Electric outboard motor

Abstract

[Problem] To provide an electric outboard motor having mounted thereon an air-cooling system capable of simultaneously air-cooling two sources of heat generation, namely an electric motor necessarily mounted on the electric outboard motor and a motor controller for electronically controlling the electric motor, inside the electric outboard motor body without directly exposing either of these sources of heat generation to outside air outside the electric outboard motor body. [Solution] An electric outboard motor characterized in that, in the body of the electric outboard motor: an internal space formed by serially connecting (fastening) a plurality of housings (or housing units) for storing (accommodating) different mechanisms therein is divided into a plurality of compartments; spaces in said compartments are in mutual air communication via common ventilation holes so as to form one air channel system; a ventilation port in air communication with outside air is provided to one end of the air channel system; an exhaust mechanism that forcibly exhausts air from the air channel system (intra-system) is disposed at the other end; and an electric motor and a motor controller having at least an inverter formed from a power semiconductor are disposed in an air passage formed in the air channel system (intra-system).

Description

electric outboard motor

[0001] The present invention relates to an electric outboard motor, and more particularly to an electric outboard motor having an air-cooling system that uses outside air (external air) as a refrigerant to cool the motor controller (electronic control unit) and electric motor, which have power semiconductors, within a housing unit that houses them without exposing them to the outside air while the electric outboard motor is running.

[0002] With the increasing focus on environmental issues in recent years, electric outboard motors, which use electric motors as their power source, have been proposed and are now in use in many places to fundamentally solve the problems inherent to gasoline-powered outboard motors, such as gasoline and lubricating oil leaks and exhaust gas discharge into the water.

[0003] However, while the environmental issues have been resolved, electric outboard motors' performance, particularly the distance they can travel on a single charge, tends to be significantly inferior to that of gasoline-engine outboard motors. This is due to issues inherent in electric outboard motors. The main cause is the deterioration of their "electric fuel economy" (the distance they can travel on 1 kW of power) due to heat generated by the electronic control devices (particularly the electronic control unit (ECU) containing power semiconductors) and the electric motor. This is due to the phenomenon where a portion of the power supplied to the electric motor is converted into heat and consumed by the electronic control unit (ECU) and the electric motor, reducing the actual amount of power consumed. Furthermore, this heat increases the electrical resistance of the electronic circuits and electrical wiring built into the various electronic control devices and the electric motor. This resistance further reduces the power flowing through the circuits, resulting in wasted energy used to generate torque for the electric motor, ultimately resulting in lower electricity economy. Furthermore, there is a potential problem that the ECU itself, which houses the inverter power semiconductors, may burn out and stop functioning or its performance may be reduced, or even if it does not reach that level, the heat from these heat sources may be transferred to other control ECUs, causing the semiconductors mounted there to stop functioning or their performance to be reduced. These potential problems become more pronounced the greater the horsepower of the electric outboard motor, i.e., the higher the voltage supplied to the electric outboard motor.

[0004] To address this potential issue, efforts are being made to improve the "electricity efficiency" of electric outboard motors through a new concept known as thermal management. The primary targets of thermal management in electric outboard motors are the motor controller (particularly the electronic control unit (ECU) having an inverter using power semiconductors) and the electric motor. Mechanisms and methods for dissipating heat generated by the electric motor to the outside of the electric outboard motor can be broadly divided into two types based on the location of the electric motor. Representative prior patent documents include, for example, Patent Document 1 and Patent Document 2 listed below.

[0005] One type, as disclosed in Patent Document 1 (Japanese Patent Publication No. 59-45296), is configured so that an electric motor is placed in front of the underwater propeller and power is supplied from a battery placed on board the boat. The other type, as disclosed in Patent Document 2 (Japanese Patent Publication No. 2005-162055), is configured so that an electric motor is installed above the water surface, similar to a conventional gasoline engine, and the rotational force from the electric motor is transmitted to the underwater propeller via a drive shaft and gear connected below the electric motor to generate propulsion.

[0006] In the former case (Patent Document 1 (JP 59-45296 A)), the heat generated by the electric motor is dissipated by housing the electric motor inside a housing placed underwater, but considering the resistance underwater, it is thought that it would be difficult to increase the size of the electric motor, i.e., to replace a gasoline engine. Also, to house and place a large electric motor inside a housing underwater, another problem arises, in that the support member for this electric motor must also be made larger. Furthermore, in the case of a large electric motor, a power source with a correspondingly large electrical capacity is required, and such a power source must necessarily be an external power source, which inevitably requires complex wiring cables to electrically connect this external power source to the electric motor inside the housing underwater.

[0007] Meanwhile, the outboard motor disclosed in Patent Document 2 takes the above-mentioned circumstances into consideration. It describes an outboard motor 1A divided vertically into three parts, with the upper and lower middle units 3 located in the middle of the three sections attached to the hull 21 via mounts 10 and 11. The electric motor 14, a battery 43 for supplying power to the electric motor 14, and a control unit 44 for controlling the rotation speed of the electric motor 14 are included. The electric motor 14 is located within a middle case 8 that constitutes the middle unit 3 and is located between the mounts 10 and 11. (Abstract from the same document) This outboard motor is positioned above the waterline, similar to conventional gasoline engines, and is equipped with a water-cooled cooling jacket around the electric motor. The coolant used in this case is seawater. To move the coolant, a variable displacement cooling water pump, typically found on gasoline-engine outboard motors, is used. Driven by the rotation of the drive shaft, the coolant is pumped through the pump, e.g., a variable displacement cooling water pump. The document states, "These water-cooled cooling devices can reliably prevent the electric motor 14 from overheating by sending cooling water to the electric motor 14 while the boat is in motion, and because they have a pumping structure similar to that conventionally used for gasoline engines and the like, they are highly reliable and easy to maintain. They are also economical because many parts can be reused." (paragraph

[0040] ) and "Furthermore, because the electric motor 14 is cooled by cooling water, there is no need to provide an outside air intake for ventilation in the upper case 5 or middle case 8. As a result, external moisture such as splashes of water or rainwater while the boat is in motion does not enter the upper case 5 or the motor room 13, improving the durability of electrical components such as the electric motor 14, battery 43, and control unit 44." (paragraph

[0041] ). This shows that the target of thermal management (heat dissipation management) is only the electric motor, and although an oil-cooled type that uses oil as a refrigerant and utilizes an oil jacket as a cooling jacket is also disclosed, in this case too the target of thermal management is only the electric motor.

[0008] Furthermore, the upper case 5, which houses electronic control elements such as an ECU equipped with power semiconductors, has its opening covered by a "lid member 6 for closing the opening of the upper case 5" (paragraph

[0018] of the same document), making it watertight or airtight to prevent "external moisture such as splashes during sailing or rainwater from entering its interior space." However, sufficient consideration is not given to the dissipation of heat generated by the control unit (naturally, such control unit is an ECU (electronic control unit) equipped with a power semiconductor module) that controls the rotation speed of the electric motor. As a result, although the document claims that "...the electric motor 14, which generates heat when continuously operated at high speed, is equipped with a cooling device, the electric motor 14 can be made larger, making it possible to replace a high-output gasoline engine" (paragraph

[0048] of the same document), it is also stated that "the battery 43 is located above the control unit 44" (paragraph

[0029] of the same document). Given this, the electric outboard motor disclosed in the document does not have an external power source, and therefore can be considered to be a medium-sized or smaller electric outboard motor.

[0009] In addition to the water-cooled systems described above, air-cooled systems are also naturally considered for cooling electronic or mechanical units. Air-cooled systems generally have the advantage of being simpler than water-cooled systems, and this approach is also being considered for electric outboard motors. A search of the Japan Patent Office's patent information platform, J-PlatPat, using the keywords "electric outboard motor" and "air-cooled system" revealed the following patent documents: Patent Documents 3 to 14. Of these, Patent Document 14 discloses an invention related to an air-cooled fuel cell unit in a fuel cell-powered electric outboard motor. Looking at the inventions disclosed in Patent Documents 3 to 13, excluding Patent Document 14, all relate to air-cooled electric outboard motors in which the electric motor itself is sealed or watertight to prevent water from entering the motor, while the electric motor is placed directly exposed to the outside air.

[0010] Each of Patent Documents 3 to 13 describes that "a signal cable 81 and a power cable 82 are connected to the electric motor 11 as cables 80 wired from the power supply / control unit 60. The connection between the signal cable 81 and the electric motor 11 is covered by a signal cable cover 18. The opening of the signal cable cover 18, through which the signal cable 81 passes, is sealed by a sealing member 19. The connection between the power cable 82 and the electric motor 11 is covered by a power cable cover 20. The opening of the power cable cover 20, through which the power cable 82 passes, and the attachment portion to the electric motor 11 are sealed by sealing members 21 and 22, respectively." This gives the impression that there will be no problems such as electric leakage caused by channeling between terminals that are directly exposed to the outside air containing external moisture such as seawater splashes and rainwater while the vessel is sailing. However, in a marine environment where the vessel may be exposed to heavy wind and rain, it is generally believed that the effect of simply using sealing members to prevent electric leakage is not very great. Furthermore, all of Patent Documents 3 to 13 only address the electric motor as a target for heat management, and do not propose a mechanism or method for simultaneously dissipating heat from both the electric motor and the electronic control unit (module) that controls the electric motor (particularly, an ECU module having an inverter using power semiconductors) to the outside of the electric outboard motor.

[0011] JP 59-45296 A JP 2005-162055 A JP 2011-213215 A JP 2011-213217 A JP 2011-213220 A JP 2011-213239 A JP 2011-213240 A JP 2011-213241 A JP 2013-39887 A JP 2013-39888 A JP 2013-39890 A JP 2013-86589 A JP 2016-37256 A JP 2018-92816 A

[0012] In any event, there are no prior patent documents that focus on air-cooling methods as part of heat management in the limited technical field of electric outboard motors using conventional technology, and propose a mechanism or method for simultaneously dissipating heat generated by both the electronic control unit (module) that controls the electric motor (particularly an ECU module having an inverter using power semiconductors) and the electric motor to the outside of the electric outboard motor (based on search results on J-PlatPat, the patent information platform of the Japan Patent Office at the time of filing this application).

[0013] The present invention has been made in light of the above-mentioned circumstances, and its object is to provide an air-cooled electric outboard motor that has at least an inverter using power semiconductors, which is always installed in electric outboard motors, and that simultaneously cools the electric motor and an ECU module (commonly referred to as a motor controller) that controls the power supplied to the electric motor using outside air from outside the electric outboard motor as a refrigerant, thereby achieving a simpler structure and fewer parts than water-cooled types, which have high "electricity consumption."

[0014] Another object of the present invention is to enable a propulsion control mechanism that combines an electric motor and a motor controller (an ECU equipped with an inverter using power semiconductors) used in land environments where there is little concern about water leakage or short circuits due to channeling between electrodes to be used in an electric outboard motor in a marine environment where there is frequent exposure to seawater splashes, without the need for any special leakage or waterproofing measures, in a manner that is fully practical for use as is. This makes it possible to fully enjoy the benefits of electric systems that are being improved and refined at a rapid pace in electric vehicles, electric firefighting pumps, and other typical electric mechanisms used in land environments, even in an electric outboard motor, which is a typical electric mechanism used in a marine environment.

[0015] As a result of extensive research into achieving the above-mentioned object, the inventor discovered that the above-mentioned object could be achieved by dividing the interior space of an electric outboard motor body into a plurality of compartments formed by connecting (fastening) in series a plurality of housings (or housing units), each of which houses (accommodates) a different mechanism, and connecting the interior spaces of these compartments in air through common air vents to form a wind tunnel system, providing an air vent at one end of the wind tunnel system that communicates with the outside air and locating an exhaust mechanism at the other end that forcibly exhausts air within the wind tunnel system (within the system), and arranging an ECU module having at least an inverter using power semiconductors, and an electric motor, in an air passage formed within the wind tunnel system (within the system). This led to the development of the present invention.

[0016] That is, a first invention is an externally powered electric outboard motor having at least an electric motor and a motor controller having an inverter using power semiconductors, which is an electronic control unit (ECU) that electronically controls the electric motor, wherein the electric outboard motor body is equipped with at least a first housing unit that houses the motor controller, a second housing unit that houses the electric motor, and a third housing unit that houses a power train mechanism from the electric motor, wherein the first housing unit defines a first compartment, the second housing unit defines a second compartment, and the third housing unit defines a third compartment, The first compartment and the second compartment are in air communication with each other via a common first air communication hole, and the second compartment and the third compartment are in air communication with each other via a common third air communication hole, thereby forming a serial wind tunnel system with the first compartment, the second compartment and the third compartment; the first compartment has an opening mechanism with an opening that is in contact with air outside the electric outboard motor; and the third compartment is in air communication with a discharge mechanism that has an exhaust port that discharges air taken into the wind tunnel system (inside the system) via the opening to the outside of the wind tunnel system (outside the system).

[0017] The second invention is characterized in that, in the first invention, the exhaust mechanism is an exhaust mechanism that forcibly exhausts the taken-in air outside the wind tunnel system (outside the system), and is an exhaust mechanism that can actively or passively place the exhaust port in a negative pressure environment.

[0018] The third invention is characterized in that, in the second invention, the exhaust mechanism is a perforated screw propeller unit having a lumen whose one end is air-communicated with the third compartment and whose other end is air-communicated with the exhaust port.

[0019] A fourth aspect of the present invention is the third aspect of the present invention, wherein the opening mechanism is two openings (first opening and second opening) formed in a housing cover disposed on the open face side of a first ECU housing that forms part of a first compartment accommodating the motor controller having a power semiconductor module that converts DC power from outside the electric outboard motor into AC power, the opening plane of the first opening being perpendicular to the opening plane of the second opening, and the two openings have a labyrinth formed of a plurality of protrusions disposed on the air flow path between the first opening and the second opening.

[0020] The fifth invention is characterized in that, in the fourth invention, the labyrinth has a three-layer structure, and from the first opening side toward the second opening side, the first layer is composed of one plate-like protrusion that forms a folded line toward the first opening side, the second layer is composed of two independent plate-like protrusions whose protrusions form a V-shape, and the third layer is composed of one plate-like protrusion that draws a convex arc upward.

[0021] A sixth invention is characterized in that, in the fifth invention, the opening mechanism further has a third opening, and the third opening is a first air communication hole provided in the bottom wall of the first ECU housing.

[0022] A seventh invention is the sixth invention, characterized in that, in the opening mechanism, an opening plane of the second opening is perpendicular to an opening plane of the third opening.

[0023] An eighth invention is the seventh invention, wherein in the opening mechanism, the second opening is disposed at a higher position than the first opening in a side view of the opening mechanism.

[0024] The ninth invention is the eighth invention, characterized in that in the opening mechanism, a first opening is arranged at the beginning of the air flow path for air taken into the wind tunnel system (inside the system), a third opening is arranged at the end, and a second opening is arranged between them.

[0025] The tenth invention is the ninth invention, characterized in that, in the opening mechanism, of the first opening, the second opening, and the third opening, the first opening is the largest in size, the third opening is the smallest in size, and the second opening is an intermediate size between these.

[0026] An eleventh invention is the tenth invention, characterized in that in the wind tunnel system, the individual air communication holes that make up the second air communication hole group that air-communicates between the first compartment and the adjacent subsequent second compartment are dispersedly arranged around the electric motor when viewed from above the electric outboard motor body.

[0027] A twelfth invention is characterized in that, in the eleventh invention, of the individual air communication holes constituting the second air communication hole group, the position of the air communication hole dedicated to the air passage is higher than the position of the third air communication hole that air-communicates between the second compartment and the adjacent third compartment when viewed from the side of the electric outboard motor body, and the second air communication hole is behind the third air communication hole when viewed from above the electric outboard motor body.

[0028] A thirteenth aspect of the present invention is the twelfth aspect of the present invention, wherein in the wind tunnel system, a third air communication hole that air-communicates between the third compartment and the adjacent subsequent fourth compartment has an upper end opening that is partially blocked by the bottom of a motor case that houses the electric motor when viewed from above the electric outboard motor body, and the cross section of the air communication hole has a zigzag shape consisting of two stages when viewed from the side of the electric outboard motor body.

[0029] The fourteenth invention is characterized in that, in the thirteenth invention, the first compartment houses a first ECU, which is a motor controller equipped with at least a power semiconductor module that converts DC power from outside the electric outboard motor into AC power, and the second compartment houses at least the electric motor controlled by the first ECU.

[0030] The fifteenth invention is the fourteenth invention, characterized in that the third compartment contains at least a drive shaft connected to the rotary torque shaft of the electric motor via a coupling and a water-cooling pump.

[0031] A sixteenth invention is the fifteenth invention, characterized in that in the powertrain mechanism, the drive shaft is linked to the propeller rotation shaft of the perforated screw propeller unit via two bevel gears mounted in a gear case.

[0032] A seventeenth aspect of the present invention is the sixteenth aspect of the present invention, characterized in that the motor room cover housing has a second housing integrally formed therewith at its upper portion for accommodating a contactor unit.

[0033] The 18th invention is characterized in that, in the 17th invention, a second ECU case that houses a second ECU is arranged on the back side of the second housing, and a heat dissipation sheet is inserted between the back side of the second housing and the second ECU case.

[0034] The 19th invention is the 18th invention, further characterized in that the motor basement, which forms part of the housing unit that defines the second compartment that houses the electric motor, is provided with a plurality of integrally molded air-cooling fins that are exposed to the outside air.

[0035] The 20th invention is characterized in that, in the above-mentioned 19th invention, the first housing constituting part of the housing unit defining the first compartment, the motor room cover housing defining the upper half of the second A compartment and the contactor housing integrally molded therewith, the motor room housing and motor basement and their air-cooling fins defining the second B compartment, and the drive shaft housing and gear case defining the third compartment are all formed by die-casting of aluminum or aluminum alloy.

[0036] With an electric outboard motor according to the present invention, when the propeller of the perforated screw propeller unit mounted on the electric outboard motor rotates underwater while the electric outboard motor is operating (while the boat is running using the electric outboard motor), the surrounding area is placed under negative pressure, and as a result, this negative pressure is transmitted to the compartment in air communication with the lumen of the perforated screw propeller unit, placing that space under negative pressure as well. This in turn creates a negative pressure in the space inside the compartment at the other end, which has an opening mechanism that is in contact with air outside the electric outboard motor, and air outside the electric outboard motor (external air) is drawn into the wind tunnel system through the vent in that opening mechanism, forming an air flow path within the wind tunnel system. The present invention makes positive use of this phenomenon, and by arranging a first ECU module, which is equipped with at least a power semiconductor module that converts DC power from outside the electric outboard motor into AC power, and an electric motor in this air flow path, it is possible to achieve the effect of simultaneously air-cooling the first ECU module and the electric motor in a single system using outside air (external air) drawn into the wind tunnel system as a coolant.

[0037] Furthermore, when exhausting the air inside the wind tunnel system (outside air (external air) serving as a refrigerant), a mechanism for generating the air flow can be used not only actively using a propeller, but also passively, taking advantage of Bernoulli's principle, which is manifested when the outboard motor is running. For example, a conventional propeller could be used instead of a perforated propeller, and a submerged exhaust port could be provided at the bottom of the third compartment to exhaust the air inside the wind tunnel system. Alternatively, an opening (e.g., a vertical slit) could be formed above the drive shaft housing that defines the third compartment, in a dry position above the surface of the seawater that has entered the drive shaft housing, even while the outboard motor is running, which would similarly provide a passive exhaust effect for the air inside the wind tunnel system.

[0038] Furthermore, an air-cooled electric outboard motor is provided that has at least an inverter using power semiconductors, which is always installed in electric outboard motors, and that cools the ECU module (commonly referred to as a motor controller) that controls the power supply to the electric motor and the electric motor simultaneously with air outside the electric outboard motor, resulting in an air-cooled electric outboard motor that has a simpler structure and fewer parts than a water-cooled type, while still having high "electricity consumption."

[0039] Furthermore, in a propulsion control mechanism that combines an electric motor and a motor controller (an ECU equipped with an inverter using power semiconductors) used in a land environment where there is little concern about leakage current due to water or short circuits (electrical shorts) due to channeling between electrodes, this mechanism allows electric outboard motors to be used in marine environments where they are frequently exposed to seawater splashes, without any special leakage current or waterproofing measures, and is fully practical for use as is. This makes it possible to fully enjoy the benefits of electric systems that are being improved and refined at a rapid pace in electric vehicles and electric firefighting pumps, which are typical examples of electric mechanisms used in land environments, even in electric outboard motors, which are typical of electric mechanisms used in marine environments.

[0040] FIG. 1 is a right-side perspective view of an electric outboard motor equipped with a wind tunnel system / air-cooling system as an example of an embodiment of the present invention (for convenience, only a transom board and a portion of the power cable are shown). FIG. 2 is a right-side side view of an electric outboard motor equipped with the wind tunnel system / air-cooling system as an example of an embodiment of the present invention shown in FIG. 1 (for convenience, the lanyard 45 in FIG. 1 has been omitted). FIG. 3 is a longitudinal cross-sectional view taken along the fore-and-aft direction of an electric outboard motor equipped with the air-cooling system / wind tunnel as an example of an embodiment of the present invention, showing by dashed dotted lines a conceptual diagram of how outside air flows as a coolant through the body of the electric outboard motor equipped with the air-cooling system / wind tunnel as an example of an embodiment of the present invention (for convenience, the lanyard 45 in FIG. 1 has been omitted). FIG. 4 shows a top view of a first housing unit as an example of an embodiment of the present invention in FIG. 4(a) and a side view in FIG. 4(b). FIG. 5 shows a right-side view of a first housing unit as an example of an embodiment of the present invention in FIG. 5(a) and a rear view in FIG. 5(b). Fig. 6 is a right perspective view of the first housing unit (as viewed from the rear right side of the electric outboard motor 10) as an example of an embodiment of the present invention. Fig. 7 is a conceptual diagram showing the flow of outside air as a refrigerant from the first opening (below the recess) to the second opening (above the recess) in the first housing unit (first compartment) as an example of an embodiment of the present invention. Fig. 8(a) is a conceptual diagram showing the air flow path through the first ECU housing unit (first compartment) where the outside air as a refrigerant enters the first compartment through the second opening of the first ECU housing unit (first compartment) and flows through the first air communication hole. Fig. 8(b) is a longitudinal cross-sectional view taken along the fore-and-aft direction of the first ECU housing unit (first compartment) mounted on the electric outboard motor. Fig. 9 is a conceptual diagram showing an air flow path in which air that enters the secondA housing unit (secondA compartment) through the first air communication hole passes through the second air communication hole group, flows toward the third air communication hole while cooling the area around the electric motor, and then flows further through the third air communication hole into the thirdA housing unit (thirdA compartment). Fig. 10 is a conceptual diagram (conceptual diagram viewed from above) showing the arrangement of the second air communication hole group in a cross-sectional view taken along line A-A in Fig. 9.11 is a conceptual diagram (conceptual diagram as viewed from above) showing the air flow path of air that passes through the second air communication hole group into the secondB housing unit (secondB compartment), flows toward the third air communication hole while cooling the area around the electric motor, and then flows through the third air communication hole into the thirdA housing unit (thirdA compartment) in a cross-sectional view taken along line A-A in Fig. 9. Fig. 12 is a conceptual diagram, in a longitudinal cross-section taken along the fore-and-aft direction of the electric outboard motor, showing the air flow path of air that flows into the thirdA housing unit (thirdA compartment), passes through a hollow portion in the thirdB housing unit (thirdB compartment), passes through the fourth air communication hole, further passes through the fifth air communication hole, passes through a lumen in the perforated propeller, flows to the exhaust port, and is then exhausted to the outside.

[0041] Definitions of Terms 1) Top, upper side, bottom, lower side: With regard to the components and units mounted on the electric outboard motor of this invention, top or top refers to the top or top side when the electric outboard motor is held upright (the side farther from the water surface when the electric outboard motor body is fastened to the transom board at the stern of the boat facing straight up), and bottom or bottom refers to the opposite side, bottom or bottom side, respectively. 2) Front, Fr (Front), Rear, Rr (Rear): The propulsion direction when the electric outboard motor is attached to the transom board at the stern of the boat is called front or Fr (Front), and the opposite direction is called rear or Rr (Rear). Furthermore, when the electric outboard motor body is fastened to the transom board facing straight up, the line or plane that passes through the center point of the electric outboard motor body and is perpendicular to the water surface is called the vertical line or vertical plane of the electric outboard motor body, and the line or plane that is perpendicular to that is called the horizontal line or horizontal plane. 3) The front side (top side) of parts, components, units, etc. in the drawings refers to the front side on the drawing, and the back side (rear side) refers to the opposite side. 4) Air communication: This refers to the state in which air can flow in and out between two spaces through a common vent, vent hole, or lumen. 5) Outside air: This refers to the air outside the electric outboard motor while it is running (air outside the wind tunnel system, described below). 6) Cooling air: This refers to the outside air (outside air) that is drawn into the housing system inside the outboard motor body and functions as a refrigerant to cool the various mechanisms installed within the housing system. 7) Housing system: This refers to the entirety obtained by fastening individual independent housing units together. 8) Compartment: This refers to the internal space of a housing unit defined by individual housing units. Therefore, compartment and housing unit are sometimes used interchangeably. That is, the term housing unit or housing refers to the appearance (hardware) of the same part, and compartment refers to the internal space. 9) Wind tunnel system (or cavity system) refers to the totality of cavities formed inside a housing system that are air-communicated with each other (focusing on the air-communication of the internal spaces).10) An air-cooled system is a system that introduces air from the outside into a wind tunnel system as a coolant and achieves cooling through the flow of that air. Note that in this specification, the terms cooling system and wind tunnel system are sometimes used interchangeably. Therefore, in this specification, the terms wind tunnel system and air-cooled system will be used side by side, and their meanings will be interpreted appropriately according to the context. 11) Inside the system, outside the system: The inside of a wind tunnel system or air-cooled system will be referred to as inside the system, and the outside will be referred to as outside the system. 12) ECU: An abbreviation for Electric Control Unit, meaning an electronic control unit. There are three types of ECUs installed in the electric outboard motor according to the present invention, differing in their functions and control hierarchy: an ECU that controls the electric motor (an ECU equipped with an inverter consisting of power semiconductors that converts DC power to AC power; referred to herein as the first ECU), an ECU that controls drive mechanisms other than the electric motor (referred to herein as the third ECU), and an ECU that is higher in hierarchy than the first and third ECUs and provides overall control of them (referred to herein as the second ECU). There is also an ECU that controls the LEDs (light emitting diodes) installed in the outboard motor according to the present invention (an ECU equipped with a DC / DC converter that supplies DC power after reducing the voltage of the DC power from the outboard power supply; referred to herein as the LED ECU). 13) "Powertrain mechanism" refers to a mechanism located below the electric motor that transmits the rotational torque of the electric motor to the propeller rotating shaft of the perforated screw propeller unit. This mechanism is composed of at least a coupling whose upper end is connected to the rotary torque shaft of the electric motor, a drive shaft connected to its lower end, two bevel gears (a combination of a drive gear and a driven gear) connected to its lower end, and a propeller rotary shaft connected to the driven gear. 14) In a side view means when viewed directly from the side. 15) In a top view means when viewed directly below from above. 16) Integral formation means being formed integrally to form a single continuous body.17) "Integral molding" means molding that is integrally molded to form a single continuous body. 18) "Active" means receiving external rotational energy, such as the rotation of a screw propeller, and actively placing the exhaust opening in a negative pressure environment. 19) "Passive" means forming an exhaust opening, for example, in the shape of a vertical slit, on the side of the upper part of the drive shaft housing (above sea level), and generating a negative pressure environment around the opening according to Bernoulli's law while the electric outboard motor is running.

[0042] An electric outboard motor according to an embodiment of the present invention will now be described with reference to the drawings. The same reference numerals throughout the drawings indicate the same parts or units. Note that the components in the following embodiment can be appropriately substituted or combined with existing components, and the description of the following embodiment does not limit the scope of the invention as defined in the claims.

[0043] 1 is a perspective view (as seen from the front right side of the electric outboard motor 10) showing the appearance of an electric outboard motor 10 equipped with a wind tunnel system / air-cooling system as an example of an embodiment of the present invention, mounted on a transom board and with an external power cable connected. For convenience, only a portion of the transom board 70, which is not part of the present invention, is shown in FIG. 1, and only a portion of the power cable 98 is shown, although it is connected to a power coupler that is connected to the lower side of the outboard motor connection coupler 96.

[0044] The wind tunnel system / air-cooling system as an example of an embodiment of the present invention is mounted inside the outboard motor main body 1 (hereinafter referred to as the "main body 1"). Inside the main body 1, at least the propulsion mechanism of the electric outboard motor 10, including the electric motor 263 (which is actually an electric motor case, but is treated as an electric motor here), which is not visible in FIG. 1 but is shown in FIG. 3, the motor controller that electronically controls the electric motor (it is housed in the first ECU housing unit 100 (first compartment 101, which represents the internal space of the first ECU housing unit 100) shown in FIG. 3, and is therefore not visible in FIG. 3), and a connection cable mechanism that connects the motor controller to an external power source (not shown) (the connection cable mechanism includes the portion of the cable mechanism whose reference numeral 92a extends rearward beyond the cowling cover 21b and into the main body 1).

[0045] The gist of the present invention lies in the wind tunnel system / air-cooling system. Therefore, while it would normally be possible to define the invention using only the components of the wind tunnel system / air-cooling system, in this application the electric outboard motor is also included as one of the defining features of the invention. Therefore, the following describes mechanisms other than the wind tunnel system / air-cooling system that are mounted on the electric outboard motor 10.

[0046] Looking at Figure 1, it can be seen that the electric outboard motor 10 comprises an outboard motor main body 1, other parts (hereinafter referred to as "other mechanisms") that mainly constitute a steering mechanism 2, an external power supply connection mechanism 3, and a connection mechanism 4 (clamp mechanism and swivel mechanism) that detachably and rotatably connects the outboard motor main body 1 to a transom board 70 of the hull. Of the other mechanisms referred to here, the connecting mechanism 4 includes, as shown in FIG. 1, two clamp brackets 62a, 62b that detachably fix the main body 1 to the transom board 70, a swivel bracket (not visible in FIG. 1, but only its upper end surface 64b) that supports the main body 1 so that it can rotate in a horizontal plane, a main body 64 of the swivel bracket (not visible in FIG. 1, but only partially visible in FIGS. 2 and 3; the main body 64 and the upper end surface 64b of the swivel bracket are integrally molded and are an inseparable unit, and the different reference numerals are used for the sake of convenience only), and a steering shaft bracket 66 (not visible in FIG. 1, but only partially visible in FIGS. 2 and 3) that is integrated with the main body 64 of the swivel bracket at the rear and forms a continuous body (not visible in FIG. 1, but only partially visible in FIGS. 2 and 3). The wind tunnel system / air-cooling system mainly includes a motor basement lower mount bracket 285 integrally molded with the motor basement, a steering shaft (not visible in any of the drawings) housed in the steering shaft bracket 66 so as to be rotatable within a horizontal plane, a steering shaft (not visible in FIG. 1 but visible in FIG. 3) housed in the steering shaft bracket 66 and supporting the steering shaft from below, and a yoke assembly (composed of a motor basement lower mount bracket 285 integrally molded with the motor basement, a separate lower mount bracket (not visible in FIG. 1 but reference number 285 in FIG. 2) that forms a pair with the motor basement lower mount bracket, and an attachment boss (not visible in FIG. 1 but reference number 54 in FIG. 2)). However, these structural elements do not constitute a part of the wind tunnel system / air-cooling system according to the present invention.

[0047] Furthermore, the steering mechanism 2 mainly includes a steering arm 47, tiller handle 44, throttle grip 42, friction knob 41, stopper 43, lanyard 45, and monitor window 48 (note that the tiller handle 44 and throttle grip 42 are equipped with electrical equipment typically required for electric outboard motors), but these structural elements do not constitute a part of the wind tunnel system / air-cooling system of the present invention. If anything, the friction knob 41, which starts the electric motor that is mechanically connected via the powertrain to the rotation of the propeller 504 in the air-cooling system, which forcibly (actively) generates an air flow that uses the outside air as a refrigerant inside the wind tunnel system, could be said to be related, albeit indirectly, to the air-cooling system of the present invention. From this perspective, it can also be said that the connection cable mechanism 3 that connects the motor controller (shown by reference number 123 in Figure 8: housed in the first ECU housing unit 100 (or the first compartment 100A formed therein) consisting of the first ECU housing 102 and its cover 106 shown in Figure 3) that controls the starting of this electric motor to an external power source is indirectly related to the air-cooling system of the present invention.

[0048] 1, if we were to explain the propulsion mechanism using the electric motor of the electric outboard motor 10, it would be necessary to refer to components not shown in Fig. 1, which would be somewhat difficult to understand, so we will now jump ahead to Fig. 3 (details of Fig. 3 will be explained later), and explain it as follows: The electric outboard motor 10, which has the wind tunnel system / air-cooling system of the present invention mounted inside the main body 1, has an electric motor (which is housed in a motor case 263 and therefore cannot be seen from the outside and is not shown in any of the drawings) in a motor room housing 282 located rearward of and at approximately the same height as the swivel bracket 64 (not visible in Fig. 1, but only its upper end surface 64b is shown), and a second compartment 220A, which is located above a second compartment B 280A defined by the motor room housing 282 (which constitutes the second housing B 280) and which is in air communication with the second compartment B 280A. An electronic control unit (first ECU indicated by reference number 123 in FIG. 8) that controls the electric motor is housed inside the first ECU housing unit 100 (defining the first compartment 100A), which is air-communicative with the 2A housing 224 (defining the 2A compartment 220A). Electric power from an external power source (not shown in FIG. 1) is supplied by a cable (not shown in FIG. 3) that is routed inside the outboard motor main body 1 as an extension of the outboard motor side cable 92a and that leads to a contactor 229 (housed inside the contactor housing indicated by reference number 221 in FIG. 3 and not visible from the outside), and from there to the first ECU.

[0049] 3, the power train from the electric motor to the propeller unit 502 is mounted through the drive shaft housing 302, the gear case housing 404, and the gear case 404a, and specifically includes a coupling 271 connected to the motor shaft of the electric motor, a drive shaft 322 connected to the lower side of the coupling 271, a bevel gear B 408 (drive gear) provided at the lower end of the drive shaft 322, a bevel gear A 409 (driven gear) configured to mesh with the bevel gear B 408, and a propeller shaft 411 having the driven gear at one end. The configuration and structural elements of this power train are basically the same as those known in the art, and a description of these mechanisms and elements will be omitted below because they are not necessary for describing the wind tunnel system / air-cooling system according to the present invention.

[0050] Now, let's return to the explanation from Fig. 3 to Fig. 2. Fig. 2 is a right side view showing the appearance of the electric outboard motor 10 in Fig. 1. Comparing Fig. 2 with Fig. 1, the only differences are that the connecting mechanism 4 (clamp mechanism and swivel mechanism) in Fig. 1 is somewhat easier to distinguish in Fig. 2 and that the cooling fin designated by reference numeral 287 is more clearly visible. For the sake of convenience, the lanyard 527 that was visible in Fig. 1 has been removed from Fig. 2.

[0051] As shown in Figure 2, the main body 1 can be divided into an upper section 1a and a lower section 1b. The upper section 1a of the main body 1 is located inside cowling covers 21a and 21b (preferably made of plastic), and most of the upper section 1a is surrounded by the cowling covers 21a and 21b. The upper front portion of the cowling cover 21b has an opening through which the left and right arm portions 47a and 47b of the steering arm 47 (only the right arm portion 47a is visible in Figure 2) pass. The space beyond this, designated by reference numeral 222 in Figure 3, where the upper mount arm (not visible in Figure 2) is secured to the main body 1, is watertight. The outlet 91, through which part of the main body 1 connection cable 92a is pulled out to connect it to an external power source (not shown), is a grommet with an insertion hole, and is watertight when the outboard motor connection cable 92a is inserted. Meanwhile, the lower end of the cowling 21a terminates slightly below the lower end of the motor basement 288, while the lower end of the cowling cover 21b terminates on the upper surface of the motor basement 288. Although a slight gap is left between the outer peripheral surface of the motor basement 288 and the inner surface of the cowling 21a around the entire circumference, it is unlikely that outside air (external air) will flow into the cowlings 21a and 21b from the lower end of the cowling 21a during sailing, thereby cooling the various functional elements mounted or arranged in the upper section 1a. Therefore, heat tends to build up inside the cowlings 21a and 21b. This is due to the fact that the design is designed to be as slim as possible in the vertical direction, i.e., to give the impression of being elongated, with an emphasis on the exterior design. This leads to the specific problem that the present invention aims to solve, as described in detail below.

[0052] 2 in combination with FIG. 3 , which will be described below, shows that in the space approximately in the lower half of the upper section 1a, i.e., in the second-B housing unit 280 (second-B compartment 280A), an electric motor 263 (the electric motor housed in the motor case 263, although interchangeable reference numerals will be used hereinafter) is air-cooled by the air-cooling system of the present invention using outside air as a refrigerant. The electric motor 263 is housed in the motor case 263 and is mounted on the upper surface of the motor basement 288 by bolts. In the following description, the electric motor 263 may also be referred to as the motor body. The electric motor 263 mounted here is a rotor / stator type electric motor. There is no limitation on the type, and other types of electric motors can also be suitably used. For example, one of the features of the present invention is that the present invention can be suitably used with electric motors used in land environments, such as electric vehicles or electric fire pumps, or general-purpose electric motors thereof.

[0053] The electric motor 263 used in the electric outboard motor according to the present invention is not equipped with a water jacket or oil jacket for cooling. In the present invention, the heat generated by the electric motor 263 is dissipated by an air-cooling system using the outside air in a marine environment (or on-water environment) as a coolant, as described below. However, the inclusion of a water jacket or oil jacket to improve heat dissipation efficiency is not excluded. The electric motor used in the present invention is an electric motor commonly used in land environments, and standardized products that meet predetermined standards can be used for this purpose. While special processing to meet or exceed the specified standard level is not excluded in some cases, when used in conjunction with the air-cooling system according to the present invention, no further special processing is required, even when used in a marine environment. Thus, one of the features of the electric outboard motor 10 according to the present invention is that it can be used in a marine environment, which is a harsh environment for electronic devices, without any further special processing or additional heat dissipation mechanism, as long as the standardized product meets the specified standards for use in a land environment.

[0054] Next, an overview of the lower section 1b in Figure 2 will be described. A powertrain mechanism similar to that of a known electric outboard motor is mounted on this lower section 1b. Specifically, the rotational torque of the electric motor 263 is transmitted to a coupling 271 connected to its lower side, and then to a drive shaft 322 connected to the lower end of the coupling 271. In the present invention, the coupling 271 is directly connected to the rotating shaft (not shown) of the electric motor 263, with no reduction gear interposed between them. However, a reduction gear may be suitably applied in some cases, if necessary.

[0055] The lower end of the drive shaft 322 is connected to a bevel gear B408, which serves as a drive gear, and the bevel gear B408 is configured to mesh with a bevel gear A409, which serves as a driven gear, and the meshing of these two gears converts the vertical rotation axis of the drive shaft 322 into a horizontal rotation axis, which then serves as the rotation axis of the perforated screw propeller unit 506. Through these mechanisms, the rotational torque of the electric motor 260 becomes the rotational torque of the perforated screw propeller unit 502. Note that the above powertrain mechanism can also be suitably applied to any known powertrain mechanism that is commonly used in gasoline engine outboard motors.

[0056] The perforated screw propeller unit 502 according to the present invention is of the same format / type as a perforated screw propeller unit in a gasoline engine outboard motor that has the function of discharging exhaust gas from the gasoline engine into the sea. In this respect, the electric outboard motor 10 according to the present invention has the advantage of being able to use the same units or actively utilize general-purpose products.

[0057] Please note that the explanation up to this point has been given in the order of the figures in the drawings, but from here on, the explanation will be given in a format that makes it easier to understand the gist of the present invention, and will not follow the order of the figures.

[0058] <Outline of Wind Tunnel System / Air-Cooling System> Next, an outline of the wind tunnel system / air-cooling system of the present invention will be described with reference to FIG. 3 (details will be provided later). FIG. 3 is a partial longitudinal cross-sectional view of the main body 1 of an electric outboard motor 10 incorporating a wind tunnel system (or air-cooling system) as an example of an embodiment of the present invention, illustrating the essential components of the main body 1. In FIG. 3, wavy brackets indicate each housing unit installed (mounted) at a particular height within the main body 1. The reason for using wavy brackets is that indicating each housing unit (comprised of multiple components) with a lead line would make the drawing more complicated and difficult to understand, and is therefore for convenience's sake only. Also, immediately below the reference number written next to each wavy bracket (on the right or left side), a reference number with the Roman letter A added to the reference number is written in parentheses. This is the reference number of the compartment when describing the internal space formed by each housing unit. This interrelationship is assumed in the following description.

[0059] According to the correspondence between the housing units and their corresponding compartments (which simply refer to the same parts with different names), the wind tunnel system / air-cooling system according to the present invention can be roughly divided into five parts, as shown in Fig. 3, when focusing on the housing units (or compartments) that constitute it: first housing unit 100 (first compartment 100A), second housing unit 200 (second compartment 200A), third-A housing unit 300 (third-A compartment 300A), third-B housing unit 400 (third-B compartment 300B), and fourth housing unit 500 (fourth compartment 400A). Of these, second housing unit 200 (second compartment 200A) is further divided into second-A housing unit 220 (second-A compartment 220A) and second-B housing unit 280 (second-B compartment 280A).

[0060] The wind tunnel system of the present invention is mounted within the main body 1 and is formed by an air-communicating continuous space of spaces (compartment spaces) defined within individual housing systems that protect various mechanisms from the external environment, and the individual housing units that make up this housing system, as shown in Figure 3, include a first housing unit 100, a second housing unit 200, a third-A housing unit 300, and a third-B housing unit 400. In the figure, the member designated by reference number 506 is a propeller unit, but since the space defined within this propeller unit 506 is also space, this propeller unit 506 can also be said to be the fourth housing unit 400, and a compartment that defines compartment 400A therein. Here, the first housing unit 100 (first compartment 100A) is mainly composed of the first ECU housing 102 and its cover 106, and the second housing unit 200 (second compartment 200A) is composed of the second A housing unit 220 (second A compartment 220A) and the second B housing unit 280 (second B compartment 280A). The second A housing unit 220 (second A compartment 220A) is composed of the second A housing 224, which is a motor room cover housing part, a gasket 231, and an electric motor cover 262. The second B housing unit 280 (second B compartment) is composed of a gasket 231, a substantially cylindrical motor room housing 282, and a motor basement 288, the third A housing unit 300 (third A compartment 300A) is composed of a drive shaft housing 302, the third B housing unit 400 (third B compartment 300B) is composed of a gear case housing 404 and a gear case 404a, and the fourth housing unit 500 (fourth compartment 400A) is essentially composed of a propeller unit 506.

[0061] In Figure 3, dashed lines are drawn, which conceptually show the air flow paths that flow through the series of housing units (or compartments) described above. Figure 3 is a vertical cross-sectional view and is two-dimensional information, but the air flow paths are three-dimensional information. Therefore, it is logically unreasonable to depict the three-dimensional information of the air flow paths in a vertical cross-sectional view, which is two-dimensional information. However, this is not considered to be an obstacle to understanding the gist of the present invention.

[0062] The main points of the air cooling system constituted by the wind tunnel system of the present invention will be described below with reference to FIG. That is, the internal spaces (i.e., compartment spaces) of the first housing unit 100 (first compartment 100A), second housing unit 200 (second compartment 200A), thirdA housing unit 300 (3A compartment 300A), thirdB housing unit 400 (3B compartment 400A), and fourth housing unit 500 (fourth compartment 500A) (i.e., perforated propeller units) shown in FIG. 3 are all air-communicated to one another via common air passage openings (air communication holes or air communication openings). Therefore, while the electric outboard motor 10 is running, that is, when the propeller unit 506 (fourth housing unit 500) is rotated in the sea / underwater to propel the electric outboard motor 10, the rotation of the propeller 504 of the propeller unit 506 creates a negative pressure environment around it. This negative pressure environment is then transmitted from propeller unit 506 (fourth housing unit 500 (fourth compartment 500A)) to third-B housing unit 400 (third-B compartment 300B), which is air-communicating with propeller unit 506, causing the third-B housing unit 400 to be placed in a negative pressure environment. Next, the internal space of third-A housing unit 300 (third-A compartment 300A) is placed in a negative pressure environment. This negative pressure environment is then transmitted to second housing unit 200, causing the internal space of second housing unit 200 (second compartment 200A) to be placed in a negative pressure environment. Next, this negative pressure environment is transmitted to first housing unit 100, causing the internal space of first housing unit 100 (first compartment 100A) to be placed in a negative pressure environment.

[0063] In this way, the negative pressure environment gradually spreads, and eventually the internal space (first compartment 100A) of the first housing unit 100 enters a negative pressure environment, causing outside air (external air) as a refrigerant to flow into the internal space (first compartment 100A) of the first housing unit 100 through the outside air intake provided in the first housing unit 100.

[0064] This air then flows in the opposite direction, passing through each air communication hole in turn through the second housing unit 200, the third-A housing unit 300, the third-B housing unit 400, and finally to the propeller unit (fourth housing unit 500) that is in air communication with the third-B housing unit 400, where it is discharged into the sea / underwater through the opening 502. The motor controller to be cooled and the electric motor operating under its control are located along this series of air paths (pathways for outside air (external air) as a coolant). This allows the air outside the main body 1 of the electric outboard motor 10 (air from the marine or surface environment) to be used as a coolant to cool the heat generated by these components while the boat is underway. Note that in the above description, substituting the term "housing unit" for the corresponding compartment will facilitate understanding of the mechanism. While the above are the main features of the wind tunnel system as an example of the present invention, the following are key features that deserve particular attention. The configuration and mechanism of air communication at each of the locations mentioned below will be described in detail later.

[0065] <Major Features of the Wind Tunnel System / Air Cooling System> Each housing unit in the present invention defines a corresponding compartment therein, with the following correspondence: first compartment 100A defined by first housing unit 100, second compartment 200A defined by second housing unit 200, third compartment 300A defined by the combination of third-A housing unit 300 and third-B housing unit 400, and fourth compartment 500A defined by fourth housing unit 500 (i.e., propeller unit 502).

[0066] Based on this correspondence, while maintaining the essential spatial positional relationships of the individual housing units (or individual compartments), the wind tunnel system of the present invention can be considered. The main features of the wind tunnel system / air-cooling system of the present invention, as shown in the longitudinal cross-sectional view of Figure 3, are as follows: 1) First compartment 100A (first housing unit 100): As shown in Figure 3, there are two outside air intakes (first intake 130 and second intake 132) that come into contact with the outside air (external air). This feature is clear from the spatial arrangement of reference numerals 130 and 132 in Figures 8(a) and 8(b). A labyrinth 113 is located between the first intake 130 and the second intake 132. This feature is clear from Figures 7 and 8. The opening planes of the first intake 130 and the second intake 132 are configured to be perpendicular to each other (this is difficult to discern from Figure 3, but is shown in Figure 8). Therefore, outside air (external air) first enters through the outside air intake 130, then flows around and through the labyrinth 113 (this phenomenon occurs because the back surface (recess side) of the recess cover 112 abuts against the upper end of the labyrinth 113, as is clear from FIG. 8( b) ), toward the second intake 132, from which it flows into the first compartment 100A. This compartment is in air communication with the second A compartment 220A (second A housing unit 220) described below via the first air communication hole 226. This compartment houses the motor controller 123 (first ECU module 123), which is one of the objects to be air-cooled by the air-cooling system of the present invention using outside air as a refrigerant. The first ECU module 123 is in close contact with the bottom wall 111 of the first housing 102, with a heat dissipation sheet (not shown) sandwiched between heat dissipation fins 124 provided on the bottom 122 (heat dissipation plate) of the first ECU module 123 and the bottom wall 111 of the first housing 102. There are no particular restrictions on the diameter of the first air communication hole 226, but it is preferable to set the size in a balanced manner taking into account the capabilities of a perforated screw propeller (described later) and the like, so that the air flows as fast as possible when it passes through the hole.

[0067] 2) Second-A compartment 220A (second-A housing unit 220): As shown in FIG. 3, this compartment is basically defined by a motor room cover housing 224, through which a conductive cable connecting the motor controller 123 and the electric motor 260 passes. This compartment is in air communication with the second-B compartment 280A (second-B housing unit 280) described below via a second air communication hole group 234 and a conductive cable insertion hole group 232. Note that only outside air serving as a refrigerant passes through the holes in the second air communication hole group 234, but the second air communication hole group 232 was originally a hole through which the above-mentioned conductive cable was passed, and the gap between the conductive cable and the hole also functions as an air communication hole.

[0068] 3) Second-B compartment 280A (second-B housing unit 280): As shown in FIG. 3 , this compartment houses the electric motor 263, which is one of the components cooled by the air-cooling system of the present invention using outside air as a refrigerant. A plate (not shown) having a hole 292-1 is inserted between the electric motor 263 housed in this compartment and a motor basement 288 to which the electric motor 263 is fixed. The electric motor 263 is fixed to the motor basement 288 with a plurality of stud bolts (not shown) so that its bottom partially covers the hole 292-1 formed in the plate. The uncovered portion of this hole 292-1 overlaps and combines with a hole 292-2 formed in the motor basement 288 to form third air communication holes 292 (292-1, 292-2) that have a two-stage zigzag shape in vertical cross section in side view. The second B compartment 280A (second B housing unit 280) is in air communication with the third A compartment 302A (third A housing unit 302) described below via the combined third air communication holes 292 (292-1, 292-2).

[0069] 4) Third-A compartment 302A (third-A housing unit 302): As shown in FIG. 3 , this compartment is defined by the drive shaft housing 302 that houses the drive shaft 322 that constitutes part of the powertrain of the main body 1 of the electric outboard motor 10. From the perspective of the air-cooling system of the present invention, the third-A housing unit 302 that constitutes this compartment does not actively support the cooling system of the present invention, but rather serves a passive role of connecting the second-B compartment 280A (second-B housing unit 280) and the third-B compartment 404A (third-B housing unit 404) described below. This facilitates the use of common parts. This compartment is in air communication with the third-B compartment 404A (third-B housing unit 404) described below via the fourth air communication hole 407a. Before the electric outboard motor 10 starts to sail, when the main body 1 is tilted down and the propeller unit 506 is lowered below sea level, and for a while after sailing begins, most of the underside of this compartment, and in some cases even a portion close to the underside of the motor basement 288, is below sea level; however, as the boat continues to sail in this state for a while, air is introduced into the upper part of this compartment, the water level inside the compartment drops, and eventually the compartment is air-communicated with the third B compartment 404A (third B housing unit 404) below, allowing air to flow from top to bottom.

[0070] 5) Third compartment 404A (third housing unit 404): Specifically, as shown in FIG. 3, this is the gear case housing 404. It houses the bevel gear A 409 (driven gear) combined with the bevel gear B 408 (drive gear) connected to the lower end of the drive shaft 322, which are main structural elements constituting part of the power train from the electric motor 260, and the propeller shaft 411. This compartment is air-communicated with the fourth compartment 500A (fourth housing unit 500), described below, i.e., the vent 507 in the perforated screw propeller unit 506, via the fifth air communication hole 405, as shown in FIG. 1. Like the above compartment, this compartment is entirely below sea level when the main body 1 is tilted down and the propeller unit 506 is lowered below sea level before the electric outboard motor 10 starts to sail, and for a while after sailing begins. However, as the boat continues to sail, the water level in this compartment drops and eventually the compartment is air-communicated with the fourth compartment 500A (fourth housing unit 500) below, allowing air to flow from right to left as you look at the drawing.

[0071] 6) Fourth compartment 500A (fourth housing unit 500): Specifically, as shown in FIG. 3, this is the perforated screw propeller unit 506 itself. In a gasoline-engine electric outboard motor, this unit has a bore 507 (vent 507) configured to allow exhaust gas from the gasoline engine to be discharged into the sea (the vent 507 is formed between the propeller shaft 411 and the inner surface of the propeller boss (a cylindrical member integrated with the propeller) and extends around the entire periphery of the propeller shaft 411). This component is generally referred to as a "perforated propeller" or "aluminum propeller" in the outboard motor industry. This configuration offers the advantage of enabling standardization and recycling of components. Like the above compartment, this compartment is entirely below sea level when the main body 1 is tilted down and the propeller unit 506 is lowered below sea level before the electric outboard motor 10 begins to sail, and for a while after sailing begins, but as the boat continues to sail for a while, the water in this compartment is pushed by the air drawn out from the wind tunnel system, and eventually the compartment is air-connected to the exhaust port 502, and the air begins to flow from right to left as viewed in the drawing. A major feature of this configuration is that no dedicated mechanism is required to drive the perforated screw propeller unit 506, which creates a negative pressure environment around it by rotating underwater, and this driving force comes from the electric motor 263, which is the core of the powertrain with the perforated screw propeller unit 506 at its tip, while the boat is sailing.

[0072] It is preferable that the diameter size of each of the individual air communication holes constituting the first air communication hole 226, the second air communication hole group 234 and the second air communication hole group 232, the third air communication hole 292 (292-1, 292-2), the fourth air communication hole 407 and the fifth air communication hole 405 be set to a balanced size that takes into consideration the ability to create a negative pressure environment caused by the rotation of the perforated screw propeller underwater, i.e., the ability to discharge the refrigerant air in the wind tunnel system into the water, so that the air flows as fast as possible when it passes through the hole, thereby smoothing the flow of refrigerant air in the wind tunnel system and preventing the creation of stagnation areas of refrigerant air.

[0073] The air flow indicated by the dashed-dotted lines in Figure 3 is roughly as follows: First, outside air serving as a refrigerant flows into the first outside air intake 130 (i.e., the first outside air intake 130 formed by the recess 116 and the recess cover plate 112) formed in the first housing unit 100 (first compartment 100A). The air flowing in from here passes upward around the labyrinth 113 and reaches the second outside air intake 132 above. From there, when it flows into the first housing unit 100 (first compartment 100A), it changes direction by 180 degrees and flows downward, enveloping the first ECU module 123 housed in the first housing unit 100 (first compartment 100A) and flowing toward the first air communication hole 226 along the entire surface of the first ECU module 123. The air then passes through the first air communication hole 226 and flows into the secondA housing unit 200 (secondA compartment 200A) in a generally horizontal direction while maintaining a generally single stream, and hits the wall of the secondA housing 224 (the wall facing forward of the electric outboard motor 10), where it splits into roughly two directions along the curved surface of the wall, branching downward as well, changing direction and flowing toward the second air communication hole group 234. Next, the air that has passed through this second air communication hole group 234 flows into the upper rear part of the gap between the secondB housing 282 and the electric motor 263, and flows through this gap toward the third air communication hole 292, tracing the entire circumference of the outer surface of the electric motor 263. Here, the air passes through a two-stage zigzag flow path formed in third air communication hole 292, passes downward through third air communication hole 292, and flows into the cathedral space formed in third-A housing unit 300 (third-A compartment 300A), i.e., drive shaft housing 302. After this, it flows through this cathedral space toward opening 407a of third-B housing unit 400 (third-B compartment 300A), passes downward through the cathedral space below opening 407a, reaches fourth air communication hole 407, changes direction by approximately 90 degrees, passes through fifth air communication hole 405, flows into lumen 507 in fourth housing unit 500 (fourth compartment 400A), flows along it toward exhaust port 502, and is finally exhausted from this exhaust port 502 to the outside of the system.

[0074] As shown in FIG. 3, the first compartment 100A defined by the first housing unit 100 houses the first ECU module (123 in FIG. 8) (an ECU module that implements at least an inverter electronic circuit and a motor controller electronic circuit using power semiconductors), and the electric motor 263 is housed in the second B housing unit 280 (second B compartment 280A). Therefore, the first ECU module (123 in FIG. 8) and the electric motor 263, which are to be air-cooled, are arranged in the flow path of the air flow described above, and therefore these two heat sources are simultaneously air-cooled by outside air used as a refrigerant.

[0075] 3 also shows the following characteristics: A second-A compartment 220A defined by the second-A housing unit 220 and a second-B compartment 280A defined by the second-B housing unit 280 are formed by dividing the internal space of the second housing unit 200 into two spaces by a common gasket 231. No active functional elements are housed in the second-A compartment 220A defined by the second-A housing unit 220, and this second-A compartment 220A is a space through which power distribution and wiring cables pass.

[0076] The second-B compartment 280A defined by the second-B housing unit 280 accommodates the electric motor 263. The third-A compartment 300A defined by the third-A housing unit 300 accommodates the coupling 271 and drive shaft 322 that constitute part of the drive train, and the fourth compartment 300B defined by the third-B housing unit 400 accommodates the bevel gear B (drive gear) 408, the bevel gear A (driven gear) 409, and the shaft support member 403 that supports the rotation shaft of the perforated screw propeller.

[0077] The first compartment 100A defined by the first housing unit 100 and the second A compartment 220A defined by the second A-housing unit 220 are air-communicated via a common first air communication hole 226 (an air vent (first air vent) formed by butting together the outlet side (not shown) of the air vent 118 in FIG. 5 and the inlet side of the air vent 227 on the second A housing 224 side), which will be described later.

[0078] Furthermore, the second A compartment 220A defined by the second A-housing unit 220 and the second B compartment 280A defined by the second B-housing unit 280 are air-communicated via a group of air holes (second air communication hole group 234) formed by a combination of the air vent 233 provided in the gasket 231 and the hole for inserting the distribution cable (232 in Figure 6).

[0079] Furthermore, the second-B compartment 280A defined by the second-B housing unit 280 and the third-A compartment 300A defined by the third-A housing unit 300 are air-communicated via an air vent provided in the motor base plate 286 (air vent 292-1 when viewed from the second-B housing unit 280 (second-B compartment 280A) side) and an air vent provided in the motor basement 288 (air vent 292-2 when viewed from the third-A housing unit 300 (third-A compartment 300A) side). This air vent is referred to as the third air communication hole 292.

[0080] Furthermore, the third A compartment 300A defined by the third A housing unit 300 and the fourth compartment 300B defined by the third B housing unit 400 are air-communicated via an air passage that is hollow downward from the opening 407a in the third housing unit 300 and continues to the fourth air communication hole 407.

[0081] Finally, the third-B compartment 300B defined by the third-B housing unit 400 and the exhaust port 502 of the perforated screw propeller unit 506 are air-communicated via a fifth air communication hole 405 of the third-B compartment 300B. Note that a support member 403 that rotatably supports the propeller shaft 411 is fitted into the fifth air communication hole 405, so that an air passage is provided not over the entire surface of the lumen inside the perforated screw propeller unit 506, but rather by an air passage with a limited cross-sectional size corresponding to the fifth air communication hole 405.

[0082] <Housing System> The essential components of the housing system according to the present invention are shown in FIG. 3. As shown in FIG. 3, the housing system according to the present invention is composed of multiple housing units (first housing unit 100, second housing unit 200, thirdA housing unit 300, thirdB housing unit 400, and fourth housing unit 500) that are fastened to each other and connected in series. FIG. 3 is a partial vertical cross-sectional view focusing on the essential components of a housing system configured such that the housing units that house the various mechanisms mounted inside the outboard motor main body 1 of the electric outboard motor 10 according to the present invention are separated into compartments, and the internal spaces of the compartments are air-communicated with each other to form a single air-communication space system as a whole (hereinafter referred to as a "wind tunnel system" or "cavity system," and the terms will be used interchangeably as appropriate). For convenience, the interior of the wind tunnel system formed by this housing system will be referred to as the "inside system," and the exterior will be referred to as the "outside system."

[0083] As shown in Figure 3, the housing system constituting the wind tunnel system according to the present invention is composed of a series connection (connection) of first to fourth housing units, each of which corresponds to the following reference numbers. The elements constituting each housing unit, or the adjacent housing units, are fastened together by bolts using a known general fastening method, with O-rings or gaskets inserted between them as necessary, thereby maintaining watertightness or airtightness at the fastened portion.

[0084] <First ECU Housing Unit> Figures 4 to 8 show the first ECU housing unit 100 (the combination of the first ECU housing 102 and its cover 106) mounted on the electric outboard motor 10. Figure 4(a) is a top view, Figure 4(b) is a front view, Figure 5(a) is a right side view, and Figure 5(b) is a bottom view. Figure 6 is a perspective view from above on the right side, and Figure 7 shows, with the recess cover plate 112 in Figure 6 removed, how outside air, acting as a refrigerant drawn from outside, flows around and through the labyrinth 113 formed in the recess 116 toward the second outside air intake 132, using dashed and dotted lines. FIG. 8(a) shows this configuration from the front of the first ECU housing unit 100 (the front when viewed from the rear to the front of the electric outboard motor 10), and FIG. 8(b) shows a vertical cross section (a vertical cross section along the fore-and-aft direction of the electric outboard motor 10) of the first ECU housed in the first ECU housing unit 100. In this vertical cross section, the flow path of air (outside air as refrigerant) drawn into the system is represented by a dashed-dotted line. The air flow at this time is as described above, and can be more easily understood by reviewing FIG. 8(b). Note that FIG. 8(b) shows the cross section of the first air communication hole 118 in detail. 8(b) shows the vertical cross section of the first ECU module 123, in which the heat dissipation fins of the first ECU module 123 abut against the bottom wall 111 of the first ECU housing 102 (a heat dissipation film is inserted between them but is not shown), thereby providing not only an air-cooling effect but also an auxiliary heat dissipation effect by thermal conduction for dissipating heat from the first ECU module 123. Although numerous reference numbers are given in Figures 4 to 8, they are not particularly important structural elements for understanding the wind tunnel system / air-cooling system according to the present invention, so detailed explanations will be omitted here and refer to the explanation column for the reference numbers.

[0085] 4 to 8 show a configuration in which a first ECU housing cover 106 (hereinafter sometimes simply referred to as the "cover") is placed over the open side of the first ECU housing 102. As shown in FIG. 8B, a first ECU module 123 is housed in a first compartment 100A defined by the first housing unit 100. The first housing unit 100 includes a substantially rectangular box-shaped first ECU housing 102 with one open side, a first ECU housing cover 106 (hereinafter referred to as the "cover") covering the open side, an O-ring 104 inserted between the first ECU housing 102 and the first ECU housing cover 106, a recess cover plate 112 for partially closing the entrance of a recess formed on the top surface of the cover, and a side cover 108 (serving as a grommet) for the first ECU housing 106, which define the first compartment 100A. As described above, the first ECU housing 102 is made of aluminum or an aluminum alloy and is formed by die-casting. In addition, its size is adjusted to match the size of the first ECU module 123 to be housed therein, and at the same time, when the base plate 122 of this first ECU module 123 is screwed to the bottom wall (111 in Figure 11) of the first ECU housing 102, the gap formed between the surrounding surface of this first ECU module 123 and the inner surface of the side wall (112 in Figure 11) of the first ECU housing 102, and further the gap formed between it and the inner surface of the cover 106, is appropriately set so that cooling air with outside air as refrigerant can achieve the air-cooling effect intended by the present invention.

[0086] The first ECU module 123 housed in the first housing unit 100 houses a motor controller (first ECU (electronic control unit or electronic control module)) that has at least the functions of an inverter that converts DC power introduced from an external power source (not shown) into AC power for the electric outboard motor main body (1 in FIG. 2) and a controller that controls the power supplied to the electric motor main body (housed in the electric motor 260) to control its rotation speed. This first ECU 123 can be suitably a well-known, general motor controller generally referred to as a power conversion device, and can also be suitably used, for example, a motor controller used in a power conversion device for an electric vehicle or an electric pump. This first ECU is under the control of a second ECU (not shown), which is the highest level and controls the entire propulsion mechanism of the outboard motor main body.

[0087] <First ECU Housing> The first ECU housing 102 is a component indicated by reference numeral 102 in Figures 3 to 8. The first ECU housing 102 is die-cast separately from the other housings, and then bolted to the back (rear) side of the upper mount arm end accommodating space 222 and contactor housing portion 221, which protrude continuously above the motor room cover housing portion 224. The motor room cover housing portion 224, the upper mount arm end accommodating space 222, and the contactor housing portion 221 are integrated into a continuous body by die-casting, and in this specification, this integrated whole will sometimes be referred to as the ECU housing for convenience.

[0088] The following features can be seen from Figures 3 to 8. The first ECU housing 102 is rectangular with rounded corners at the opening on the open side, and the upper end surfaces of the rims on the four sides of the rectangular opening lie within a single plane along their entire length. The thickness of all four side walls of this box-shaped housing 102 is approximately the same. The shape, depth, and size of this box-shaped housing 102 are appropriately determined to match the shape, height, and size of the first ECU module (123 in Figure 8) to be installed therein, so as to achieve the air-cooling effect intended by the present invention. A groove is formed around the entire rim along a center line passing through the center of the width of the rim of this side wall. A well-known, general-purpose rubber O-ring is inserted into this groove 114, forming a watertight and airtight structure between the rim on the open side of the first ECU housing cover 106 and its flat upper end surface, preventing water from penetrating (or air from entering) into the first housing unit 100 from the outside. The watertight structure is not limited to this, and other known watertight structures can also be suitably employed.

[0089] The rectangular open surface of the first ECU housing 102 defines a flat surface that faces rearward and slightly to the left when viewed from the front of the outboard motor body, and is angled slightly downward (toward the sea surface). This angle is required by space constraints determined by the design of the cowling covers 21a, 21b, but because of this angle, when the electric outboard motor 10 is running, the rectangular open surface of the box-shaped housing 102 is inclined toward the sea surface, which is advantageous in preventing seawater splashing into the wind tunnel system through the fresh air intake (first intake 130) of the first ECU housing cover 106 while the electric outboard motor 10 is running.

[0090] As shown in FIGS. 3 to 8 , all four side walls of the first ECU housing 102 are perpendicular to the bottom wall 111 (the side facing the open surface). The four side walls are rounded and integrated with each other. The inner bottom wall 111 (the side facing the open surface) of the first ECU housing 102 is the same size as the inside rim of the rectangular opening, and the lower ends (bottom surface sides) of the four side walls are slightly rounded to form a continuous unit. The bottom wall 111 has one air vent 118 slightly to the right of the center of the lower end. This air vent 118 (which, together with the air vent on the second A housing side, forms the first air communication hole 226) allows air to be communicated between the first housing unit 100 and the second housing unit 200, which are defined by the first ECU housing 102 and its cover 106.

[0091] Further, screw holes (not shown) for screwing (screw-fixing) a first ECU case 123 (described later) are formed in the four corners of the bottom wall 111, but these screw holes do not penetrate the bottom wall 111. The through holes penetrating the bottom wall 111 include two through holes 135 for reinforcing the first ECU housing 102 by screwing it with bolts to a support member that is disposed on the back side of the first ECU housing 102 and extends integrally from the outer upper surface of the motor room cover housing portion 224.

[0092] On the outer surface of the right housing wall as viewed from the opening side, three protrusions 117 (mounting bosses 117) having central screw holes for screwing a first ECU housing cover 106 (described later) to the opening side of the first ECU housing 102 are formed (one at approximately the center of the length of the right side wall, and one each near the upper and lower ends of the right side wall 112). On the left side wall, which has the same shape and size as the right side wall, one protrusion is formed slightly lower than the protrusion formed near the upper end of the right side wall, and one protrusion is formed slightly higher than the protrusion formed near the lower end of the right side wall. The upper end faces of these protrusions are all in the same plane, and their height from the surface of the bottom wall 111 is approximately the same as the upper end face of the rim of the opening.

[0093] The first ECU housing 102 is die-cast using aluminum or an aluminum alloy (e.g., A5052TD). The cover 106 is injection-molded using a plastic suitable for injection molding, although the material and manufacturing method may be selected as appropriate. The recess cover plate 112, which is disposed on the upper surface of the cover 106 and partially covers the recess 116 toward the open side of the cover 106, is preferably made of stainless steel, but is not limited to this. For example, a transparent or translucent plastic plate could also be used. The side cover 108 of the first ECU housing cover 106 is made of a grommet material. Any material can be used for this cover 106 as long as it maintains the watertightness and airtightness of the first compartment 100A defined by the first housing unit 100. An O-ring (not shown) is inserted between the first ECU housing 102 and the first ECU housing cover 106 to make the gap watertight or airtight, and while a rubber material is preferably used for the O-ring, any commonly known material can also be used as long as it can maintain watertightness and airtightness. The size (thickness, width, etc.) of the O-ring can be selected appropriately depending on the purpose of the present invention.

[0094] 3 to 8 show the first ECU housing cover 106, which is a dedicated plastic cover that covers the open surface of the first ECU housing 102. This cover 106 has a recess 116 (FIG. 8(b)) formed on the open surface side. The rim on the open surface side of this cover 106 (the rim on the bottom surface: not shown) has a rectangular outline with rounded corners, and the top surface side is flat except for the recess 116 formed slightly above the center, and the edges of this flat area also have a rectangular outline with rounded corners.

[0095] Of the side walls of this cover, the upper side wall forms an uphill slope from the upper end of the flat area on the top surface side toward the corresponding rim on the bottom surface side, and the slope is configured so that, at a point slightly before the rim on the bottom surface side, from that point to the rim on the bottom surface side, it is perpendicular to the plane defined by the rim on the bottom surface side.

[0096] The cover's lower sidewall extends from the bottom edge of the flat area on the top side toward the corresponding rim on the bottom side, forming a curved surface that is perpendicular to the plane defined by the rim on the bottom side. The height of the top edge of the cover's upper sidewall from the bottom surface is slightly lower than the height of the top edge of the cover's lower sidewall from the bottom surface. This height is determined based on constraints such as the detailed shape of the first ECU module 123 housed inside the cover, and this configuration can be selected as needed. The purpose of this height adjustment is to minimize the width of the gap formed between the inner surface of the cover 106 and the top surface of the first ECU module 123, thereby creating a labyrinth effect in the flow path of fresh air (external air) drawn into the system, as described below.

[0097] An opening 109 is formed in the right side wall of the cover 106 when viewed from the top surface side, for passing a branch cable from the power cable, a cable extending from the first ECU module 123 to the electric motor 263, etc. This opening is covered with a rubber cromet made entirely of rubber, having a contour that matches the contour and size of the opening and having holes through which the required number of cables can be inserted. Any known, commonly-used rubber cromet can be suitably used as this rubber cromet, as long as it can achieve the object of the present invention.

[0098] The contour of the top surface of this cover 106 is similar to the contour of the rim on the open surface side, but is slightly smaller in size. The shape, size, and wall thickness of the rim on the open surface side of the cover 106 are approximately the same as the shape, size, and wall thickness of the rim 113 on the open surface side of the first ECU housing 102 described above, and are configured to ensure the watertightness of the internal space defined by the first ECU housing unit 100 by inserting an O-ring between the first ECU housing 102 and the cover 106. Holed fixing protrusions for screwing the cover 106 to the opposing first ECU housing 102 with bolts are formed along the rim on the open surface side of the cover 106 (the rim is formed around the entire circumference, but is represented by rim 113) in three locations on the right side and two locations on the left side when viewed from the top surface side of the cover. These protrusions correspond to the protrusions 117 with bolt receiving holes formed on the outer side of the side wall of the opposing first ECU housing 102.

[0099] A recess 116 is formed in the upper surface of the cover 106, approximately in the center. The contour of the entrance to this recess 116 is a continuous polygonal shape consisting of a rectangle and a quadrangle where the lower center of the rectangle overlaps with a portion of the center of the rectangle. A total of four plate-like protrusions 113 serving as baffles are formed on the bottom surface of this recess 116, positioned at three levels. The top level has a plate-like protrusion with a downwardly curved arc shape and both ends at the same height. The level below that has two plate-like protrusions positioned at the same height, each inclined toward the center line of the recess space (when viewed from the top of the recess, the right edge of the left plate-like protrusion is lower than the left edge, while the left edge of the right plate-like protrusion is lower than the right edge). Finally, the bottom level has a plate-like protrusion with an interior angle of approximately 90 degrees at its center. The height at which these plate-like protrusions 113 protrude from the bottom surface of the recess is approximately the same as the height (height from the bottom surface of the recess) of the inner surface of the cover plate of the recess, which is expected to more effectively obtain the effect of the first labyrinth structure (the effect of preventing sea spray from being pushed by the flow of outside air (external air) sucked into the inside of the first ECU housing unit 100 covered by this cover and being blown into the inside). Note that this labyrinth structure is formed by a known general method. Furthermore, its shape and size can be selected appropriately as needed.

[0100] The rectangular portion of the contour of the entrance surface of this recess 116 is closed by a plate 112 of the same contour and size, with screw holes at its four corners. At the four corners of the recess 116, steps 116 corresponding to the screw fastenings protrude from the bottom surface of the recess to the same height as the plate-like protrusions 113 that form the labyrinth, with their side surfaces forming an arc. While the heights of the steps 116 (their protrusion heights from the bottom surface of the recess) are the same between them, the lower two are slightly lower than the upper two when viewed from the top surface of the cover 106. As a result, the plane defined by the SUS recess cover plate 112 that covers the rectangular area of ​​the recess entrance opening is parallel to the plane defined by the rim (not shown) on the bottom surface side of the cover 106, and therefore also parallel to the plane defined by the bottom wall 111 of the first ECU housing 102 that is covered by this cover 106.

[0101] A smaller recess (second recess) 114 is formed in the lower side wall of the recess 116. This second recess 114 forms a groove, the bottom of which slopes upward as it approaches the back when viewed from the top of the cover 106. This inclined configuration, combined with the fact that the planar position of the upper end of the first ECU housing 102 to which the cover 106 is attached is located rearward (opposite the direction of propulsion of the outboard motor body 1) relative to the planar position of the lower end, ensures that the plane defined by the bottom of the groove formed by the second recess 114 is as nearly perpendicular to the water surface as possible when the electric outboard motor 10 is mounted vertically at the stern. This is expected to have the effect of preventing sea spray from being pushed by the flow of outside air (external air) drawn into the interior of the first ECU housing unit 100 covered by this cover and being blown into the space along with the outside air (external air).

[0102] An upper side wall of the recess 116 is formed with a vent hole (indicated by 115 in FIG. 3 ) for introducing outside air that has passed through the labyrinth into the space enclosed by the first ECU housing 102 and its cover 106 (the space behind the cover 106). This vent hole is formed in the upper recess side wall (indicated by 115 in FIG. 3 ) of the recess 116, and this recess side wall is approximately perpendicular to the inlet surface of the recess 116, and as a result, is approximately perpendicular to the inlet surface of the groove formed in the second recess 114. This configuration is also expected to contribute to the effect of preventing sea spray from being pushed by the flow of outside air that is sucked into the interior of the first ECU housing unit 100 covered with this cover and being blown into the space together with the outside air.

[0103] In addition, all cables that pass through the cable insertion holes 139 provided in the rubber grommets 108 that cover the openings 109 on the sides of the cover 106 are housed in waterproof sheaths.

[0104] <First ECU Module> Figure 8(b) shows the first ECU module 123, which is the target of forced air-cooling in the first housing unit 100 using outside air as a refrigerant in the air-cooling system of the present invention. The first ECU module 123 has a power semiconductor inverter (DC / AC converter) in its circuit, and the entire module is mounted in a case 123 shown in the figure (hereinafter, for convenience, the entire module, including the case 123, will be referred to as the first ECU module 123). Five terminals 125 are exposed on the top surface of the first ECU module 123, and a pin fixing box 126 for connection pins 127 of an ECU mounted inside is also provided. The bottom exterior surface of this case has a heat dissipation base plate 122 for dissipating heat from the internal ECU (particularly the inverter using power semiconductors), and a plurality of cooling fins 124 protruding from the heat dissipation base plate 122 in parallel. Four flat, star-shaped protrusions (recesses when viewed from the back) are formed, and the height of these flat surfaces (height from the surface of the heat dissipation base plate 122) is flush with the upper surfaces of the cooling fins 124. While the extension direction of each fin 124 is shown in the drawing as being horizontal when mounted in the first ECU housing, this is not necessarily limited to this configuration. It is preferable that the fins 124 function as a second labyrinth in the air flow path after outside air is drawn in as a refrigerant. Various methods for forming such a labyrinth shape may be appropriately selected. As shown in Figure 12, this first ECU module is placed vertically on the bottom wall 111 of the first ECU housing 102, with a heat dissipation sheet 121 inserted between them, and then screwed (fastened) at the four corners of the heat dissipation base plate 122.In this way, the area of ​​surface contact between the cooling fins 124 protruding from the base plate 122 of the first ECU module 123 and the bottom wall 111 of the first ECU housing 102 is increased when the modules are fastened together, and at the same time, a passage / flow path for cooling air using outside air as a coolant is secured between the case 123 of the first ECU module 123 and the inner surface of the first ECU housing, thereby eliminating the need to provide a separate, dedicated air-cooling passage and achieving a reduction in the number of parts and space savings. Note that the first ECU module 123 used in one embodiment of the present invention is a motor controller ECU mounted on an electric fire pump commonly used in land environments, and this first ECU module 123 is a standard product that meets predetermined standards, and no further special treatment is performed when used in a marine environment. Thus, one of the features of the electric outboard motor 10 of the present invention is that even a motor controller ECU module used in a land environment can be used in a marine environment, which is a harsh environment for precision electronic circuitry mounted devices, without any further special processing or additional heat dissipation mechanism, as long as it is a standard product that meets the predetermined standards for use in a land environment.

[0105] <Second-A Housing Unit 220 Constituting the Upper Half of the Second Housing Unit 200> As shown in FIG. 3 , the second-A housing unit 220 (or reference numeral 240 if the gasket 231 shared between the upper and lower units is added) occupies the upper half of the second housing unit 200. The main components shown in FIG. 3 define a second-A compartment 220A. The main structural element of the second-A housing unit 220 is the motor room cover housing portion 224. These structural elements are integrally molded into a continuous body by die-casting, preferably using aluminum or an aluminum alloy (e.g., A5052TD). The gasket (first gasket) 231 (reference numeral 231 in FIG. 11 ) may be made of either metal or rubber, as long as the object of the present invention can be achieved. Note that this gasket (first gasket) 231 is also common to the second-B compartment 280A, described below. These dimensions (thickness, width, etc.) can be appropriately selected depending on the object of the present invention.

[0106] <Second-B housing unit 280, constituting the lower half of the second housing unit 100> The second-B compartment 280A is defined by the main components shown in FIG. 3. Of these components, the lower mount bracket 285, motor basement 288, and cooling fins 287 are die-cast integrally using aluminum or an aluminum alloy (e.g., A5052TD) to form a continuous body. The motor room housing 282 (motor room housing cover 282) is also die-cast separately from the motor basement 288 using aluminum or an aluminum alloy (e.g., A5052TD) and is then bolted to the top surface of the motor basement 288 along the outer periphery of its lower end. The gasket (first gasket) 231 can be made of either metal or rubber, as long as it achieves the objectives of the present invention. This gasket (first gasket) 231 is common to the second-A compartment 220A described above. These dimensions (length, width, thickness, etc.) can be appropriately selected depending on the object of the present invention.

[0107] 3 and 11 , a first gasket 231 is disposed at the lower end of the second-A housing unit 220. This first gasket 231 communicates with air through a second group of air communication holes, consisting of a dedicated ventilation hole 233 and a conductive cable insertion hole (232 in FIG. 11 ) that can also serve as a ventilation hole. This first gasket 231 is a common partition member with the second-B housing unit 280 below it. The reason for providing the dedicated ventilation hole 233 (reference number 233 in FIG. 11 ) in this first gasket 231 is to ensure that the cooling air taken in (or, more accurately, sucked in) by the outside air serving as a coolant flows as uniformly as possible throughout the entire gap space formed between the inner wall surface of the motor room housing 282 and the outer surface of the electric motor case 263 housed within the motor room housing 282. Although the number of holes is two in Fig. 5, any number of holes can be suitably applied as long as the flow of cooling air can achieve the object of the present invention. The same applies to the inner diameter of each hole.

[0108] <Third-A Housing Unit 300> As shown in FIG. 3, the third-A housing unit 300 is, for example, a drive shaft housing 302, and has a cavity inlet 407a that connects to a fourth air communication hole 408 provided in the third-B housing unit 400.

[0109] The lower end of the rotary shaft of the electric motor 260 is connected to the upper end of the coupling 271, and the opposite portion 271 extends near the upper end of the third housing 302 and is connected to the upper end of the drive shaft 322. In the electric outboard motor 10 according to the present invention, no transmission gear is used to transmit the rotational torque of the electric motor 260 to the drive shaft 322. This is an advantage because the first ECU 120 can control the rotation speed of the electric motor 260 over a wide range from low to high speeds, and is one of the major advantages compared to gasoline engine electric outboard motors. However, the use of a transmission gear is not necessarily excluded, and a transmission gear may be used in some cases.

[0110] The drive shaft housing 302 and the underside (not shown) of the motor basement 288 define a compartment 3A 302A. The lower end of the drive shaft housing 302 is fastened to a gear case housing 404 (described below), and there is no bulkhead between them, so their internal spaces are continuous. Well-known, commonly-used drive shaft housings 302 and gear case housing 404 can be suitably used, including those commonly used in gasoline-engine outboard motors. Therefore, one of the features of the present invention is that general-purpose or readily available parts can be utilized.

[0111] Like a normal outboard motor, the electric outboard motor 10 of the present invention has the lower end of the drive shaft housing 302 located below the water surface while the motor is running, and this water surface contributes to defining the third A compartment 302 A. However, as described above, when the electric outboard motor 10 is running, the inside of the drive shaft housing 302 also becomes a negative pressure environment due to the underwater rotation of the propeller 504 of the perforated screw propeller 506, and the air inside is discharged together with the seawater inside through the outlet 502 of the perforated screw propeller 506, forming an air flow path inside.

[0112] The drive shaft housing 302 can be made of aluminum or an aluminum alloy (e.g., A5052TD) using a known method such as sheet metal processing. The dimensions (length, thickness, etc.) can be selected appropriately depending on the objectives of the present invention. The drive shaft housing 302 can be similar to those used in conventional gasoline-engine outboard motors, which makes it economical since many parts are readily available.

[0113] 3 , the third-B housing unit 400 includes the following: a gear case housing 404, a gear case 404a, a fourth air communication hole 407, a cavity entrance 407a connected to the fourth air communication hole 407 below, and a propeller shaft support 403. A gap is formed between the inner wall surface of the gear case 404a and the propeller shaft support 403, and this gap communicates with an air discharge passage 507 formed inside the screw propeller unit 506 via the fourth air communication hole 407 and further via the fifth air communication hole 405.

[0114] The third-B housing unit 400 can be molded using a known die-cast method using aluminum or an aluminum alloy (e.g., A5052TD). The size (shape, length, thickness, etc.) of the above components can be selected appropriately depending on the objectives of the present invention. The third-B housing unit 400 can be of a type that is commonly installed in conventional gasoline-engine outboard motors using known methods. This makes it highly reliable, easy to maintain, and economical because many parts can be reused.

[0115] <Fourth Housing Unit 500> Figure 10 shows a vertical cross-sectional view of the fourth housing unit 500 (i.e., a perforated screw propeller unit 506 as an example) attached to the gear case 404a. Specifically, this is a partial vertical cross-sectional view (taken along the fore-and-aft direction of the electric outboard motor 10) illustrating the structure of the cavity inlet 407a, the fourth air communication hole 407, and the fifth air communication hole 405 and their surrounding components. Other than these essential components, the internal mechanisms and components near the lower end of the gear case housing 404 and the internal mechanisms and components of the perforated screw propeller unit 506 can be essentially the same as those used in gasoline engine outboard motors. The fifth air communication hole between the compartment 400A defined by the third-sub-housing unit 400 and the compartment 500A defined by the fourth housing unit 500 is designated by reference numeral 405 in the same figure.

[0116] In addition, this fifth air communication hole 405 is generally formed in a gear case housing that has a mechanism for discharging exhaust gas from the gasoline engine into the sea in a gasoline engine-type outboard motor. As for other mechanisms and components thereof, a person skilled in the art will be able to see Figure 8 and understand the names, features, functions, etc. of the parts shown therein, and any mechanism or component can be suitably used as long as it can achieve the object of the present invention, so detailed explanations thereof will be omitted.

[0117] Next, the mechanism for air-communicating the internal spaces of these housing units will be described in detail. <Air Communication Mechanism Between the First Housing Unit and the Second-A Housing Unit> FIG. 9 illustrates the air communication mechanism between the first housing unit and the second-A housing unit. FIG. 9 is a partial vertical cross-sectional view (a partial vertical cross-sectional view taken along the fore-and-aft direction of the electric outboard motor 10) showing the first air communication hole 226 between the first housing unit 100 and the second-A housing unit 220 and the main components in the vicinity. The first air communication hole 226, one of the main components of the present invention, is formed by assembling the components described above. The descriptions of these components can be found in the above descriptions by using the reference numbers in FIG. 9 as factors. Therefore, the following description will focus on the first air communication hole 226. The first air communication hole 226 is formed by coaxially butting the vent hole 118 of the first ECU housing 102 and the vent hole 227 of the motor room cover housing portion 224, with or without a watertight or airtight seal between their surfaces. This butting is achieved by fastening the first ECU housing 102 to the rear side (rear side of the outboard motor body 1) of a space 222 that houses an upper mount arm end fixing bracket (not shown) that is continuous with the top of the motor room cover housing portion 224, and to the rear side (rear side of the outboard motor body 1) of the contactor housing 221 using two bolts. No dedicated positioning member is used for this butting. Note that this configuration is intended to firmly secure the first housing unit 100 within the main body 1 of the electric outboard motor 10. The fixing method is not limited to the method described here; those skilled in the art can apply other fixing methods as needed.

[0118] The inner diameter size of this first air communication hole 226 is determined by submerging the perforated screw propeller unit 500 in the sea (underwater) and starting the electric outboard motor 10 to rotate the propeller 504 and place the vicinity thereof under a negative pressure environment. This negative pressure state is transmitted to the first outside air intake 130 formed in the cover 106 of the first ECU housing unit 100, and then to the second outside air intake 132. As a result, outside air from the first outside air intake 130 flows through the labyrinth 113, splits to the right and left, then merges again, and flows out the second outside air intake 132. The air flows into the first ECU housing unit 100, is then drawn into the first ECU housing unit 100, and flows in the order indicated by the arrows in FIG. 9 , passes through the first air communication hole, hits the wall of the motor room cover housing portion 224 opposite it, and after hitting that wall, reaches the second air communication hole group 234 provided in the gasket 231 inserted between the second A housing unit 220 and the second B housing unit 280 to separate them. However, such a preferable phenomenon is not essential, and any size of the second air communication hole group 234 provided in the gasket 231 can be suitably applied as long as the heat dissipation effect of the air-cooling system of the present invention can be obtained by combining the size and number of the second air communication hole group 234. Note that the surrounding components forming the first air communication hole 226 can be identified from the above description using the corresponding reference numbers in the figure, and therefore will not be described here.

[0119] The dashed-dotted lines in the figure conceptually show the air flow path that follows when the electric outboard motor 10 starts running and the air-cooling system of the present invention is operating: outside air (external air) enters the recess 116, which is partially covered by the recess cover plate 112, passes through the first outside air intake 130, detours around the labyrinth 113 provided in the recess 116, passes through the second outside air intake 132, is drawn into the interior of the first housing unit 100 (into the first compartment 100A), reaches the first air communication hole 226, passes through the first air communication hole 226, passes through the second group of air communication holes 234, and further passes through the third air communication hole 292 before flowing into the third-A housing unit 300 (third-A compartment 300A). The air flow here has been described above. It should be noted that for members that are not related to the air flow, the corresponding explanations can be derived from the above explanation using the reference numbers in the figure, and therefore the explanations will be omitted here.

[0120] <Air Communication Mechanism Between the Second-A Housing Unit and the Second-B Housing Unit> Figure 10 illustrates the air communication mechanism. Figure 10 illustrates the second air communication hole group 234 (a combination of a cable insertion hole indicated by reference number 232 in a gasket 231 and a dedicated vent hole indicated by reference number 233) formed between the second-A housing unit 220 and the second-B housing unit 280, as well as the components in its vicinity. This illustrates that the combination is made up of the vent hole 233 and the hole 232 for inserting a conductive cable provided in the gasket 231. Note that the components surrounding the third air communication hole group 234 will not be described here, as the corresponding descriptions can be derived from the above explanation using the reference numbers in Figure 10.

[0121] Figure 11 conceptually illustrates the flow of air that has passed downward through the third air communication hole group 234 in Figure 10. Figure 11 conceptually illustrates, with dashed-dotted lines, the air flow path in which the air passes downward through the vent holes 232 formed in the gasket 231, flows around the entire periphery of the gap formed between the inner surface of the motor room housing 282 and the outer surface of the electric motor 263, and flows toward the third air communication hole 292. As is clear from this figure, the position of the vent holes 233 is preferably configured so that, when viewed from above the second housing unit 200, the position of the projected plane of the vent holes 233 onto a plane is substantially the same as the position of the projected plane of the first air communication hole 226 described above. This configuration allows the outside air (external air) drawn into the second-A compartment 220A defined by the second-A housing 224 (motor room cover housing portion 224) and the gasket 231 to circulate as evenly as possible around the entire periphery of the gap formed between the inner surface of the second-B housing 282 (motor room housing 282) and the outer surface of the electric motor 263, thereby improving the efficiency of the heat dissipation effect. As a result, the cooling effect of the air-cooling system of the present invention can be expected to be more efficient. However, this arrangement is not essential, and any size can be suitably applied as long as the heat dissipation effect of the air-cooling system of the present invention is obtained by combining the arrangement, size, and number of the air vents 233 and the conductive cable insertion holes 232 provided in the gasket 231.

[0122] <Third Air Communication Hole Between the Second-B Housing Unit 280 and the Third-A Housing Unit 300> Fig. 9 shows a detailed cross section (a longitudinal cross section along the fore-and-aft direction of the electric outboard motor 10) of the third air communication hole 292. Fig. 9 also shows detailed cross sections of the first air communication hole 226 and the second air communication hole group 234. As shown in Fig. 9, the third air communication hole 292 between the second-B housing unit 280 and the third housing unit 300 is formed by assembling the electric motor 263 over a hole 292 opened in the motor basement 288 so that the hole 292 is partially blocked. Another feature of the present invention is that the rear end of the lower mount bracket 285 on the outboard motor body 1 side, designated by reference number 285, partially protrudes below the hole designated by reference number 292. The lower mount bracket 285 and the motor basement 288 are one continuous piece, and are molded as a single unit by die casting.

[0123] As shown by the dashed-dotted line in Figure 9, the cooling air flowing down from above along the side of the electric motor 263 enters vertically into the third air communication hole 292, which is partially blocked by the electric motor 263, then turns horizontally and again vertically to flow into the third-A compartment 300A formed inside the third-A housing unit 300. By forming the cooling air flow path in a zigzag shape to increase air resistance, the cooling air that flows into the second-B housing unit 280 (second compartment 280A) through the second air communication hole group 234 is allowed to remain within the second-B housing unit 280 (second compartment 280A) for as long as possible, thereby enabling as uniform cooling as possible around the entire circumference of the electric motor 263. This effect is achieved in combination with the dedicated air communication hole 233 provided in the gasket 231 according to the present invention, and is conceptually shown by the dashed-dotted line in Figure 9. If the air communication hole 233 dedicated to air communication were not provided and only the hole 232 for inserting the conductive cable were provided, the flow of cooling air would be biased toward the area below it, making it impossible to cool the entire periphery of the electric motor 263 evenly. Note that explanations of structural elements other than those described above can be derived from the above explanation using the reference numbers in the same figure, so explanations will be omitted here.

[0124] Furthermore, by forming the third air communication hole 292 in a zigzag shape, the following effect different from the flow of cooling air is achieved: When the electric outboard motor 10 is sailing and rough waves occur, causing seawater that has penetrated into the third A compartment 300A to become violent and splash up to the top of this compartment and reach the underside of the motor base, a zigzag shape such as that shown in Figure 17 can be expected to prevent or reduce the amount of splashed seawater from entering the motor room (i.e., the second B compartment).

[0125] <Fourth air communication hole between the 3A housing unit 300 and the 3B housing unit 400> Fig. 10 shows a detailed cross section (a longitudinal cross section along the fore-and-aft direction of the electric outboard motor 10) of the fourth air communication holes 407a, 407. Fig. 10 is a partial longitudinal cross section along the fore-and-aft direction of the electric outboard motor 10, showing the main parts of the fastening portion between the 3A housing unit 300 and the 3B housing unit 400. In Fig. 10, the hole designated by reference number 407 is the fourth air communication hole. The fourth air communication holes 407a, 407 can be configured the same as, or substantially the same as, the air communication holes used in a gasoline engine-type outboard motor when the drive shaft housing 302 and the gear case housing 404 are fastened together to allow exhaust gas from the gasoline engine to flow therethrough when exhaust gas from the gasoline engine is discharged into the sea through the exhaust port of the perforated screw propeller. The spatial relationship between the fourth air communication hole 407 and the fifth air communication hole 405 can also be configured in the same or substantially the same way as when exhaust gas from a gasoline engine in a gasoline engine-type outboard motor is configured to flow from the third A compartment through the fourth air communication hole 407 toward the fifth air communication hole 405, specifically as shown in Fig. 10. Note that the explanations for the surrounding members that form the fourth air communication hole 407 and the fifth air communication hole 405 can be derived from the above explanation using the reference numbers in the figure, so explanations for these members will be omitted here.

[0126] <Fifth Air Communication Mechanism Between the Third-B Housing Unit and the Perforated Screw Propeller Unit> Figure 10 also shows a detailed cross section (longitudinal cross section along the fore-and-aft direction of the electric outboard motor 10) of the fifth air communication hole 405. As can be easily understood from Figure 10, the fifth air communication hole 405 of the air communication mechanism between the third-B housing unit 400 and the fourth housing unit 500 (i.e., the perforated screw propeller unit 506) is the same type and configuration as the air communication hole used in a gasoline engine outboard motor when the gear case housing and the perforated screw propeller are fastened together to allow exhaust gas from the gasoline engine to flow therethrough when exhaust gas from the gasoline engine is discharged into the sea through the outlet of the perforated screw propeller. The details of this configuration are as shown in the partial vertical cross section of Figure 10. That is, as indicated by the dashed-dotted line in the figure, the cooling air that has passed through the fourth air communication hole 407 and the fifth air communication hole 405 passes through the fifth air communication hole 405 formed in part of the periphery of the rotation support member 403 of the propeller shaft 411, and is then discharged directly into the sea while passing through the lumen 507 between the propeller boss 506 and the tip of the propeller shaft 411. The perforated screw propeller 506 is the same type as that mounted on gasoline-engine outboard motors, and since the corresponding explanations for its structural elements can be derived from the above explanation using the reference numbers in the figure, a detailed explanation will be omitted here.

[0127] 2. Second Embodiment The first embodiment has been described above, and a second embodiment will now be described. The second embodiment includes a second air-cooling system in addition to the air-cooling system (first air-cooling system) of the first embodiment. Specifically, the electric outboard motor includes a plurality of cooling fins 287, which are integrally formed with and continuous with the motor basement 288, arranged parallel to one another below the motor basement 288. In this case, the orientation of each cooling fin 287 is along the fore-and-aft direction of the electric outboard motor body. The shape, size (length, thickness), spacing, etc. of each cooling fin are not particularly limited, and any suitable configuration may be adopted as long as it is suitable for achieving the objectives of the present invention. Note that the cooling fins 287 are merely auxiliary to the air-cooling system described above. Therefore, the cooling fins 287 are not essential elements for implementing the present invention.

[0128] Finally, based on the description of the above embodiments, it can be understood that the present invention also has the following features: (Feature 1) An electric outboard motor equipped with at least an ECU module having an inverter using power semiconductors and an electric motor, comprising a wind tunnel system in which the internal spaces of a housing unit that houses the ECU module, a housing unit that houses the electric motor, and a housing unit that houses a drive shaft are air-communicating with each other, and a perforated screw propeller unit at one end of the wind tunnel system having an air vent that air-communicates with outside air and at the other end having a lumen that air-communicates with the internal space of the wind tunnel system. (Feature 2) An electric outboard motor equipped with at least an ECU module having an inverter using power semiconductors and an electric motor, comprising: a housing unit that houses the ECU module, a housing unit that houses the electric motor, a housing unit that houses a drive shaft, and a perforated screw propeller unit; the housing unit that houses the ECU module has an air vent at one end for drawing outside air into the wind tunnel system; the housing unit that houses the ECU module and the housing unit that houses the electric motor are in air communication with each other through a common first air hole; and the internal space of the housing unit that houses the electric motor and the lumen of the perforated screw propeller unit are in air communication with each other through a second air hole provided in a motor basement that constitutes the lower part of the housing unit that houses the electric motor, and through the internal space of the drive shaft that is in air communication with the second air hole.(Feature 3) The electric outboard motor according to Feature 1 or 2, wherein the vent comprises: a first planar vent formed in an upper surface of a housing cover of a housing that accommodates the ECU module, the first vent being arranged in a location that first comes into contact with outside air; and a second planar vent formed in a side wall of a recess formed in the upper surface of the housing cover, the second vent being arranged next to the first vent in contact with outside air, a plurality of labyrinth-type baffle plates arranged on a bottom surface of the recess are inserted between the first vent and the second vent, and a plane A of the opening surface of the first vent and a plane B of the second vent are orthogonal to each other. (Feature 4) The electric outboard motor according to Feature 3, wherein a motor basement that constitutes a base portion of a housing unit that accommodates the electric motor is provided with a plurality of integrally molded air-cooling fins that are exposed to outside air. (Feature 5) An electric outboard motor comprising a plurality of housing units each housing various mechanisms mounted inside the outboard motor body of the electric outboard motor, fastened together, and configured to air-communicate the internal spaces defined by each housing unit with one another to form a single air-communicated space as a whole, with an intake port disposed at one end of the housing system for drawing in air outside the outboard motor body, and an exhaust mechanism disposed at the other end for exhausting air drawn into the internal spaces of the housing system from the outside air intake port. (Feature 6) An electric outboard motor equipped with at least an ECU module having an inverter using power semiconductors and an electric motor, the electric outboard motor having a wind tunnel system in which a plurality of housing units each accommodating various mechanisms mounted inside the outboard motor body are fastened to one another, and the internal spaces defined by the respective housing units are air-communicated to one another, the wind tunnel system having an air vent at one end that is in contact with the air outside the outboard motor body, and an exhaust mechanism at the other end that exhausts air that has flowed into the internal space of the wind tunnel system from the air vent to the outside of the wind tunnel system.(Feature 7) The electric outboard motor according to Feature 7, wherein the vent at one end is provided by a recess provided in an upper surface of a housing cover that constitutes a part of a housing unit that houses the ECU module, and the exhaust mechanism at the other end is a perforated screw propeller unit. (Feature 8) The electric outboard motor according to Feature 8, wherein the vent at one end is provided by a recess provided in an upper surface of a housing cover that constitutes a part of a housing unit that houses the ECU module, and the exhaust mechanism at the other end is a vent opened in a side surface of a drive shaft housing unit.

[0129] The present invention provides an air-cooled electric outboard motor with a simpler structure and fewer parts than a water-cooled type, which has a high "electricity cost" and is notable for its never-before-proposed configuration. Furthermore, in a propulsion control mechanism that combines an electric motor and a motor controller (an ECU equipped with a power semiconductor inverter) for use in land environments where there is little concern about water leakage or short circuits due to channeling between electrodes (electrical shorts), the electric outboard motor can be used in its current state in a marine environment where it is frequently exposed to seawater splashes, without the need for special leakage or waterproofing measures. This makes it possible to fully enjoy the benefits of electric systems that are being improved and refined at a rapid pace in electric vehicles, electric firefighting pumps, and other typical electric mechanisms used in land environments, even in electric outboard motors, which are typical electric mechanisms used in marine environments.

[0130] The above embodiment illustrates one form of the electric outboard motor according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. Therefore, various modifications may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

[0131] 1: Outboard motor body 1a: Upper section 1b: Lower section 2: Steering mechanism 3: External power supply connection mechanism 4: Coupling mechanism 10: Electric outboard motor 21a: Cowling cover 21b: Cowling cover 30: Lower mount 41: Friction knob 42: Throttle grip 43: Stopper 44: Tiller handle 45: Lanyard 46: Steering bracket 47: Steering arm (body) 47a: Steering arm (right) 48: Co-pilot lever 52: Mount bracket 52f: Steering shaft upper end receiving portion 54: Mounting boss 62: Trim lock lever 62a: Clamp bracket (right) 62b: Clamp bracket (left) 62c: Trim lock lever 63a: Clamp bracket bolt knob (right) 63b : Clamp bracket bolt knob (left) 64 : Swivel bracket 64b : Upper end surface of swivel bracket 67d : Mounting washer70: Transom board 80: Carrying handle 91: Connection cable outlet 92a: Outboard motor side connection cable 93: Cable base 94: Cable sheath 96: Outboard motor side coupler 97: Power supply side coupler 98: Power supply side cable 100: First ECU housing unit 100A: First compartment 102: First ECU housing 105: Connection terminal 106: First ECU housing cover 107: Mounting boss 108: Side cover (grommet) of first ECU housing cover 110: Step portion 111: Bottom of first ECU housing 112: Cover plate of recess 116 113: Labyrinth 114: Groove (recess in wall of recess 116) 116: Recess 118: First air communication hole 119 : Mounting bolt 122 : Base plate 123 : First ECU module 124 : Heat dissipation fin 130 : First outside air intake 132 : Second outside air intake 135 : Protrusion for mounting bolt hole136: Screw receiving projection 137: Conductive cable insertion projection 138: Spacer projection 139: Conductive cable insertion hole 200: Second ECU housing unit 200A: Second compartment 220: Second A housing unit 220A: Second A compartment 221: Second ECU housing 222: Upper mount arm fixing space 224: Motor room cover housing part 226: First air communication hole 231: Gasket 233: Second air communication hole 234: Second air communication hole group 250: Electric motor connection terminal 262: Electric motor cover 263: Electric motor 271: Coupling 280: Second B housing 280A: Second B compartment 282: Second B housing 285 : Motor basement side bracket 287 : Cooling fin 288 : Motor basement 292 : Third air communication hole 300 : Third A housing unit 300A: Third A compartment 302 : Drive shaft housing 322 : Drive shaft400: Third B housing unit 400A: Third B compartment 402: Cavitation plate 403: Propeller shaft support member 404: Gear case housing 404a: Gear case 405: Fifth air communication hole 406: Skeg 407: Fourth air communication hole 407a: Vent 408: Bevel gear B 409: Bevel gear A 411: Propeller shaft 500: Fourth housing unit 500A: Fourth compartment 502: Exhaust port 504: Propeller 506: Screw propeller unit 507: Lumen in screw propeller unit

Claims

1. An externally powered electric outboard motor having at least an electric motor and a motor controller having an electronic control unit (ECU) that electronically controls the electric motor, wherein the electric outboard motor body is equipped with at least a first housing unit that houses the motor controller, a second housing unit that houses the electric motor, and a third housing unit that houses a powertrain mechanism from the electric motor, wherein the first housing unit defines a first compartment, the second housing unit defines a second compartment, and the third housing unit defines a third compartment, wherein the first compartment and the second compartment are in air communication with each other via a common first air communication hole, and the second compartment and the third compartment are in air communication with each other via a common third air communication hole, thereby forming a serial wind tunnel system with the first compartment, the second compartment, and the third compartment. the first compartment has an opening mechanism with an opening that is in contact with air outside the electric outboard motor, and the third compartment is in air communication with an exhaust mechanism having an exhaust port that exhausts air taken into the wind tunnel system through the opening to the outside of the wind tunnel system.

2. The electric outboard motor according to claim 1, characterized in that the exhaust mechanism is a mechanism that forcibly exhausts the taken-in air outside the wind tunnel system and is a mechanism that can actively or passively place the exhaust port in a negative pressure environment.

3. The electric outboard motor according to claim 2, wherein the exhaust mechanism is a perforated screw propeller unit having a lumen whose one end is in air communication with the third compartment and whose other end is in air communication with the exhaust port.

4. The electric outboard motor according to claim 3, characterized in that the opening mechanism is two openings (first opening and second opening) formed in a housing cover arranged on the open face side of a first ECU housing that forms part of a first compartment that houses the motor controller having a power semiconductor module that converts DC power from outside the electric outboard motor into AC power, the opening plane of the first opening being perpendicular to the opening plane of the second opening, and the two openings having a labyrinth made up of multiple protrusions arranged on the air flow path between the first opening and the second opening.

5. An electric outboard motor as described in claim 4, characterized in that the labyrinth is made up of three layers, with the first layer consisting of a single plate-like protrusion that forms a folded line toward the first opening from the first opening side toward the second opening side, the second layer consisting of two independent plate-like protrusions that form a V-shape, and the third layer consisting of a single plate-like protrusion that forms a convex arc upward.

6. An electric outboard motor according to claim 5, wherein the opening mechanism further has a third opening, the third opening being a first air communication hole provided in the bottom wall of the first ECU housing.

7. An electric outboard motor according to claim 6, wherein in the opening mechanism, the opening plane of the second opening is perpendicular to the opening plane of the third opening.

8. An electric outboard motor according to claim 7, wherein the second opening is positioned higher than the first opening in a side view of the opening mechanism.

9. An electric outboard motor according to claim 8, wherein the opening mechanism has a first opening at the beginning of the air flow path for air taken into the wind tunnel system, a third opening at the end, and a second opening between them.

10. An electric outboard motor according to claim 9, wherein, in the opening mechanism, of the first, second and third openings, the first opening is the largest in size, the third opening is the smallest in size, and the second opening is of an intermediate size between these.

11. An electric outboard motor according to claim 10, characterized in that in the wind tunnel system, the individual air communication holes constituting the second air communication hole group that air-communicates between the first compartment and the adjacent subsequent second compartment are dispersedly arranged around the electric motor when viewed from above the electric outboard motor body.

12. An electric outboard motor as described in claim 11, characterized in that, among the individual air communication holes constituting the second air communication hole group, the position of the air communication hole dedicated to the air passage is higher than the position of the third air communication hole that air-communicates between the second compartment and the adjacent third compartment when viewed from the side of the electric outboard motor body, and the second air communication hole is behind the third air communication hole when viewed from above the electric outboard motor body.

13. An electric outboard motor according to claim 12, characterized in that in the wind tunnel system, the third air communication hole, which air-communicates between the third compartment and the adjacent subsequent fourth compartment, has an upper end opening that is partially blocked by the bottom of the motor case that houses the electric motor when viewed from above the electric outboard motor body, and the cross section of the air communication hole has a two-stage zigzag shape when viewed from the side of the electric outboard motor body.

14. An electric outboard motor according to claim 13, wherein the first compartment houses a first ECU, which is a motor controller equipped with at least a power semiconductor module that converts DC power from outside the electric outboard motor into AC power, and the second compartment houses at least the electric motor controlled by the first ECU.

15. The electric outboard motor according to claim 14, wherein at least a drive shaft connected to the rotary torque shaft of the electric motor via a coupling is housed in the third compartment.

16. An electric outboard motor according to claim 15, characterized in that in the power train mechanism, the drive shaft is linked to the propeller rotation shaft of the perforated screw propeller unit via two bevel gears mounted in a gear case.

17. An electric outboard motor according to claim 16, wherein a second housing for accommodating a contactor unit is integrally formed on the upper part of the motor room cover housing.

18. An electric outboard motor according to claim 17, characterized in that a second ECU case for accommodating a second ECU is disposed on the back side of the second housing, and a heat dissipation sheet is inserted between the back side of the second housing and the second ECU case.

19. An electric outboard motor according to claim 18, characterized in that the motor basement, which constitutes part of the housing unit defining the second compartment that houses the electric motor, is provided with a plurality of integrally molded air-cooling fins that are exposed to the outside air.

20. An electric outboard motor according to claim 19, characterized in that the first housing constituting part of the housing unit defining the first compartment, the motor room cover housing defining the upper half of the second A compartment and the contactor housing integrally molded therewith, the motor room housing and motor basement and their air-cooling fins defining the second B compartment, and the drive shaft housing and gear case defining the third compartment are all formed from die-cast aluminum or aluminum alloy.

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