Electric outboard motor

Abstract

[PROBLEM] To provide an electric outboard motor equipped with a cooling system capable of simultaneously radiating, to an ocean or a lake having a huge heating capacity, heat emitted during running of the electric outboard motor and emitted from an electric motor and from a motor controller for electronically controlling the electric motor, such radiation carried out without using any special driving component or active component and by causing thermal communication with seawater or fresh water outside of the running electric outboard motor via a wall of a housing that accommodates the electric motor necessarily installed in the electric outboard motor and the motor controller for electronically controlling the electric motor. [Solution] This electric outboard motor includes at least an electric motor and a motor controller having an electronic control unit (ECU) for electronically controlling the electric motor, wherein the electric outboard motor is characterized in that: the electric outboard motor includes the electric motor, a wall of a housing for accommodating the motor controller, and a refrigerant flow path having walls in mutual thermal communication; one end of the refrigerant flow path constitutes a closed end and the other end constitutes an open end; the refrigerant flow path includes a refrigerant inflow opening in a region extending upward from the closed end; the open end constitutes a refrigerant discharge opening; the refrigerant inflow opening has a plurality of holes arranged discretely; each of the plurality of holes is configured so that during running of the electric outboard motor the refrigerant flow path is caused to be in fluid communication with seawater or fresh water outside the electric outboard motor; and the refrigerant discharge opening is disposed behind the refrigerant inflow opening.

Description

electric outboard motor

[0001] The present invention relates to an electric outboard motor. Specifically, the present invention relates to an electric outboard motor having a water cooling system comprising a refrigerant flow path that enables the heat generated from the electric motor and the motor controller (an electronic control unit having power semiconductors) that electronically controls it to be dissipated to the heat sink by using seawater or freshwater outside the electric outboard motor as a heat sink while the electric outboard motor is running, via the walls of the housings that house them. The present invention also relates to an electric outboard motor having, as an option, a passive air cooling system that is automatically configured by a housing system specific to the electric outboard motor of the present invention (a housing system that houses each functional element in separate housing units (compartments) and allows air to communicate between these compartments).

[0002] In recent years, with the increased focus on environmental issues, electric outboard motors, equipped with electric motors as their power source, have been proposed and are actually being used in various locations, in order to fundamentally resolve problems specific to gasoline-engine outboard motors, such as gasoline and lubricating oil leaks and the discharge of exhaust gases into the water.

[0003] However, although the environmental problems have been solved, its performance, especially the distance that can be traveled on a single charge, tends to be significantly inferior compared to that of an outboard motor with a gasoline engine. This is due to the specific problems inherent in an electric outboard motor. The main factor is that the "electricity cost" (the distance that can be traveled with 1 kW of power) of the electric outboard motor deteriorates due to the heat generated respectively from the electronic control equipment (especially the electronic control unit (ECU) incorporating a power semiconductor) and the electric motor installed inside the main body of the electric outboard motor. This is a phenomenon where a part of the power supplied to the electric motor is converted into heat generated from the electronic control equipment (ECU) and the electric motor and consumed, resulting in a decrease in the actual amount of electric power. Furthermore, due to this heat, the electrical resistance of the electronic circuits and electrical wiring built into various electronic control equipment and the electric motor increases, and the power flowing through the circuit further decreases due to this resistance, and the energy supplied to the rotational torque force of the electric motor is wasted and consumed, resulting in a decrease in the electricity cost. Moreover, there is also a potential problem that the ECU itself incorporating a power semiconductor for an inverter may burn out and stop functioning, or its function may deteriorate, or even if it does not reach that level, the heat from these heat sources is transmitted to other control ECUs and the semiconductors installed there stop functioning or their function deteriorates. These potential problems become more prominent as the horsepower of the electric outboard motor increases, that is, as the supply voltage to the electric outboard motor increases.

[0004] Regarding this potential problem, efforts have been made to improve the "electricity cost" of the electric outboard motor with a new concept called heat management. The main targets of heat management in an electric outboard motor are the motor controller (especially the electronic control unit (ECU) having an inverter with a power semiconductor) and the electric motor. Among these, the mechanisms and methods for dissipating the heat generated from the electric motor to the outside of the electric outboard motor are roughly classified into two types from the perspective of the installation position of the electric motor. Representative prior patent documents include, for example, Patent Document 1 and Patent Document 2 below.

[0005] One type, as disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 59-45296), is configured to have an electric motor positioned in front of the underwater propeller and power supplied from a battery located inside the ship. The other type, as disclosed in Patent Document 2 (Japanese Unexamined Patent Publication No. 2005-162055), is configured to have an electric motor positioned above the water surface, similar to a conventional gasoline engine, and to obtain thrust by transmitting the rotational force from the electric motor to the underwater propeller via a drive shaft and gears connected below the electric motor.

[0006] In the former case (Patent Document 1 (Japanese Patent Publication No. 59-45296)), the heat generated from the electric motor is dissipated by housing the electric motor in a housing positioned below the water surface. However, considering the resistance in water, it is considered difficult to increase the size of the electric motor, i.e., to replace it with a gasoline engine. Furthermore, housing a large electric motor in a housing below the water surface presents other problems, such as the need to enlarge the support members for the electric motor. In addition, since the case 22, which houses the device that controls the electric motor below the water surface, is above the water surface, the case 22 is air-cooled, and neither the electric motor nor the device that controls it is water-cooled. Moreover, the electric outboard motor in the same document is considered to be of medium size or smaller, and it is said that it is difficult to scale up such a configuration to create a medium to large electric outboard motor. Furthermore, it is expected that special technology will be required for the water resistance and maintenance of an electric motor operating below the water surface, which presents a potential challenge of higher manufacturing and running costs.

[0007] On the other hand, in the case of the outboard motor according to the invention disclosed in Patent Document 2 (Japanese Patent Application Publication No. 2005-162055), the above circumstances were taken into consideration, and "the outboard motor 1A is divided into three parts vertically, and the upper and lower parts of the middle unit 3 located in the middle section are attached to the hull 21 via mounting devices 10 and 11, and it is equipped with an electric motor 14, a battery 43 that supplies power to the electric motor 14, and a control unit 44 that controls the rotation speed of the electric motor 14, and the electric motor 14 is arranged in the middle case 8 that constitutes the middle unit 3 between the mounting devices 10 and 11." (Abstract of the same document) In the case of this outboard motor, the position of the electric motor is above the water surface, similar to the case of a conventional gasoline engine, and at the same time, a water-cooled cooling jacket is mounted around the electric motor. In this case, the refrigerant is seawater, and in order to move this refrigerant, a chilled water pump, such as a volumetric variable cooling water pump, which is mounted on a gasoline engine type outboard motor, is used, driven by the rotation of the drive shaft. The document states, "...These water-cooled cooling systems can reliably suppress overheating of the electric motor 14 by supplying cooling water to the electric motor 14 during operation, and because they have a water pumping structure similar to those conventionally used in gasoline engines, they are highly reliable and easy to maintain. Also, many parts can be reused, making them economical." (Column

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

[0041] ) Thus, the target of thermal management (heat dissipation management) is only the electric motor. The document also discloses an oil-cooled system that uses oil as a refrigerant and utilizes an oil jacket as a cooling jacket, but in this case as well, the target of thermal management is only the electric motor.

[0008] Moreover, the upper case 5, which houses electronic control function elements such as an ECU equipped with power semiconductors, has its opening sealed by a "lid member 6 that seals the opening of the upper case 5" (see section

[0018] of the same document), and is watertight or airtight to prevent "external moisture such as splashes and rainwater during navigation..." from entering its internal space. Therefore, it is thought that insufficient consideration has been given to the heat dissipation from the control unit that controls the rotation speed of the electric motor, etc. (naturally, such a control unit is an ECU (electronic control unit) equipped with a power semiconductor module). The document claims that "...by providing a cooling device to the electric motor 14, which generates heat when operated continuously at high speeds, the electric motor 14 can be made larger and can replace a high-output gasoline engine" (section

[0048] of the document). However, since it states that "the battery 43 is located above the control unit 44" (section

[0029] of the document), the power supply for the electric outboard motor disclosed in the document is not external, so it can be said that the electric outboard motor is of medium size or smaller, and it can be said that it would be difficult to scale up such a configuration to create a medium to large electric outboard motor.

[0009] Furthermore, in the invention described in the same document, the electric motor 14 has a water jacket 52 formed between the electric motor 14 and the motor cover 51 through which cooling water flows. A variable-volume cooling water pump 53, for example, driven by the rotation of the drive shaft 34, is provided to pump the cooling water, which consists of seawater, into this cooling jacket (same document

[0037] ). As a result of these features, the weight of the electric outboard motor increases, which worsens the power consumption (distance that can be traveled with 1 kW of power). In addition, the presence of actively moving parts such as the variable-volume cooling water pump necessitates maintenance complexity, and consequently, there are inherent problems of higher manufacturing and running costs.

[0010] The inventions disclosed in these Patent Documents 1 and 2 all focus on thermal management only for electric motors, and are not inventions that can simultaneously cool both the heat generated from the electronic control unit (module) that controls the electric motor (particularly the ECU module having an inverter made of power semiconductors) and the heat generated from the electric motor. Furthermore, all of these inventions have inherent problems, such as the cooling mechanism not being simple and therefore expected to result in high manufacturing and running costs.

[0011] Japanese Patent Publication No. 59-45296 Japanese Patent Publication No. 2005-162055

[0012] Generally, it is said that the electric motor generates more heat during operation than the ECU module (commonly referred to as the motor controller). However, the ECU module has a temperature limiter that activates and shuts down if it exceeds a certain temperature, resulting in the electric outboard motor itself ceasing to function. Therefore, the risk of overheating is said to be greater for the ECU module. Consequently, a system that cannot cool both the electric motor and the ECU module simultaneously has room for improvement from the perspective of risk hedging in the operation of electric outboard motors.

[0013] This invention was made to solve the various inherent problems described above. Specifically, it aims to provide an electric outboard motor with a water-cooling system that is energy-efficient, simple and easy to maintain, has a small number of parts, does not use active functional elements such as impeller pumps, has a simple structure with few parts, and has a refrigerant flow path having a thermally conductive wall that is in thermal communication (heat is transferred from the high-temperature side to the low-temperature side by thermal conduction) with the wall of the housing that houses the electric motor and the ECU module that controls it, respectively, and a pressure-driven flow is generated in this flow using seawater or freshwater outside the electric outboard motor while it is running as the refrigerant fluid. Heat from the running electric motor and ECU module (motor controller) is dissipated into the seawater or freshwater carried by this pressure-driven flow, and the seawater or freshwater, which has been heated by this heat, is dissipated into the sea (in seawater) or lake (in freshwater) outside the electric outboard motor while it is running. Finally, the heat from the running electric motor and ECU module (motor controller) is simultaneously dissipated into a heat sink with a huge heat absorption capacity, such as the ocean or lake.

[0014] As a result of diligent research to achieve the above objectives, the inventors have conceived of a cooling system primarily based on a water cooling system, in which an electric motor and an ECU module that controls it are housed in separate housings that are in thermal communication with each other by heat conduction, a refrigerant flow path is configured within the main body of the electric outboard motor, having walls that are in thermal communication with the walls of each housing, and while the electric outboard motor is running, the inlet and outlet of the refrigerant flow path are positioned below the water surface, generating a pressure-driven flow of seawater or freshwater taken in from the inlet into the refrigerant flow path, thereby causing the seawater or freshwater, which has become hotter due to the electric motor and the ECU module that controls it as it flows through the flow path, to merge with seawater or freshwater outside the electric outboard motor for heat dissipation, thus conceiving the present invention.

[0015] In the above, the phrase "cooling system mainly consisting of a water cooling system" means that, in this invention, while a water cooling system is the main component, an air cooling system or a variation thereof, as disclosed in Japanese Patent Application No. 2024-18955 filed separately by the applicant, may also be included as an option. Therefore, in this specification, the term "cooling system" can refer to either "consisting solely of a water cooling system" or "including a water cooling system and an optional air cooling system," and the distinction between these two shall be made in a manner that is reasonably clear depending on the context in which the term "cooling system" is used.

[0016] Furthermore, the term "pressure-driven flow" as used herein refers to the flow of refrigerant fluid in a refrigerant flow path having a refrigerant fluid intake opening at one end and a refrigerant fluid discharge opening at the other end, due to the pressure difference (P1-P2; however, P1>P2) between the total water pressure at the refrigerant fluid intake opening (P1) and the total water pressure at the refrigerant fluid discharge opening (P2).

[0017] Furthermore, "thermal communication" as used here means that heat is conducted between two objects, from one object to the other, but the direction of this heat conduction is not fixed. Moreover, "air communication" as used here means that air flows between two adjacent compartment spaces, each compartmentized by the walls of a housing, from one compartment space to the other, but the direction of this airflow is not specified.

[0018] That is, the first invention relates to an electric outboard motor having at least an electric motor and a motor controller having an electronic control unit (ECU) for electronically controlling the electric motor, wherein the electric motor and the wall of the housing housing the motor controller each have a refrigerant flow path having a wall that communicates thermally with the electric motor, the wall of the housing housing the motor controller, the refrigerant flow path having a closed end at one end and an open end at the other end, the region extending upward from the closed end having a refrigerant inlet opening, the open end having a refrigerant outlet opening, the refrigerant inlet opening having a plurality of discretely arranged holes, each of the plurality of holes being configured to allow the refrigerant flow path to communicate fluidly with seawater or freshwater outside the electric outboard motor while the electric outboard motor is in motion, and the refrigerant outlet opening is located behind the refrigerant inlet opening.

[0019] The second invention is characterized in that, in the first invention, the orientation of the central axis of each of the multiple holes in the refrigerant inlet opening intersects the propulsion direction of the electric outboard motor at an internal angle of 0°.

[0020] The third invention is characterized in that, in the second invention, the refrigerant discharge opening has at least one hole located behind the refrigerant inlet opening, and the orientation of the central axis of each of the holes intersects the propulsion direction of the electric outboard motor at an internal angle of 0° to 90°.

[0021] The fourth invention is characterized in that, in the third invention described above, there is one hole, and when the angle of intersection between the orientation of the central axis of the hole and the propulsion direction of the electric outboard motor is 0°, the hole constitutes an outlet at the rear end of the propeller shaft housing of the perforated screw propeller for propulsion of the electric outboard motor.

[0022] The fifth invention is characterized in that an electric outboard motor of one of the first to fourth inventions is equipped with a water cooling system that, while the electric outboard motor is in motion, has a refrigerant inlet opening and a refrigerant outlet opening located below the sea surface, generates a pressure-driven flow of the refrigerant fluid in the refrigerant passage due to the pressure difference of the water pressure between the two, and uses the pressure-driven flow to move seawater or freshwater outside the electric outboard motor while it is in motion along the refrigerant passage.

[0023] The sixth invention is an invention relating to an electric outboard motor, characterized in that, in addition to the water cooling system of the fifth invention, it further comprises a passive air cooling system obtained by air-connecting compartment space A housing the ECU module and compartment space B housing the electric motor, and air-connecting compartment space A and compartment space B to the outside air outside the electric outboard motor.

[0024] According to the present invention, it is possible to cool both the electric motor and the motor controller simultaneously while the electric outboard motor is running by connecting them to the ocean or lake with a large heat absorption capacity via seawater or freshwater, without using moving parts such as impeller pumps or active parts (parts or units that operate themselves to generate a pressure-driven flow in the refrigerant passage, such as a dedicated pump). This allows for the creation of an electric outboard motor equipped with a water-cooling system with high cooling efficiency. Furthermore, the pressure-driven flow of seawater or freshwater flowing through the refrigerant passage while the electric outboard motor is running is a passive flow generated in the refrigerant passage by the difference between the total water pressure at the refrigerant fluid inlet at one end of the refrigerant passage and the total water pressure at the refrigerant fluid outlet at the other end. In the electric outboard motor according to the present invention, since no moving parts such as impeller pumps or active parts are used, the overall structure of the cooling system is simplified, the number of parts is reduced, maintenance is easier, and reductions in manufacturing and running costs can be expected.

[0025] Furthermore, when creating a negative pressure environment in the vicinity of the refrigerant fluid outlet, which is one of the factors that generate pressure-driven flow, it is not necessarily required to use a perforated propeller (where the outlet of the perforated propeller constitutes the refrigerant fluid outlet). If an opening (outlet) is formed in a predetermined orientation in the part of the electric outboard motor body that is located below the water surface while the motor is underway, according to Bernoulli's principle, then it is possible to passively place the vicinity of the opening (outlet) into a negative pressure environment by using a regular propeller or a jet water flow propulsion mechanism that can propel the electric outboard motor, even without a perforated propeller, by utilizing Bernoulli's principle that manifests during the operation of the electric outboard motor. For example, even if a conventional propeller is used instead of a perforated propeller, and an outlet is provided on the lower side of the wall of the third A housing unit 300 that defines the third A compartment 300A, which is submerged in water and in fluid communication with the refrigerant flow path, and the direction of the surface of the outlet (direction perpendicular to the surface) intersects the propulsion direction of the electric outboard motor at an internal angle of 0° to 90°, it is still possible to generate a pressure-driven flow in the refrigerant flow path in combination with the dynamic pressure generated at the opening (intake) formed in the front part of the gear case. Therefore, the water cooling system of the present invention offers a wide variety of variations, and its cooling effect can be expected even in electric outboard motors equipped with propulsion mechanisms other than perforated propellers.

[0026] Furthermore, by appropriately designing the shape, size, orientation, and position of the opening that allows air to communicate between the compartment space housing the motor controller (ECU equipped with an inverter using power semiconductors) and the outside air of the electric outboard motor (for example, by setting the configuration of the first ECU housing 102 and the first ECU housing cover 106 as described in Japanese Patent Application No. 2024-18955 by the present applicant), the motor controller (ECU equipped with an inverter using power semiconductors) and electric motor used in land environments can be used in a fully practical manner in an electric outboard motor in a marine environment where they are frequently exposed to seawater spray, without requiring any special measures against electrical leakage or waterproofing. This allows electric outboard motors, a representative example of electric mechanisms in marine environments, to fully enjoy the benefits of electric systems, which are being improved at a rapid pace in typical examples of electric mechanisms used in land environments such as electric vehicles and electric fire pumps.

[0027] Figure 1 is a right-side perspective view of an electric outboard motor, viewed from the front in the direction of propulsion, with a cooling system implemented as an example of an embodiment of the present invention. In this figure, a portion of the wall at the lower end of the drive shaft housing (housing wall) is cut off, partially exposing the interior (for convenience, only a portion of the transom board and external power cable are shown). Figure 2 is a right-side view of an electric outboard motor, with a cooling system implemented as an example of an embodiment of the present invention shown in Figure 1 (for convenience, the lanyard 45 in Figure 1 has been removed). In Figure 2, the main body of the electric outboard motor is shown in perspective, and the outlines of the main components and units mounted inside are indicated by dashed lines. Figure 3 is a vertical cross-sectional view of the internal configuration of the main body of an electric outboard motor, with a higher resolution than Figure 2, showing a vertical cross-section along the front-rear direction of the electric outboard motor. Figure 3 shows a conceptual diagram, represented by a dashed line, of how seawater or freshwater, as the refrigerant fluid, flows through a refrigerant passage arranged within the main body of the electric outboard motor, and through a motor basement void provided inside the motor basement, while swirling around the central axis of the coupling (for convenience, the lanyard 45 in Figure 1 has been removed). Figure 4 is a partial longitudinal cross-sectional view along the front-rear direction of the gear case of the main body of the electric outboard motor as an example of an embodiment of the invention. Figure 4 shows a conceptual diagram, represented by a dashed line, of how seawater or freshwater, as the refrigerant fluid, flows through the propeller housing unit (refrigerant discharge opening) and is discharged to the outside from the discharge port. Figure 5 is a right-side perspective view of the bottom surface of a first ECU housing unit as an example of an embodiment of the present invention, viewed from the front in the direction of propulsion of the electric outboard motor. This figure illustrates an embodiment in which a first ECU housing cooling passage pipe for flowing seawater or freshwater as the refrigerant fluid is provided on the outside of the bottom wall of the first ECU housing unit as an example of an embodiment of the present invention. In Figure 5, the single dashed line with an arrow indicates the direction of the refrigerant fluid flow. Figure 6(a) is a bottom view of a first ECU housing unit as an example of an embodiment of the present invention. Figure 6(b) is a cross-sectional view along the line A-A' in Figure 6(a).

[0028] Definitions of Terms 1) Upper, Upper Side, Lower, Lower Side: With respect to the components and units mounted on the electric outboard motor of the present invention, "upper" or "upper side" refers to the upper or upper side when the electric outboard motor is standing upright (the side furthest from the water surface when the electric outboard motor body is fastened straight upward to the transom board at the stern), and "lower" or "lower side" refers to the lower or lower side in the opposite direction. 2) Front, Fr (Front), Rear, Rr (Rear): When the electric outboard motor is attached to the transom board at the stern of the hull, the direction of propulsion is called front, Fr (Front), and the opposite direction is called rear, Rr (Rear). Furthermore, when the electric outboard motor body is fastened straight upward to the transom board, the line or plane passing through the center point of the electric outboard motor body and perpendicular to the water surface is called the vertical line or vertical plane of the electric outboard motor body, and the line or plane perpendicular to it is called the horizontal line or horizontal plane. Furthermore, "front" and "back" refer to the front and back sides, respectively, as described above. 3) For parts, components, units, etc., as shown in the drawing, the front side (top side) refers to the front side on the drawing, and the back side (back side) refers to the opposite side.

[0029] 4) The "direction of the hole" or "direction of the hole" refers to the orientation of the central axis extending in the longitudinal direction of the space occupied by the hole or hole, which is assumed to be long and narrow in shape in the space occupied by the hole or hole. Therefore, the orientation of the hole or hole refers to the direction of the central axis extending in the longitudinal direction of the space occupied by each hole or hole. Accordingly, this orientation of the central axis may coincide with the direction perpendicular to the opening surface of the hole or hole (for example, when a hole is drilled perpendicular to the flat surface of the object with a drilling tool such as a drill, and the intersection angle between the shaft of the drill and the flat surface is 90°), or it may not coincide with the direction perpendicular to the direction perpendicular to the opening surface of the hole or hole (for example, when a hole is drilled on an inclined flat surface of the object with a drilling tool such as a drill, and the intersection angle between the shaft and the flat surface is less than 90°).

[0030] 5) In this specification, two types of expressions are used: "water cooling system" and "air cooling system." A water cooling system refers to a cooling system specific to the present invention, while an air cooling system refers to an air cooling system that is installed in addition to the water cooling system of the present invention as an option, whether actively or passively, in accordance with the air cooling system disclosed in Japanese Patent Application No. 2024-18955 filed separately by the applicant, or an equivalent type of air cooling system that follows the same basic technical concept. Here, "actively" means, for example, installing an air cooling system that relies on a method of actively circulating cooling air within the body of the electric outboard motor, while "passively" means, for example, installing an air cooling system that is necessarily configured as a result of combining the components of the body of the electric outboard motor (housing unit or the compartment defined thereby), and does not require any active components.

[0031] 6) "Pressure-driven flow" refers to the flow of refrigerant fluid generated in a refrigerant flow path having a refrigerant fluid intake opening at one end and a refrigerant fluid discharge opening at the other end, due to the pressure difference (P1-P2: however, P1>P2) between the total water pressure (P1) at the refrigerant fluid intake opening and the total water pressure (P2) at the refrigerant fluid discharge opening. 7) "Thermal communication" refers to the manner in which heat is conducted between two objects via a heat conductor, with the direction of heat conduction being from the high-temperature side to the low-temperature side. 8) "Fluid communication" is a concept that also includes air communication, and refers to the manner in which a fluid (liquid and gas) flows between two adjacent spaces (voids), with no regard to the direction of the fluid (liquid and gas) flow. 9) "Refrigerant fluid" means a refrigerant that is in the form of a fluid, and in this invention, it means seawater or freshwater outside the electric outboard motor while it is in motion. 10) "Outside air" means the air outside the electric outboard motor while it is in motion (air outside the wind tunnel system described later). 11) "Cooling air" means outside air (outside air) that is drawn into the wind tunnel system inside the body of the outboard motor and functions as a refrigerant to air cool the various mechanisms housed in the various compartments that constitute the wind tunnel system.

[0032] 12) "Housing system" means the whole obtained by connecting individual independent housing units to each other. 13) "Compartment" means the internal space of a housing unit defined by individual housing units. Therefore, compartment and housing unit are sometimes used as interchangeable concepts. That is, when referring to the external appearance (hardware) of the same part, it is called a housing unit or housing, and when referring to the space inside it, it is called a compartment. 14) "Air tunnel system" means the whole obtained by the air communication between cavities formed inside the housing system (focusing on the air communication of the internal space). 15) "Air cooling system" means a system that introduces outside air as a coolant into the air tunnel system and achieves cooling by the flow of that air. In this case, the driving force when introducing cooling air from the outside and flowing it inside the air tunnel system can be based on a passive mechanism such as natural convection, or on an active mechanism such as a fan, but when referred to in the description of the present invention, it mainly refers to the one based on natural convection. 16) The terms "inside the system" and "outside the system" can refer to the inside of a cooling system as "inside the system" and the outside as "outside the system," or to the inside of any arbitrary region or closed space as "inside the system" and the outside as "outside the system." These terms should be used appropriately depending on the context.

[0033] 17) "ECU" is 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 function and control hierarchy: an ECU that controls the electric motor (an ECU equipped with an inverter made of power semiconductors that converts DC power to AC power, referred to as the first ECU in this specification); an ECU that controls drive mechanisms other than the electric motor (referred to as the third ECU in this specification); and an ECU that is at a higher level than the first and third ECUs and controls them comprehensively (referred to as the second ECU in this specification). There is also an ECU that controls the LED (Light Emitting Diode) installed in the outboard motor according to the present invention (an ECU equipped with a DC / DC converter that supplies DC power after the DC power from the outboard power supply has been reduced in voltage, referred to as the LED ECU in this specification). 18) The term "powertrain mechanism" refers to a mechanism located below the electric motor that transmits the rotational torque of the electric motor to the rotational torque of the propeller rotation shaft of the perforated screw propeller unit. This mechanism consists of at least a coupling whose upper end is connected to the rotational 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 rotation shaft connected to this driven gear.

[0034] 19) "In a side view" means when the object is viewed from its side and directly in front of it. 20) "In a top view" means when viewed from above and directly downwards. 21) "Integrated formation" means that it is formed integrally to form a single continuum. 22) "Integrated molding" means that it is molded integrally to form a single continuum.

[0035] 23) In this specification, "active" is used to represent a concept that refers to its commonly used meaning, and means, for example, to actively use energy such as electricity supplied from outside the system to operate in order to obtain any desired effect at any desired time. For example, it means operating an active unit such as an impeller pump or fan in the middle of the refrigerant flow path to actively discharge the refrigerant fluid in the refrigerant flow path to the outside from the refrigerant fluid outlet. And an active heat dissipation mechanism means such a heat dissipation mechanism. 24) In this specification, "passive" is used to represent a concept that refers to its commonly used meaning, and means a manner in which something is moved by something outside the system. For example, it means forming a vertical slit-shaped exhaust opening on the side of the drive shaft housing below the sea surface (a surface approximately parallel to the direction of travel of the electric outboard motor), and while the electric outboard motor is traveling, generating a negative pressure environment around the opening according to Bernoulli's principle, thereby discharging the air in the compartment space that is in air communication with the exhaust opening to the outside of the system through the exhaust opening.

[0036] Hereinafter, an embodiment of the electric outboard motor according to the present invention will be described with reference to the drawings. In the drawings, the same reference numeral indicates the same part or unit. The components in the following embodiment can be replaced or combined with existing components as appropriate, and the description of the following embodiment does not limit the content of the invention as described in the claims.

[0037] <Configuration of the Electric Outboard Motor of the Present Invention Excluding the Cooling System Configuration> The configuration of the electric outboard motor of the present invention, excluding the cooling system configuration, is basically substantially the same as the configuration of the electric outboard motor described in Japanese Patent Application No. 2024-18955 by the present applicant, excluding the air-cooling system of the invention related to said application. An overview thereof will be described below. Figure 1 is a perspective view (viewed from the front right side of the electric outboard motor 10) showing the appearance of an electric outboard motor 10, which implements a cooling system as an example of an embodiment of the present invention, mounted on a transom board and with an external power cable connected. In Figure 1, for convenience, only a part of the transom board 70, which does not constitute the present invention, is shown, and only a part of the power supply cable 98, which is connected to a power supply coupler connected to the lower side of the outboard motor side connection coupler 96, is shown. In the lower end region of the drive shaft housing 302, a portion is cut off to expose the piping (routing) configuration of the pipes (first ascending channel pipe 320, second descending channel pipe 324) provided inside, and the configuration of the drive shaft 322 running vertically between them. However, this cutoff is merely for convenience, and in the embodiment of the electric outboard motor of the present invention, such a cutoff region does not exist, and the wall of the drive shaft housing constitutes a continuous body.

[0038] As shown in Figure 1, the electric outboard motor 10 can be seen to have an outboard motor body 1, a steering mechanism 2 which mainly constitutes the other parts (hereinafter referred to as "other mechanical parts"), an external power supply connection mechanism 3, and a connecting mechanism 4 (clamp mechanism and swivel mechanism) which detachably and rotatably connects the outboard motor body 1 to the transom board 70 of the hull. Among the other mechanical parts mentioned here, the connecting mechanism 4 includes, as shown in Figure 1, two clamp brackets 62a and 62b that detachably fix the main body 1 to the transom board 70, a swivel bracket that supports the main body 1 so that it can rotate in the horizontal plane (not shown in Figure 1, but its upper end surface 64b is shown instead), the main body 64 of the swivel bracket (not shown in Figure 1, but a part of it is shown in Figures 2 and 3. Note that the main body 64 and the upper end surface 64b of the swivel bracket are integrally molded and are configured as a single, inseparable piece, but different reference numbers are assigned in this configuration for convenience only. Also, it is not essential that it be a single piece, and it is also possible to configure it by fastening individual members together.), and a steering shaft that is integrated with the main body 64 of the swivel bracket at its rear and forms a continuous unit. The system mainly includes a bracket 66 (not shown in Figure 1, but partially shown in Figures 2 and 3), a steering shaft (not shown in any of the figures as it is housed inside the steering shaft bracket 66) that is rotatably housed in the horizontal plane within the steering shaft bracket 66, and a yoke assembly (composed of a motor base side lower mount bracket 285 integrally molded with the motor base, a separate lower mount bracket that forms a pair with it (not shown in Figure 1, but reference numeral 285 in Figure 2), and a mounting boss (not shown in Figure 1, but reference numeral 54 in Figure 2)) that holds the lower mount unit 30 (not shown in Figure 1, but shown in Figure 3) that pivotally supports the steering shaft from below. However, these structural elements do not constitute part of the cooling system according to the present invention.

[0039] Furthermore, the steering mechanism 2 mainly includes a steering arm 47, a tiller handle 44, a throttle grip 42, a friction knob 41, a stopper 43, a lanyard 45, and a monitor window 48 (note that the tiller handle 44 and throttle grip 42 are equipped with electrical components generally required for electric outboard motors). However, these structural elements do not constitute part of the water cooling system according to the present invention. If anything, the throttle grip 42, which starts an electric motor mechanically connected via the powertrain to the rotation of the propeller 504 that generates a pressure-driven flow of refrigerant fluid consisting of seawater or freshwater outside the electric outboard motor while it is underway, can be said to be indirectly related to the water cooling system according to the present invention. From this perspective alone, the connection cable mechanism 3 that connects the motor controller (shown as reference no. 123 in Figure 6(b): housed in the first ECU housing unit 100 (or the first compartment 100A configured inside it), which consists of the first ECU housing 102 and its cover 106 shown in Figure 3) that controls the starting of the electric motor, to an external power supply can also be said to be indirectly related to the water cooling system according to the present invention.

[0040] At the resolution of Figure 1, explaining the propulsion mechanism of the electric outboard motor 10 would require referring to components not shown in Figure 1, which would make it somewhat difficult to understand. Therefore, we will now jump ahead and refer to Figure 3 (a detailed explanation of Figure 3 will be given later) as follows. That is, the electric outboard motor 10, which has the cooling system according to the present invention mounted inside the main body 1, has an electric motor (housed inside the motor cover 263 and therefore not visible from the outside, and not shown in any figure. Note that the electric motor and motor cover are used as a pair, so in this specification, the electric motor and motor cover are given the same reference number and are used as interchangeable terms, and their usage should be appropriately determined according to the context) inside the motor room housing 282 (which constitutes the second B housing 280) and a second B compartment 280. Above A, the second A housing 224 (which defines the second A compartment 220A) is in air communication with the second B compartment 280A, and within the first ECU housing unit 100 (which defines the first compartment 100A) is an electronic control unit (first ECU, shown as reference no. 123 in Figure 8) that controls the electric motor. Power from an external power source (not shown in Figure 1) is routed into the outboard motor body 1 as an extension of the outboard motor side cable 92a, and the end of that is connected to a contactor 229 (which is housed inside the contactor housing shown as reference no. 221 in Figure 3 and is not visible from the outside), and from there power is supplied by a cable (not shown in Figure 3) that connects to the first ECU.

[0041] Furthermore, as shown in Figure 3, the powertrain 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. Specifically, it includes a coupling 271 connected to the motor rotation shaft of the electric motor, a drive shaft 322 connected to its lower side, a bevel gear B408 (drive gear) provided at the lower end of the drive shaft 322, a bevel gear A409 (driven gear) configured to mesh with it, and a propeller shaft 411 having the driven gear at one end. The configuration and structural elements of this powertrain are basically the same as those known, and from the viewpoint that explanations of these mechanisms and elements are unnecessary for explaining the cooling system according to the present invention, they are omitted below.

[0042] Now, let's return to Figure 2 from Figure 3 to explain. Figure 2 is a combination of a right-side view showing the external appearance of the electric outboard motor 10 in Figure 1 and a perspective view showing the outlines of the internal components of the main body 1 of the electric outboard motor with dashed lines. Comparing Figure 2 and Figure 1, the only differences are that the coupling mechanism 4 (clamp mechanism and swivel mechanism) in Figure 1 is slightly easier to distinguish, and the cooling fins shown by reference numeral 287 are more clearly visible. For convenience, the lanyard 527 shown in Figure 1 has been removed in Figure 2.

[0043] As shown in Figure 2, the main body 1 can be said to be divided into an upper section 1a and a lower section 1b. The upper section 1a of the main body 1 is located inside the cowling covers 21a and 21b (plastic is preferably used), and most of it is surrounded by the cowling covers 21a and 21b. The front upper part of the cowling cover 21b has a partial opening through which the left and right arm sections 47a and 47b of the steering arm 47 (only the right arm section 47a is shown in Figure 2) are inserted. The space (reference number 222 in Figure 3) for fixing the upper mount arm (not shown in Figure 2) to the main body 1 is watertight. In addition, the outlet 91 through which a portion of the connection cable 92a on the main body 1 side is pulled out to connect to an external power source (not shown) is a grommet with an insertion hole, and is watertight when the outboard motor side connection cable 92a is inserted. On the one hand, the lower end of the cowling 21a ends slightly below the lower end of the motor basement 288, while the lower end of the cowling cover 21b ends on the upper surface of the motor basement 288. Although there is a small gap around the entire circumference between the outer surface of the motor basement 288 and the inner surface of the cowling 21a, it cannot be expected that outside air will flow into the inside of the cowlings 21a and 21b from the lower end of the cowling 21a during operation, thereby providing air cooling for the various functional elements mounted or arranged in the upper section 1a. Consequently, the inside of the cowlings 21a and 21b tends to accumulate heat relatively easily. This is due to the design prioritizing the appearance, which is as slim as possible in the vertical direction, i.e., gives the impression of being elongated, and this leads to the specific problem that the present invention aims to solve, which will be described in detail below.

[0044] Referring to the combination of FIG. 2 and FIG. 3 described below, an electric motor 263, which is one of the objects to be cooled in the present invention, is housed in a second B housing unit 280 (second B compartment 280A) disposed within a space approximately in the lower half of the above-described upper section 1a. Note that since the electric motor 263 is generally commercially available and used as a pair with a motor cover covering it, in the following description, the motor cover covering the electric motor 263 is given the same reference number as the electric motor for convenience. However, the distinction between them shall be made reasonably according to the context where the terms "electric motor" or "motor cover" are used so that the meaning is clear.

[0045] In the present invention, the electric motor 263 is bolted and fixed to the upper surface side of a motor base mount 288. In that case, the bottom surface of the electric motor 263 facing the upper surface of the motor base mount 288 may be either exposed (uncovered by a motor cover) or covered by a motor cover. In either case, it is preferable to interpose a heat conduction sheet (also referred to as a heat conduction and heat dissipation sheet) (not shown) between the upper surface of the motor base mount 288 and then bolt and fix it to the motor base mount 288, although it is not necessary to interpose it. For the heat conduction sheet (not shown) to be interposed, any material properties (e.g., size, material, thermal conductivity, etc.) can be suitably used as long as the object of the present invention can be achieved.

[0046] In the following description, when explicitly distinguishing between the electric motor 263 and the motor cover 263 covering it, it may be referred to as a motor body. The electric motor 263 mounted here is a rotor / stator type electric motor. There is no limitation on its type, and other types of electric motors can also be suitably used. For example, one of the features of the present invention is that electric motors used in on-land environments such as electric vehicles or electric fire pumps, or their general-purpose products, can also be suitably used.

[0047] The electric motor 263 used in the outboard motor according to the present invention does not have a water jacket or an oil jacket for cooling, but it does not actively exclude the provision of a water jacket or an oil jacket in order to improve the heat dissipation efficiency. In the present invention, the main method of dissipating heat from this electric motor 263 to the outside of the system is to support the lower surface of the electric motor 263 from directly below it, and the refrigerant fluid (specifically, seawater or fresh water outside the outboard motor during navigation) flowing through the motor basement gap 324 formed in the motor basement 288 having a surface in thermal communication with the lower surface is used as a heat sink in a water cooling method. Further, as an auxiliary method, a passive air cooling system (details will be described later) that does not use active functional elements is also preferably included.

[0048] The electric motor used in the present invention can preferably use an electric motor generally used in a land environment, and standard products that meet predetermined standards can preferably be used. Although it does not actively exclude the need for special treatment to exceed a predetermined standard level in some cases, when used in combination with the cooling system according to the present invention, even when used in a marine environment, it does not require special treatment beyond the treatment performed at the time of shipment before being commercially available in the general market. Thus, in the electric motor used in the outboard motor 10 according to the present invention, even in a marine environment, which is a harsh environment for electronic devices, as long as it is a standard product that meets a predetermined standard corresponding to use in a land environment or a substantially equivalent product thereof, it can be used without requiring further special treatment and without requiring an active heat dissipation mechanism that requires a new active element, which is also one of the features of the outboard motor 10 according to the present invention.

[0049] Next, an overview of the lower section 1b in Figure 2 will be described. The powertrain mechanism is implemented in this lower section 1b, and a known one for electric outboard motors, or a combination of a functionally equivalent one, can be suitably used. That is, the rotational torque force of the electric motor 263 is transmitted to the coupling 271 connected to its lower side, and then to the drive shaft 322 connected to the lower end of the coupling 271. In this invention, the coupling 271 is directly connected to the rotating shaft (not shown) of the electric motor 263, and no gear reduction device is interposed between them, however, a gear reduction device can be suitably applied as needed in some cases.

[0050] The lower end of the drive shaft 322 is connected to a drive gear, a bevel gear B408, which is configured to mesh with a driven gear, a bevel gear A409. The meshing of these two gears converts the vertical rotation axis of the drive shaft 322 into a horizontal rotation axis, which becomes the rotation axis of the perforated screw propeller unit 506. Through this mechanism, the rotational torque force of the electric motor 260 becomes the rotational torque force of the perforated screw propeller unit 502. It should be noted that the above powertrain mechanism can also be suitably applied to known powertrain mechanisms commonly used in gasoline engine outboard motors.

[0051] The perforated screw propeller unit 502 according to the present invention is of the same type as the perforated screw propeller unit used in gasoline engine outboard motors, which has the function of discharging exhaust gas from the gasoline engine into the sea. In this respect as well, the electric outboard motor 10 according to the present invention has the advantage of being able to use common units or actively utilize general-purpose parts.

[0052] The above is an overview of the structural features of the electric outboard motor (screw type and external power supply type) that constitutes the present invention, excluding the configuration of the cooling system of the present invention. From here on, the description will focus on the features of the cooling system (including a water cooling system and, as an option, a passive air cooling system) installed in the electric outboard motor according to the present invention. Note that the description up to this point follows the order in which the figures are shown in the drawings, but from here on, the description will follow the order in which the figures are referenced to make the explanation of the gist of the present invention easier to understand, and will not follow the order in which the figures are shown in the drawings.

[0053] <Water Cooling System According to the Present Invention> The water cooling system among the cooling systems of the present invention will be described below with appropriate reference to Figures 2 and 3, respectively. 1. Configuration The water cooling system according to the present invention does not include any moving parts or active parts (parts that operate themselves to generate a pressure-driven flow in the refrigerant flow path, such as an impeller pump) in the middle or within the refrigerant flow path (refrigerant fluid flow path). Therefore, such a water cooling system is the refrigerant flow path (refrigerant fluid flow path) itself, and its outline is illustrated in Figure 2 by dashed lines running through a perspective view showing the main components (components and units) in the upper section 1a and lower section 1b of the main body 1 of the electric outboard motor 10. The configuration of the refrigerant flow path (refrigerant fluid flow path) shown by the dashed lines in the figure can be explained as follows, following the dashed lines in Figures 2 and 3: The refrigerant fluid enters through a plurality of holes 426 (more specifically, the inlets 405 of the holes 426, which also serve as strainers) into which it is taken into the system, circulates within the system along the refrigerant flow path, and finally reaches the refrigerant discharge opening 502 (a discharge port already provided on the perforated propeller during its manufacturing stage) into which the refrigerant fluid is discharged.

[0054] 1) As shown in Figures 2 and 3, the gear case 404 has a plurality of holes 426 formed in its lower region, at a height below the surface of seawater or freshwater when the electric outboard motor is underway. These holes have their axes oriented horizontally and are discretely arranged at equal or unequal intervals in the vertical direction. Each individual hole 426 has an inlet 405 facing forward, and its opposite rear end is in fluid communication with a vertically extending void 420 formed inside the gear case 404. There are no particular restrictions on the number of holes in a row consisting of these plurality of holes 426. However, since each individual hole 426 provides an inlet 405 for introducing refrigerant fluid (seawater or freshwater in the present invention) into the refrigerant flow path system, a larger number is advantageous when high cooling capacity is required. However, it is preferable to have a number that allows for a balanced flow rate of the refrigerant fluid flowing through the refrigerant flow path, taking into consideration the effort required for processing, acceptable costs, etc. Furthermore, the inlets 405 of each hole 426 are preferably sized and shaped to function as strainers. The term "strainer" here refers to a strainer commonly used in gasoline engine outboard motors, and specifically refers to a part with multiple holes formed on the side of the gear case to remove debris when seawater, which is necessary for driving the water cooling system by the impeller pump, is drawn into the water cooling system from outside the gasoline engine outboard motor.

[0055] Figure 3 shows multiple holes 426 arranged in a vertical line on the right side of the gear case 404 (the right side when looking forward of the electric outboard motor). On the reverse side of the drawing, i.e., on the left side of the gear case 404, there are also multiple holes (not shown) of the same shape as those on the right side, arranged vertically at a position symmetrical to the plane parallel to the front-to-back direction of the gear case 404, and formed in the same number and manner (not shown).

[0056] The orientation of these individual holes 426 is preferably such that, during the operation of the electric outboard motor, dynamic pressure is generated in its vicinity, and this pressure allows seawater or freshwater, which will serve as a coolant, to be injected into the system through the inlet 405 of each hole 426. When there is only one row of these holes 426, the orientation of each individual hole 426 is preferably the same as the direction of operation (propulsion direction) of the electric outboard motor. On the other hand, when there are two rows, it is preferable that the individual holes 426 are arranged vertically in a manner similar to that of a single row, at symmetrical positions when viewed from the front of the gear case. In the case of two rows, as an example, each hole 426 can be suitably formed by drilling a narrow horizontal hole that extends vertically through the gear case 404, at a position symmetrically separated from the front end of the cross-section when viewed from above. Alternatively, if it is possible to cast the gear case 404 with the void 420 and the multiple holes 426 already connected during the casting process, then a method for forming them can also be suitably applied.

[0057] The orientation of each individual hole 426 formed in this manner (the orientation of its central axis along its depth direction) is preferably approximately the same as the direction of travel of the electric outboard motor, regardless of the contour of the gear case 404. In this case, in a top view, the orientation of the opening surface that becomes the entrance 405 of the hole 426 (the direction perpendicular to the opening surface) is perpendicular to the tangential direction of the contour (profile) of the gear case 404 at the location where each individual hole 426 is drilled, and is dependent on the contour of the gear case 404, but is preferably between 0° and less than 90°, more preferably between 0° and 45°. However, the orientation of the cross-section along the plane perpendicular to the central axis along the depth direction of each individual hole 426 (the direction perpendicular to the cross-section) is preferably approximately the same as the direction of travel of the electric outboard motor.

[0058] 2) The rear ends of these multiple holes 426 are in fluid communication with a gap 420 that extends vertically inside the gear case 404. "Fluid communication" means a configuration in which a fluid (liquid and gas) flows from one space (gap) to the other between two adjacent spaces (gaps), but the direction of the fluid (liquid and gas) flow is not specified. The upper end of this gap 420 is connected to the lower end of the first upward flow channel pipe 320. A known general method can be suitably applied to this connection. Furthermore, since pressurized seawater or freshwater is introduced into it, a sealing material such as a rubber gasket is suitably applied to the fastening part.

[0059] 3) The upper end of the first upward flow channel pipe 320 is an open end, and its upper end terminates at the front part of the annular gap 324 (referred to as the "motor basement gap 324") which is a void providing a refrigerant flow path within the motor basement 288 and is centered on the rotation axis of the electric motor, thereby establishing fluid communication between the first upward flow channel pipe 320 and the motor basement gap 324. The material of the first upward flow channel pipe 320 is preferably one that does not rust or deteriorate due to seawater, and there are no particular restrictions on its shape, size, etc., as long as the objective of the present invention can be achieved. Furthermore, a known general method can be preferably applied to connect the first upward flow channel pipe 320 and the motor basement gap 324. Also, since pressurized seawater or freshwater is introduced into it, a sealing material such as a rubber packing is preferably applied to the connection part.

[0060] 4) The motor basement gap 324 is formed in an annular shape around the rotation axis of the electric motor 263 (part of which is exposed between the lower end of the electric motor 263 and the upper end of the coupling 271) or the axis of the coupling 271 connected to its lower end, and the lower end surface of the motor basement gap 324 is sealed by the seal plate 289. In a top view, it is preferable that the planar size of the lower surface of the electric motor 263 is smaller than the planar size of the annular gap of the motor basement gap 324 directly below it. In this case, sealing can be achieved by inserting a known general sheet-like sealing material between the lower end surface of the motor base 288 and the upper end surface of the seal plate 289.

[0061] 5) The rear side of the motor basement gap 324 is connected to the open end of the lower end of the second rising flow pipe 265, thereby creating fluid communication between the rear side of the motor basement gap 324 and the second rising flow pipe 265. The volume of the motor basement gap 324 is preferably made as large as possible, within a range that can support the weight of the electric motor 263 or within other structurally permissible ranges, for example, by reducing the wall thickness of the motor basement 288 above the motor basement gap 324. This is expected to improve the cooling efficiency of the electric motor 263 by the refrigerant fluid (seawater or freshwater outside the electric outboard motor while it is running) flowing through the motor basement gap 324. A known general method can be suitably applied to connect the lower end of the second rising flow pipe 265 to the rear side of the motor basement gap 324. Furthermore, since pressurized seawater or freshwater is introduced into the interior, a sealing material such as a rubber packing is suitably applied to the connection.

[0062] 6) The second rising channel pipe 265, whose lower open end is connected to the gap 324 on the rear side of the motor basement gap 324 (180 degrees opposite to the position of the upper end of the first rising channel pipe 320), has an open upper end which is connected to the lower open end of the first ECU housing cooling channel pipe 103 (Figure 5) (hereinafter simply referred to as "cooling channel pipe 103"). This creates a fluid connection between the second rising channel pipe 265 and the cooling channel pipe 103. The material, shape, and size of the second rising channel pipe 265 can be suitably applied as long as the objective of the present invention can be achieved. A known general method can be suitably applied to connect the upper end of the second rising channel pipe 265 and the lower end of the cooling channel pipe 103. Furthermore, since pressurized seawater or freshwater is introduced into the interior, a sealing material such as a rubber packing is suitably applied to the connection part.

[0063] 7) It is preferable that the cooling channel pipe 103 is integrally molded to the outer surface of the bottom of the first ECU housing 100 (bottom of the first ECU housing 111). In this case, it is preferable to form the channel after integral molding using a known method (for example, by drilling). This is expected to increase heat conduction to the refrigerant fluid (seawater or freshwater) flowing through the cooling channel pipe 103 compared to creating the cooling channel pipe 103 from a metal pipe or the like and then joining or bonding it to the outer surface of the bottom of the first ECU housing 100 as an afterthought. The cooling channel pipe 103 is preferably positioned directly below the center of the arrangement of the converter (not shown), which is a heat-generating part in the first ECU module 123 (its outline is shown by a dashed line in Figure 3) mounted in the first ECU housing unit 102, within the bottom of the first ECU housing 111, and its length is preferably as close as possible to the vertical length of the bottom of the first ECU housing 111.

[0064] 8) The upper end of the cooling channel pipe 103 is an open end and is connected to the upper end of the open end of the second descending channel pipe 266, thereby enabling fluid communication between the two members. The material, shape, and size of the second descending channel pipe 266 can be suitably applied as long as it is durable enough for use at sea and achieves the objectives of the present invention. The lower end of the second descending channel pipe 266 is an open end and terminates inside the void 325 formed on the rear side of the motor basement 288. This enables fluid communication between the second descending channel pipe 266 and the void 325. A known general method can be suitably applied to connect the upper end of the second descending channel pipe 266 to the upper end of the cooling channel pipe 103. Since pressurized seawater or freshwater is introduced into the connection, a sealing material such as a rubber packing is suitably applied to the connection. Furthermore, a known general method can be suitably adopted to connect the lower end of the second descending channel pipe 266 to the void 325. Since pressurized seawater or freshwater is introduced into the interior, a sealing material such as a rubber gasket is preferably applied to the connecting part.

[0065] 9) The upper end, which is the open end of the first downflow pipe 321, partially protrudes from the lower side of the gap 325, thereby creating fluid communication between the gap 325 and the first downflow pipe 321. A known general method can be suitably applied to connect the upper end of the first downflow pipe 321 to the gap 325. Furthermore, since pressurized seawater or freshwater is introduced into the interior, a sealing material such as a rubber packing is suitably applied to the connection. 10) The first downflow pipe 321 has an end inside the gap 325 and extends to its lower side, and its lower end, which is the open end, is connected to the upper end of the downflow passage 424 in the gear case, thereby creating fluid communication between the first downflow pipe 321 and the downflow passage 424 in the gear case. A known general method can be suitably applied to connect the lower end of the first downflow pipe 321 to the upper end of the downflow passage 424 in the gear case. Furthermore, since pressurized seawater or freshwater is introduced into it, a sealing material such as a rubber packing is preferably applied to the connection. 11) The lower end of the descending passage 424 in the gear case is fluidly connected to the front part of the intermediate connecting passage 405, which is also formed in the gear case, and the rear end of this intermediate connecting passage 405 is configured to fluidly connect to the front part of the lumen 507 (hereinafter simply referred to as "lumen 507") in the screw propeller unit. A known general method can be preferably applied to connect the rear end of the intermediate connecting passage 405 in the gear case and the front end of the lumen 507. Furthermore, since pressurized seawater or freshwater is introduced into it, a sealing material such as a rubber packing is preferably applied to the connection. 12) The rear part of the lumen 507 constitutes a refrigerant discharge opening 502, thereby fluidly connecting the descending passage 425 in the gear case and the refrigerant discharge opening 502.

[0066] 13) As a result of the above, the refrigerant discharge opening 502 and the plurality of holes 426 formed on the front side of the gear case 404 are in fluid communication, and through these plurality of holes 426, the refrigerant discharge opening 502 is in fluid communication with seawater or freshwater outside the electric outboard motor.

[0067] <Materials, shapes, sizes, etc. of each component constituting the water cooling system of the present invention> 1) The following are examples of components that can be suitably applied, as long as the material used is durable enough for use at sea and the shape, size, etc. can be any shape as long as the objective of the present invention can be achieved: a) First ascending channel pipe, second ascending channel pipe b) First descending channel pipe, second descending channel pipe 2) The following are examples of components that can be suitably applied, as long as the material used is aluminum or an aluminum alloy and the shape, size, etc. can be any shape as long as the objective of the present invention can be achieved: a) Gear case 404 (including integrally molded skeg 406) b) Motor basement lower seal plate (seal plate) 289 c) Motor basement 288 (including integrally molded motor basement side bracket 285 and cooling fins 287) d) First ECU housing cooling channel pipe 103 (including integrally molded first ECU housing 102) 3) The material, shape, size, etc. of the components of the electric outboard motor other than the components of the water cooling system of the present invention are the same as the material, shape, size, etc. of the components of the electric outboard motor described in the specification of Japanese Patent Application No. 2024-18955 (by the same applicant as the applicant of this application), which is referenced in the description of this specification and has the same reference number as the reference number described in this specification or drawings. 4) In addition, regarding the structure and connection method of the connecting parts between different members in the water cooling system of the present invention, known general structures and connection methods for ensuring watertightness at the connecting parts can be suitably applied.

[0068] 2. Flow of refrigerant fluid (seawater or freshwater) As is clear from the configuration described in 1 above, the water cooling system of the present invention does not include any active components (components that operate on their own to generate a pressure-driven flow in the refrigerant flow path, such as an impeller pump). Therefore, the refrigerant fluid (hereinafter, for convenience, represented by seawater) flows through the refrigerant flow path, riding on the pressure-driven flow generated in the refrigerant flow path having the above configuration, only when the electric outboard motor is running, that is, when the propeller located below the sea surface is rotating and the electric outboard motor is being propelled, from the multiple holes 426 (and their inlets 405) toward the refrigerant discharge opening 502. The sequence, described in accordance with the flow of refrigerant fluid entering the system, is as follows: multiple holes 426 (and their inlets 405), the upward flow path 420 in the gear case, the first upward flow path pipe 321, the gap in the front part of the motor basement gap 324, the rear part of the motor basement gap 324, the second upward flow path 265, the first ECU housing cooling flow path pipe 103, the second downward flow path pipe 266, the gap 325 formed in the rear part of the motor basement 288, the first downward flow path pipe 321, the downward flow path 425 in the gear case, the lumen 507 in the screw propeller unit, and the refrigerant discharge opening 502. Of the above flow, the flow of refrigerant fluid from the gap in the front part of the motor basement gap 324 to the rear part of the motor basement gap 324 is illustrated in Figure 3 by a single dashed line going from the former to the latter.

[0069] 3. Heat Dissipation Flow 1) The heat generated from the electric motor 263 travels along the wall of the motor basement 285 below the electric motor 263 and is transferred to the refrigerant fluid (seawater or freshwater) flowing through the motor basement void 324. The refrigerant fluid, now with increased heat (higher temperature), then rises through the second upward flow channel 265 towards the first ECU housing cooling flow channel 103 in order to cool the first ECU module 123.

[0070] 2) Heat generated from the converter (a converter that converts alternating current to direct current) (not shown) inside the first ECU module 123 is transferred to the heat dissipation fins 124 integrally molded on the outside of the first ECU module 123 via the bottom wall (base plate) of the first ECU module 123, then to the bottom 111 (first ECU housing bottom 111) of the first ECU housing 102, which is configured to have thermal communication with the bottom of the heat dissipation fins 124 (for example, by inserting a heat dissipation sheet between the two members to create thermal communication), and this heat is transferred to the wall of the first ECU housing cooling channel pipe 103, and finally to the refrigerant fluid (seawater or freshwater) flowing through the cooling channel pipe 103, where the temperature of the refrigerant fluid is increased and ultimately released into the sea.

[0071] <Air cooling system that can be added as an option to the water cooling system> The air cooling system referred to in this invention is not actively configured at the stage of designing the main body 1 of the electric outboard motor 10 of the present invention, except for the air cooling fins 287, but is a passive air cooling system that is inevitably formed from the configuration of the housing system, which is one of the features of the main body 1 of the electric outboard motor 10 of the present invention. Passive means that the system does not contain any active or movable parts. In the housing system configured in the main body 1 of the electric outboard motor 10 of the present invention, as shown in Figure 3, a plurality of housing units, each defining a compartment, are connected in series.

[0072] Specifically, the first compartment 100A (defined by the first ECU housing unit 100) housing the first ECU module 123, the second A compartment 200A (defined by the second A housing unit 200A) in the space above the cover of the electric motor 263, the second B compartment (defined by the second B housing 282) in the space below the cover of the electric motor 263, and the third A compartment (defined by the third A housing unit 300) to which the lower part of the coupling 271, the first rising cooling channel pipe 320, the first descending cooling channel pipe 321, and the drive shaft 322 extend, are each configured so that air flows through them via common air communication holes.

[0073] Specifically, these air vents are: a first air vent 118 between the first compartment 100A and the second A compartment 200A; a second air vent (not shown) and a group of second air vents (not shown) opened in the gasket 231 between the second A compartment 200A and the second B compartment; and an optional third air vent (not shown) opened in the motor base 285 and the seal plate 289 (motor base lower seal plate 289) between the second B compartment and the third A compartment. Additionally, a fourth air vent (not shown) connected to the outside air is optionally formed in the wall of the third A housing unit 300 (i.e., the drive shaft housing 300) that defines the third A compartment, at a position above sea level.

[0074] In the above configuration, a single wind tunnel system is formed by compartments connected in series via air vents. When the air occupying a portion of this wind tunnel system rises in temperature due to the heat generated by the heat-generating elements contained within, an upward airflow is generated due to the chimney effect. Heat from the electric motor 263 and the first ECU module is then transferred to this upward airflow, and the increased heat and resulting higher temperature of the air are finally discharged to the outside air through an opening (first outside air intake 130) provided in the first ECU housing cover 106 that connects to the outside air. This phenomenon occurs automatically from the moment the electric outboard motor finishes sailing, docks in port, and the electric motor 263 is stopped (air-cooled A while docked).

[0075] On the other hand, while the electric outboard motor is underway, the outer surface of the first ECU housing cover 106 faces away from the direction of propulsion of the electric outboard motor, so air flows around it, forming turbulence. According to Bernoulli's principle, this creates a negative pressure environment, which is transmitted from the opening (first air intake 130) through the compartment and air communication holes to the third A compartment. This negative pressure environment draws outside air into the third A compartment through a fourth air communication hole (not shown) located in the wall of the third A housing unit 300 that defines the third A compartment. This drawn-in outside air flows upward through the wind tunnel system, cooling the electric motor 263 and the first ECU module located in the process from the outside (air cooling A during operation).

[0076] Furthermore, by aligning the central axis of the fourth air communication hole (not shown), which is provided in the wall of the third A housing unit 300 defining the third A compartment and connects to the outside air, with the same direction as the propulsion of the electric outboard motor, dynamic air pressure is generated at the opening. Additionally, by increasing the size of the opening, outside air can be forcibly pushed into the third A compartment, thereby further enhancing the above effect (a variation of air-cooled A during voyage).

[0077] Furthermore, the main body 1 of the electric outboard motor 10 of the present invention has a plurality of cooling fins 287 arranged parallel to each other, which are integrally formed with the motor base 288 on the underside of the motor base 288. In this case, the orientation of each cooling fin 287 is in line with the front-rear direction of the electric outboard motor body. The shape, size (length, thickness), spacing, etc. of each cooling fin are not particularly limited and can be suitably adopted as long as they are suitable for achieving the objectives of the present invention. Note that these cooling fins 287 are merely auxiliary to the air cooling system according to the present invention, and these cooling fins 287 are not an essential element in the implementation of the present invention (air cooling B during voyage and air cooling B while at anchor).

[0078] <Referencing the matters described in Japanese Patent Application No. 2024-18955 by the present applicant> Regarding the configuration of the wind casing system supporting the above air cooling system, and the air cooling mechanism therefor, we believe that the matters that clearly specify the invention (inventive features) are sufficiently described in the above explanation. However, if a more detailed explanation is required to determine the inventive features, we hereby referencing the matters described in Japanese Patent Application No. 2024-18955, which use the same names and reference numbers for each component constituting the electric outboard motor of the present invention as the names and reference numbers in the drawings attached to this application. For members, parts, units, etc. that are not explicitly described in the above specification but are shown in the drawings with reference numbers, please refer to the section on explanations of symbols.

[0079] The cooling system of the present invention is primarily a water-cooling system, and can be a hybrid type with an air-cooling system as an option.According to the present invention, it is possible to provide an electric outboard motor equipped with a cooling system (primarily a water-cooling system with an optional auxiliary air-cooling system) that is expected to have high "energy efficiency," a simple structure, a small number of parts, easy maintenance, and low manufacturing costs in a form never before proposed.Furthermore, by enabling the use of a motor controller (ECU equipped with an inverter using power semiconductors) and an electric motor, which are used in land environments where there is little concern about leakage current due to water or short circuits due to channeling between electrodes, in an electric outboard motor in a marine environment where they are often exposed to seawater spray, without any special leakage current countermeasures or waterproofing measures for each, it is expected that the advantages of electric systems, which are being improved at a rapid pace in representative examples of electric mechanisms used in land environments such as electric vehicles and electric fire pumps, can be fully enjoyed in electric outboard motors, which are representative examples of electric mechanisms used in marine environments.

[0080] The above description of the embodiments 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 embodiments. Therefore, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0081] For example, based on the description of the above embodiments, it can be understood that the electric outboard motor according to the present invention can be defined by the following inventive features. (1) An electric outboard motor with an external power supply, comprising at least an electric motor, a motor controller having an electronic control unit (ECU) for electronically controlling the electric motor, and a perforated screw propeller that rotates using the rotational force of the electric motor as a driving force at the end of a power chain from the electric motor, wherein the body of the electric outboard motor has a water cooling system that cools the electric motor and the electronic control unit (ECU) using seawater as a refrigerant, the water cooling system having a refrigerant flow path with an inlet opening and an outlet opening for the refrigerant at both ends, the walls of the refrigerant flow path having a refrigerant flow path that is thermally conductively connected to the electric motor and the electronic control unit, respectively, and the electric outboard motor is configured to use the negative pressure generated in the vicinity of the perforated screw propeller located below the water surface as a driving force to take the refrigerant into the refrigerant flow path from the inlet opening located below the water surface and discharge it to the outside of the body of the electric outboard motor from the outlet opening. (2) The cooling system in Feature 2 above is a refrigerant flow path having an inlet opening and an outlet opening for the refrigerant fluid at both ends, wherein the wall of the refrigerant flow path is thermally conductively connected to the wall of the housing that houses the electric motor and the electronic control unit, and is configured to take in the refrigerant fluid from the inlet opening into the refrigerant flow path and discharge it from the outlet opening to the outside of the main body of the electric outboard motor, using the pressure difference between the inlet pressure at the inlet opening and the discharge pressure at the outlet opening, which are located below the water surface, as a driving force while the electric outboard motor is running. (3) The inlet opening in Feature 2 above has a plurality of holes in the wall of the refrigerant flow path, each of which is fluidly connected to the outside of the electric outboard motor via holes formed in the wall of the gearbox, and the orientation of each of the plurality of holes is substantially the same as the propulsion direction of the electric outboard motor.(4) The electric outboard motor according to claim 3, wherein the discharge opening in feature 4 has at least one hole located behind the inlet opening, and the orientation of the central axis of the hole intersects the propulsion direction of the electric outboard motor at an internal angle of 0° to 90°. (5) The electric outboard motor according to claim 4, wherein if the intersection angle between the orientation of the central axis of the hole in feature 4 and the propulsion direction of the electric outboard motor is 0°, the hole constitutes a discharge port at the rear end of the propeller shaft housing of the perforated screw propeller for propulsion of the electric outboard motor. (6) An electric outboard motor with an external power supply, comprising at least an electric motor and a motor controller having an electronic control unit (ECU) for electronically controlling the electric motor, wherein the electric outboard motor is equipped with a cooling system that, during the operation of the electric outboard motor, dissipates the heat generated from the electric motor and the motor controller to a refrigerant fluid flowing through a refrigerant passage via the walls of the housings that house the electric motor and the motor controller, respectively, and the refrigerant fluid is seawater or freshwater taken into the refrigerant passage from outside the electric outboard motor while it is in operation.

[0082] 1: Outboard motor body 1a: Upper section 1b: Lower section 2: Steering mechanism 3: External power 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 (main body) 47a: Steering arm (right) 48: Copilot lever 52: Mounting bracket 52f: Steering shaft upper end receiving part 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: Swivel bracket upper end surface 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 101: First ECU module 102: First ECU housing 103: First ECU housing cooling channel pipe 105: Connection terminal 106: First ECU housing cover 107: Mounting boss 108: Side cover (grommet) of first ECU housing cover 112: Cover plate of recess 116 113: Labyrinth 118: First air vent 122: Base plate 123: First ECU module 124 : Heat dissipation fin 130 : First outside air intake 132 : Second outside air intake 135 : Projection for mounting bolt hole 136 : Projection for screw receiver 137 : Projection for conductive cable insertion 138 : Projection for spacer 139 : Conductive cable insertion hole200A: Second compartment 220: Second A housing unit 220A: Second A compartment 221: Contactor housing 222: Upper mount arm fixing space 224: Motor room cover housing section 226: First air communication hole 231: Gasket 263: Electric motor 265: Second upward flow pipe 266: Second downward flow pipe 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 289: Motor basement bottom seal plate (seal plate) 300: Third A housing unit 300A: Third A compartment 302: Drive shaft housing 322: Drive shaft 320 : First ascending passage pipe 321 : First descending passage pipe 324 : Motor basement gap 325 : Gap 400 : Third B housing unit 400A : Third B compartment 402 : Cavitation plate 403 : Propeller shaft support member 404 : Gear case 405 : Refrigerant inlet opening 406 : Skeg 408 : Bevel gear B (drive gear) 409 : Bevel gear A (driven gear) 411 : Propeller shaft 420 : Ascending passage in gear case 424 : Descending passage in gear case 425 : Intermediate connecting passage in gear case 500 : Fourth housing unit 500A : Fourth compartment 502 : Refrigerant outlet opening 504 : Propeller 506 : Screw propeller unit 507 : Lumen inside the screw propeller unit

Claims

1. An electric outboard motor comprising at least an electric motor and a motor controller having an electronic control unit (ECU) for electronically controlling the electric motor, wherein the electric motor and the wall of a housing housing the motor controller each have a refrigerant flow path having a wall that communicates thermally with the electric motor, the wall of the housing housing the motor controller, the refrigerant flow path having a closed end at one end and an open end at the other end, the region extending upward from the closed end having a refrigerant inlet opening, the open end having a refrigerant outlet opening, the refrigerant inlet opening having a plurality of discretely arranged holes, each of the plurality of holes being configured to allow the refrigerant flow path to communicate fluidly with seawater or freshwater outside the electric outboard motor while the electric outboard motor is in motion, and the refrigerant outlet opening being located behind the refrigerant inlet opening.

2. The electric outboard motor according to claim 1, characterized in that the orientation of the central axis of each of the multiple holes in the refrigerant inlet opening intersects the propulsion direction of the electric outboard motor at an internal angle of 0°.

3. The electric outboard motor according to claim 2, wherein the refrigerant discharge opening has at least one hole located behind the refrigerant inlet opening, and the orientation of the central axis of the hole intersects the propulsion direction of the electric outboard motor at an internal angle of 0° to 90°.

4. The electric outboard motor according to claim 3, characterized in that, if there is one hole and the angle of intersection between the orientation of the central axis of the hole and the propulsion direction of the electric outboard motor is 0°, the hole constitutes an outlet at the rear end of the propeller shaft housing of the perforated screw propeller for propulsion of the electric outboard motor.

5. An electric outboard motor according to one of claims 1 to 4, characterized in that, while the electric outboard motor is underway, the refrigerant inlet and the refrigerant outlet are located below the sea surface, and a pressure-driven flow of the refrigerant fluid is generated in the refrigerant flow path by the pressure difference of the water pressure between the two, and the water cooling system is obtained by using the pressure-driven flow to move seawater or freshwater outside the electric outboard motor while it is underway along the refrigerant flow path.

6. An electric outboard motor further comprising, in addition to the water cooling system, a passive air cooling system obtained by creating air communication between compartment space A housing the ECU module and compartment space B housing the electric motor, and by creating air communication between compartment space A and compartment space B with the outside air outside the electric outboard motor.

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