JP2950790B2 - Small planing boat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a personal watercraft such as a motor boat or a leisure watercraft.

[0002]

2. Description of the Related Art As a personal watercraft of this type, one having a structure shown in FIG. 8 is known. FIG. 8 is a view of the state of installation of the engine in a personal watercraft equipped with a three-cylinder two-cycle engine E for the purpose of increasing the output, as viewed from the stern side. In this two-cycle engine E, a cylinder 11 is mounted in a vertical direction on a crankcase 1 rotatably supporting a crankshaft 2, and an intake device 12 and an exhaust device 13 are provided on one side and the other side of the cylinder 11, respectively. A motor-driven starter 14 is mounted on the crankcase 1 below the exhaust device 13.

The two-stroke engine E has a plurality of mounting seats 4 provided on a hull 3a of the hull 3 with the axis of the crankshaft 2 set so as to coincide with the longitudinal direction of the hull 3.
It is mounted by the following mounting structure (Japanese Unexamined Patent Application Publication No.
-74687 (see Fig. 3). That is, first, the mounting base 5 in which the rubber mount 7 is baked and fixed between the metal base plate 6 and the mounting plate 8 is mounted on the mounting base 4. On the other hand, the engine E is mounted on an upper surface of a mount plate 10 having both sides bent upward in accordance with the V-shaped ship bottom, and is fixed with bolts 9. The mount plate 10 to which the engine E is fixed is mounted on a plurality of mounts 5 in a bridging state, and is fixed by screwing a bolt 9 into a screw hole of the mount plate 8 from diagonally above. Usually, the mount plate 10 is stably mounted by fixing at least four places to the mounting base 5, and the vibration of the engine E is absorbed by the mount plate 10 and the rubber mount 7.

[0004]

The hull 3 of this type of personal watercraft is constructed by joining a deck 3b on a hull 3a, and the deck 3b has a seat 30 and a foot on which the occupant sits. As is clear from FIG. 8, since the space between the left and right footrests 31 is limited, a sufficient space cannot be secured inside the hull 3 and the engine E The installation space is naturally limited.
Therefore, the engine E needs to be downsized as much as possible, and its center of gravity needs to be lowered to be installed in the ship.

However, in order to obtain a high output,
In a conventional personal watercraft equipped with a cylinder engine, in order to suppress a large vibration of the engine E, the engine E
Is fixed to the mounting base 5 on the mounting seat 4 of the hull 3a after being mounted on the mounting plate 10 having a relatively large area, so that the overall shape is increased by the size of the mounting putt 10, and the mounting plate 10 and the hull 3a There is a space between the two, and the installation position of the engine E becomes higher by that amount, and accordingly, the center of gravity of the hull 3 becomes higher. Further, in order to suppress a large vibration of the engine E, it is necessary to make the hull 3a and the mout plate 10 large in thickness, which increases the weight. Further, since the number of components such as the mount plate 10 and the bolts 9 for fixing the engine E to the mount plate 10 is large, the number of work steps is increased. Further, since the mounting base 5 is provided in an inclined state facing the center of the hull corresponding to the side of the mount plate 10 facing obliquely upward, the bolts 9 for fixing the mount plate 10 to the mount 5 are provided.
Tightening work becomes oblique, and it becomes slightly troublesome.

Accordingly, an object of the present invention is to provide a personal watercraft that can be installed at a low position close to the bottom of a hull by a simple and compact mounting structure of an in-line three-cylinder engine. Things.

[0007]

In order to achieve the above object, a personal watercraft according to the present invention comprises an in-line three-cylinder engine main body and a rotationally connected crankshaft for suppressing the vibration of the engine main body. A propulsion engine driving engine having a balancer is provided, the axis of the crankshaft is set in the front-rear direction of the hull, and the front and rear ends of a crankcase supporting the crankshaft are fixed to the hull.

[0008] In the personal watercraft, the balancer rotatably connected to the crankshaft suppresses the vibration of the in-line three-cylinder engine body. In addition, since the front and rear ends of the crankcase are fixed to the hull, the support points of the engine body are largely separated, so that a large moment can be canceled by a small balancer, so that vibration can be effectively suppressed. . Accordingly, each support member of the engine can be reduced in size and weight, and the engine can be directly mounted on a hull mounting seat of a hull without a conventional mount plate. As a result, the in-line three-cylinder engine can be mounted at the low center of gravity position as close as possible to the hull, and since there is no member that protrudes from the engine body such as a conventional mount plate, it is arranged in a small installation space. it can.

In the embodiment of the present invention, in an in-line three-cylinder engine in which the balancers are arranged one by one in front and behind, the mass of the rotating part around the crankshaft is balanced in a symmetrical arrangement, and the mass of the reciprocating part such as a piston is increased. The vibrating force in the vertical direction becomes the largest vibration source, and the vibrating force of the cylinders located at the front and rear ends generates a moment that causes pitching vibration of the entire engine. On the other hand, the balancers that are arranged one after the other in the opposite phase generate moments of the same magnitude in opposite phases to the moments of the corresponding cylinders, so that pitching vibration can be canceled.

In the above embodiment, the front balancer is arranged further forward than the front end cylinder web, and the rear balancer is arranged further rearward than the rear end cylinder web. As a result, the distance between the two balancers is increased, so that even a balancer having a small mass can easily cancel the moment, and the mounting structure of the engine can be reduced accordingly.

In another embodiment of the present invention, the engine is fixed to the hull at three points. According to this configuration, since the vibration of the whole in-line three-cylinder engine can be largely suppressed, it is sufficient for the engine to fix the three points to the hull. The structure can be simplified and the size can be further reduced.

In the above embodiment, the propulsion unit is connected to the rear of the engine, and the engine is connected to a front end of the engine.
It is fixed to the hull at two points, the point and the rear end. When the engine is fixed to the hull at three points, the rear end of the engine must be firmly supported because a propulsion device is disposed and various torsional vibrations are likely to occur. Is preferred.

In still another embodiment of the present invention, the engine is fixed to the hull via a separate mounting member. This makes it possible to remove the mounting member and to pack the product in a small size during transportation, which facilitates handling.

In the above embodiment, the mounting member includes
A coupling cover that covers the periphery of the coupling that rotationally connects the propulsion device and the engine can be integrally formed. Thereby, the mounting member of the engine is integrated with the coupling cover, so that the number of parts and the number of assembling steps are reduced.

[0015]

[0016]

[0017]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view showing a personal watercraft according to an embodiment of the present invention, and FIG. 2 is a horizontal sectional view thereof. The hull 3 of this personal watercraft is a hull 3a
The seat 3 and the footrest 31 are provided on the deck 3b.
2 is provided.

This personal watercraft has an in-line three-cylinder two-cycle engine 17 mounted on the hull 3a in such a direction that the axis of the crankshaft 2 coincides with the longitudinal direction of the hull 3. I have. The means for attaching the engine 17 will be described later. A propulsion shaft 19 is connected to the crankshaft 2 of the engine 17 via a coupling 18, and is disposed at the rear end of the engine 17 and the hull 3 via the crankshaft 2, the coupling 18 and the propulsion shaft 19. A propulsion device (water jet pump) 20 is connected, and the propulsion device 20 is rotationally driven by the engine 17 and jets water from a nozzle 21 to obtain a propulsion force. The exhaust gas from the muffler 22 (FIG. 2) of the engine 17 is
The exhaust gas guided to the water muffler 24 arranged in the hull 3 and silenced is discharged from the exhaust outlet 28 to the rear of the hull 3 through the exhaust pipe 27. The coupling 18
As shown by a two-dot chain line in FIG. Further, a fuel tank 25 is disposed in a space in front of the engine 17 in the hull 3.

FIG. 3 is a rear view of the engine of the personal watercraft as viewed from the stern side, and FIG. 4 is a partial longitudinal sectional view of the engine 17 viewed from port. In these figures, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals. As shown in FIG. 4, the engine 17 includes an in-line three-cylinder engine body 40 and two balancers 3 that are rotationally connected to the crankshaft 2 and suppress vibration of the engine body 40.
8a and 38b, and the balancers 38a and 38b
Will be described later. As shown in FIG. 3, in the engine body 40, a cylinder 41 is vertically mounted on an upper portion of the crankcase 1, and the two balancers 38 a are provided on one side (in this example, port side) of the cylinder 41. , 38
and an exhaust manifold 37, an exhaust pipe 23 and a muffler 22 which constitute the exhaust device 13 and are located above the balancers 38a and 38b, and the intake device 12 is located on the other side (in this example, on the starboard side). Are arranged. An arrester case 35 and a carburetor 33 are arranged.

In FIG. 4, the crankshaft 2 connected via a web 39 to a piston (not shown) reciprocating in a cylinder 41 is rotatably supported inside the crankcase 1 via a bearing 26. The two balancers 38a, 38b have balancer rotating shafts 42a, 42b for supporting the respective balancers, and a balancer gear 43.
a and 43b are integrally formed.

The rear balancer 38a is arranged further rearward than the web 39 of the rear end cylinder, and covers the crankcase 1 and a cover 47 that covers the rear end face of the crankcase 1 via the rear balancer rotation shaft 42a. Are supported rotatably in parallel with the crankshaft 2 by a pair of bearings 44 held therein. The front balancer 38b is disposed further forward than the front end cylinder web 39, and is connected to the crankcase 1 and the generator cover 48 covering the front end face of the crankcase 1 via the front balancer rotation shaft 42b. The pair of bearings 49 are rotatably supported in parallel with the crankshaft 2.

The rear balancer 38a is provided with a balancer driving gear 50a attached to the rear end of the crankshaft 2.
Is meshed with a balancer gear (driven gear) 43a, so that it is rotationally connected to the crankshaft 2. The front balancer 38 b is provided with a bolt 51 at the front end of the crankshaft 2.
The balancer gear 43b is meshed with the balancer drive gear 50b integrally formed with the boss 52 fixed by the above, so that the balancer gear 43b is rotationally connected to the crankshaft 2. Therefore, both balancers 38a and 38b are rotated in the opposite directions to the crankshaft 2, respectively.

The engine 17 is mounted on the hull 3 in the following configuration. That is, as clearly shown in FIG. 2, the crankcase 1 has a pair of mounting flanges 5.
3 are integrally formed so as to protrude obliquely rearward from the left and right side surfaces of the rear part and are integrally formed, and a single mounting flange 54 is formed integrally with the front generator cover 48 so as to protrude horizontally from the center part to the front. ing. These three mounting flanges 53, 53, 54 are mounted on a mounting base 5 composed of a rubber mount fixed to the upper end receiving surface of the mounting seat 4 of the hull 3 a in FIG. It is fixed to the hull 3. Thus, the engine 17
It is fixed to the hull 3 at a total of three points, one at the front end and two at the rear end. FIG. 3 shows an attached state of the rear part of the engine, and the attached state of the front part has a similar form as shown in FIG.

Next, the vibration of the personal watercraft will be described. Now, in FIG. 3, the X axis is orthogonal to the crankshaft 2 in the horizontal direction through its axis, the Y axis is orthogonal to the crankshaft 2 in the vertical direction through the axis, and the axis of the crankshaft 2. The Z axis to be set, and the X axis,
Exciting moments around the Y-axis and the Z-axis are Mx, My, and Mz. Therefore, the excitation moment Mx causes the hull 3 to pitch and vibrate (pitch) around the X axis in a vertical plane, and the excitation moment My causes the hull 3 to yaw vibration (yaw) in the horizontal direction around the Y axis in a horizontal plane. Then, the vibration exciter Mz causes the hull 3 to roll (roll) around the Z axis.

FIG. 5 is a rear view showing the phases of the balancers 38a and 38b with respect to the counter-went 61 attached to the web 39 in the embodiment (FIG. 4). Is shown. In this embodiment, in order to balance the mass of the rotating portion such as the crank web 39, the mass of the counter weight 61 attached to the crank web 39 on the opposite side of the crank pin 36 is set excessively, and the overbalance ratio is reduced. 50% is set.

The overbalance ratio δ is represented by r as the crank arm length, rw as the radius of rotation of the counterweight 61,
The mass of the counterweight 61 is mw, and the mass of the rotating part is mo
The mass of the reciprocating portion of the piston, the connecting rod, the piston pin, etc. is represented by the following equation (1).

[0027]

(Equation 1)

The overbalancing method has been conventionally used as a means for reducing the vibration based on the inertial force of the reciprocating portion. In the equation (1), (rw / r) × mw = mo
, The overbalance ratio δ becomes 0%,
If (rw / r) .times.mw-mo = me, the overbalance ratio .delta. Becomes 100%. Therefore, if the counter weight 61 is set to the mass of (mo + me) w (rw / r) × 2, the overbalance ratio δ becomes 50%.

In the above embodiment, the balancer 38
The phases a and 38b of the counterweight 61 are set so that the excitation motion My becomes zero. That is, as shown in FIG. 5, when the direction of the crank pin 36 (arrow D) of the rear end cylinder becomes 30 ° with respect to the X axis, the weight direction (arrow C) of the balancer 38a changes to the X axis. The angle is set to 120 °. It should be noted that the lancers 38a and 38b are connected to the crankshaft 2 rotating in the direction of arrow A.
Is rotated in the direction of the arrow B opposite to the direction shown in FIG. This engine 17
An example of the result of calculating the excitation moments Mx, My, and Mz in is shown in (c) of Table 1 below.

[0030]

[Table 1]

(A) and (b) in Table 1 show excitation moments Mx and M in other engines shown for comparison.
7A is an example of a result of calculating y and Mz. FIG. 7A is a result of an engine in which the balancers 38a and 38b of the embodiment are not provided and the overbalance ratio is set to 0%, and FIG. This is the result of an engine that was not provided with an overbalance rate of 50%. Each of these engines (a) to (c) has a displacement of 900 cc, the number of revolutions is set to 6000 (rpm), and the vibrating force Fy due to the reciprocating mass is set to 15 (N). This shows a case where the motor is driven to rotate. Hereinafter, the vibration of the embodiment will be described based on Table 1.

In the case of Table 1 (a), in the in-line three-cylinder engine 17, the crankpins 36 of the respective cylinders are set so as to have a phase difference of 120 °, so that the entire rotating portion of the three cylinders is combined. The mass is balanced in a symmetrical arrangement, and the excitation moment Mz that causes rolling vibration is 100 (N
・ The value is as small as m) or less. In addition, the exciting moment My that causes the yawing vibration is also approximately zero. However, the vibrating moment Mx has a large value of 1557 (N · m) because the vibrating force in the vertical direction due to the reciprocating mass is greatly affected and the phases of the two cylinders at the front and rear ends are different by 240 °. , The moment causing the entire engine 17 to pitch and vibrate.

In the case of (b) in Table 1, since the overbalance ratio δ is set to 50%, the mode can be changed to a vibration mode that cancels the pitching vibration. Therefore, the excitation moment Mx is reduced to 1000 (N · m) or less. However, the pitching vibration is reduced by the yawing vibration and the excitation moment My is reduced to 70 (N · m).
7 (N · m). That is, the unbalance force generated around the crankshaft of each cylinder is in a state of rotating in a direction opposite to the rotation direction of the engine 17 with a constant magnitude. The mass of the counterweight 61 rotates in the direction opposite to that of the crankshaft 2 to form a vibration system that swings back and forth, and the component force of the front and rear end cylinders remains.

Therefore, as shown in FIG. 5, the balancers 38a and 38b always generate the same magnitude of moment in the opposite phase to the counterweight 61 in which the overbalance ratio δ is set to 50%. When the balancers 38a and 38b are rotated in the direction B opposite to that of the crankshaft 2, the vibrating moment My is negated and becomes zero, and the vibrating moment Mx for generating longitudinal vibration becomes (a ) Is reduced to about 1/3. on the other hand,
Although the exciting moment Mz for generating the rolling vibration slightly increases, it is almost の of the exciting moment Mx at this time.
It can be suppressed to the extent.

Moreover, the front balancer 38b is located further forward than the crank web 39 of the front cylinder, and the rear balancer 38a is located further rearward than the crank web 39 of the rear cylinder. The distance between the two balancers 38a, 38b is increased, and a large moment can be easily canceled by the small balancers 38a, 38b, and the size can be reduced. In addition, the engine 17 has a mounting flange 54 that projects in the front-rear direction from the crankcase 1 in which the axis of the crankshaft 2 is arranged in the front-rear direction of the hull 3.
53 supports the hull 3. Thereby, the support points before and after the engine 17 are relatively largely separated from each other, so that a large moment can be canceled by the balancers 38a and 38b having a small mass. As a result, vibration can be effectively suppressed.

As described above, the in-line three-cylinder engine 17 of the embodiment can suppress the whole vibration, so that it is not necessary to use the conventional mount plate 10 for mounting. It can be supported without trouble at three points. In particular, since the excitation moment My of the yawing vibration due to the reciprocating portion mass can be suppressed, the remaining excitation moments Mx and Mz and the weight of the engine 17 may be simply received by the mounting base 5, and these are applied as vertical loads to the mounting base 5. Therefore, the engine 17 can be directly fixed to the hull 3 by the mounting flanges 53 and 54 formed integrally with the crankcase 1 and the generator cover 48.

Therefore, since a large and heavy conventional mount plate is not required, the mounting seat 4 and the mounting base 5 for supporting the engine 17 can be reduced in size, and the hull 3a can be reduced by the reduced vibration. It can be thinned. Further, as shown in FIG.
a with a low center of gravity as close as possible to the engine 17 as well as a conventional mount plate.
Since there is no member that protrudes greatly from the side, it can be arranged in a small installation space. In addition, since the mounting flanges 53 and 54 can be formed so as to protrude from the crankcase 1 and the generator cover 48 in the horizontal direction, the bolts 57 can be set up and down without any inclination. It can be done easily with a tool on it, and workability is improved.

In the above embodiment, as shown in FIG. 3, the balancers 38a, 38
By arranging b, the space on one side of the engine 17 can be effectively used and can be stored compactly. Therefore, the vibrations are suppressed by the balancers 38a and 38b, so that the conventional mount plate for mounting the engine becomes unnecessary, and the whole engine device including the engine and its mounting structure can be further reduced in size. Also, the balancer 38a,
Since 38b is located below, the center of gravity of the engine E,
Therefore, the center of gravity of the personal watercraft can be lowered.

FIG. 6 is a partial longitudinal sectional view of an engine 17 in a personal watercraft according to another embodiment of the present invention, and FIG. 7 is a view taken in the direction of arrow C, which shows a part of FIG. This embodiment is different from the above embodiment only in the configuration of a portion for fixing the engine 17 to the hull 3 at two points at the rear end. That is, the crankcase 1 in the above embodiment
Instead of the mounting flange 53 integrally formed with the mounting member 59, a mounting member 59 fixed to the rear end of the crankcase 1 with a bolt 58 and closing the rear end opening of the crankcase 1 is directed obliquely rearward from the left and right side surfaces of the rear. A pair of mounting flanges 60 each protruding in the horizontal direction are integrally formed,
The engine 17 is mounted on the hull 3 by fixing the mounting flange 60 to the mounting base 5 mounted on the mounting seat 4 with bolts 57.

The coupling member 29 is formed integrally with the mounting member 59. In the existing personal watercraft, the coupling 18 for rotatably connecting the crankshaft 2 and the propulsion shaft 19 is covered with a separate coupling cover. In this embodiment, however, a mounting member 59 having a mounting flange 60 is provided. The coupling cover 29 is formed as a single unit, and thus has the advantage of reducing the number of parts and the number of assembly steps. Moreover, during transportation or the like, the mounting member 59 can be removed to reduce the size of the entire crankcase 1 and the size of the crankcase 1 can be reduced, thereby facilitating handling.

[0041]

As described above , according to the present invention, the vibration of the in-line three-cylinder engine body is suppressed by the balancer rotatably connected to the crankshaft, and the crankcase arranged in the longitudinal direction of the hull is provided. Since the front and rear ends are fixed to the hull and the support points of the engine main body are separated from each other to cancel large moments with a small balancer, vibration of the in-line three-cylinder engine main body can be greatly suppressed. As a result, the engine can be directly mounted on the hull without the interposition of the conventional mount plate, the engine support members can be reduced in size and weight, and the engine body is brought as close as possible to the bottom of the hull. It can be installed with a low center of gravity and can be placed in a small installation space without hindrance.

[0042]

[Brief description of the drawings]

FIG. 1 is a side view showing a personal watercraft according to an embodiment of the present invention.

FIG. 2 is a horizontal sectional view of the personal watercraft.

FIG. 3 is a rear view of the state of the engine of the small planing boat as viewed from the stern side.

FIG. 4 is a partial vertical sectional view of the engine of the personal watercraft as viewed from the left side (port side).

FIG. 5 is a rear view showing the phase of the balancer with respect to the crankshaft in the personal watercraft.

FIG. 6 is a partial longitudinal sectional view of an engine in a personal watercraft according to another embodiment of the present invention.

7 is a view as viewed in the direction of the arrow C in FIG. 6;

FIG. 8 is a rear view of an engine installed state of a conventional personal watercraft equipped with a three-cylinder two-cycle engine as viewed from the stern side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Crank case, 2 ... Crank shaft, 3 ... Hull, 12
... intake device, 13 ... exhaust device, 17 ... engine, 18 ...
Coupling, 20: propulsion device, 29: coupling cover, 38a, 38b: balancer, 39: crank web, 40: engine body, 59: mounting member.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B63H 21/30 B63B 35/73 F16F 15/26

Claims (7)

(57) [Claims] An in-line three-cylinder engine main body and a balancer rotatably connected to a crankshaft thereof and a balancer for suppressing vibration of the engine main body are provided for an engine for driving a propulsion device, and the axis of the crankshaft is a hull. A small personal watercraft in which the front and rear ends of a crankcase that supports the crankshaft are fixed to a hull. 2. The personal watercraft according to claim 1, wherein the balancers are arranged one by one in front and behind. 3. The personal watercraft according to claim 2, wherein the front balancer is further disposed forward of the front end cylinder web, and the rear balancer is disposed further rearward of the rear end cylinder web. . 4. The personal watercraft according to claim 1, wherein the engine is fixed to the hull at three points. 5. The personal watercraft according to claim 4, wherein the propulsion device is connected to the rear of the engine, and the engine is fixed to the hull at one point at a front end and at two points at a rear end. 6. The personal watercraft according to claim 1, wherein the engine is fixed to a hull via a mounting member separate from the engine. 7. The personal watercraft according to claim 6, wherein a coupling cover that covers a periphery of a coupling that rotationally connects the propulsion device and the engine is formed integrally with the attachment member.