Patent Application
20170210454
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-010877, filed on Jan. 22, 2016, the entire contents of which are incorporated herein by reference.
Field of the Invention
The present invention relates to a mounting device that supports an outboard motor body with a swivel bracket in an outboard motor mounted to a ship via this swivel bracket.
Description of the Related Art
Usually, an outboard motor is mounted to a transom of a ship via a swivel bracket. In this case, the outboard motor is turnably mounted to the swivel bracket. For example, a steering handle with a throttle grip to adjust engine output at a distal end typically extends from a front lower portion of an engine forward. Horizontally steering this steering handle changes a direction of the entire outboard motor, thus ensuring the steering of a ship.
There has been provided a mounting structure for an outboard motor, for example, like the following outboard motor according to Patent Document 1. A drive shaft housing, which includes a drive shaft in an internal exhaust passage, is disposed below an engine. The drive shaft housing is turnably supported to a turning support portion of a swivel bracket. A resilient body is mounted to an outer peripheral surface of the drive shaft housing. A handle bracket to support a base of the steering handle is mounted to an outer peripheral surface of this resilient body. A bracket cover to which the swivel bracket is mounted is slidably mounted to an outer peripheral surface of the handle bracket via a bush. This mounting structure reduces a transmission of engine vibrations to the steering handle side and a ship side by the resilient body.
An outboard motor according to Patent Document 2 includes a resilient member interposed between a steering handle and an engine side. This resilient member is configured to be freely vibratable in a clearance between the steering handle and the engine side. The outboard motor further includes an abutting portion, which can be brought into abutment with the engine side, on a steering handle side. This mounting structure minimizes vibrations transmitted from the engine to the steering handle.
Conventionally, as described above, a steering function and a vibration damping function are obtained by a mount shape, approximately cylindrical shape, of the resilient body or the resilient member. In this case, a spring constant in a rotation direction of the resilient body is generally preferable to be large in terms of the steering function. In terms of the vibration damping function, the spring constant is generally preferable to be small. Reducing the spring constant of the mount (resilient body) to reduce vibrations causes a problem of making responsiveness or operational feeling of the steering worse. Thus, a balance between the functions conflicting in the approximately cylindrical mount shape needs to be considered. Therefore, achieving further improvement both in the vibration damping function and the steering performance is not easy.
The present invention has been made to solve such circumstances, and an object of the present invention is to provide a mounting device for outboard motor that ensures effectively improving the vibration damping function and the steering performance with simple configuration.
A mounting device for outboard motor according to the present invention includes an engine, a drive shaft housing, and a swivel bracket. The engine includes a crankshaft in a vertical direction. A cylinder axis line of the engine extends rearward in a ship advancing direction. The drive shaft housing internally includes a longitudinally-oriented drive shaft. The drive shaft is coupled to the crankshaft at a lower side of the engine. The swivel bracket turnably supports a tubular outer peripheral portion of the drive shaft housing by upper and lower mount portions. A mount member is fitted to at least the upper mount portion. The mount member is formed of a resilient body and rotates integrally with the outer peripheral portion of the drive shaft housing. A handle bracket is fitted onto an outer periphery of the mount member. The handle bracket supports a steering handle. The steering handle is turnable with respect to the upper mount portion. In the upper mount portion, a steering central axis related to a steering force of the steering handle and a vibration central axis related to a torque reaction force of the engine are configured to be shifted back and forth. The mount member is formed such that a spring constant related to the vibration central axis is smaller than a spring constant related to the steering central axis.
The mounting device for outboard motor according to the present invention is configured as follows. The mount member forms an approximately cross-shaped steering force transmission portion with protrusions on a front and a rear and protrusions on a right and a left to form an inner peripheral surface of the handle bracket into a shape approximately similar to the mount member. Right and left protrusions with shape approximately similar Lo the mount member are formed on an outer peripheral surface of the drive shaft housing. The mount member is configured to have the steering central axis at a cross-shaped intersection portion.
The mounting device for outboard motor according to the present invention is configured as follows. Clearances are disposed between the respective right and left steering force transmission portions and the inner peripheral surface of the handle bracket or the outer peripheral surface of the drive shaft housing.
The mounting device for outboard motor according to the present invention is configured as follows. A curvature radius of an outer peripheral surface of the protrusion on a rear of the mount member is configured smaller than a curvature radius of the inner peripheral surface of the handle bracket.
The mounting device for outboard motor according to the present invention further includes protrusions. The protrusions each project from the drive shaft housing outside at inside the protrusion on the rear and the right and left protrusions of the mount member. The protrusions are configured to have radial thicknesses of the mount member thinner than a radial thickness of the protrusion at the front of the mount member.
The following describes preferred embodiments of a mounting device for outboard motor according to the present invention with reference to the drawings.
Referring to
Referring to
The lower rotation support portion 17B is disposed near the lower portion of the middle unit 13 separated by a predetermined distance from the upper rotation support portion 17A downward. The drive shaft housing 23 is turnably supported horizontally also at this rotation support portion 17B. In this case, a mount 22B, which is formed of a resilient body, is inserted inside a lower end portion of the swivel bracket 16. In this manner, the outboard motor body has the supporting structure that elastically supports the drive shaft housing 23 at the upper and lower end portions of the swivel bracket 16 via the mount 22A and the mount 22B.
The drive shaft housing 23 has a tubular hollow shape on the whole and on which the engine 11 is integrally joined together. A drive shaft 24, which is coupled to a lower end portion of the crankshaft 15, is penetratingly disposed in the vertical direction inside the drive shaft housing 23. A driving force of the drive shaft 24 is transmitted to a propeller shaft in a gear case 25 of the lower unit 14. The propeller shaft includes a propeller 26 on a rear end, and the power of the engine 11 passes through a power transmission path, which is constituted of the crankshaft 15, the drive shaft 24, the propeller shaft, and a similar component, to be finally transmitted to the propeller 26. Then, the propeller 26 can be rotatably driven.
In the above-described case, the upper unit 12 is covered with an exterior cover 27. The exterior cover 27 includes an upper cover 2/A, which covers around an upper portion of the upper unit 12, and a lower cover 27B, which covers around a lower portion of the upper unit 12. The upper cover 27A and the lower cover 27B are integrally joined together to form an appearance form such as an approximately egg shape or lemon shape as a whole.
Giving an outline of the engine 11, for example, an Over Head Valve (OHV) engine may be used as the engine 11. As illustrated in
The engine case 28 is divided into an upper engine case 28A and a lower engine case 28B each of which integrally includes the cylinder block 29. Although detailed illustration and a similar description will be omitted, as illustrated in
To the engine 11, additionally, an intake system, an exhaust system, a cooling system, a lubricating system, and a control system (Engine Control Unit: ECU) are attached. The intake system supplies air-fuel mixture containing air (intake air) and fuel. The exhaust system discharges burnt exhaust gas in the cylinder from the engine 11. The cooling system cools the engine 11. The lubricating system lubricates movable parts of the engine 11. The control system controls operations of these systems. The control by the control system causes the plurality of functional systems to collaborate with the above-described auxiliary machines and a similar member so as to perform the smooth operation as the entire engine 11.
Appropriately turning the tiller handle 20 in the outboard motor 10 with the above-described configuration rotates the outboard motor body including the engine 11 and the drive shaft housing 23 at the upper rotation support portion 17A and the lower rotation support portion 17B via the handle bracket 21. The turning operation, namely, the steering of the tiller handle 20 horizontally turns the power unit on the rotation support portion 17A and the rotation support portion 17B, allowing the propeller 26 to be steered at a desired angle.
With the outboard motor 10 of the present invention, the drive shaft housing 23 is supported to be slidably rotatable by the swivel bracket 16. The outboard motor 10 includes a steering force adjusting mechanism that adjusts a steering force to slidably rotate this drive shaft housing 23.
The pressing surface 38 on the handle bracket 21 is formed into a small-diameter shoulder 40 with diameter smaller than a site corresponding to the upper rotation support portion 17A. The small-diameter shoulder 40 is configured by concentrically reducing the diameter of a lower end portion of the handle bracket 21, and an outer peripheral surface thereof is formed as the pressing surface 38. An operation knob 41 is joined to be integrally rotatable with a base end side of the screw shaft 37. Steering this operation knob 41 to the right and left advances and retreats the screw shaft 37 in its axial direction, thus adjusting a magnitude of strength of pressing against the pressing surface 38 by the pressing member 39. In the above-described case, as illustrated in
As described above, the pressing surface 38 is disposed at the small-diameter shoulder 40, which is the lower end portion of the handle bracket 21. In this case, as illustrated in
In the actual use of the outboard motor 10, the turning operation of the tiller handle 20 by a passenger turns the outboard motor body via the upper rotation support portion 17A and the lower rotation support portion 17B, thus allowing the propeller 26 to be steered at the desired angle. Then, the pressing member 39 at the distal end of the screw shaft 37 appropriately pushes and is slidably in contact with the pressing surface 38, thus ensuring obtaining the appropriate steering force of the tiller handle 20. When the outboard motor 10 is thus steered, the drive shaft housing 23, specifically the handle bracket 21 is rotatably supported to be slidable by the swivel bracket 16. The screw shaft 37 is screwed into the screw hole 35 and the pressing member 39 pushes the pressing surface 38 on the handle bracket 21 to increase a friction force at the contact surface. Thus, the steering force to the drive shaft housing 23 at the time is strengthens. That is, the turning operation by the operation knob 41 allows setting the desired steering force.
As described above, the present invention disposes the crankshaft 15 that faces the vertical direction in the engine 11 and orients the rear side in the horizontal direction, a direction of the cylinder axis line Z being perpendicular to the vertical direction. As described above, the mount 22A is fitted to the upper mount portion. The mount 22A is formed of the resilient body and rotates integrally with the outer peripheral portion of the drive shaft housing 23. The handle bracket 21 is fitted onto the outer periphery of this mount 22A. The handle bracket 21 supports the tiller handle 20 (steering handle) turnable with respect to the upper mount portion.
Referring to
The mount 22A (hereinafter simply referred to as a mount 22) is formed such that a spring constant related to the vibration central axis 51 is smaller than the spring constant related to the steering central axis 50. A specific configuration for the specification will be described later.
As illustrated in
A curvature radius r of an outer peripheral surface of the protrusion 44 on the rear of the mount 22 is configured smaller than a curvature radius of an inner peripheral surface of the handle bracket 21.
The mount 22 has a flange 22a with predetermined thickness at the upper portion. This flange shape allows setting the spring constant according to the need with respect to own weight of the outboard motor 10 and the load in a top-bottom direction with the thickness and the shape of this part, thus having vibration damping and displacement regulating functions.
In
In the steering force transmission portion 54, a clearance 55 is configured between the inner peripheral surface of the handle bracket 21 and the mount 22. In this case, displacement restricting portions 56 (right-left direction) that restrict a displacement caused by a lift during the steering are provided. The clearance 55 may have a structure disposed between the outer peripheral surface of the drive shaft housing 23 and the mount 22.
Especially, at a base side of the protrusion 44 on the rear of the mount 22, a vibration reducing portion 57 is provided. The vibration reducing portion 57 reduces or damps the vibrations, which are caused by the torque reaction force of the engine 11, around the vibration central axis 51. The inner peripheral surface of the handle bracket 21 is formed into a shape approximately similar to the mount 22.
In the above-described case, a contact portion where an inner surface of the mount 22 contacts an outer surface of the drive shaft housing 23 and a contact portion where the outer surface of the mount 22 contacts the inner surface of the handle bracket 21 have a cylindrical surface around the vibration central axis 51 or a shape similar to the cylindrical surface. This shape forms a structure by which the rotational vibration (displacement) around the vibration central axis 51 is less likely to be transmitted to the outer peripheral side (that is, the spring constant is small). On the other hand, the clearance 55 is configured at the site perpendicular to the cylindrical surface. Accordingly, the drive shaft housing 23 freely rotates, namely, vibrates within some extent of range.
Further specifically describing the configuration of the mount 22 of the mounting device according to the present invention, the thrust transmitting portion 52 for forward movement prevents a rearward displacement of the drive shaft housing 23. The operation of the outboard motor 10 obtains propelling power through the rotation of the propeller 26. Meanwhile, as illustrated in
In this case, the thrust generated at the propeller 26 inclines the outboard motor body portion supported by the upper and lower mounts 22A and 22B as illustrated in
As illustrated in
The thrust transmitting portion 53 for rearward movement prevents the drive shaft housing 23 from being displaced forward. During the rearward movement, opposite from the case of the forward movement, the outboard motor 10 is inclined forward and attempts to displace the drive shaft housing 23 forward. In this case, the thrust transmitting portion 53 has the vibration damping function against a small load that displaces the drive shaft housing 23 forward and a function against a large load that increases the contact area with the handle bracket 21 to transmit the propelling power. As illustrated in
Both the thrust transmitting portion 52 for forward movement and the thrust transmitting portion 53 for rearward movement are configured to have a small spring constant against the load around the vibration central axis 51.
Further, in
Next, the vibration reducing portions 57 are sites configured to reduce the transmission of the vibrations (the rotational vibrations caused by the torque reaction force) generated by the reaction force of the driving torque from the engine 11. The burning of the engine 11 generates a torque variation, and the reaction force of the torque generates the vibrations in the rotation direction in the outboard motor body. The pressure variation generated by the burning of the engine 11 is transmitted to the crankshaft 15 via the piston 33, thus causing the torque variation. At this time, an engine block receives the torque reaction force and rotates (is displaced) around the shaft of the crankshaft 15. In this case, at the position (height direction) of the mount 22, the vibration central axis 51 of the vibrations caused by the reaction force of the torque does not match the steering central axis 50 of the outboard motor body and the steering handle, that is, is positioned appropriately shifted rearward.
The vibration reducing portions 57 have a function to transmit the steering force in addition to the vibration reduction function. The vibration reducing portions 57 are easily displaced around the vibration central axis 51 in
In the above-described case, the outboard motor 10 has the structure that positions the cylinder block 29, the cylinder head 30, the cylinder head cover 31, the piston 33, and a similar member at the rear of the crankshaft 15. Therefore, a center of gravity of the outboard motor body (a part supported by the mount 22) is positioned rearward with respect Lo the crankshaft 15.
The following describes main operational advantages with the mounting device for outboard motor according to the present invention. First, the steering central axis 50 and the vibration central axis 51 are configured shifted back and forth. The spring constant related to the vibration central axis 51 of the mount 22 is formed to be smaller than the spring constant related to the steering central axis 50. Against the rotational vibration caused by the torque reaction force generated by the reaction force of the driving torque from the engine 11, the mount 22 is easily displaced around the vibration central axis 51 (namely, the spring constant is small), and the force is easily transmitted around the steering central axis 50 (the spring constant is large).
Thus, the setting by changing the magnitude of the spring constants related to the steering central axis 50 and the vibration central axis 51 by the single mount 22 allows the accurate transmission of the steering load and the reduction in the transmission of the rotation vibration caused by the torque reaction force from the engine 11.
Specifically, as illustrated in
Thus, devising the shape of the mount 22 ensures obtaining the nonlinear spring constant with the identical member (rubber hardness). With the steering force transmission portions 54 and the vibration reducing portions 57, the nonlinear spring constant is obtained against the steering force. These other parts also ensure obtaining the nonlinear spring constant through the shear, compression, or a similar operation of the mount 22. This ensures forming the mount 22 with the easy molding structure (one-way molding structure) with the single member.
Since the mount 22 has a configuration falling within between the mutual components, a member such as a bolt and a bracket for the mounting is not required. Accordingly, the mount 22 is simple and lightweight, also excellent in compactification and attachability. Although being the single member, the mount 22 has many functions depending on the shape of each site. Designing the mount 22 so as to extend in the identical cross-sectional shape to the top and bottom (vertical direction) is also easy, ensuring the change (reduction) in surface pressure applied to the mount 22. Accordingly, changing the hardness (rubber hardness) of the mount 22 allows the appropriate adjustment for the required spring constant.
Further, disposing the clearances 55 between the respective right and left steering force transmission portions 54 and the inner peripheral surface of the handle bracket 21 does not interrupt the swing of the outboard motor 10 in the right-left direction, thus improving the vibration damping performance. The protrusion 43 on the front side of the mount 22 needs not to be excessively flexible. This avoids losing the steering feel of the tiller handle 20 during steering, that is, this avoids a limp steering feel.
Configuring the curvature radius r of the outer peripheral surface of the protrusion 44 on the rear side of the mount 22 smaller than the curvature radius of the inner peripheral surface of the handle bracket 21 does not interrupt the turning near the vibration central axis 51 against the rotational vibration caused by the torque reaction force. Accordingly, the protrusion 43 on the front side needs not to be excessively flexible. This case also ensures obtaining the good steering feel while the steering feel of the tiller handle 20 during steering intact.
Further, configuring the radial thickness of the mount 22 thinner than the protrusion 43 on the front side of the mount 22 ensures appropriately changing the hardness of the mount 22 as necessary without changing the material (mechanical property). This improves productivity of the mount 22, ensuring achieving a cost reduction. The drive shaft housing 23 includes the protrusions 47, 48, and 49 to prevent a positional displacement of the mount 22, allowing securing and maintaining predetermined performance.
While the present invention has been described with the above-described various embodiments, the present invention is not limited only to these embodiments. Changes and similar modification are possible within the scope of the present invention.
For example, although the embodiment describes the example of the OHV engine as the engine 11, the engine 11 may be another form, for example, an OHC engine.
With the present invention, the setting by changing the magnitude of the spring constant related to the steering central axis and the vibration central axis by the single mount member allows the accurate transmission of the steering load and the reduction in the transmission of the rotation vibration caused by the torque reaction force from the engine. Additionally, the present invention features the simple configuration and lightweight, also excellent in compactification and attachability.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-010877 | Jan 2016 | JP | national |
