the connectors 1426 are visible, i.e. visible from the outside. Alternatively, it could be housed in the device, for example to protect it from external moisture.

[0085] In the example visible in particular in figures 5 to 7 and 11, the controller is housed under the battery 140. Other arrangements are of course possible, typically depending on the degree of miniaturization of the controller 142. The power supply module thus comprises a housing 144 forming the housing of the battery 140 and, where appropriate, and the housing of the controller 142.

[0086] The controller 142 could, as a variant (not shown in the figures), be arranged in a housing separate from the power supply module 14, and connected to the latter by an electrical cable.

[0087] The motor group 16 is arranged at a distance from the power module 14. The motor group 16 comprises an electric motor 160. This electric motor 160 is electrically connected to the power module 14. The motor group 16 comprises an output shaft 162 on which the propeller 18 is secured. The output shaft 162 defines a propeller axis U.

[0088] In more sophisticated variants, several propellers may, as a variant, be mounted on the output shaft of the motor group 16. Still as a variant, the motor group 16 comprises several output shafts on which one or more propellers are mounted.

[0089] The bar 20 is of elongated shape, and rigid. The bar 20 has a proximal portion 22 and a distal portion 24, respectively close to the connecting member 12 and at a distance from the connecting member 12. The power module 14 is secured to the proximal portion 22. The motor group 16 is secured to the end portion 24.

[0090] The motor group 16 is thus arranged at a distance from the power module 14. The motor group 16 has the function of driving the propeller 18 in rotation, so as to propel the boat 3.

[0091] From the particular arrangement described above, it is understood that the motor unit 16 is in the immediate vicinity of the propeller 18 and is intended to be at least partially immersed in the water when the propeller 18 is itself immersed in the water to play its propulsion role.

[0092] Thanks to this new arrangement, the electric motor 160, and more generally the motor group 16, are immersed, which allows them to be cooled by the surrounding water. This cooling makes it possible to do without the heavy radiators usually used in the cooling of electric motors.

[0093] The device 10 thus defines a reference point of its own, formed of three directions x, y and z. The z direction coincides with the yaw direction Z of the boat. The y direction is the other of the two pivot directions of the connecting member 12. The x direction is a third direction making it possible to define a reference point.

[0094] In the example described here, and for the sake of brevity, the (x, y, z) reference frame is an orthogonal reference frame and coincides with the (X, Y, Z) reference frame of the boat when the device is oriented in line with the boat, i.e. the propeller 18 is neither oriented to port nor oriented to starboard. By convention, the z (yaw) direction is oriented upwards when the boat is floating. By convention again, the X direction corresponds to the U direction of the propeller axis. In fact, this reference (X, Y, Z) makes it possible to define the top and bottom of the motorization device 10 (in the Z direction), port and starboard of the motorization device 10 (in the Y direction) and a front and a rear of the motorization device 10 (in the X direction), corresponding to these same directions (top, bottom, port, starboard, front, rear) of the boat 3.

[0095] The power supply module 14 is capable of housing a battery 140 to power the motorization device. This battery 140, removable or not, will be described below.

[0096] The motor unit 16 may comprise, in addition to the motor 160, a geared motor making it possible to adjust the torque or rotational speed at the motor output. The motor unit 16 is preferably waterproof, at least for its electrical part, so that it can be submerged. The motor unit may be entirely waterproof, including any geared motor or any other part whose exposure to water would be detrimental. The motor unit 16 may also be streamlined, so as to limit friction once submerged.

[0097] The bar 20 is, by definition, of elongated and rigid shape. Its role is to connect the propulsion group 28 formed by the engine group 16 and the propeller 18 to the connecting member 12, so that a pivoting of the bar 20 around one of them causes a movement of the propeller and the engine to port or starboard (around the z direction), or upwards or downwards (around the y direction).

[0098] The bar 20, as well as the fixed parts secured to the bar 20 including the housing 144 of the power supply module 14, together form the chassis 50 of the motorization device 10.

[0099] The pivoting of the device 10 around the rotations permitted by the connecting member 12 can be done directly, for example by an operator who would “force” the movement of the bar 20 manually. As a variant, shown in Figures 2 to 7, the motorization device 10 comprises a rudder member 26 by means of which the operator pivots the entire motorization device 10. This rudder member 26 can for example be a tiller, also called a tiller.

[0100] The tiller 26 may be retractable, foldable and / or removable, so as to facilitate its storage. Here, the tiller 26 is arranged in the extension of the power supply box 14. The tiller 26 may be bent and / or oriented upwards (in the z direction, therefore). In the example visible in Figures 5 to 7, the tiller 26 is bent in the y direction (to starboard), but not in the z direction (upwards). This bend makes it possible to orient the tiller 26 towards the outside of the edge of the boat. Gripping the tiller 26 is made easier, and above all it provides the motorization device 10 with greater vertical travel to surface the propeller 18 and the motor unit 16. In other words, this allows a greater angular amplitude before the power module 14 or the tiller 26 comes into abutment against one of the parts of the boat (bottom, crossmember, side, etc.).

[0101] As is apparent in Figures 4 and 6, the example of a motorization device illustrated there is, with a few exceptions such as the drawbar 26, substantially symmetrical with respect to the plane (x, z).

[0102] In continuous operation, the motorization device 10 releases heat in three locations: the electric motor 160, the controller 142, when there is one, and to a lesser extent the battery 140.

[0103] In addition to immersion cooling, the power unit 16 can be cooled by relative wind when the power unit is partially or completely out of the water. Since the air around the water is slightly cooler than that at the electrical box, this allows for cooler air.

[0104] The controller 142 is cooled primarily by the relative wind when the boat 3 is propelled. To improve this cooling, the chassis 50 of the motorization device 10, in particular the housing 144 of the power module 14 and the bar 20, may be made of a thermally conductive material, in particular a metal. In such a case, the controller is bonded to this chassis 50 by thermal paste.

[0105] The chassis 50 may for example be made of aluminum, or alternatively of stainless steel. 6061 aluminum is a suitable material for making this chassis, due to its mechanical strength and its thermal conductivity of 170 W / mK. 6061 aluminum has good resistance to corrosion, including in a marine environment. This conductive metal chassis may also have a surface treatment such as anodizing or electrophoresis. The chassis 50 may comprise several materials depending on the part, for example stainless steel for the housing 144 and aluminum for the bar 20.

[0106] Due to its large dimensions (compared to the rest of the elements of the motorization device 10), the chassis 50 made of thermally conductive material can act as a heat sink for the controller 142, both for its submerged part cooled by the surrounding water and for its emerged part cooled by the air or the relative wind. In addition, since the chassis is large, it has a large heat capacity, and therefore remains warm when the motorization device is in operation, where the controller 142 can be significantly hotter. This limits the risk of burns when in contact with the motorization device. This also improves the heat dissipation of the motor 160.

[0107] In the tests conducted by the inventors, the motorization device operates normally up to a motor temperature of approximately 65°C. The controller 142 may integrate a thermal probe (not visible in the figures) making it possible to implement a reduction in the supply current of the electric motor if the temperature exceeds a certain threshold, whether due to an external reason or an internal anomaly. The thermal management of the battery may also follow a similar logic, thanks to a battery management system, also called BMS (battery management system). It is thus possible to protect the electric motor and / or the battery from overheating.

[0108] 5.2. Connecting body

[0109] In the example shown in Figures 5 to 7 and in particular Figure 7, the connecting member 12 comprises a first pivot 120 around the direction z and a second pivot 122 around the other direction of rotation permitted by the connecting member 12. As expressed above, this other direction of rotation preferably corresponds to the direction Y, which simplifies navigation since the motorization device 10 can pivot in the yaw direction Z and in the pitch direction y (relative to the motorization device). Nothing prevents this other direction from being non-orthogonal to the yaw direction Z.

[0110] In the example described here, see Figure 7, the connecting member 12 works in conjunction with a plate 124, visible in Figure 10, to form the first pivot 120. The connecting member 12 comprises a sleeve 126, of generally cylindrical shape. The plate 124 is designed to be fixed to all possible boats and to provide a cylindrical housing, of a shape complementary to that of the sleeve 126. When the plate 124 is fixed to a boat 3, the axis of symmetry of the cylindrical housing is substantially parallel to the yaw direction Z. The cooperation of shape of the sleeve 126 and the cylindrical housing makes it possible to obtain the first pivot 120.

[0111] In the example visible in Figure 10, this plate 124 is fixed — removably or not — to a crossbar 30 of a boat 3. Here, the crossbar 30 extends in the Y direction, i.e. the pitch axis. This assembly would naturally work with a crossbar 30 in the roll axis X of the boat 3, and more generally any direction of the crossbar as long as the cylindrical housing is vertical (in the Z direction) once the plate 124 is fixed.

[0112] When fixed to the boat, the plate 124 rests against the crossbar 30 via an upper surface 1240. One or more nuts 1242 secure the plate 124 to the crossbar 30, for example by tightening. This plate 124 thus makes it possible to fix the motorization device 10 to a huge variety of boats, in particular traditional boats from Southeast Asia.

[0113] Other plate attachment systems 124 may be envisaged, making it possible to vary the shape of the plate according to the nature of the boat. Other variants of the first pivot 120 may be envisaged, for example with a plate directly integrated into the motorization device 10 and a different first pivot 120, for example with ball bearings or bushings.

[0114] The second pivot 122 may comprise, as can be seen for example in Figure 7, a stop 1220. This stop 1220 comprises a surface 1222 against which a wall 1224 of the chassis 100 of the motorization device 10 (here, a lower wall 1224 of the housing 144 of the power module 14) comes into contact when the motorization device 10 is in the so-called horizontal rest position. In this horizontal rest position, the motor unit 16 is stopped, and the propeller 18 is submerged, and its propeller axis leans very slightly below the horizontal, that is to say that the propeller axis U is almost but not totally oriented in the Y direction. In such a situation, the weight of the bar 20 and the propulsion assembly 28 hold the wall 1224 against the surface 1222 of the stop 1220.

[0115] This stop 1220 allows the entire motorization device 10 to remain in this horizontal rest position without rubbing on the rear of the boat 3 when the motorization device 10 is stopped and the lateral fins 40 forming the trim stabilizer are therefore inoperative (since there is little or no propulsion). When the propeller 18 is driven and propels the boat 3, the latter lifts slightly from its horizontal rest position and stabilizes horizontally (i.e. propeller axis thanks to the lateral fins forming the trim stabilizer.

[0116] In the example of Figure 7, this stop 1220 here comprises an arm, finger or oblique cleat in the plane (X, Z) playing a role similar to that of a strut in carpentry. Other alternatives for forming the stop 1220 are of course conceivable.

[0117] Thus, the stop 1220 and the trim stabilizer cooperate to keep the propeller axis substantially horizontal over the entire propulsion speed range, avoiding any friction or impact with the hull of the boat 3.

[0118] The second pivot may optionally comprise rotation-enhancing parts, for example a ball bearing or a bushing. The second pivot 122 may optionally still comprise a rotation lock in the y direction by clamping or by an elastic element such as a spring.

[0119] 5.3. Battery

[0120] The battery 140 is, in the example visible in the figures, removable and visible, that is to say accessible from the outside of the motorization device 10. The battery 140 is here preferably waterproof, or at least splash-proof, as is its electrical connection with the rest of the power supply module 14. Alternatively, the power supply module 14 may comprise a housing having a closed housing, and the battery 140 is then received in this closed housing, this closed housing of the housing protecting the battery from water. The two options (waterproof battery and closed waterproof housing) are obviously cumulative.

[0121] The battery 140 may be formed in two parts, so as to distribute the weight between port and starboard. Alternatively, several separate batteries may be considered to be able to be housed simultaneously in the power module 14.

[0122] A battery management system (BMS) was mentioned above. The battery management system, in addition to the overheating protection described above, also allows for the implementation of an energy-saving mode, in which the motor supply current is reduced depending on the remaining battery capacity. Activation of this energy-saving mode may, for example, depend on the battery output voltage, which decreases as the battery capacity decreases. The propulsion speed of the boat is reduced, for example to 4 km / h, compared to 10 to 20 km / h at cruising speed. This allows the range in kilometers of the motorization device to be multiplied by at least three times, or even up to ten times.

[0123] The inventors have produced three prototypes of motorization devices, suitable for motorizing a 500 kg boat. In these prototypes, the battery has a capacity of 800, 2000 and 3300 Wh, respectively. The weight of the battery is then approximately 4, 13 and 19 kg, respectively, and the autonomy of these prototypes is respectively approximately 1 h at 10 km / h (or 30 km at 4 km / h), 1 h at 15 km / h (or 80 km at 4 km / h) and 1 h at 18 km / h (or more than 120 km at 4 km / h). These values ​​concern prototypes, and are in no way limiting, the battery can have a wide range of capacities and weights. In large and high-power models, the motorization device can propel a boat weighing several tons.

[0124] The weight of the battery makes it possible to act as a counterweight with the motor unit located at the end of the bar 20. To improve this counterweight role, the battery 140 is arranged so that its center of gravity is located slightly to the front relative to the pivot in the Y direction. This weight counterbalances that of the electric motor, without the size of the motorization device 10 as a whole being any greater.

[0125] The electric motor may have a continuous power of 1 to 6 kW, with a peak power (over short periods) of 15 kW. For a very powerful version of the motorization device 10, for example with a motor of more than 10 kW, the power module may optionally comprise aluminum fins, for example arranged under the housing of the power module 14, to increase the heat dissipation thereof. It is also possible, to achieve high propulsion powers, to couple two motorization devices side by side.

[0126] 5.4. Ailerons

[0127] In the vicinity of the propulsion unit 28, the motorization device 10 may comprise one or more fins, secured to the chassis 28. The motorization device may in particular comprise a pair of lateral fins 40. These lateral fins 40 are arranged on either side of the propulsion unit 28. Here, the lateral fins extend in the plane (X, Y). The lateral fins 40 are secured to the bar 20. In the example visible in particular figures 8 and 9, the fins are fixed by screwing to the motor unit 16. Alternatively, the lateral fins 40 may be secured directly to the bar 20, for example by welding.

[0128] The lateral fins 40 act as a pitch stabilizer. In addition, the lateral fins 40 protect the propeller 18 laterally from debris or obstacles. The pair of lateral fins 40 could be replaced by a single fin covering both sides of the propeller.

[0129] Near the propulsion unit, i.e. the engine unit 16 and the propeller 18, it may further comprise a lower fin 42. The lower fin 42 is arranged under the propulsion unit 28, in particular under the propeller 18.

[0130] In the example shown in Figure 7, the lower fin 42 is formed by the end of the bar 20, in the extension thereof. This one-piece design simplifies the manufacture of the bar / lower fin assembly. Alternatively, the lower fin 42 could be a separate part, secured to the bar 20 for example by welding, screwing, gluing, etc.

[0131] The lower fin 42 forms a protective member for the propulsion group 28, particularly in the event of encountering debris or a shoal.

[0132] The fins are here plate-shaped, and made of a rigid material, for example the same as that of the bar. The lateral fins 40 and the lower fin 42 here have constant thicknesses. They can alternatively have an optimized profile to reduce friction, for example a hydrofoil profile.

[0133] 5.5. Bar geometry

[0134] In one embodiment, the bar 20 comprises an oblique section 200, arranged between the two proximal 22 and distal 24 portions. This oblique section 200 extends in a longitudinal direction V forming an angle between 30 and 60° with the direction U, that is to say the axis of the helix 18, as can be seen in particular in FIG. 3.

[0135] The geometry of the bar 20 with this oblique section 200 makes it possible to drastically reduce the size of the motorization device 10. This makes it possible in particular to immerse the propulsion group 28 much closer to the boat than in the case of a long-tail motorization.

[0136] The length of the motorization device is thus very reduced — 1.30 m for an oblicity of 45°, and 1.15 m for an oblicity of 60°, whereas long-tail motorizations have a length of more than 3.40 m. This geometry of the bar 20 allows tight turns to be taken in narrow waterways with low draft. The motorization device thus described has a size comparable to that of an electric outboard motor of the same power, but is significantly lighter. For example, with an 800 Wh battery, the device weighs approximately 12 kg, including 4 kg of battery. With a 1000 Wh version, the device weighs approximately 13 kg.

[0137] This reduced size also allows, when the boat is stopped, the motorization device 10 to be stored in the boat, by pivoting it to house the electric motor, the propeller and the steering member in its entirety in a small boat. Parking small boats is simplified since the motorization device no longer protrudes from it.

[0138] The advantages of the oblique section geometry do not stop at the gains linked to reduced size: since the oblique section is, as its name suggests, oblique to the propeller axis, this oblique section enters the water at a much greater angle when the propeller is fully submerged. This angle of penetration into the water, much greater than that of a long-tail motor pole, limits the length of the submerged bar member and therefore the friction when the boat is propelled.

[0139] The range between 30 and 60° has several advantages.

[0140] Angles of less than 30° between the propeller axis 162 and the longitudinal direction V of the oblique section 200 do not allow for a gain in compactness and satisfactory efficiency at the bar level, in particular for storing the motorization device when stationary in small boats, for the length of submerged pole or for maneuverability in turns. The inventors have further observed that angles greater than 60° should be avoided if possible, because, in the event of contact with an obstacle (for example a shoal or a floating object), a vertical (90°) or insufficiently oblique (for example 70°) section would be equivalent to a quasi-frontal impact of the obstacle on the distal portion 24 of the bar 20 and the propeller 18, possibly on the lower fin 42. On the contrary, with an oblique section angle 200 whose angle with the propeller axis is less than 60°, for example equal to 45°, this angle makes it possible in practice to deflect the impact.This is similar to the armor of a tank or ship, which is less affected by shell impact when it has an oblique side.

[0141] Furthermore, angles greater than 60° generally lead to angular travel problems, because the angular travel required to bring the propeller to the surface is greater the closer the angle is to 90°, while the angular range available to actually pivot the motorization device once installed on the boat is limited by the geometry of the boat. This could cause the device to come into contact with the boat, for example its bottom, its bench, a transom, etc., before the propeller is completely out of the water, preventing good navigation. In other words, the maneuverability of the motorization device 10 comes in particular from the leverage effect that the geometry with an angle (U, V) less than 60° allows (including for small angles, around 30°).

[0142] The inventors have found that this oblique geometry of the bar 20 allows, combined with the attitude stabilizer described above, to obtain a dynamic balance of the propulsion. In other words, the combination of these two aspects makes it possible to obtain propulsion that can be freely oriented or surfaced without having to exert effort to maintain it by default in its horizontal attitude of optimal thrust.

[0143] The bar 20 preferably has a refined profile in the y direction, so as to reduce friction with the water. More precisely, the bar 20 has a thickness e (visible in Figure 8) in the y direction at least three times smaller than its width L (visible in Figure 7). In the example illustrated in Figures 5 to 7, the ratio L / e is approximately 8.

[0144] Thanks to this refined geometry of the bar, the bar generates considerably less friction once submerged, improving the efficiency and discretion of the motorization device.

[0145] Furthermore, thanks to this refined geometry, the bar 20 can act as a rudder for the boat 3. The motorization device thus offers an additional function, in addition to its motorization. With this rudder function, the motorization device 10 also allows maneuvering of the boat even with a stationary electric motor, so that it can turn or brake completely silently.

[0146] The bar 20 may also have a hydrodynamic profile, also called a hydrofoil profile. A NACA 0012 type hydrodynamic profile has given satisfaction to the inventors for the production of prototypes, in particular for its properties of penetration into water, laminar flow and absence of vortex which would generate cavitation in the propeller. Other hydrodynamic profiles having similar properties could be envisaged. The bar 20 may also have a hollow profile, so as to house inside it electrical cables electrically connecting the motor unit 16 to the power module 14. This also lightens the bar 20.

[0147] This geometry with a refined and / or hydrodynamic profile is made possible by moving the electric motor close to the propeller.

[0148] The hydrodynamic profile thus described makes it possible to greatly reduce the cavitation phenomenon that would be found on a cylindrical bar beyond 6-7 knots. It is thus possible to propel the boat at high speeds, beyond 15 knots. The hydrodynamic profile also makes it possible to improve the rudder function described above.

[0149] 5.6. Bar Variants

[0150] In an example shown in Figure 12, the bar 20 is formed from a pole 300 at the end of which the propulsion unit 28 is fixed. The pole is here conventionally cylindrical, but can alternatively adopt a hydrofoil profile.

[0151] The pole 300 may be hollow, making it lighter. In such a case, the cables used to electrically connect the power module 14 to the motor unit 16 may be housed in the pole 300, so as to protect them from water. The propulsion unit 28 may be fixed to the pole 300 so that the axis U' of the propeller forms a non-zero angle with the longitudinal direction V'. This angle may be at least 3° for a straight pole as in this example of Figure 12. This arrangement, made possible by the attachment of the propeller 18 to the output axis of the motor unit 16, allows the propeller 18 to be horizontal once submerged, eliminating the losses of horizontality of conventional long-tail thermal engines. This improves efficiency.

[0152] It is of course possible that this angle between the pole 300 and the propeller axis could be 30°, or even 40° or more. In such a case, the pole 300 forms the oblique section described above.

[0153] Reference is made to Figures 13 and 14.

[0154] In these two figures, the bar is a pole 400 having an elbow 410. The pole 400 thus has a proximal pole portion 420, comprising the proximal portion described above (i.e. to which the power supply module 14 is fixed) and a distal pole portion 430, comprising the distal portion described above (to which the motor group 16 is fixed).

[0155] The distal portion of pole 430, intended to be submerged so that the propeller 18 can propel the boat, thus forms the oblique section described above.

[0156] The angled pole 400 may also be hollow, and possibly house the cables connecting the power module 14 and the motor unit 16. The angled pole 400 may be of cylindrical section, or have a different profile, for example hydrodynamic to reduce friction once submerged and act as a rudder, as explained above.

[0157] In the example of Figure 13, the proximal pole portion 420 is horizontal (i.e., extends in the x direction) and the distal pole portion 430 is bent at about 45° relative to the proximal pole portion 420. In the example of Figure 14, the proximal pole portion 420 forms an angle of 5° with the y direction and the distal pole portion 430 is bent at about 50° relative to the proximal pole portion 420. Thus, when the propeller 18 is submerged to propel the boat, the distal pole portion 430 forms an angle of about 45° with the water, in both cases.

[0158] This bar shape, with a 400 bent pole, simplifies manufacturing. It is thus possible to start from a standard, cylindrical pole and bend it using standard metalworking techniques. This bent geometry is made possible by moving the electric motor close to the propeller.

[0159] An electric motorization device was thus seen, whose size, efficiency, maneuverability and ecological character are drastically improved compared to the state of the art.

[0160] The improvements described above, however, make it possible to propose a variant of the motorization device, capable of being mounted on a boat via a connecting member as described above. In such a case, the motorization device comprises a power module, capable of housing at least one energy reservoir (for example a battery or gasoline tank), a motor unit comprising at least one motor connected to the energy reservoir, and a bar-forming member of elongated shape. The bar-forming member has a proximal portion, close to the connecting member, and fixed to the power module, and a distal portion, at a distance from the pivot connection, carrying a propeller secured to an output shaft of the motor unit, so as to be able to be driven in rotation by the motor.The bar-forming member comprises an oblique section, arranged between the two distal and proximal portions, extending in a longitudinal direction forming an angle of at least 30° with the axis of the helix.

[0161] This oblique section provides the same advantages as the oblique section geometry described above, namely reduced friction (since less submerged length), improved maneuverability, a reduction in the length of the device and an absence of losses linked to the non-horizontality of the propeller. Such a configuration of the motorization device also allows the bar-forming member to act as a rudder, depending on its geometry.

[0162] To ensure transmission and non-horizontality, the motor unit may be arranged at the distal portion of the bar-forming member—as described above for the electric motor. Alternatively, the motor unit may be fixed at another location on the motorization device. For example, the motor unit may be arranged at a location on the motorization device that is not intended to be submerged, such as near the power module. In the latter case, it may be necessary to obtain a non-zero motor axis / propeller axis angle, and the transmission may then comprise a universal joint or a bevel gear for this purpose. The motor unit may alternatively be offset upwards along the z axis, and the transmission with the propeller may be achieved by a set of gears, a belt, a chain, or any other suitable solution for transmitting forces at the output of the motor unit.

[0163] 5.7. Motor shaft extension

[0164] The inventors found that when the propeller is mounted just behind the engine (i.e. with a very small distance between the propeller and the engine unit), only the distal parts of the propeller blades bite into the water to produce thrust when the propulsion unit is flush with the water. This phenomenon occurs in shallow water (15-20 cm), but also when a user wishes to finely maneuver his boat, and to do so raises the propeller until it is flush.

[0165] In such cases, the flush propeller coupled with the speed of the boat causes a deformation of the water surface behind the power unit 16. This water surface sinks behind the power unit 16, due to the drag effect. The propeller can then no longer bite as high as if the boat were stationary and the water surface was flat.

[0166] This can lead to a large loss of efficiency, since the surface area of ​​the blades in contact with the water, and therefore the thrust surface, is smaller in such a configuration. The inventors have found that in practice, at cruising speed, only the portions of the blades exceeding the diameter of the power unit 16 "bite" into the water and produce thrust. The parts of the propeller 18 proximal to the axis 162 are located in the groove of the power unit 16, and therefore produce little or no thrust. This effect is all the more significant as the speed of the boat increases, and the speed of the boat is particularly limited in the case of shallow water and it is difficult to reach or exceed 15 knots in such a situation.

[0167] To maximize efficiency and overcome this drawback, inventors have considered increasing the propeller diameter so that the propeller protrudes further radially from the engine, and thus increase the proportion of propeller blades that bite into the water, even when flush. However, this approach is limited by the maximum propeller diameter allowed by the engine torque. Large propeller diameters would imply a more powerful, larger engine and therefore increased thrust loss, thus an even larger propeller, and so on.

[0168] The inventors then had the clever idea of ​​deliberately lengthening the propeller shaft. This manufacturing trick is illustrated in Figures 15 and 16, representing a device in which a propeller shaft, called elongated, 164 projects from the motor unit 16 so that the portion of shaft 180 on which the propeller 18 is fixed is distant from the motor by a given elongation L. This elongation L of the elongated propeller shaft 164 is substantially greater than the minimum necessary to mount the propeller at the outlet of the motor unit glued to it. The propeller thus mounted is axially distant from the motor.

[0169] Indeed, the aforementioned water subsidence (in the case of a flush propulsion unit and at cruising speed) decreases as one moves away from the engine unit. Also, an elongated shaft so that the propeller is distant from the engine significantly increases the thrust surface without requiring an increase in diameter.

[0170] In practice, the inventors have found that a propeller located approximately 10 cm from the engine gives satisfactory results and significantly improves efficiency. Other elongations L of the elongated propeller shaft 164 can be envisaged, for example in the range 8 to 20 cm depending on the engine power and the desired speeds. By elongation L of the elongated propeller shaft 164, we mean the axial distance between the output face of the engine 18 and the portion of the shaft 180 on which the propeller is mounted.

[0171] This cleverly extended propeller shaft significantly increases the device's performance in shallow water or with a flush propeller, without the need to increase the propeller diameter and / or engine power. This makes it possible to achieve higher speeds in shallow water with equivalent engine power.

[0172] Furthermore, and optionally, the device provided with an elongated propeller shaft 164 may comprise a flow guide 166 surrounding the elongated propeller shaft 164. This flow guide 166 here comprises a cone section. This cone section is mounted so that it tapers progressively towards the shaft portion 180 receiving the propeller 18 (i.e. towards the rear of the device). Its large diameter is thus on the motor unit side and its small diameter on the propeller side. This flow guide 166 may be made of aluminum, plastic, or any other material suitable for immersion. When the boat equipped with the device is propelled, the flow guide 166 prevents the appearance of turbulence between the motor unit and the propeller. This prevents the formation of bubbles behind the motor in the case of an elongated shaft.Furthermore, when the user of the device encounters a shoal and needs to raise the propulsion unit, the truncated cone shape of the flow guide ensures the continuity of the flow of water towards the propeller, without hindering propulsion.

[0173] Thus, according to a particular aspect of the invention, the propeller is axially distant from the motor, this distance being between 8 and 20 cm, and preferably 10 cm.

[0174] According to an even more particular aspect of the invention, the propeller axis is surrounded by a flow guide. This flow guide can taper towards the propeller.

[0175] This flow guide limits turbulence between the engine unit and the propeller, and therefore improves efficiency.

[0176] 5.8. Plunging axis

[0177] Reference is made to Figure 17.

[0178] In relation to this figure 17, the following angles are defined. The angle referenced U' is the angle between the propeller axis and the longitudinal direction of the oblique bar 200. The angle referenced V is the angle between the oblique bar 200 and a horizontal plane. The angle referenced W is the angle between the propeller axis and a straight line (in the plane (X, Z)) passing through the center of the propeller and the pivot connection around the pitch axis of the connection member.

[0179] The connecting member here allows at least rotations of the motorization device in the pitch direction Y and the yaw direction Z.

[0180] The inventors have found that, in the case of a perfectly horizontal thrust (see for example the device in Figure 3), the thrust force passes very largely below the pitch axis of the connecting member. This induces a diving torque, that is to say a torque tending to lower the propeller. This diving effect must be compensated, very often manually by an operator, otherwise the propeller or the lower fin will hit the bottom of the watercourse. This risks damaging the submerged part of the device, even protected by a member such as the lower fin 42 described above. This risk is all the greater since certain users, in particular canoeists in South-East Asia, major users of long-tail engines, are accustomed to a nose-up torque (i.e. tending to surface the propeller) and not a diving torque (tending to dive the propeller).

[0181] In the embodiments described above, this diving torque is compensated by the lateral fins (acting as nose-up fins) described above. However, these fins only come into action with speed and the problem of the diving torque remained at the instant of start-up.

[0182] To overcome this significant drawback, the inventors had the idea of ​​modifying the geometry of the entire motorization device, and more specifically of tilting the propeller axis downwards (i.e. making it dip backwards), so that the thrust direction of the propeller is substantially directed towards the pitch axis of the connection between the device and the boat.

[0183] To maintain the nose-up effect of long-tail engines, this thrust direction can be slightly above the pitch direction as can be seen in Figure 17. In practice, the inventors have estimated with their tests that an angle W of between 1° and 5° was relevant to both limit the intensity of the torque while preserving the existence of a torque to maintain the nose-up torque effect. In the embodiment described here, this angle W is approximately 2°.

[0184] The angle U' between the propeller axis and the oblique section 200 is between 12 and 22°, and in the embodiment shown in Figure 17, approximately 17°. This angle U' is much greater than 3°, which makes it possible to benefit from the advantages resulting from the horizontality of the propeller 18 once immersed as described above in relation to Figure 12.

[0185] This allows, in use, to obtain a diving angle of the oblique bar in the water of approximately 40° in the embodiment described here. This angle is represented in figure 17, by the angle referenced V. This angle corresponds to the angle between the oblique bar and the surface of the water when, at cruising speed, when the entire device is hydrodynamically stable.

[0186] The torque along the pitch axis is more particularly visible in Figure 17. When stopped, the device rests on the rear of the boat, under the action of gravity. When starting, it lifts under the action of the thrust force F generating a pitching torque, as well as under the action of the water flow. The pitch axis of the connecting member being strongly offset forward, this torque remains moderate and therefore easy to control for an operator. At maximum speed, the propeller balances just under the surface of the water, and the front of the engine comes out slightly from the water, allowing rapid navigation in shallow water, typically 20 cm deep.

[0187] The groove produced by this embodiment creates an extra thickness that keeps the propeller entirely underwater, and therefore efficient. The loss of horizontality, approximately equal to 1 — cos (LT) (4.4% for the 17° case above) is then largely compensated by the gain in efficiency due to the fact that the propeller bites entirely into the water. This also makes it possible to recreate the sensation of nose-up torque, appreciated by canoeists accustomed to long-tail engines, and therefore improves the safety and general ergonomics of the device.

[0188] For the reasons explained above, the angle between the oblique section and the surface of the water once the oblique bar is submerged, at cruising speed, remains within the range 30 to 60° described above. We then benefit from the same technical advantages as when the propeller angle and the oblique section is greater than 30°, namely a gain in compactness and a gain in efficiency compared to long-tail motors, in particular for storing the motor device when stationary in small boats, for the length of submerged pole or for maneuverability in turns. Thus, the invention proposes according to a particular aspect that the axis of the propeller is substantially directed towards the pitch angle (i.e. less than 5°).

[0189] According to a more preferred aspect of the invention, this angle is between 1 and 5°, and more preferably approximately 2°.

Claims

CLAIMS 1. Motorization device (10) for a boat (3), capable of being mounted on a boat (3) around a connecting member (12) allowing at least two rotations in independent directions including a yaw direction (Z) of the boat (3), the motorization device comprising: a power module (14), capable of housing at least one battery (140); a motor unit (16) comprising at least one electric motor (160) electrically connected to said power module (14); and a bar-forming member (20, 300, 400), of elongated shape, having a proximal portion (22), close to the connecting member (12), fixed to the power module (14), and a distal portion (24), at a distance from the pivot connection (12), carrying the motor unit (16) so that the motor unit (16) is arranged at a distance from the power module (14); the motor group (16) comprising an output shaft (162) on which at least one propeller (18) is secured.

2. Motorization device according to claim 1, in which the bar-forming member (20, 300, 400) comprises a so-called oblique section (100, 200, 300, 430), arranged between the two distal and proximal portions, extending in a longitudinal direction (V, V') forming an angle of at least 30° with the axis of the propeller (U).

3. Motorization device according to one of the preceding claims, in which the bar-forming member (20, 300, 400) comprises a so-called oblique section (100, 200, 300, 430), arranged between the two distal and proximal portions, extending in a longitudinal direction (V, V') forming an angle of at most 60° with the axis of the propeller (U).

4. Motorization device according to one of the preceding claims, in which the bar-forming member has (20, 300, 400) at least over part of its length a cross-section whose thickness (e) transversely to the propeller axis is at least three times smaller than the width (L).

5. Motorization device according to one of the preceding claims, in which the bar-forming member (20, 300, 400) has a hydrodynamic profile.

6. Motorization device according to one of the preceding claims, further comprising at least one attitude stabilizer (40) secured to the distal portion, close to the propeller (18).

7. Motorization device according to one of the preceding claims, further comprising a protection member (42) arranged under the propeller (18).

8. Motorization device according to one of the preceding claims, further comprising a drawbar (26), fixed to the power module (14) or to the proximal portion (22) of the bar-forming member (20, 300, 400), the drawbar (26) being bent and / or retractable.

9. Motorization device according to one of the preceding claims, in which at least the bar-forming member (20, 300, 400) is made of stainless steel or aluminum.

10. Motorization device according to one of the preceding claims, in which the at least one battery (140) which can be housed in the power supply module is removable.

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