Outboard motor

An outboard motor 10 includes a drive shaft 33, a propeller shaft 35, a worm wheel 66, and a worm 67. The drive shaft is connected to a drive motor 37 via a reduction unit 38. The propeller shaft is connected via a bevel gear unit to intersect the drive shaft. The worm wheel is disposed coaxially with the drive shaft and rotates to turn the propeller shaft around the drive shaft. The worm engages with the worm wheel and is connected to a steering motor. The worm has a torque receiving portion.

CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2021-036426, filed Mar. 8, 2021, the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an outboard motor.

Description of Related Art

In general, outboard motors transmit, in a standard posture of a usage state, a rotational output of a power engine or electric motor to a drive shaft disposed in a vertical direction and convert rotation of the drive shaft into rotation around a horizontal shaft through a bevel gear to transmit it to a propeller shaft. By rotating the propeller shaft, a propeller attached to the propeller shaft is rotated around the horizontal shaft to propel a hull.

Here, among outboard motors, for example, there is an outboard motor including a steering mechanism that is electrically steered. In the steering mechanism, for example, a steering motor is connected to a steering shaft via a steering force transmission device. The steering force transmission device is provided with a lock clutch. According to this steering mechanism, by transmitting rotation of the steering motor to the steering shaft via the steering force transmission device, the steering shaft rotates to steer an outboard motor body in a left to right direction.

On the other hand, for example, even in a case in which a reaction force received from the water is exerted in the left to right direction during navigation, due to the lock clutch, it is not necessary to constantly drive the steering motor in order to maintain a steering direction.

The steering mechanism is configured, for example, to support the lock clutch with a casing and restrict rotation of the casing with a detent mechanism. The lock clutch can be invalidated by releasing rotation restriction of the casing by this detent mechanism. Accordingly, a user can manually rotate (steer) a steering portion in the left to right direction by pressing the steering portion (see, for example, Patent Document 1 (Japanese Patent Application, First Publication No. 2015-71315)).

SUMMARY OF THE INVENTION

However, for example, the outboard motor of Patent Document 1 needs to include a lock clutch in order to maintain a steering direction even in a case in which a reaction force received from the water is exerted to a steering portion in a left to right direction. For this reason, the number of parts increases, and from this perspective, it can be expected there is room for improvement.

Further, in a case in which a steering motor malfunctions, a direction of a propeller will be fixed to that at the time of malfunction. For this reason, for example, in a case in which a drive system for propelling is normally driven on the water, when the steering motor malfunctions, a hull will be in a state of not being propelled.

Thus, it is necessary to allow a steering mechanism to be manually operated when the steering motor malfunctions, thereby allowing a call at a port. When the steering mechanism is manually operated, first, an angle of a propeller is steered in the left to right direction, and then a hull is propelled toward a destination. Next, by returning the angle of the propeller to make the hull go straight, it is possible to go straight toward the destination. However, in the outboard motor of Patent Document 1, the steering mechanism cannot be manually operated from the hull side on the water.

An object of the present invention is to provide an outboard motor in which a steering direction can be maintained against a reaction force received from the water without increasing the number of parts, and which can be manually operated on the water.

In order to solve the above problems, an outboard motor of the present invention has adopted the following configurations.

(1) An outboard motor according to one aspect of the present invention is an outboard motor that propels a hull by rotating a propeller with a drive source, including: a drive shaft connected to the drive source; an output shaft that is connected to intersect the drive shaft and with which a propeller is provided; a worm wheel that is disposed coaxially with the drive shaft and rotates to turn the output shaft around the drive shaft; and a worm that engages with the worm wheel and is connected to a rotating electric machine, in which the worm includes a torque receiving portion that receives a torque for rotating the worm at the other end portion on a side opposite to one end portion connected to the rotating electric machine.

According to the aspect (1), the worm wheel is disposed coaxially with the drive shaft, and the output shaft is turned around the drive shaft by rotating the worm wheel. The worm is caused to engage with the worm wheel, and the worm is connected to the rotating electric machine.

Accordingly, by rotating the worm with the rotating electric machine, the worm wheel can be rotated with the worm. Thus, the outboard motor can be steered by turning the output shaft around the drive shaft.

The worm is caused to engage with the worm wheel that turns the output shaft. Accordingly, during navigation, for example, even in a case in which a reaction force received from the water is exerted in a left to right direction, self-locking due to the worm wheel and the worm (that is, a worm gear) can be secured. Thus, a steering direction can be maintained against the reaction force received from the water without increasing the number of parts with a simple configuration of the worm wheel and the worm. Accordingly, it is not necessary to constantly energize the rotating electric machine to constantly drive the rotating electric machine in order to maintain the steering direction of the outboard motor, and power consumption can be reduced. Further, by reducing a load on the rotating electric machine, durability of the rotating electric machine can be improved.

Furthermore, the torque receiving portion is formed at the other end portion of the worm on the side opposite to the rotating electric machine. Accordingly, for example, by manually rotating the torque receiving portion, the output shaft can be rotated by the worm wheel. Thus, the outboard motor can be manually steered without increasing the number of parts with a simple configuration of forming the torque receiving portion in the worm.

Incidentally, for example, when the worm is manually operated to call at a port in a case in which the rotating electric machine malfunctions on the water, first, the torque receiving portion is manually rotated to turn (steer) the output shaft (that is, the propeller) in the left to right direction, and then the hull is propelled toward the direction of a destination. Next, the torque receiving portion is manually rotated again to return the propeller to a go-straight state of the hull, thereby causing it to go straight toward the destination.

Here, self-locking of the worm wheel and worm are secured by a worm gear mechanism. Accordingly, even when the propeller receives a force such as resistance from the water, the propeller can be held in a go-straight position of the hull. Thus, the hull can be kept in the go-straight state even when hands are released from the torque receiving portion. That is, on the water, the steering mechanism of the worm wheel and the worm can be manually operated.

(2) The outboard motor according to the above aspect (1) may include a case that covers the worm and includes an opening portion formed at a portion corresponding to the torque receiving portion, and a cap that is detachably attached to the opening portion and covers the opening portion.

According to the aspect (2), the worm is covered with the case, and the opening portion is formed at the portion of the case corresponding to the torque receiving portion. Further, the cap is detachably attached to the opening portion, and the opening portion is covered with the cap. Thus, the worm can be protected from the water with the cap. Furthermore, the torque receiving portion can be easily rotated manually simply by removing the cap from the opening portion.

(3) The outboard motor according to the above aspect (1) may include a case that covers the worm and includes an opening portion formed at a portion corresponding to the torque receiving portion, and the torque receiving portion may be a member having corrosion resistance.

According to the aspect (3), for example, the torque receiving portion is made of a corrosion-resistant material, or the torque receiving portion is subjected to a corrosion-resistant surface treatment, thereby forming the torque receiving portion as a member having corrosion resistance. Accordingly, for example, it is possible to eliminate the need for a cap that protects the torque receiving portion from the water. Thus, for example, the torque receiving portion can be manually rotated more easily.

(4) In the outboard motor according to any one of the above (1) to (3), the torque receiving portion may be disposed at a position at which it is rotatable from the hull.

According to the aspect (4), the torque receiving portion is disposed at a position at which it is rotatable from the hull. Thus, a user can easily rotate the torque receiving portion from the hull, and the outboard motor can be easily steered manually.

(5) The outboard motor according to the aspect (2) or (3) may include a cover that is detachably attached to the case and covers the rotating electric machine provided in the case.

According to the aspect (5), the rotating electric machine is provided outside the case, and the rotating electric machine is covered with the cover. Thus, the rotating electric machine can be protected from the water by the cover. Simply by removing the cover from the case, for example, the rotating electric machine can be maintained and inspected.

According to the present invention, the steering direction can be maintained against the reaction force received from the water without increasing the number of parts.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described below with reference to the drawings. Also, “Fr” indicates forward with respect to a traveling direction, and “Rr” indicates rearward with respect to the traveling direction. Hereinafter, “forward with respect to the traveling direction” may be simply referred to as “forward,” and “rearward with respect to the traveling direction” may be simply referred to as “rearward.” A “front to rear direction with respect to the traveling direction” may be simply referred to as a “front to rear direction,” and a direction orthogonal to the “front to rear direction” may be simply referred to as a “left to right direction.”

Hereinafter, an outboard motor10of the embodiment will be described based on a standard posture in which a drive shaft33is disposed substantially vertically, and a propeller shaft35is disposed in the front to rear direction.

As shown inFIGS.1to3, the outboard motor10is a propelling device that is provided in a stern13of a hull12via a stern bracket15to propel the hull12. The outboard motor10includes a case21, an oil pan22, a drive shaft case23, a gear case24, a power unit31, a steering mechanism32, the drive shaft33, a bevel gear unit34, the propeller shaft (an output shaft)35, and a propeller36.

The case21is fixed to an upper portion of the oil pan22. The power unit31and the steering mechanism32(particularly, a worm gear63) are housed in the case21. The case21is mounted on the stern13of the hull12via the stern bracket15. More specifically, the case21is attached to the stern bracket15to be swingably supported in a vertical direction via a tilt axis (not shown) of the stern bracket15.

The oil pan22stores, for example, oil that cools and lubricates an electric motor37and a reduction unit38of the power unit31, which will be described later, the worm gear63of the steering mechanism32, and the like.

The power unit31includes the electric motor37and the reduction unit38. The electric motor37will be described below as a “drive motor37.” The drive motor37is an electric motor that serves as a power source (a drive source) for rotating the propeller36, which will be described later.

In the drive motor37, for example, a rotation shaft43is disposed to face in the vertical direction, and a rotor42is rotatably supported inside a stator41. The rotation shaft43is supported by the rotor42, and the reduction unit38is connected to the rotation shaft43.

In the reduction unit38, a sun gear45is fixed to a rotation shaft, and a plurality of planetary gears46engage with the sun gear45. The plurality of planetary gears46are rotatably supported by a carrier47and engage with a ring gear (an internal gear)48. The ring gear48is fixed to the case21, for example. The drive shaft33is coaxially fixed to the carrier47. The reduction unit38decelerates a rotation speed of the drive motor37at a reduction ratio i and transmits it to the drive shaft33.

The drive shaft33extends coaxially downward from the carrier47of the reduction unit38and is connected to the bevel gear unit34in a state in which it is inserted inside the drive shaft case23. That is, the drive shaft33is connected to the drive motor37via the reduction unit38and is disposed substantially vertically.

The drive shaft33is housed in the drive shaft case23and is rotatably supported by the drive shaft case23via a bearing51. The drive shaft case23is rotatably supported by, for example, the case21via bearings52and52.

The bevel gear unit34includes a first bevel gear55on an input side and a second bevel gear56on an output side. The first bevel gear55is coaxially fixed to the drive shaft33and engages with the second bevel gear56. The second bevel gear56is coaxially fixed to the propeller shaft35. The bevel gear unit34is housed in the gear case24. The gear case24is integrally fixed to the drive shaft case23.

The propeller shaft35extends in a direction intersecting the drive shaft33and rearward from the second bevel gear56. That is, the propeller shaft35is connected to intersect the drive shaft33via the bevel gear unit34. A base end portion of the propeller shaft35fixed to the second bevel gear56is housed in the gear case24.

The propeller shaft35protrudes rearward from the second bevel gear56via a propeller holder28. The propeller holder28is fixed to the gear case24. For example, the base end portion of the propeller shaft35is rotatably supported by the propeller holder28via a bearing58. The propeller36for propelling is provided at a portion35aof the propeller shaft35that protrudes rearward from the propeller holder28. The propeller36is provided with blades36bon a propeller cylinder portion36athat rotates together with the propeller shaft35.

Here, the drive shaft case23, the gear case24, and the propeller holder28are integrally fixed. The propeller cylinder portion36aextends horizontally rearward from the propeller holder28. Accordingly, the drive shaft case23, the gear case24, the propeller holder28, and the propeller cylinder portion36aare formed in an L shape when seen from a side view.

By driving the drive motor37, rotation of the rotation shaft43is transmitted to the propeller36via the reduction unit38, the drive shaft33, the bevel gear unit34, and the propeller shaft35. The hull12is propelled by rotation of the propeller36.

As shown inFIGS.3and4, the steering mechanism32includes the worm gear63and a steering motor (a rotating electric machine)64. The worm gear63is disposed, for example, in a state in which it is covered with the case21and includes a worm wheel66and a worm67. For example, the worm wheel66is fixed to an outer circumferential wall of the drive shaft case23in a state in which it is disposed coaxially with the drive shaft33. The worm67engages with a front end portion66aof the worm wheel66.

The worm67extends in a direction intersecting the front to rear direction (that is, in the left to right direction) and in a horizontal direction. The worm67is rotatably supported by the case21via, for example, a pair of bearings69. In the worm67, one end portion68aof a worm shaft68is connected to a rotation shaft71of the steering motor64.

Accordingly, by driving the steering motor64, the worm shaft68(that is, the worm67) can be rotated by the rotation shaft71. By rotating the worm67, the worm wheel66can be rotated by the worm67. By rotating the worm wheel66, the drive shaft case23can be rotated in a direction of arrow A or B about the drive shaft33.

Here, as described above, the drive shaft case23, the gear case24, the propeller holder28, and the propeller cylinder portion36aare formed in an L shape in a side view. The propeller shaft35is rotatably supported by the propeller holder28via the bearing58. Accordingly, by rotating the drive shaft case23with the worm wheel66, the propeller shaft35and the propeller36can be turned in the direction of arrow A or B with the drive shaft33as a central axis, and thus the outboard motor10can be steered.

As shown inFIGS.2,4, and5, the steering motor64is an electric motor attached to an outer portion of the case21. Specifically, the steering motor64is attached to a motor attachment portion21a, which is located on one side wall in the left to right direction and on a front side closer to the hull12in an outer circumferential wall of the case21. That is, the steering motor64is disposed near the hull12so that it is visible from the hull12and can be maintained and inspected from the hull12. The steering motor64is covered with a cover73from the outside of the case21.

The cover73is detachably attached to the motor attachment portion21aof the case21from the outside with, for example, bolts75. A wire harness76connected to the steering motor64is arranged inside the cover73via a grommet77. Thus, the steering motor64can be protected from the water by the cover73. For example, the steering motor64can be easily maintained and inspected simply by removing the cover73from the case21.

As shown inFIGS.3,4, and6, a torque receiving portion81is formed at the other end portion68bon a side opposite to the one end portion68aof the worm shaft68. The torque receiving portion81is formed to have, for example, six surfaces in a hexagonal shape like a head of a bolt. In the embodiment, the hexagonal surfaces will be described as an example of the torque receiving portion81, but the torque receiving portion81is not limited thereto. As another example, for example, the torque receiving portion81may be formed to have four surfaces in a quadrangular shape, or the torque receiving portion81may be formed in a spline shape or the like.

The torque receiving portion81is disposed at a position corresponding to an opening portion84(which will be described later) of the case21. Thus, for example, by manually turning a tool such as a ratchet or torque wrench for tightening a bolt, the torque receiving portion81can receive a manual torque transmitted from the tool (hereinafter, may be referred to as a manual torque).

That is, for example, when the steering motor64malfunctions, the torque receiving portion81receives the manual torque transmitted from the tool, and the torque receiving portion81can be rotated by the manual torque. By rotating the torque receiving portion81, the worm shaft68(that is, the worm67) can be rotated. By rotating the worm67, the worm67can rotate the worm wheel66in the direction of arrow A or B. By rotating the worm wheel66, the drive shaft case23can be rotated about the drive shaft33.

By rotating the drive shaft case23, the propeller shaft35can be turned in the direction of arrow A or B with the drive shaft33as the central axis, and thus the outboard motor10can be steered. Thus, the outboard motor10can be manually steered without increasing the number of parts with a simple configuration of forming the torque receiving portion81on the worm67.

Here, in the case21, the opening portion84is formed at a portion corresponding to the torque receiving portion81. The opening portion84is formed by opening to a boss83that protrudes from an opening forming portion21b, which is located on the other side wall on a side opposite to the steering motor64in the left to right direction and on a front side closer to the hull12in the outer circumferential wall of the case21. That is, the opening portion84is disposed near the hull12to be visible from the hull12and within reach of the user from the hull12.

The torque receiving portion81is disposed to be exposed from the opening portion84to the outside of the case21. Accordingly, the torque receiving portion81is disposed near the hull12to be visible from the hull12and within reach of the user from the hull12. An oil seal86is provided in the opening portion84, and a space between the opening portion84and the torque receiving portion81is sealed by the oil seal86.

As shown inFIGS.1,6, and7, a cap88is detachably attached to the opening portion84. Accordingly, the cap88is disposed near the hull12to be visible from the hull12and within reach of the user from the hull12.

The cap88has a cap body91and an attachment piece92. The attachment piece92is detachably attached to a boss93by screwing a bolt95to the boss93(specifically, a screw hole93a) of the opening forming portion21b.

In this state, the cap body91can cover the opening portion84from the outside of the case21. Further, an O-ring94of the cap body91can seal a gap between the cap body91and the opening portion84. Thus, the torque receiving portion81of the worm67(specifically, the worm shaft68) can be protected from the water by the cap88.

By removing the bolt95from the boss93, the cap88can be removed from the opening portion84. In this way, simply by removing the cap88from the opening portion84, the torque receiving portion81can be easily rotated manually.

Here, the cap88is disposed at a position visible to the user from the hull12and at a position within reach of the user. Accordingly, the user can easily remove the cap88from the hull12by loosening the bolt95.

With the cap88removed from the opening portion84, the torque receiving portion81is exposed to the outside of the case21from the opening portion84. Here, the torque receiving portion81is disposed at a position visible to the user from the hull12and at a position within reach of the user. Accordingly, a manual torque can be easily applied from the hull12to the torque receiving portion81by using a tool.

Also, the torque receiving portion81may be made of a corrosion-resistant material, or the torque receiving portion81may be subjected to a corrosion-resistant surface treatment. Accordingly, a member having corrosion resistance can be used for the torque receiving portion81, and for example, the cap88that protects the torque receiving portion81from the water can be eliminated. Thus, for example, the torque receiving portion81can be manually rotated more easily.

As described above, according to the outboard motor10of the embodiment, as shown inFIGS.3and4, a torque T of the drive motor37is transmitted to the reduction unit38by driving the drive motor37. The rotation speed of the drive motor37is decelerated by a reduction ratio i of the reduction unit38, and a torque T×i is transmitted to the drive shaft33. The torque T×i of the drive shaft33is transmitted to the propeller shaft35via the bevel gear unit34, and the propeller shaft35rotates. As the propeller shaft35rotates, the propeller36rotates to propel the hull12.

Here, the torque T×i is transmitted from the reduction unit38to the drive shaft33, and the torque T×i is also transmitted to the drive shaft case23as a reaction force. Thus, the worm wheel66of the worm gear63is provided on the drive shaft case23, and the worm67is caused to engage with the worm wheel66. Accordingly, the torque T×i transmitted as the reaction force to the drive shaft case23can be supported by the worm67. That is, the reaction torque T×i transmitted to the drive shaft case23is supported by self-locking of the worm gear63configured of the worm wheel66and the worm67, such that the drive shaft case23can be maintained in the steering direction.

Thus, the steering direction can be maintained with respect to the reaction torque T×i received from the drive motor37and the reduction unit38without increasing the number of parts with a simple configuration of the worm wheel66and the worm67.

During navigation, for example, even in a case in which a reaction force received from the water is exerted to the propeller36in the left to right direction, self-locking due to the worm wheel66and the worm67(that is, the worm gear63) can be secured. Thus, the steering direction can be maintained with respect to the reaction force received from the water without increasing the number of parts with a simple configuration of the worm wheel66and the worm67.

In this way, the reaction torque T×i received from the reduction unit38(that is, the drive motor37) and the reaction force received from the water can be supported by the self-locking of the worm gear63. Thus, it is not necessary to constantly energize the steering motor64to constantly drive the steering motor64in order to maintain the steering direction of the outboard motor, and power consumption can be reduced. Further, by reducing a load on the steering motor64, durability of the steering motor64can be improved.

As shown inFIGS.1,6and7, the cap88and the torque receiving portion81are disposed at the position visible to the user from the hull12and at the position within reach of the user. Accordingly, the user of the hull12can easily apply manual torque to the torque receiving portion81using a tool by removing the cap88from the opening portion84. Thus, for example, if the steering motor64malfunctions, the user of the hull12can safely rotate the torque receiving portion81, and the outboard motor10can be easily steered manually.

Incidentally, as shown inFIGS.3and4, for example, on the water, when the worm67is manually operated to call at a port in a case in which the steering motor64malfunctions, first, the torque receiving portion81is manually rotated to turn (steer) the propeller shaft35(that is, the propeller36) in the left to right direction, and then the hull12(seeFIG.1) is propelled toward a destination. Next, the torque receiving portion81is manually rotated again to return the propeller36to a go-straight state of the hull12, thereby causing the hull12to go straight toward the destination.

Here, self-locking of the worm wheel66and worm67are secured by the worm gear mechanism. Accordingly, even when the propeller36receives a reaction force (a force such as resistance due to water) from the water, the propeller36can be held in a go-straight position of the hull12(seeFIG.1). Thus, the hull12can be kept in a go-straight state even when hands are released from the torque receiving portion81. That is, the steering mechanism of the worm wheel66and the worm67can be manually operated on the water.

Also, the technical scope of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention.

In addition, it is appropriately possible to replace constituent elements in the above-described embodiment with well-known constituent elements without departing from the spirit of the present invention, and the above-mentioned modified examples may be appropriately combined.

EXPLANATION OF REFERENCES