JP2007296910A - Outboard motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outboard motor capable of covering a tool inserting indentation on a bottom face of a cavitation plate without deteriorating a degree of freedom in design of a fastening portion between a drive shaft case and a gear case and a trim tab. <P>SOLUTION: An extension case 7 and a gear case 10 are fastened in front of a trim tab 42 by a hexagon bolt 51 screwed from a bottom of the gear case 10. The tool inserting indentation 53 is formed, and a cover 54 covering the tool inserting indentation 53 is mounted on a bottom face of the gear case 10. The cover 54 has a body 54a, a bolt head holding indentation 54b, and an approximate-L-shaped lock part 54c nipped by the gear case 10 and the trim tab 42. Under an assembled condition, the cover 54 is approximately flush with the bottom face of the cavitation plate 41, and a bottom end of a head 56a of a bolt 56 with a hexagonal hole is approximately flush with the bottom face of the cover 54. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an outboard motor used as a power source for propulsion of small and medium-sized ships, and more particularly to a technique for suppressing cavitation caused by a tool insertion recess for a gear case fastening bolt.

  Many small and medium sized ships employ outboard motors as a power source for propulsion. In an outboard motor, the power of the engine mounted on the upper part is transmitted to the propeller shaft at the lower end via a vertical shaft and a bevel gear set, and propulsion is obtained by rotating the propeller attached to the propeller shaft. Generally, a drive shaft case that accommodates a vertical shaft is fastened to a lower portion of a mount case that supports the engine, and a gear case that houses a bevel gear set and a propeller shaft is further fastened to the lower end of the drive shaft case. The gear case is fastened to the drive shaft case by about five fastening members (hexagonal bolts, hexagonal nuts, etc .: hereinafter referred to as bolts), and the rearmost bolt is often located immediately above the propeller.

In the outboard motor gear case, a cavitation plate is formed above the propeller in order to prevent an air draw phenomenon during turning. The cavitation plate needs to have a smooth lower surface in order to prevent an increase in resistance due to water flow separation. However, since the fastening bolt described above is tightened from below, a tool insertion recess into which a drive tool (socket wrench or the like) is inserted is formed on the lower surface of the cavitation plate, and the navigation speed is significantly reduced as it is. Therefore, there is known a technique in which a tool insertion recess is covered with a trim tab substrate and the lower surface of the cavitation plate is smoothed (see Patent Documents 1 and 2). The trim tab is a member provided with a current plate that rectifies the water flow behind the propeller, and a circular substrate that is fastened to the lower surface of the cavitation plate so that the angle of the current plate can be changed according to the specifications of the propeller. have.
Japanese Unexamined Patent Publication No. 60-25892 Japanese Patent Laid-Open No. 57-130896

  When the method of covering the tool insertion recess with the substrate of the trim tab as in Patent Documents 1 and 2, the following problems may occur. For example, in an outboard motor, the fastening parts of both are determined according to the shape of the drive shaft case and the gear case. The trim tab also has an installation site (a center position of the substrate) and an outer diameter depending on the position of the propeller, the size of the cavitation plate, and the like. However, in order to cover the tool insertion recess with the trim tab substrate, it is necessary to retract the fastening part between the drive shaft case and the gear case from the optimum position, or to advance the installation part of the trim tab from the optimum position. It will happen.

  The present invention has been made in view of such a background, and has made it possible to cover the tool insertion recess on the lower surface of the cavitation plate without reducing the design freedom of the fastening portion between the drive shaft case and the gear case and the trim tab. The purpose is to provide an outboard motor.

  According to the first aspect of the present invention, the power of the prime mover located in the upper part is transmitted to the propeller shaft located in the lower part through the vertical shaft and the direction change gear set, and propelled by rotating the propeller mounted on the propeller shaft. An outboard motor for obtaining a force, comprising: a drive shaft case that accommodates the vertical shaft; and a gear case that is fastened to a lower end of the drive shaft case by a fastening member and accommodates the direction change gear set and the propeller shaft. The lower surface of the gear case is formed with a tool insertion recess for insertion of the driving tool for the fastening member, and a cover covering the tool insertion recess is substantially flush with the lower surface of the gear case. It is attached.

  According to a second aspect of the present invention, in the outboard motor according to the first aspect, a trim tab is attached to the lower surface of the gear case behind the tool insertion recess, and the rear end of the cover is locked by the trim tab. It is characterized by that.

  According to a third aspect of the present invention, in the outboard motor according to the first or second aspect, the cover is fastened to the lower surface of the gear case by a hollow head screw.

  According to the outboard motor of the first aspect, it becomes possible to freely set the installation location and the outer diameter of the trim tab without being affected by the fastening location between the drive shaft case and the gear case, and the degree of design freedom is improved. . Further, according to the outboard motor of the second aspect, the number of fastening members for fastening the trim tab can be reduced. Further, according to the outboard motor of the third aspect, for example, by making the lower end of the hollow head screw substantially flush with the lower surface of the cover at the time of fastening, the lower surface of the cavitation plate becomes smoother, and the navigation performance And the like are realized.

Hereinafter, embodiments of an outboard motor to which the present invention is applied will be described in detail with reference to the drawings.
1 is a longitudinal sectional view of a main part of an outboard motor according to an embodiment, FIG. 2 is an enlarged sectional view of a portion II in FIG. 1, and FIG. 3 is a sectional view taken along an arrow III in FIG. FIG. 4 is a perspective view of an adjustment piece.

<Overall configuration>
In the outboard motor 1 shown in FIG. 1, the outboard motor main body 3 is fixed to the transom board T of the outboard motor ship B via the stern bracket 2. A swivel case 5 is connected to the stern bracket 2 so as to be rotatable about a tilt shaft 4 disposed horizontally. A swivel case 5 has a front end portion of an engine mount case 6 that holds the engine E at an upper end thereof, and an extension case 7 that is a drive shaft case at a lower end portion thereof. It is connected to. An engine mount case 6 is supported in an anti-vibration manner at the upper end portion of the extension case 7, and a gear case 10 that supports a propeller 9 is connected to the lower end portion of the extension case 7. On the upper surface of the engine mount case 6, a detachable engine cover 11 having a deep bowl shape whose lower surface is opened is mounted so as to mainly cover the upper half of the engine E.

  A stay 21 extends from the front of the engine mount case 6, and a handle bracket 22 that supports the steering handle 23 at a substantially horizontal navigation position (shown by a solid line) is bolted to the front end of the stay 21. . In addition to the navigation position, the steering handle 23 can take an upper retracted position (indicated by a two-dot chain line). The steering handle 23 is provided with a shift lever 24 for switching the gear stage between forward / neutral / reverse, a throttle grip 25 for controlling the output of the engine E, and the like.

  The extension case 7 accommodates a drive shaft 31 as a drive shaft, while the gear case 10 accommodates a bevel gear set (direction changing gear set) 32 and a propeller shaft 33, and the power of the engine E is used to drive these drive shafts. 31, the bevel gear set 32, and the propeller shaft 33 are transmitted to the propeller 9.

  As shown in FIGS. 1 and 3, a cavitation plate 41 is formed on the gear case 10 so as to protrude right and left immediately above the propeller 9 in order to prevent an increase in resistance due to separation of water flow. A trim tab 42 that rectifies the water flow behind the propeller is attached to the rear lower surface of the cavitation plate 41. The trim tab 42 protrudes in the center of the upper surface of the substrate 42a, a circular substrate 42a that fits into a circular recess 41a formed on the lower surface of the cavitation plate 41, a rectifying plate 42b that protrudes downward from the rear portion of the substrate 42a. The boss 42c is fastened to the gear case 10 by a hexagon bolt 43 screwed from above. The trim tab 42 can be rotated within a predetermined angle range around the central axis C of the substrate 42a so as to correspond to the specifications of the propeller 9 and the like. In FIG. 2, a member denoted by reference numeral 44 is a resin cover that closes the tool insertion hole 45 formed in the gear case 10.

<Tool insertion recess and cover>
In the present embodiment, the extension case 7 and the gear case 10 are fastened in front of the trim tab 42 by a relatively large-diameter hexagon bolt (fastening member) 51 screwed from below the gear case 10. A tool insertion recess 53 into which a socket wrench (driving tool) 52 (indicated by a two-dot chain line in FIG. 2) for driving the hexagon bolt 51 is inserted is formed on the lower surface of the gear case 10. A cover 54 covering 53 is attached.

  The cover 54 is fitted into a cover holding recess 41 b formed in the cavitation plate 41, and is fastened to the gear case 10 by a hexagon socket head cap screw (hollow head screw) 56. As shown in FIG. 3, the cover 54 and the cover holding recess 41 b have a rectangular shape with the front portion sunk in a downward view. As shown in FIG. 4, the cover 54 protrudes from the main body 54a fitted into the cover holding recess 41b, the bolt head holding recess 54b formed below the front of the main body 54a, and the rear upper surface of the main body 54a. And a locking portion 54c having a substantially L-shaped cross section sandwiched between the gear case 10 and the trim tab 42. In this embodiment, in the assembled state, the cover 54 is substantially flush with the lower surface of the cavitation plate 41, and the lower end of the head 56 a of the hexagon socket head bolt 56 is substantially flush with the lower surface of the cover 54. ing. The rear end of the main body 54a has an arc shape so as to follow the outer periphery of the substrate 42a of the trim tab 42.

<< Operation of Embodiment >>
When the outboard motor 1 is activated and the propeller 9 rotates, a backward water flow is generated from seawater or lake water in front of the propeller 9, and the outboard motor ship B is propelled forward by this water flow. In the outboard motor 1, the propeller 9 is installed at a position relatively close to the water surface, so that the water flow described above flows along the lower surface of the cavitation plate 41. At this time, in this embodiment, the tool insertion recess 53 is covered with a cover 54 that is substantially flush with the lower surface of the cavitation plate 41, and the lower end of the head portion 56 a of the hexagon socket head bolt 56 that fastens the cover 54 to the gear case 10. Is substantially flush with the lower surface of the cover 54, so that almost no irregularities are formed on the lower surface of the cavitation plate 41. As a result, almost no separation of the water flow occurs on the lower surface of the cavitation plate 41, and the above-described decrease in the navigation speed is unlikely to occur. In addition, the hexagon bolt 51 that fastens the extension case 7 and the gear case 10 does not need to be covered with the substrate 42a of the trim tab 42, and therefore can be set to an optimal position according to the shape of the extension case 7 and the gear case 10. it can. Further, since the rear end of the cover 54 is locked by the trim tab 42, the cover 54 can be fastened by using one hexagon socket head bolt 56, thereby reducing the number of parts and the number of assembly steps. I was able to.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, although the hexagon socket head cap screw is used as the hollow head screw in the above embodiment, a T-shaped hex lobe bolt, a cross-head countersunk bolt, or the like may be employed. In the above embodiment, the rear end of the cover is locked by the trim tab. However, when the cover and the trim tab are separated from each other, the cover may be fastened to the gear case by a pair of bolts. Good. In addition, the specific structure of the outboard motor, the specific shape of the gear case, and the like can be changed as appropriate without departing from the spirit of the present invention.

1 is a side view of an outboard motor according to an embodiment. It is an expanded sectional view of the II section in FIG. FIG. 3 is a view taken along arrow III in FIG. 2. It is a perspective view of a cover.

Explanation of symbols

1 Outboard motor 7 Extension case (drive shaft case)
9 Propeller 10 Gear case 31 Drive shaft 32 Bevel gear set (Direction change gear set)
33 Propeller shaft 41 Cavitation plate 42 Trim tab 51 Hexagon bolt (fastening member)
53 Tool insertion recess 54 Cover 54a Main body 54b Bolt head holding recess 54c Locking portion 56 Hexagon socket head cap screw (hollow head screw)

Claims (3)

An outboard motor that transmits the power of the prime mover located in the upper part to the propeller shaft located in the lower part through the vertical shaft and the direction change gear set, and obtains propulsive force by rotating the propeller mounted on the propeller shaft. There,
A drive shaft case that houses the vertical shaft;
A gear case that is fastened to a lower end of the drive shaft case by a fastening member, and that houses the direction change gear set and the propeller shaft;
A tool insertion recess for insertion of the driving tool for the fastening member is formed on the lower surface of the gear case, and a cover that covers the tool insertion recess is attached to be substantially flush with the lower surface of the gear case. An outboard motor characterized by   2. The outboard motor according to claim 1, wherein a trim tab is attached to a lower surface of the gear case behind the tool insertion recess, and a rear end of the cover is locked by the trim tab.   The outboard motor according to claim 1, wherein the cover is fastened to a lower surface of the gear case by a hollow head screw.

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