Mounting Structure of Propulsion Device for Water-Surface Movable Body and Propulsion Unit for Water-Surface Movable Body

The present invention relates to a mounting structure of a propulsion device for a water-surface movable body, and a propulsion unit for the water-surface movable body provided with the propulsion device for the water-surface movable body and the mounting structure.

In recent years, efforts have been actively made to realize a low-carbon or decarbonized society, and research and development of electrification technology is being conducted in a propulsion device for a water-surface movable body, such as an outboard motor, to reduce COemissions and improve energy efficiency.

For example, JP6327052B2 discloses a propulsion device for a water-surface movable body (an electric outboard motor) that includes an electric motor and a propulsor (a propeller shaft and a propeller) configured to rotate by a driving force of the electric motor. The electric motor is supported by a swivel via a pair of upper and lower mounting members.

In the propulsion device for the water-surface movable body using the electric motor as a driving source, vibrations caused by the driving source are smaller than in the propulsion device for the water-surface movable body using an internal combustion engine as a driving source. However, since the vibrations caused by the driving source are small, the vibrations caused by the propulsor may be perceived as large. Accordingly, there is still a strong demand for reducing vibrations.

In view of the above background, an object of the present invention is to effectively reduce the vibrations of the propulsion device for the water-surface movable body using the electric motor as a driving source.

To achieve such an object, one aspect of the present invention provides a mounting structure (,, and) of a propulsion device (,, and) for a water-surface movable body, wherein the propulsion device comprises: a case (); an electric motor () accommodated in the case; and a propulsor () supported by the case and configured to rotate by a driving force of the electric motor, the mounting structure comprising: a fixed member (,, and) fixed to a hull () of the water-surface movable body (); a support member (,, and) attached to the fixed member via an attachment shaft (,, and) and supporting the case; and a plurality of mounting members (,,,, and) arranged between the support member and the case, wherein in a plan view or a bottom view, the plurality of mounting members is arranged on an opposite side of the hull with a virtual line interposed therebetween, the virtual line passing through a center of an output shaft () of the electric motor and being parallel to the attachment shaft.

According to this aspect, by arranging the plurality of mounting members on the opposite side of the hull with the virtual line (the line passing through the center of the output shaft of the electric motor, which is a heavy object) interposed therebetween, the support member can stably support the case via the plurality of mounting members. Accordingly, it is possible to effectively reduce vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, the case includes: an upper case () that accommodates the electric motor; and a lower case () rotatably supported by the upper case and supporting the propulsor, the plurality of mounting members includes: at least one upper mounting member () attached to an upper surface of the upper case; and at least one lower mounting member () attached to a lower end of the upper case, and at least a portion of the upper mounting member overlaps with the electric motor in the plan view.

According to this aspect, by arranging the plurality of mounting members so as to sandwich the upper case from above and below, the support member can more stably support the case via the plurality of mounting members. Accordingly, it is possible to more effectively reduce the vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, the at least one upper mounting member comprises a pair of upper mounting members, the at least one lower mounting member comprises a pair of lower mounting members, and a gap between the pair of lower mounting members is wider than a gap between the pair of upper mounting members.

According to this aspect, by widening the gap between the pair of lower mounting members that receive the load of the upper case, the swing of the propulsion device for the water-surface movable body can be suppressed. Accordingly, it is possible to more effectively reduce the vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, the upper case comprises: a motor case () that accommodates the electric motor; and a lower bracket () formed separately from the motor case and attached to a lower end of the motor case, the upper mounting member is attached to the motor case, and the lower mounting member is attached to the lower bracket.

According to this aspect, the lower mounting member is attached to the lower bracket, which is formed separately from the motor case. Accordingly, an attachment position of the lower mounting member can be easily adjusted without being restricted by the shape of the motor case.

In the above aspect, preferably, the support member comprises: a base plate () that extends in an up-and-down direction; an upper stay () that extends from an upper end of the base plate toward the opposite side of the hull; and a lower stay () that extends from a lower end of the base plate toward the opposite side of the hull, the upper mounting member is attached to a tip of the upper stay, and the lower mounting member is attached to a tip of the lower stay.

According to this aspect, by using the support member having a simple structure, the upper mounting member and the lower mounting member can be arranged on the opposite side of the hull with the virtual line interposed therebetween.

In the above aspect, preferably, a position and a spring constant of each of the plurality of mounting members are set so that an elastic center of the propulsion device for the water-surface movable body coincides with a center of gravity of the propulsion device for the water-surface movable body.

According to this aspect, resonance in the six degrees of freedom-forward/back, left/right, up/down, yaw, pitch, and roll-occurs independently at each frequency without affecting each other. In other words, resonance in the six degrees of freedom can be unrelated to each other. Accordingly, it is possible to suppress the amplification of vibrations of degrees of freedom that are not related to the input form, and further effectively reduce a couple (a couple that arises according to the distance between the elastic center and the center of gravity) acting on the plurality of mounting members. Accordingly, the vibrations of the propulsion device for the water-surface movable body can be further effectively reduced. Furthermore, when the vibration-proof properties of the mounting structure are designed, characteristics such as the spring constant can be designed separately for each direction, which makes it easier to design the characteristics.

In the above aspect, preferably, the plurality of mounting members comprises: a pair of first side mounting members () attached to both side surfaces of the case; and a pair of second side mounting members () attached to both the side surfaces of the case and arranged lower than the pair of first side mounting members.

According to this aspect, by arranging the plurality of mounting members so as to sandwich the upper case from both sides, the support member can more stably support the case via the plurality of mounting members. Accordingly, it is possible to more effectively reduce the vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, a center of gravity of the propulsion device for the water-surface movable body is arranged within an area surrounded by the plurality of mounting members.

According to this aspect, the mounting structure with the center of gravity support method can effectively reduce the vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, at least a portion of the plurality of mounting members is arranged on a principal axis of inertia of the propulsion device for the water-surface movable body.

According to this aspect, the mounting structure with the principal axis of inertia support method can effectively reduce the vibrations of the propulsion device for the water-surface movable body.

In the above aspect, preferably, the plurality of mounting members includes a pair of side mounting members () attached to both side surfaces of the case, and the pair of side mounting members are arranged on a pitch axis as the principal axis of inertia of the propulsion device for the water-surface movable body.

According to this aspect, the mounting structure with the principal axis of inertia support method can more effectively reduce the vibrations of the propulsion device for the water-surface movable body.

To achieve such an object, another aspect of the present invention provides a propulsion unit (,and) for the water-surface movable body comprising: the propulsion device for the water-surface movable body; and the mounting structure, wherein the propulsion device for the water-surface movable body further comprises a controller () configured to control the electric motor, and at least a portion of the controller is arranged behind the electric motor and overlaps with the electric motor in a front view.

According to this aspect, by aligning the electric motor and the controller in the front-and-rear direction, the lateral width of the propulsion device for the water-surface movable body can be reduced. Accordingly, it is possible to make the propulsion device for the water-surface movable body more compact.

Thus, according to the above aspects, it is possible to effectively reduce the vibrations of the propulsion device for the water-surface movable body using the electric motor as a driving source.

Hereinafter, with reference to, a propulsion unitfor a water-surface movable body (hereinafter, abbreviated as “the propulsion unit”) according to the first embodiment of the present invention will be described. The arrow Fr in the figures indicates the front of the propulsion unit.

With reference to, the propulsion unitis attached to a hullof a ship(an example of a water-surface movable body) such as a boat so as to apply a propulsion force to the ship. The propulsion unitincludes an outboard motor(an example of a propulsion device for a water-surface movable body) disposed outside the hull, and a mounting structurefor mounting the outboard motorto the hull. In the following, the outboard motorand the mounting structurewill be described one by one.

With reference to, the outboard motorcomprises a case, an electric motoraccommodated in the case, a controllerconfigured to control the electric motor, a propulsorsupported by the caseand configured to rotate around a propulsion axis Xby a driving force of the electric motor, a drive shaftprovided in a driving force transmission path R that leads from the electric motorto the propulsorand extending along a rotation axis X, a bevel gear mechanismthat connects the drive shaftand the propulsor, and a deceleration mechanismprovided in the driving force transmission path R and configured to decelerate a rotation of the electric motor. In the following, a description will be given based on a state where the propulsion axis Xextends in the front-and-rear direction and the rotation axis Xextends in a vertical direction (see).

With reference to, the caseincludes an upper caseand a lower caserotatably supported around the rotation axis Xby the upper case.

The upper caseincludes a motor case, a lower bracketfixed to a lower end of the motor case, and a control casefixed to the upper rear part of the motor case.

With reference to, the motor caseincludes a cylindrical circumferential wallextending in the up-and-down direction, and a plate-shaped upper wallclosing the upper end of the circumferential wall. The upper wallis integrally formed with the circumferential wall. A pair of upper pedestalsprotrude upward from the upper surface of the upper wall. The pair of upper pedestalsare provided at an interval in the lateral direction. The upper surface of each upper pedestalis provided with an upper fitting grooveextending in the front-and-rear direction. The upper surface of each upper pedestalis provided with upper engagement holeson both the left and right sides of the upper fitting groove.

With reference to, the lower bracketis formed separately from the motor case. The lower brackethas an annular shape. A pair of lower pedestalsprotrude laterally outward from the lower bracket. The pair of lower pedestalsare provided at an interval in the lateral direction. The lower surface of each lower pedestalis provided with a lower fitting grooveextending in the front-and-rear direction. The lower surface of each lower pedestalis provided with lower engagement holeson both the left and right sides of the lower fitting groove.

With reference to, the control caseis formed separately from the motor case. The control caseis arranged behind the motor case. The control caseis arranged on the opposite side of the mounting structurewith the motor caseinterposed therebetween.

The lower caseis connected to a steering motor (not shown) and is configured to rotate relative to the upper casearound the rotation axis Xby the driving force of the steering motor. The lower caseincludes a rotation bodyand a main bodyarranged below the rotation body.

The rotation bodyhas a cylindrical shape centered on the rotation axis X. The upper part of the rotation bodyis accommodated in the motor case. The rotation bodyis attached to the motor casevia a plurality of the bearings.

The main bodyis fixed to the rotation body. A bullet-shaped gear caseextending in the front-and-rear direction is provided at the lower part of the main body. A shaft holeextending in the up-and-down direction is provided in the upper part of the main body, and an internal space of the gear casecommunicates with an internal space of the rotation bodyvia the shaft hole.

With reference to, the electric motoris accommodated in the motor case. The electric motorincludes a motor bodyand an output shaftextending downward from the motor body.

With reference to, the controlleris accommodated in the control case. The controllerconsists of a power control unit (PCU). The controlleris connected to the electric motorand a battery (not shown), and configured to control the power supply from the battery to the electric motor.

With reference to, a portion of the controlleris arranged behind the electric motorand overlaps with the electric motorin a front view. In another embodiment, the entire controllermay be arranged behind the electric motorand overlap with the electric motorin a front view.

With reference to, the propulsoris rotatable relative to the lower casearound the propulsion axis X, and is also rotatable integrally with the lower casearound the rotation axis X. The propulsorincludes a propeller shaftextending along the propulsion axis Xand a propellerfixed to the rear part of the propeller shaft. A front part of the propeller shaftis rotatably supported by the gear case.

With reference to, the drive shaftincludes an upper shaftand a lower shaftarranged below the upper shaft. The upper end of the upper shaftis fixed to the output shaftof the electric motor. This allows the upper shaftto rotate integrally with the output shaftof the electric motor. The lower shaftis rotatable relative to the upper shaft. The lower shaftpenetrates through the shaft holein the main bodyof the lower case. The lower shaftis rotatably supported by the lower casevia a plurality of bearings.

With reference to, the bevel gear mechanismincludes a first bevel gearand a second bevel gearthat engages with the first bevel gear. The first bevel gearis fixed to the lower end of the lower shaft. The second bevel gearis fixed to the front end of the propeller shaft.

The deceleration mechanismis accommodated in the rotation bodyof the lower case. The deceleration mechanismconsists of, for example, a planetary gear mechanism. An input portion of the deceleration mechanismis fixed to the lower end of the upper shaft. An output portion of the deceleration mechanismis fixed to the upper end of the lower shaft.

With reference to, when the output shaftof the electric motorrotates, the rotation of the output shaftis transmitted to the input portion of the deceleration mechanismvia the upper shaft, and the rotation of the output shaftis decelerated by the deceleration mechanism. The decelerated rotation of the output shaftis transmitted from the output portion of the deceleration mechanismto the lower shaft, causing the lower shaftto rotate. The rotation of the lower shaftis transmitted to the propulsorvia the bevel gear mechanism, causing the propulsorto rotate around the propulsion axis X. Accordingly, a propulsion force is applied to the ship, causing the shipto be propelled.

When the motor shaft of the steering motor (not shown) rotates, the rotation of the motor shaft is transmitted to the lower case, and the lower caseand the propulsorrotate around the rotation axis X. Accordingly, a turning force is applied to the ship, causing the shipto turn.

With reference to, the mounting structurecomprises a fixed memberfixed to the hull, a support memberattached to the fixed memberand supporting the case, and a plurality of mounting membersandarranged between the support memberand the case.

With reference to, the fixed memberincludes a main wallextending in the up-and-down direction, and a pair of attachment wallsextending forward from the upper end of the main wall. The main wallis fixed to the rear end (transom) of the hull. The pair of attachment wallsare provided at an interval in the lateral direction.