ELECTRICALLY POWERED OUTBOARD MOTOR

Abstract

Electric outboard motor (1) for a watercraft (2), comprising: an electric motor (8); a propeller (12) which is connected to the electric motor (8) via a power transmission mechanism (9, 10, 11); a control element (33) configured for operation by a user and having an operating position that is switchable between a forward rotation control position for instructing forward rotation of the electric motor (8) and a reverse rotation control position for instructing reverse rotation of the electric motor (8); and a control device (35) configured to switch between a drive state of the electric motor (8) according to the operating position of the control part (33) between a forward rotation state in which the electric motor (8) rotates in the forward direction, a reverse rotation state in which the electric motor (8) rotates in the reverse direction, and a neutral state in which the electric motor (8) does not drive; wherein the control device (35) is configured to set the drive state to the forward rotation state when the operating position of the control element (33) is in the forward rotation operating position, and to set the drive state to the reverse rotation state when the operating position of the control element (33) is in the reverse rotation operating position; and wherein, when the operating position of the control element (33) is switched from the forward rotation operating position to the reverse rotation operating position while the watercraft (2) is moving, the control device (35) sets the drive state to the neutral state for a predetermined period of time and then sets the drive state to the reverse rotation state.

Description

TECHNICAL AREA

[0001] The present invention relates to an outboard motor for a watercraft, which is equipped with an electric motor as a drive source. TECHNICAL BACKGROUND

[0002] Until now, many outboard motors for watercraft have used combustion engines as their power source. In recent years, vehicle emission regulations for motor vehicles, such as automobiles, have been tightened worldwide to reduce the adverse impact of exhaust emissions on the global environment. In this context, outboard motors powered by electric motors, which produce no exhaust fumes, have become more attractive. In the case of electrically driven outboard motors, switching between forward and reverse propeller rotation is achieved by reversing the direction of rotation of the electric motor. Thus, unlike outboard motors using combustion engines, an electrically driven outboard motor does not have a gearshift mechanism (reverse mechanism), but rather a power transmission mechanism that connects an electric motor to a propeller without a shifting mechanism.

[0003] An example of such technology is an electrically driven outboard motor for a watercraft, in which the outboard motor housing contains an electric motor in its upper section and a propeller in its lower section. The electric motor generates a driving force that rotates the propeller (JP 2014 - 80 077 A). This electrically driven outboard motor includes a control unit configured so that the electric motor, operating in regenerative mode, acts as a generator driven by the propeller's rotation to produce electrical energy, which is then used via an inverter to charge a battery. The control unit includes an operator controller configured to control the inverter, thereby controlling the operation of the electric motor based on signals from a throttle grip and a switch located on the watercraft's steering wheel.The switch is separate from the throttle handle and is used to switch the direction of rotation of the electric motor between forward and reverse rotation.

[0004] An example of such a technique is an electrically driven outboard motor for a watercraft, in which an accelerator grip is attached to a handlebar of the watercraft and is rotatable around the axis of the handlebar in forward and reverse directions. The accelerator grip is an actuating element used to change the direction of rotation and adjust the speed of an electric motor (JP 2014 - 172 518 A). The electrically driven outboard motor further includes a switching sensor and an accelerator sensor, each for detecting the direction and amount of rotation of the accelerator grip. The electrically driven outboard motor also includes a control unit configured to drive and control the electric motor depending on the direction and amount of rotation of the accelerator grip. CONVENTIONAL DOCUMENTATION SUMMARY OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION

[0005] However, the electrically driven outboard motors disclosed in JP 2014-80077A and JP 2014-172518A are designed without consideration for cases in which the direction of rotation of an electric motor is switched (reversed) by an operation (i.e., a switching operation on a reversing switch or a direction-change operation on an accelerator handle) while the watercraft is moving. For example, in some cases, while the watercraft is moving forward, a user operates the reversing switch to change the direction of rotation of the electric motor from forward to reverse in order to bring the watercraft to a sudden stop and thus avoid a collision with an obstacle.In this case, a sudden change in the direction of rotation (of the drive state) of the electric motor from forward rotation (forward rotation state) to reverse rotation (reverse rotation state) can cause a strong force to act on a propeller and a power transmission mechanism that connects the propeller to the electric motor, which can cause damage to these mechanical parts.

[0006] The present invention has been made in view of the problem described above from the prior art, and the primary object of the present invention is to provide an electrically driven outboard motor for a watercraft (hereinafter also referred to simply as an "electric outboard motor") which is configured to avoid damage to mechanical parts of a watercraft which may occur when the direction of rotation of an electric motor is switched (reversed) by operation of a control element while the watercraft is moving. MEANS OF SOLVING THE TASK

[0007] To solve the problem, an electric outboard motor according to claim 1 and a method according to claim 10 are specified. Preferred embodiments are specified in the dependent claims.

[0008] When the control unit is operated to switch its position from the forward to the reverse rotation position while the watercraft is moving, the electric motor's drive state does not immediately change from forward to reverse. Instead, during and before the transition is complete, the drive state is held in neutral for a predetermined period. As a result, when the direction of rotation of the electric motor is reversed, less force is exerted on the power transmission mechanism and the propeller, thus preventing damage to these mechanical parts.

[0009] The above outboard motor can further be configured such that the electric outboard motor has a watercraft speed detection device (27) to detect a watercraft speed, wherein, when the drive state is the neutral state, the control device (35) changes the predetermined time period for which the drive state is kept in the neutral state depending on the watercraft speed detected by the watercraft speed detection device.

[0010] When the propulsion state is reverse rotation, the higher the speed of the watercraft, the greater the force exerted on the power transmission mechanism and the propeller. This configuration allows the predetermined time period for which the propulsion state is held in neutral to be varied depending on the speed of the watercraft, further preventing damage to the power transmission mechanism and propeller.

[0011] The above outboard motor can further be configured such that the electric outboard motor also has a torque sensor (26) to detect a torque applied to the power transmission mechanism (9, 10, 11), wherein, when the drive state is the neutral state, the control device (35) changes the predetermined time period for which the drive state is kept in the neutral state depending on the torque applied to the power transmission mechanism.

[0012] When the drive state is reverse rotation, the greater the torque acting on the drive mechanism, the more likely it is that the drive mechanism and propeller will be damaged. This configuration allows the predetermined time period for which the drive state is held in neutral to be varied depending on the torque, further preventing damage to the drive mechanism and propeller.

[0013] The above outboard motor can further be configured such that the electric outboard motor also includes a watercraft speed sensing device (27) for sensing a watercraft speed, and a torque sensor (26) for sensing a torque applied to the power transmission mechanism, wherein the control device causes the drive state to change from the neutral state to the reverse rotation state (ST3) after the torque detected by the torque sensor becomes equal to or less than a predetermined torque (ST7: JA), and the watercraft speed detected by the watercraft speed sensing device becomes equal to or less than a predetermined speed (ST8).

[0014] In this configuration, a force acting on the power transmission mechanism and the propeller when the propulsion state is changed to the opposite rotational state can be adjusted to be equal to or less than a level corresponding to a predetermined speed, and this adjustment of the acting force can further prevent damage to the power transmission mechanism and propeller and prevent a sudden drop in the speed of the watercraft.

[0015] The above outboard motor can also be configured such that the forward and reverse directions of rotation of the electric motor correspond to a forward and a reverse movement of the watercraft, respectively.

[0016] In this configuration, if the control unit is activated during the forward movement of the watercraft to switch the drive state of the electric motor to the reverse rotation state, a less force acts on the power transmission mechanism and the propeller, which further prevents damage to these mechanical parts.

[0017] The above outboard motor can further be configured such that when the position of the control unit (33) is switched from the reverse rotation position to the forward rotation position (ST1: YES) while the watercraft is moving, the control device (35) causes the drive state to change from the reverse rotation state to the forward rotation state (ST3) such that during and before completion of the transition, the control device holds the drive state in the neutral position for a predetermined period of time (ST4).

[0018] In this configuration, if the control unit is activated during the reverse movement of the watercraft to switch the direction of rotation of the electric motor, thereby changing the drive state to the forward rotation state, a less force acts on the power transmission mechanism and the propeller, which further avoids damage to these mechanical parts.

[0019] The above outboard motor can further be configured such that, when the drive state is the neutral state, the control device (35) causes the poles of the electric motor to be short-circuited.

[0020] If the propulsion state is neutral in this configuration, the rotational resistance of the propeller increases, and thus a watercraft propelled by inertia experiences greater resistance from the water, resulting in a rapid decrease in the watercraft's speed.

[0021] The above outboard motor can further be configured such that when the drive state is neutral, the control device (35) causes the poles of the electric motor to be switched open.

[0022] If the propulsion state is neutral in this configuration, it is less likely that a force caused by the propulsion of the watercraft and acting on the propeller will damage the propeller and the power transmission mechanism.

[0023] The above outboard motor can further be configured such that, when the drive state is the neutral state, the control device (35) switches a state of poles of the electric motor between a first state in which the poles are short-circuited and a second state in which the poles are open.

[0024] This configuration avoids damage to the propeller and power transmission mechanism and also allows for a rapid reduction in the speed of the watercraft. EFFECT OF INVENTION

[0025] As described above, the present invention may provide an electric outboard motor configured to prevent damage to mechanical parts of a watercraft that may occur when the direction of rotation of an electric motor is reversed by operating a control unit while the watercraft is moving. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of a watercraft equipped with an electric outboard motor according to an embodiment of the present invention; Fig. 2 is a function block diagram of the in Fig. 1 electric outboard motor shown; Fig. 3 is a circuit diagram of the in Fig. 1 electric outboard motor shown; and Fig. Figure 4 is a flowchart of operations performed by a control device to control the drive motor of an electric motor. DESCRIPTION OF THE PREFERRED VERSION(S)

[0026] The following describes embodiments of an electric outboard motor of the present invention with reference to the accompanying drawings. The directional terms used herein refer to their respective directions (such as front / back and top / bottom), which are determined by the directions of a watercraft hull 2 ​​on which the electric outboard motor is mounted.

[0027] Fig. Figure 1 is a side view of a watercraft equipped with an electric outboard motor 1. As in Fig. As shown in Figure 1, the electric outboard motor 1 is detachably attached to the stern of a watercraft hull 2, in particular to a transom 3 of the watercraft hull, to propel the watercraft hull 2 ​​according to the operation of a user (driver). The electric outboard motor 1 is powered by electricity supplied by a battery attached to the watercraft hull 2.

[0028] The electric outboard motor 1 comprises an outboard motor body 5 and a mounting device 6 for attaching the outboard motor body 5 to the watercraft hull 2. The outboard motor body 5 includes a housing 7, an electric motor 8, a drive shaft 9, a gearbox 10, a propeller shaft 1, a propeller 12, a control unit 13, an input device 14, and a steering rod 15. The mounting device 6 includes a clamping fitting 16, a tilting mechanism 17, and a swiveling mechanism 18. Details of these elements of the electric outboard motor 6 are described below.

[0029] The housing 7 is made of metal or hard plastic and configured with a predetermined rigidity. The housing 7 comprises an upper housing section 19 located on its top and a lower housing section 20 located beneath the upper housing section 19. The upper housing section 19 and the lower housing section 20 can be made of the same material or of different materials. The upper housing section 19 is hollow and generally flat, with smaller dimensions in the vertical direction and elongated in the front-to-back direction. The upper housing section 19 accommodates the electric motor 8 and the control unit 13. The lower housing section 20 is hollow and vertically elongated. The lower housing section 20 accommodates a drive shaft 9 and a gearbox 10.

[0030] The lower housing section 20 contains a gearbox housing 21 for accommodating the gearbox unit 10 and an anti-cavitation plate 22. The gearbox housing 21 is integrally mounted to the lower part of the lower housing section 20, and the anti-cavitation plate 22 is integrally mounted above the gearbox housing 21. The gearbox housing 21 has a torpedo shape, which is laterally convex relative to the lower housing section 20 and elongated in the front-to-rear direction. The anti-cavitation plate 22 has a horizontally extending plate shape and extends rearward to cover the propeller 12 from above.

[0031] The electric motor 8 is a drive source for rotating the propeller 12, and one example of an electric motor is a permanent magnet synchronous motor. The type of electric motor 8 is not limited to this; that is, any type of electric motor can be used. The electric motor 8 is arranged in a front part of the upper housing section 19, such that its output shaft extends vertically downwards. The electric motor 8 has a flat shape that extends horizontally when mounted in the upper housing section 19, with its horizontal dimension being greater than its vertical dimension (height).

[0032] The drive shaft 9 extends vertically beneath the electric motor 8. The upper end of the drive shaft 9 is connected to the output shaft of the electric motor 8. A drive gear 23 is integrated at the lower end of the drive shaft 9 and consists primarily of a first bevel gear.

[0033] The drive shaft 9 is rotatably mounted in the lower housing section 20 by a pair of bearings (i.e. upper and lower bearings).

[0034] The propeller shaft 11 extends in the front-to-back (horizontal) direction beneath the drive shaft 9; i.e., the axial direction of the propeller shaft 11 is the longitudinal direction. A front section of the propeller shaft 11 is received in the gearbox housing 21 and is rotatably mounted in the gearbox housing 21 by a pair of bearings (i.e., front and rear bearings). An output gear 24 is integrated at the front end of the propeller shaft 11 and consists primarily of a second bevel gear that meshes with the input gear 23. The propeller shaft 11 extends through a bearing hole in the gearbox housing 21 and protrudes rearward within the gearbox housing 21, so that it is exposed to the outside of the fuselage housing 7.

[0035] The gear unit 10 contains the drive gear 23 at the lower end of the drive shaft 9 and the output gear 24 at the front end of the propeller shaft 11. The rotation of the drive shaft 9 is transmitted to the propeller shaft 11 via the gear unit 10.

[0036] The propeller 12 is attached to the outer circumference of a rear section of the propeller shaft 11. The propeller 12 is located behind the rear end of the gearbox housing 21 and is exposed to the outside of the fuselage housing 7. The propeller 12 has several blades 25 that project radially from an outer circumferential surface of the propeller 12.

[0037] The outboard motor 5 is equipped with a torque sensor 26 to detect a torque T applied to the drive shaft 9. The torque sensor 26 detects the torque T output by the electric motor 8 when the electric motor 8 is in operation. When the electric motor 8 is not in operation while the watercraft is moving; i.e., the watercraft hull 2 ​​is moving forward at a speed relative to the water, the torque sensor 26 detects the torque transmitted from the propeller 12 to the electric motor 8. The torque sensor 26 may primarily consist of a current sensor to detect the current flowing through the electric motor 8. A watercraft speed sensor 27 is located on the lower part of the lower housing section 20, which is immersed in the water, and is configured to detect the speed of the water flow; i.e.,, a watercraft speed V (the speed of the watercraft hull 2 ​​relative to the water). In some cases, the watercraft speed sensor 27 can be arranged on the watercraft hull 2.

[0038] The control unit 13 is connected via a cable 28 to a battery 4, which is located on the hull 2 ​​of the watercraft. The control unit 13 is also connected to the input device 14. The control unit 13 supplies current to the electric motor 8 and controls the operation of the propeller 12 based on operating signals sent by the input device 14, as well as sensor signals from the torque sensor 26 and the watercraft speed sensor 27.

[0039] The input device 14 is a device for receiving user input and is integrated into the upper housing section 19 of the outboard motor body 5. In the present embodiment, the input device 14 includes a control handle 29, a throttle handle 31, a throttle sensor 32, and a switch 33, which are arranged on the control handle 29. The control handle 30 is rotatably mounted on the upper housing section 19 about a transverse axis; i.e., an axis in the left-right direction. The control handle 30 is arranged such that, during use of the electric outboard motor, the control handle 30 projects forward, and when the electric outboard motor is stored, the control handle 30 is pivoted so that it extends along the upper housing section 19.

[0040] The throttle grip 31 is a control element used to change the output (speed and torque T) of the electric motor 8. The throttle grip 31 is arranged at the free end of the control handle 29, allowing it to rotate about the axis of the control handle 29 between a closed position and a fully open position. A preload element is provided to keep the throttle grip 31 permanently tensioned towards the closed position. The throttle sensor 32 is configured to detect the amount of rotation of the throttle grip 31 (the amount of rotation from the closed position) and send signals to the control unit 13.

[0041] The switch 33 is a control element primarily consisting of a switch for reversing the direction of rotation of the electric motor 8 between forward rotation (forward direction) and reverse rotation (reverse direction). The switch 33 is located on the top of the control handle 29, allowing it to be moved (switched) between a forward rotation position and a reverse rotation position. The forward rotation position is a position in which the watercraft is propelled forward, and the reverse rotation position is a position in which the watercraft is propelled backward. The switch 33 is configured to send signals to the control unit 13 indicating this position.

[0042] Fig. 2 is a function block diagram of the in Fig. 1. Electric outboard motor shown. 1. As shown in Fig. As shown in Figure 2, the control unit 13 contains a control device 35, a motor driver 36 and a connection control switch 37.

[0043] The control device 35 is an electronic control unit (ECU) containing a CPU, non-volatile memory (ROM), volatile memory (RAM), and other components. By executing process instructions via the CPU, the control device 35 controls the motor driver 36 and the connection control switch 37, thereby controlling the operation of the electric motor 8. The control device 35 can be configured as a single piece of hardware or as a unit formed by several hardware components.

[0044] The motor driver 36, which includes an inverter and a voltage regulator, is configured to switch the excitation direction with a transition speed determined based on the rotational speed of the electric motor 8, and to control the voltage by switching it on and off according to a PWM signal. A change in the voltage applied by the motor driver 36 changes the current flow through the electric motor 8, resulting in a change in the output (power) of the electric motor 8.

[0045] The connecting control switch 37 is configured to reverse the direction of current flow through the electric motor 8 between one direction for forward rotation (forward current direction) and the other for reverse rotation (reverse current direction), thereby switching the direction of rotation of the electric motor 8 between forward and reverse. When the current flows in the forward current direction, the propeller 12 rotates in the direction corresponding to the forward movement of a watercraft (forward movement direction). When the current flows in the reverse current direction, the propeller 12 rotates in the opposite direction corresponding to the reverse movement of a watercraft (reverse movement direction). In other words, the forward and reverse rotation directions of the electric motor 8 correspond, respectively, to the forward and reverse movement of the watercraft.When the control device 35 controls the connecting control switch 37 such that the current flows in the forward current direction, the drive state of the electric motor 8 becomes a forward rotation state, in which the electric motor 8 rotates in the forward direction. When the control device 35 controls the connecting control switch 37 such that the current flows in the reverse current direction, the drive state of the electric motor 8 becomes a reverse rotation state, in which the electric motor rotates in the reverse direction.

[0046] When the throttle handle 31 is turned while the connection control switch 37 is in the forward rotation position, the control device 35 controls the motor driver 36 to rotate the electric motor 8 in the forward direction with a power equal to the rotation amount of the throttle handle 31. When the throttle handle 31 is turned while the connection control switch 37 is in the reverse rotation position, the control device 35 controls the motor driver 36 to rotate the electric motor 8 in the reverse direction with a power equal to the rotation amount.

[0047] If the throttle handle 31 is not turned, the control device 35 does not drive the electric motor 8 to rotate. In this case, the electric motor 8 is not driven regardless of the position of the connection control switch 37, which means that the driving state of the electric motor 8 is a neutral state in which the electric motor 8 is not driven.

[0048] Fig. 3 is a circuit diagram of the in Fig. 1 electric outboard motor shown. As in the Fig. As shown in Figure 3, the connecting control switch 37 includes forward poles 37a for applying current to the electric motor 8 in the forward current direction, and reverse poles 37b for applying current to the electric motor 8 in the reverse current direction. The connecting control switch 37 also includes short-circuit poles 37c for short-circuiting the two poles of the electric motor 8. When the connecting control switch 37 connects the poles of the electric motor 8 to the short-circuit poles 37c, the electric motor 8 is not driven. This means that when the connecting control switch 37 short-circuits the poles of the electric motor 8, the driving state of the electric motor 8 is also the neutral state, in which the electric motor 8 is not driven. A variable resistor 39, controlled by the control device 35, is arranged in the circuit to short-circuit the poles of the electric motor 8.

[0049] There are also cases in which the direction of rotation of the electric motor 8 is reversed by an operator (switching operation on the changeover switch 33) while the watercraft is moving. Although details are described later, during and before the change of direction is completed, the propulsion state transitions to a state in which the connecting control switch 37 connects the poles of the electric motor 8 to the short-circuited poles 37c (one of the neutral states). In this state, the watercraft continues to move by rotational force, which results in the propeller 12 generating a torque T, and the generated torque T is transmitted to the electric motor 8, rotating its rotor. When the rotor is rotated while the poles of the electric motor 8 are short-circuited, the rotational resistance of the propeller 12 increases.As a result, the watercraft, which is propelled by inertia, encounters greater resistance from the water, leading to a rapid decrease in speed. Furthermore, by controlling the resistance of the variable resistor 39, the control device 35 can alter the rotational resistance of the propeller 12, thereby adjusting the resistance the watercraft experiences from the water.

[0050] Furthermore, the connection control switch 37 is able to assume a position in which the poles of the electric motor 8 are not connected to any of the forward poles 37a, the reverse poles 37b, or the short-circuit poles 37c; i.e., the poles of the electric motor 8 are open. When the connection control switch 37 opens the poles of the electric motor 8, the driving state of the electric motor 8 is also in the neutral state, in that the electric motor 8 is not driven.

[0051] When the connecting control switch 37 opens the poles of the electric motor 8 while the watercraft is moving (the other neutral state), the rotor of the electric motor 8 rotates due to the torque T generated by the propeller 12. Since the poles of the electric motor 8 are open in this case, the propeller 12 can rotate with minimal resistance. As a result, a force acting on the propeller 12 due to the rotational force of the watercraft's movement is prevented from damaging the power transmission mechanism and the propeller 12.

[0052] Furthermore, if the drive state of the electric motor 8 is set to a neutral state, the control device 35 can first short-circuit the poles of the electric motor 8 until the watercraft speed V has decreased sufficiently, and then open the poles of the electric motor 8. In this way, the control device 35 can switch the connecting control switch 37 during the transition of the drive state of the electric motor 8 to the neutral state, thereby achieving both a rapid decrease in the watercraft speed V and preventing damage to the propeller 12 and the power transmission mechanism.

[0053] The following describes 35 operations performed by the control device for controlling the drive state. Fig. Figure 4 is a flowchart of the operations performed by the control device 35 to control the drive state of the electric motor 8.

[0054] The control device 35 repeatedly performs the following operations in a predetermined cycle. First, the control device 35 determines whether the switch 33 is actuated to reverse the direction of rotation; that is, whether a switching operation is performed by the switch or not (step ST1). This switching operation is either an operation to move the switch 33 from the forward rotation position to the reverse rotation position, or an operation to move the switch 33 from the reverse rotation position to the forward rotation position. If no switching operation is performed (ST1: NO), the control device 35 terminates the routine.

[0055] When a switching operation is present (step ST1: YES), the control device 35 determines whether the vessel speed V is equal to or lower than a predetermined speed Vth, which is a predetermined threshold value (step ST2). The speed of a vessel can be represented by a positive value for forward motion and a negative value for reverse motion. However, in this embodiment, a vessel speed V is defined as an absolute value, and the predetermined value Vth is a threshold value common to both forward and reverse motion. In other embodiments, two threshold values ​​with different absolute values ​​can be used, one for positive and one for negative values ​​of the vessel speed V.

[0056] If the watercraft speed V is equal to or less than the predetermined speed Vth (step ST2: YES), the control device 35 changes the drive state of the electric motor 8 from its original rotation state to the opposite rotation state; that is, the direction of rotation determined in step ST1 is reversed (step ST3), and the routine is completed. In other words, if the drive state of the electric motor 8 is the forward rotation state before the change, the control device 35 switches the drive state to the reverse rotation state, whereas then, if the drive state of the electric motor 8 is the reverse rotation state before the change, the control device 35 switches the drive state to the forward rotation state.

[0057] If the watercraft speed V exceeds the predetermined speed Vth (step ST2: NO), the control device 35 switches the drive state of the electric motor 8 to the neutral state (step ST4). Then, the control device 35 determines whether another switching condition is present (step ST5). If another switching condition is present (ST5: YES), the control device 35 further switches the drive state of the electric motor 8 to the opposite rotation state; i.e., the rotation state prior to the first change determined in step ST1 (step ST6), and terminates the routine.

[0058] If no switching operation is present in step ST5 (step ST5: NO), the control device 35 determines whether a torque T applied to the drive shaft 9 is equal to or less than a predetermined torque Tth (step ST7). The torque T can be represented by either a positive or a negative value. However, in this embodiment, the torque T is defined as an absolute value, and the predetermined torque Tth is a threshold value common to both positive and negative torque values. In other embodiments, two threshold values ​​with different absolute values ​​can be used, one for positive and one for negative torque values ​​T.

[0059] If the torque T is equal to or less than the predetermined torque Tth (step ST7: YES), the control device 35 determines whether the vessel speed V is less than or equal to a predetermined speed Vth (step ST8). This predetermined speed Vth, used as a threshold, can be the same as or different from the predetermined speed Vth used in step ST2. The greater the absolute value of the vessel speed V determined in step ST2, the longer the time it takes for the torque T to become equal to or less than the predetermined torque Tth (step ST7: YES).

[0060] If the torque T exceeds the predetermined torque Tth (step ST7: NO), the control device 35 returns to step ST5 in the process. If, in the case of YES in step ST7 for the torque T, the watercraft speed V exceeds the predetermined speed Vth (step ST8: NO), the control device 35 returns to step ST5 in the process. If the watercraft speed V is equal to or less than the predetermined speed Vth (step ST8: YES), the control device 35 switches the drive state of the electric motor 8 to the opposite rotation state before the change in step ST1 (step ST3) and ends the routine. Specifically, if the drive state of the electric motor 8 is the forward rotation state in step ST1, the control device 35 switches the drive state to the reverse rotation state.If the drive state of the electric motor 8 in step ST1 is the reverse rotation state, the control device 35 switches the drive state to the forward rotation state. Generally, the greater the absolute value of the watercraft speed V determined in step ST2, the longer the time it takes for the watercraft speed V to become equal to or less than the predetermined speed Vth (step ST8: YES).

[0061] In particular, when the switch 33 is changed from the forward rotation position to the reverse rotation position while the watercraft is moving (ST1: YES), the control device 35 changes the drive state of the electric motor 8 to the neutral state and holds the neutral state for a predetermined period (ST4) before completing the transition to the reverse rotation state (ST3). In other words, the drive state of the electric motor 8 does not immediately change from the forward rotation state to the reverse rotation state, but rather the drive state is held in the neutral state for the predetermined period during and before the completion of the transition. As a result, when the direction of rotation of the electric motor 8 is switched (reversed) in step ST3, less force is exerted on the gearbox 10 and the propeller 12, thus preventing damage to these mechanical parts.

[0062] When the drive state of the electric motor 8 is changed to the reverse rotation state in step ST3, the higher the watercraft speed V, the greater the force exerted on the gearbox and propeller 12. In the present embodiment, the control device 35 switches the drive state of the electric motor 8 such that the predetermined time period for which the drive state is held in neutral is changed depending on the watercraft speed V. In particular, when the switch 33 is switched from the forward rotation position to the reverse rotation position in step ST1, the higher the watercraft speed V determined in step ST2, the longer the predetermined time period. This change in the predetermined time period can further prevent damage to the gearbox 10 and the propeller 12.

[0063] When the drive state of the electric motor 8 is changed to the reverse rotation state in step ST3, the greater the torque T applied to the gearbox 10, the more likely it is that the gearbox 10 and the propeller 12 will be damaged. In the present embodiment, the control device 35 switches the drive state of the electric motor 8 such that the predetermined time period for which the drive state is held in neutral is changed depending on the torque applied to the gearbox 10. In particular, when the switch 33 is switched from the forward rotation position to the reverse rotation position in step ST1, the greater the torque T determined in step ST7, the longer the predetermined time period. This change in the predetermined time period can further prevent damage to the gearbox 10 and the propeller 12.

[0064] Furthermore, the control device 35 causes the drive state of the electric motor 8 to change from the neutral state to the opposite rotation state after the torque T in step ST7 (JA) becomes equal to or less than the predetermined torque Tth, and in step ST8 (JA) the watercraft speed V becomes equal to or less than the predetermined speed Vth. These conditions for changing the drive state allow for the adjustment of a force acting on the gearbox 10 and the propeller 12, which occurs when the drive state of the electric motor 8 is changed to the opposite rotation state in step ST3, such that the effective force is adjusted to be equal to or less than a level corresponding to the predetermined speed V. This adjustment of the effective force can further prevent damage to the gearbox 10 and the propeller 12 and prevent a sudden drop in the watercraft speed V.

[0065] As described above, the forward and reverse directions of rotation of the electric motor 8 correspond to a forward and a reverse movement of the watercraft, respectively. Therefore, when the switch 33 is actuated to change its position while the watercraft is moving forward (ST1: YES), and in step ST3 the drive state of the electric motor 8 is switched from the forward rotation state to the reverse rotation state, a smaller force acts on the gear unit 10 and the propeller 12, further preventing damage to these mechanical parts.

[0066] In the present embodiment, when switch 33 is changed from the reverse rotation position to the forward rotation position (ST1: YES), the control device 35 causes the drive state of the electric motor 8 to change from the reverse rotation state to the forward rotation state (ST3), so that during and before the completion of the transition, the control device 35 holds the drive state in the neutral position for the predetermined period of time (ST4). Thus, when switch 33 is actuated to change its position while the watercraft is moving backward (ST1: YES), and the drive state of the electric motor 8 is changed from the reverse rotation state to the forward rotation state, less force acts on the gear unit 10 and the propeller 12, which prevents damage to these mechanical parts.

[0067] Specific details of the present disclosure are described herein for illustrative purposes. However, the present disclosure is not limited to these specific details, and various modifications may be made to the details without altering the scope of the present disclosure.

[0068] For example, in the embodiments described above, the input device 14 includes the switch 33. However, in some cases, the throttle handle 31 can also be designed as an operating element for switching the drive state, thus eliminating the need for the switch 33. In particular, the throttle handle 31 can be rotatable from the neutral position in both forward and reverse directions of rotation. In this case, the input device can be configured such that if the throttle handle 31 is rotated in the reverse direction during forward movement, the drive state of the electric motor 8 does not immediately change from the forward to the reverse state, but rather, during and before the completion of the transition, the drive state is held in the neutral state for a predetermined period of time.

[0069] Although in the embodiments described above, user operation (including switching operation) for changing the drive state of the electric motor 8 is performed at the input device 14 (in particular the switch 33 and the throttle handle 31), which is integrated into the outboard motor hull 5, the configuration of the input device is not limited to this. For example, the input device 14 can be separate from the outboard motor hull 5 and configured to transmit operating signals to the control unit 13 via wired or wireless connections. In this case, the input device 14 can, for example, be located in the wheelhouse of a watercraft. In other cases, the input device 14 need not have any operating element, such as the switch 33 or the throttle handle 31.For example, the input device 14 can be configured by a smartphone or tablet, and an operating element can be arranged as one or more operating switches displayed on a touch-sensitive screen that can be operated by the user. In this case, a touch input on an operating element (forward rotary knob or toggle switch) to switch the drive state to the forward rotation state is equivalent to a toggle operation on the input device to switch the drive state to the forward rotation position, whereas a touch input on an operating element (reverse rotary knob or toggle switch) to switch the drive state to the reverse rotation state is equivalent to a toggle operation on the input device to switch the drive state to the reverse rotation position.

[0070] In the embodiments described above, the control device 35 causes the drive state of the electric motor 8 to transition from the neutral state to the reverse rotation state after, in step ST7 (JA), the torque T becomes equal to or less than the predetermined torque Tth, and in step ST8 (JA), the watercraft speed V becomes equal to or less than the predetermined speed Vth. In other embodiments, the control device 35 can refer to a characteristic map or other data to determine the predetermined time period for which the drive state is held in the neutral state. For example, the control device 35 can determine the predetermined time period depending on the watercraft speed V determined in step ST2 and / or the torque determined in step ST7.In this case, the predetermined time period is preferably changed so that it becomes longer with increasing watercraft speed V and increasing torque T.

[0071] In the embodiments described above, the vessel speed V is defined as the speed of the vessel hull 2 ​​relative to the water. However, the vessel speed V can also be the speed of a vessel determined from positional data. In this case, a GPS device is used as a vessel speed detection device to determine the vessel speed V. Generally, various changes and modifications can be made to features of the embodiments, such as specific configurations, location, quantity, material, and mounting angle of each component or element in the embodiments, without deviating from the scope of the disclosure. In the embodiments described above, not all elements are essential. Thus, various modifications can be made to the embodiments as needed, including the omission of some elements.

[0072] [Problem] To avoid damage to parts of an electric outboard motor 1 when the direction of rotation of an electric motor 8 is reversed during movement of a watercraft.

[0073] [Solution] An electric outboard motor 1 includes a control unit 33 that is switchable between forward and reverse rotation positions; a control device 35 configured to switch a drive state of the electric motor 8 between forward, reverse, and neutral states based on the position of the control unit. When the position of the control unit is switched from the forward rotation position to the reverse rotation position (ST1: YES) while a watercraft is moving (ST2: YES), the control device causes the drive state to change from the forward rotation state to the reverse rotation state (ST3), such that before the transition is completed, the drive state is held in the neutral state for a predetermined period of time (ST4). REFERENCE MARK LIST 1 electric outboard motor 2 Watercraft hull 4 batteries 8 Electric motor 9 Drive shaft (power transmission mechanism) 10 Gear unit (power transmission mechanism) 11 Propeller shaft (power transmission mechanism) 12 propellers 13 Control unit 14 Input device 26 Torque sensor 27 Watercraft speed sensor (watercraft speed detection device) 31 Throttle grip 32 Throttle sensor 33 Switches (control unit) 35 Control device 36 motor drivers 37 connection control switches

Claims

[1] Electric outboard motor (1) for a watercraft (2), comprising: an electric motor (8); a propeller (12) which is connected to the electric motor (8) via a power transmission mechanism (9, 10, 11); a control element (33) configured for operation by a user and having an operating position that is switchable between a forward rotation control position for instructing forward rotation of the electric motor (8) and a reverse rotation control position for instructing reverse rotation of the electric motor (8); and a control device (35) configured to switch between a drive state of the electric motor (8) according to the operating position of the control part (33) between a forward rotation state in which the electric motor (8) rotates in the forward direction, a reverse rotation state in which the electric motor (8) rotates in the reverse direction, and a neutral state in which the electric motor (8) does not drive; wherein the control device (35) is configured to set the drive state to the forward rotation state when the operating position of the control element (33) is in the forward rotation operating position, and to set the drive state to the reverse rotation state when the operating position of the control element (33) is in the reverse rotation operating position; and wherein, when the operating position of the control element (33) is switched from the forward rotation operating position to the reverse rotation operating position while the watercraft (2) is moving, the control device (35) sets the drive state to the neutral state for a predetermined period of time and then sets the drive state to the reverse rotation state. [2] The electric outboard motor (1) according to claim 1, which further comprises a watercraft speed detection device (27) to detect a speed of the watercraft (2), wherein the control device (35) changes the predetermined time interval depending on the speed of the watercraft (2) when the drive state is set to the neutral state. [3] The electric outboard motor (1) according to claim 1, which further comprises a torque sensor (26) for detecting a torque applied to the power transmission mechanism (9, 10, 11), wherein the control device (35) changes the predetermined time period depending on the torque when the drive state is set to the neutral state. [4] The electric outboard motor (1) according to claim 1, which further comprises: a watercraft speed detection device (27) for detecting the speed of the watercraft (2); and a torque sensor (26) for detecting a torque applied to the power transmission mechanism (9, 10, 11), wherein the control device (35) switches the drive state from the neutral state to the reverse rotation state after the torque becomes equal to or less than a predetermined torque and the speed of the watercraft (2) becomes equal to or less than a predetermined speed. [5] The electric outboard motor (1) according to claim 1, wherein the forward direction of rotation of the electric motor (8) corresponds to a forward movement and the reverse direction of rotation of the electric motor (8) corresponds to a reverse movement of the watercraft (2). [6] The electric outboard motor (1) according to claim 1, wherein when the operating position of the control part (33) is switched from the reverse rotation operating position to the forward rotation operating position while the watercraft (2) is moving, the control device (35) sets the drive state to the neutral state for a predetermined period of time and then sets the drive state to the forward rotation state. [7] The electric outboard motor (1) according to claim 1, wherein, when the drive state is set to the neutral state, the control device (35) puts the positive and negative terminals of the electric motor (8) into a short-circuit state. [8] The electric outboard motor (1) according to claim 1, wherein, when the drive state is set to the neutral state, the control device (35) puts the positive and negative terminals of the electric motor (8) into an open state. [9] The electric outboard motor (1) according to claim 1, wherein, when the drive state is set to the neutral state, the control device (35) switches the positive and negative terminals of the electric motor (8) between a short-circuited state and an open-circuited state. [10] Method for controlling a drive state of an electric motor (8) in an electric outboard motor (1) for a watercraft (2) by means of a control device (35), wherein the electric outboard motor (1) has: an electric motor (8); a propeller (12) which is connected to the electric motor (8) via a power transmission mechanism (9, 10, 11); and a control element (33) configured for operation by a user and having an operating position that is switchable between a forward rotation control position for instructing forward rotation of the electric motor (8) and a reverse rotation control position for instructing reverse rotation of the electric motor (8); and wherein the method features that the control device (35) performs the following operations: to switch between a forward rotation state, in which the electric motor (8) rotates in the forward direction, a reverse rotation state, in which the electric motor (8) rotates in the reverse direction, and a neutral state, in which the electric motor (8) does not drive, according to the operating position of the operating part (33); to set the drive state to the forward rotation state when the operating position of the control element (33) is in the forward rotation operating position; to set the drive state to the reverse rotation state when the operating position of the control element (33) is in the reverse rotation operating position; and in order to set the drive state to the neutral state for a predetermined period of time when the operating position of the control part (33) is switched from the forward rotation operating position to the reverse rotation operating position while the watercraft (2) is moving, and subsequently to set the drive state to the reverse rotation state.

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