MARINE PROPULSION DEVICE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2024-062697 filed on Apr. 9, 2024. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to marine propulsion devices.

2. Description of the Related Art

A marine propulsion device having two drive shafts is known. For example, Japanese Patent Laid-Open Publication No. 2022-135453 (JP2022-135453A) discloses an outboard motor in which torque of a motor as a drive source is transmitted from a first drive shaft to a second drive shaft via a speed reduction mechanism.

Japanese Patent Laid-Open Publication No. 2021-30819 (JP2021-30819A) discloses an outboard motor in which power of an engine as a drive source is transmitted from a first drive shaft to a second drive shaft via a transmission unit such as gears. Rotation of the second drive shaft is transmitted to a propeller shaft via a shift mechanism that switches a shift position. At this time, the shift mechanism can switch a direction of the rotation transmitted from the second drive shaft to the propeller shaft.

However, since the shift mechanism to switch the shift position is disposed in a lower portion of the outboard motor in JP2021-30819A, available space in the lower portion is reduced. Therefore, when the shift mechanism is disposed in the marine propulsion device including two drive shafts, there is room for improvement from a viewpoint of saving available space in the lower portion.

SUMMARY OF THE INVENTION

Example embodiments of the present invention provide marine propulsion devices that save space in lower portions of the marine propulsion devices.

According to an example embodiment of the present invention, a marine propulsion device includes a drive source, a first drive shaft rotationally drivable by the drive source, a drive gear rotatable integrally with the first drive shaft, a second drive shaft parallel or substantially parallel to the first drive shaft, a driven gear drivable by the drive gear rotatable around a center axis of the second drive shaft, and a shift mechanism to switch a shift position. The drive gear and the driven gear are in an upper portion of the marine propulsion device, and the shift mechanism is above the driven gear.

According to another example embodiment of the present invention, a marine propulsion device includes a drive source, a first drive shaft rotationally drivable by the drive source, a drive gear rotatable integrally with the first drive shaft, a second drive shaft, a driven gear drivable by the drive gear and rotatable around a center axis of the second drive shaft, and a shift mechanism to switch a shift position. The drive gear and the driven gear are in an upper portion of the marine propulsion device, and the shift mechanism is above the driven gear.

According to another example embodiment of the present invention, a marine propulsion device includes a drive source, a first drive shaft rotationally drivable by the drive source, a drive gear rotatable integrally with the first drive shaft, a drive gear rotatable integrally with the first drive shaft, a second drive shaft parallel or substantially parallel to the first drive shaft, a driven gear drivable by the drive gear rotatable around a center axis of the second drive shaft, and a shift mechanism to switch a shift position. The drive gear and the driven gear are in an upper portion of the marine propulsion device, and at least a portion of the shift mechanism is above the driven gear.

According to the above example embodiments, space in the lower portions of the marine propulsion devices is saved.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing a marine vessel to which a marine propulsion device according to an example embodiment of the present invention is provided.

FIG. 2 is a schematic left side view showing the marine propulsion device.

FIG. 3 is a perspective view showing a main drive mechanism to drive a water pump assembly and a propeller.

FIG. 4 is a vertical sectional view showing a principal portion of the main drive mechanism.

FIG. 5 is a vertical sectional view showing a steering mechanism and its periphery.

FIG. 6 is a vertical sectional view showing a principal portion of a main drive mechanism according to a modification.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Hereinafter, example embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing a marine vessel to which a marine propulsion device according to an example embodiment of the present invention is provided. FIG. 2 is a schematic left side view showing the marine propulsion device.

The marine vessel 220 includes a hull 210 and two outboard motors 100. In FIGS. 1 and 2, FWD, BWD, L, R, Z1, and Z2 respectively indicate forward, backward, leftward, rightward, upward, and downward directions of the marine vessel 220.

As shown in FIG. 1, the two outboard motors 100 are attached to a stern 211 of the hull 210 so as to be arranged side-by-side in a left-right direction. Since the two outboard motors 100 have the same configuration, only one of the outboard motors 100 will be described as a representative. The outboard motor 100 is a marine propulsion device to propel the hull 210. The outboard motor 100 includes an engine 131, a steering mechanism 140, an ECU (Engine Control Unit) 151, and an SCU (Steering Control Unit) 152.

As shown in FIG. 1, the hull 210 includes a controller 213 and a manual operator 212 that accepts an operation to control (steer) the marine vessel 220. The manual operator 212 includes a remote controller 212a, a steering wheel 212b, and a joystick 212c.

A tilting operation of a lever (not shown) provided on the remote controller 212a changes a thrust of the outboard motor 100 (rpm of a propeller 135 (FIG. 2)) or switches a shift state of the outboard motor 100 (a forward state, a backward state, and a neutral state). A rotating operation of the steering wheel 212b steers the outboard motor 100 (changes a direction of the propeller 135 with respect to the hull 210). The marine vessel 220 moves translationally and turns by a combination of operations of the remote controller 212a and the steering wheel 212b.

The joystick 212c includes a lever (not shown) that can be tilted and rotated. When the lever of the joystick 212c is tilted, rotated, or tilted and rotated, the thrust of the outboard motor 100 is changed, the shift state of the outboard motor 100 is switched, and/or the outboard motor 100 is steered. The marine vessel 220 can move translationally, turn, or change a course by operating the lever of the joystick 212c.

The controller 213 is configured or programmed to control the ECU 151 and the SCU 152 of the outboard motor 100 based on an operation on the manual operator 212. The controller 213 includes, for example, a CPU, a ROM, and a RAM.

In the outboard motor 100, the ECU 151 controls driving of the engine 131 and driving of a shift actuator (not shown) under the control of the controller 213. The SCU 152 controls driving of the steering mechanism 140 under the control of the controller 213. Each of the ECU 151 and SCU 152 includes, for example, a CPU, a ROM, and a RAM.

As shown in FIG. 2, the outboard motor 100 includes an outboard motor body 102. The outboard motor body 102 is attached to the stern 211 of the hull 210 via a bracket 101.

The outboard motor body 102 includes an upper portion 110, a lower portion 120, and a support portion 60 (see FIG. 3). The configuration of the support portion 60 will be described in detail with reference to FIGS. 3 and 5, but the support portion 60 generally includes a movable case 17 and a steering shaft assembly 5. The support portion 60 supports the lower portion 120 so as to be relatively rotatable with respect to the upper portion 110 around a steering shaft 5a of the steering shaft assembly 5, and rotates integrally with the lower portion 120. That is, in the outboard motor 100, the upper portion 110 of the outboard motor body 102 does not rotate with respect to the hull 210, and the lower portion 120 rotates.

Hereinafter, the vertical direction in the outboard motor body 102 is specified with reference to the attitude during navigation shown in FIG. 2.

The upper portion 110 is attached to the stern 211 via the bracket 101. The lower portion 120 includes the propeller 135 and is disposed below the upper portion 110. The upper portion 110 includes a cowl 111 that houses the engine 131 and an upper case 112 that is disposed below the cowl 111 and attached to the stern 211. The lower portion 120 includes a lower case 121.

The outboard motor body 102 includes the engine 131, a first drive shaft 7, a second drive shaft 14, a gearing 133, a propeller shaft 134, and the propeller 135. The engine 131 is an example of a drive source that provides a rotational force to rotate the propeller shaft 134. An engine output shaft 138 of the engine 131 is rotated by an output from a crankshaft (not shown). The first drive shaft 7 is concentric with the engine output shaft 138 and rotates integrally with the engine output shaft 138. The first drive shaft 7 corresponds to a first rotation shaft, and the second drive shaft 14 corresponds to a second rotation shaft.

The second drive shaft 14 is separate from (i.e., not concentric with) the first drive shaft 7 and the engine output shaft 138, and is parallel or substantially parallel to the first drive shaft 7 and the engine output shaft 138. The first drive shaft 7 is rotatable in one direction, and the second drive shaft 14 is rotatable in both directions. The gearing 133 is disposed in the lower case 121. The gearing 133 is connected to a lower end of the second drive shaft 14. The propeller shaft 134 is connected to the gearing 133. The propeller shaft 134 is disposed behind the gearing 133 so as to extend in a front-back direction. The propeller 135 is connected to a rear end of the propeller shaft 134. The propeller 135 is disposed outside the lower case 121 so as to be exposed to the outside of the outboard motor body 102.

A fixed case 31 is relatively fixed to the upper portion 110. The fixed case 31 is fixed to a steering housing (not shown) that covers the steering mechanism 140, and the steering housing is fixed to the upper portion 110. A water pump assembly 10 is disposed in the fixed case 31. The water pump assembly 10 is disposed at a lower end 7a of the first drive shaft 7 and is driven by the first drive shaft 7. The first drive shaft 7 is rotated by the rotational force from the engine 131 via the engine output shaft 138. The water pump assembly 10 supplies cooling water to the engine 131.

FIG. 3 is a perspective view showing a main drive mechanism that drives the water pump assembly 10 and the propeller 135. Components shown in FIG. 3 are located in the upper portion 110 except for the support portion 60.

FIG. 4 is a vertical sectional view showing a principal portion of the main drive mechanism. FIG. 5 is a vertical sectional view showing the steering mechanism 140 and its periphery. The cross section shown in FIGS. 4 and 5 are parallel to a center axis P1 of the first drive shaft 7 and a center axis P2 of the steering shaft assembly 5 and include the central axes P1 and P2. The center axis Pl is parallel or substantially parallel to the center axis P2.

The main drive mechanism will be described with reference to FIGS. 3 to 5.

First, as shown in FIG. 3, the main drive mechanism includes a dog clutch 1, a first bevel gear 2, a drive gear 4, the steering shaft assembly 5 (see also FIG. 5), a pinion gear 6, the first drive shaft 7, a gear 8, the water pump assembly 10, a second bevel gear 11, a pinion gear 12, and a driven gear 13. The main drive mechanism further includes the second drive shaft 14, a reduction gear 15, a gear 16, the support portion 60, and a hydraulic cylinder 144 (see FIG. 2, not shown in FIGS. 3 to 5). The water pump assembly 10 includes an upper housing 9 and a lower housing 41. Both the drive gear 4 and the driven gear 13 are helical gears.

The steering mechanism 140 includes the support portion 60, a first mechanism, and a second mechanism. The first mechanism includes a motor (not shown), the reduction gear 15, the gear 16, and the gear 8. The second mechanism includes the hydraulic cylinder 144 (FIG. 2), a rack gear (not shown), and the pinion gear 6.

The engine output shaft 138 is rotationally driven by the output from the crankshaft (not shown). Then, the water pump assembly 10 is driven by the first drive shaft 7 that rotates integrally with the engine output shaft 138. In parallel with this, the drive gear 4 rotating integrally with the first drive shaft 7 drives the driven gear 13 to rotate.

A transmission mechanism to transmit the rotation of the first drive shaft 7 to the second drive shaft 14 includes the dog clutch 1, the first bevel gear 2, the drive gear 4, the second bevel gear 11, the pinion gear 12, and the driven gear 13.

The rotation of the driven gear 13 is transmitted to the first bevel gear 2 and further to the second bevel gear 11 via the pinion gear 12. The first bevel gear 2 and the second bevel gear 11 rotate in opposite directions.

As will be described in detail below, a shift mechanism 30 to switch a shift position is disposed above the driven gear 13. In the shift mechanism 30, forward, backward, and neutral are switched by moving the dog clutch 1 in the axial direction of the second drive shaft 14.

The second drive shaft 14 rotates integrally with the dog clutch 1 around the center axis P2 (FIG. 5). The second drive shaft 14 rotates in the same direction as the first bevel gear 2 or the second bevel gear 11 that is engaged with the dog clutch 1. The rotational force of the second drive shaft 14 rotates the propeller shaft 134 (FIG. 2) via the gearing 133 in the lower portion 120. The axial direction of the propeller shaft 134 intersects (in the present example embodiment, is perpendicular to) the axial direction (the direction of the center axis P2) of the second drive shaft 14.

The first bevel gear 2 and the driven gear 13 are disposed around a common sleeve 53 (FIG. 4) on the outer periphery of the second drive shaft 14. The first bevel gear 2 includes an extension 2a extending downward (FIG. 4). The extension 2a is always engaged with the driven gear 13, and thus the first bevel gear 2 is always engaged with the driven gear 13 and rotates integrally with the driven gear 13. That is, the driven gear 13 is driven by the drive gear 4, and thus the first bevel gear 2 rotates around the center axis P2 (axial center) integrally with the driven gear 13. Further, the engagement between the drive gear 4 and the driven gear 13 transmits the rotation of the first drive shaft 7 to the first bevel gear 213 while reducing the rotation speed.

The center axis P2 is the center axis of the steering shaft 5a of the steering shaft assembly 5 and is also the center axis of the second drive shaft 14. That is, the steering shaft assembly 5 is concentric with the second drive shaft 14. The pinion gear 6 and the gear 8 rotate integrally with the steering shaft assembly 5.

In the steering mechanism 140, either the first mechanism or the second mechanism is selectively operated in response to an instruction from a vessel operator. It is not necessary to provide both the first mechanism and the second mechanism, and a configuration in which only one of these mechanisms is provided is possible.

First, when the first mechanism is operated, a rotational force from a motor (not shown) in the first mechanism is transmitted to the gear 8 via the reduction gear 15 and the gear 16. Thus, the movable case 17 is rotationally driven integrally with the steering shaft assembly 5. As a result, the lower portion 120 is steered (rotationally driven) with respect to the upper portion 110.

On the other hand, when the second mechanism is operated, a rack gear (not shown) is moved by a driving force from the second mechanism (the hydraulic cylinder 144 (FIG. 2)), and the pinion gear 6 is rotationally driven by the rack gear. As a result, the lower portion 120 is steered (rotationally driven) with respect to the upper portion 110.

A water flow path is defined by the inner spaces of the lower case 121, the movable case 17, the fixed case 31, and the lower housing 41 of the water pump assembly 10. The movable case 17 of the support portion 60 is fixed to the lower portion 120, and in particular, the movable case 17 is fixed to an upper portion of the lower case 121. A plate 33 (FIG. 5) is interposed between the lower case 121 and the movable case 17. The plate 33 is made of, for example, metal.

As shown in FIG. 5, a filter 35 is fixed to the support portion 60 in a space inside the support portion 60. In the inner space of the movable case 17, the filter 35 is first fixed to a top of a cylindrical member 34, and the filter 35 is further fixed to the movable case 17. Specifically, an annular member 36 is sandwiched between a bottom of the cylindrical member 34 and an upper surface of the plate 33. The filter 35 and the top of the cylindrical member 34 are jointly fastened to the movable case 17 with bolts, for example. Therefore, the filter 35 is also fixed to the lower portion 120 via the cylindrical member 34 and the annular member 36. The annular member 36 is made of an elastic member such as rubber.

As described above, the movable case 17 is driven to rotate by the first mechanism or the second mechanism. Since the fixed case 31 does not rotate, a sliding portion is generated between the fixed case 31 and the movable case 17. Seals 37 and 38 are disposed in the sliding portion. Therefore, the sliding portion between the fixed case 31 and the movable case 17 is sealed by the seals 37 and 38.

The shift mechanism 30 will be described with reference to FIGS. 3 and 4. The shift mechanism 30 is mainly disposed on the second drive shaft 14, and includes the dog clutch 1, the first bevel gear 2, the second bevel gear 11, the pinion gear 12, and a drive mechanism (a shift rod 56 and a slide shaft 57). The shift mechanism 30 is disposed in the upper portion 110. Since the shift mechanism 30 does not need to be disposed in the lower portion 120, the space of the lower portion 120 can be saved.

The first bevel gear 2 and the second bevel gear 11 are rotatable around the center axis of the second drive shaft 14. The second bevel gear 11 is disposed above the first bevel gear 2 in the direction of the center axis P2. The pinion gear 12 is always engaged with the first bevel gear 2 and the second bevel gear 11. The dog clutch 1 is prevented from moving in the rotational direction with respect to the second drive shaft 14, and is movable in the direction of the center axis P2.

The shift rod 56 and the slide shaft 57 of the drive mechanism drive the dog clutch 1 in the direction of the center axis P2. First, the slide shaft 57 is inserted into the second drive shaft 14 and moves in the direction of the center axis P2. The slide shaft 57 is inserted into the second drive shaft 14 so that the shift mechanism 30 is compact.

The dog clutch 1 and the slide shaft 57 are connected with a pin 51, and both move integrally in the direction of the center axis P2. An upper end of the slide shaft 57 includes a cam engagement portion 57a having a constricted shape (FIG. 4). On the other hand, a tip end of the shift rod 56 serves as a cam portion 56a (FIG. 3). The cam portion 56a is engaged with the cam engagement portion 57a. The cam portion 56a is eccentric with respect to the center axis of the shift rod 56. The cam portion 56a moves up and down by the shift rod 56 rotating around the center axis in a predetermined range and drives the cam engagement portion 57a. Therefore, the slide shaft 57 moves in the vertical direction (the direction of the center axis P2) by the shift rod 56 rotating within the predetermined range. Then, the dog clutch 1 moves integrally with the slide shaft 57.

The dog clutch 1 switches a rotating direction of the second drive shaft 14 by selecting engagement with the first bevel gear 2 or engagement with the second bevel gear 11. When the dog clutch 1 moves downward, it engages with the first bevel gear 2. In this case, the rotation of the first drive shaft 7 is transmitted to the second drive shaft 14 through the drive gear 4, the driven gear 13, the first bevel gear 2, and the dog clutch 1. Since the first bevel gear 2 transmits the rotation in one of the two directions to the second drive shaft 14 without passing through the pinion gear 12 and the second bevel gear 11, a rotation transmission efficiency between the drive shafts 7 and 14 is high.

On the other hand, when the dog clutch 1 moves upward, the dog clutch 1 engages with the second bevel gear 11. In this case, the rotation of the first drive shaft 7 is transmitted to the second drive shaft 14 through the drive gear 4, the driven gear 13, the first bevel gear 2, the pinion gear 12, the second bevel gear 11, and the dog clutch 1. Therefore, the first bevel gear 2 transmits the rotation in the direction opposite to the above-mentioned direction to the second drive shaft 14 through the pinion gear 12, the second bevel gear 11, and the dog clutch 1.

The shift position where the dog clutch 1 engages with the first bevel gear 2 corresponds to a forward drive position, and the shift position where the dog clutch 1 engages with the second bevel gear 11 corresponds to a backward drive position. It is considered that a frequency of forward movement is higher than that of backward movement, and a driving force of the forward movement transmitted by the transmission mechanism is also larger than that of the backward movement. Since the rotation is transmitted without passing through the pinion gear 12 during the forward movement, the transmission efficiency can be improved particularly during the forward movement.

Since the driven gear 13 and the drive gear 4 are both helical gears, the driven gear 13 is biased upward because it is driven by the drive gear 4. Moreover, the first bevel gear 2 is arranged above the driven gear 13. Therefore, the driven gear 13 and the first bevel gear 2 are firmly engaged with each other.

Next, a configuration related to lubrication will be described with reference to FIG. 4.

A spiral groove 7b is provided on the outer periphery of the first drive shaft 7. The spiral groove 7b is directly provided on the outer peripheral surface of the first drive shaft 7. The spiral groove 7b is disposed in the upper portion 110. When the first drive shaft 7 rotates, the spiral groove 7b moves oil from the lower side to the upper side. An oil passage 54 is connected to a top of the spiral groove 7b. The oil passage 54 guides the oil from a first position Q1 higher than an oil level Q0 in the spiral groove 7b to a second position Q2 higher than the first position Q1.

A discharge port 55 of the oil passage 54 opens toward components disposed on the axis of the second drive shaft 14. For example, the oil is supplied to the cam engagement portion 57a of the slide shaft 57 and the cam portion 56a of the shift rod 56 in the shift mechanism 30, and the engagement therebetween is smoothed.

According to an example embodiment, the drive gear 4 and the driven gear 13 are disposed in the upper portion 110, and the shift mechanism 30 is disposed above the driven gear 13. Thus, when the shift mechanism 30 is disposed in the marine propulsion device including two drive shafts parallel or substantially parallel to each other, the space of the lower portion 120 is not consumed. Therefore, the space in the lower portion 120 can be saved.

According to an example embodiment, the first bevel gear 2 transmits the rotation in one of the two directions to the second drive shaft 14 via the dog clutch 1 without passing through the pinion gear 12. This can increase the rotation transmission efficiency between the two drive shafts.

Further, since the driven gear 13 is biased toward the first bevel gear 2 there above because it is driven by the drive gear 4, the engagement between the driven gear 13 and the first bevel gear 2 is increased. Further, the first bevel gear 2 is always engaged with the driven gear 13 by the extension 2a being always engaged with the driven gear 13 and rotates integrally with the driven gear 13, and therefore, the inclination of the driven gear 13 is reduced or prevented while saving space. Moreover, since the first bevel gear 2 and the driven gear 13 are disposed around the common sleeve 53 (FIG. 4) provided on the outer periphery of the second drive shaft 14, the integral rotation of the driven gear 13 and the first bevel gear 2 is increased. These also increase the rotation transmission efficiency between the two drive shafts.

Also, according to an example embodiment, the water pump assembly 10 is disposed on and driven by the first drive shaft 7. This increases the space efficiency. For example, one of the two shafts may have a plurality of functions including a water absorbing function.

Further, since the first drive shaft 7 rotates in one direction, the mechanism to drive the water pump assembly 10 is not complicated. The engagement of the drive gear 4 with the driven gear 13 transmits the rotation of the first drive shaft 7 to the second drive shaft 14 while reducing the rotation speed. The water pump assembly 10 is provided on the first drive shaft 7 that rotates at a high speed, so that various types of water pumps are possible. Further, since the water pump assembly 10 is disposed at a bottom 7a of the first drive shaft 7 that is not concentric with the second drive shaft 14, the maintenance of the water pump assembly 10 is easy.

According to an example embodiment, since the spiral groove 7b provided on the outer periphery of the first drive shaft 7 moves the oil from the lower side to the upper side by the rotation of the first drive shaft 7, it is possible to lubricate the components located at the positions higher than the oil level Q0 without using a separate pump.

Further, the oil passage 54 guides the oil from the first position Q1 higher than the oil level Q0 in the spiral groove 7b to the second position Q2 higher than the first position Q1, and thus it is possible to lubricate the components such as the shift mechanism 30 at a higher location.

In an example embodiment, the driven gear 13 is directly driven by the drive gear 4. However, this is not limited. As shown in a modification in FIG. 6, when helical gears are not used as the drive gear 4 and the driven gear 13, a chain drive may be used. In this case, the drive gear 4 and the driven gear 13 may function as sprockets. A chain 61 is wound around the drive gear 4 and the driven gear 13. The rotation is transmitted from the drive gear 4 to the driven gear 13 via the chain 61.

From the viewpoint of obtaining the effect of saving the space in the lower portion 120, it is not essential that the drive shaft (first drive shaft 7) rotationally driven by the drive source is parallel or substantially parallel to the drive shaft (second drive shaft 14) driven by the drive gear 4. Further, not all but at least a portion of the shift mechanism 30 may be arranged above the driven gear 13.

The drive source that rotationally drives the first drive shaft 7 may not be the engine 131, and may be an electric motor.

While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.