JP2003056356A - Small-sized planing boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized planing boat mounted with an easy to overhaul overhead camshaft type four-cycle engine without limiting a crankshaft diameter. SOLUTION: The small-sized planing boat is composed so that water pressurized and accelerated by a water-jet-pump driven by the overhead camshaft type four cycle engine with a crankshaft arranged along the longitudinal direction of the boat is jetted from a nozzle opened in the rear, and it is propelled by reaction of the water. The engine E is provided with an intermediate shaft 3 between the crankshaft 1 and a camshaft 2 positioned in a cylinder head 6, and it is composed so that the camshaft 2 is driven by transmitting power from the crankshaft 1 to the intermediate shaft 3 via a first power transmission mechanism 13 (13A and 13B) and transmitting power from the intermediate shaft 3 to the camshaft 2 via second power transmission mechanisms Sk2, Sk3 and 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small jet propulsion type planing boat (Personal Watercraft; also called PWC) which jets a water stream backward and travels on the water by its reaction. Regarding the engine of a planing boat.

[0002]

2. Description of the Related Art So-called jet propulsion type small planing boats have been widely used in recent years for leisure, sports or rescue. In this jet-propelled small-sized planing boat, generally, water sucked from a water inlet provided on the bottom surface of the boat is pressurized and accelerated by a water jet pump and jetted backward to propel the hull.

In the case of this jet propulsion type planing boat, the steering direction of the water jet pump is changed to the left or right by swinging the steering nozzle arranged behind the jet nozzle to the left or right. And steer the boat to the right or left.

By the way, a four-cycle engine has begun to be mounted also on this jet propulsion type small planing boat.
In such a compact and high-performance 4-cycle engine, an overhead cam type engine is generally adopted. In the case of this overhead cam type four-cycle engine for small-sized planing boats, a camshaft for driving the camshaft from the crankshaft located in the lower part of the engine to the camshaft arranged in the cylinder head is connected via a chain. Power is transmitted. In the case of a 4-cycle engine, one cycle is completed by rotating the crankshaft twice, so that the camshaft rotates once while the crankshaft rotates two times.

Therefore, a small diameter sprocket is attached to the crankshaft, and a sprocket having a diameter approximately twice that of the sprocket attached to the crankshaft is attached to the camshaft.

Further, in the case of a small planing boat, it is required to make the entire engine as small as possible, and therefore it is necessary to make the sprocket diameters of both the crankshaft and the camshaft as small as possible. .

Therefore, the diameter of the sprocket attached to the crankshaft side limits the crankshaft diameter, that is, the crankshaft diameter cannot be increased, and in some cases, the crankshaft has high strength and is expensive. You will have to use the material.

Further, as described above, since the power is transmitted from the crankshaft to the camshaft through the chain, the piston or the piston ring must be replaced with the above-mentioned one without fail. It is necessary to remove the cylinder head cover, remove the chain wound between the crankshaft and the camshaft, and remove the cylinder head from the cylinder block. In this case, it is a troublesome work that requires a lot of time. In particular, at the time of reassembling, the crankshaft and the camshaft must be accurately aligned with each other in the rotation angle position, and the chain must be passed through a cam chain tunnel that is difficult to handle, and both ends of the chain must be connected to form an endless shape. It is a difficult task because it does not happen.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a small planing boat equipped with an overhead cam type 4-cycle engine in which the crankshaft diameter is not restricted. The second purpose is to provide an overhead cam type 4 that easily overhauls the engine.
It is to provide a small planing boat equipped with a cycle engine.

[0010]

The present invention aims to achieve the above object by
This is solved by a jet propulsion type small planing boat having the following configuration. That is, a small planing boat according to the present invention comprises an overhead cam type four-cycle engine and a water jet pump driven by this engine, and the crankshaft of the engine is arranged along the longitudinal direction of the boat, and The pump shaft of the water jet pump is configured to be driven via a crankshaft, and water pressurized and accelerated by the water jet pump is jetted from a jet opening opened rearward, and by reaction of the jet. In a small planing boat configured to propel, the engine, between a crankshaft and a camshaft located at the cylinder head,
An intermediate shaft is provided, and power is transmitted from the crankshaft to the intermediate shaft via a first power transmission mechanism, and power is transmitted from the intermediate shaft to the camshaft via a second power transmission mechanism. The camshaft is driven by being driven.

In the small planing boat thus constructed, however, the power is transmitted from the crankshaft to the camshaft via the intermediate shaft, so that the desired rotation ratio can be obtained even if the crankshaft diameter is arbitrary. (2: 1 rotation ratio),
Power can be transmitted from the crankshaft to the camshaft. Therefore, the shaft diameter of the crankshaft can be set to a desired shaft diameter, and it becomes unnecessary to use an expensive material having high strength.

In the small planing boat, the first
The power transmission mechanism may be composed of a drive gear that is attached to the crankshaft so as to rotate integrally therewith, and a driven gear that is attached to the intermediate shaft so as to rotate integrally and meshes with the drive gear. In this case, since power is transmitted by the joint between the pair of gears and can be separated as it is, the crankcase can be easily separated from the cylinder side when replacing the piston (or piston ring), and can be easily reassembled. It becomes a structure that can be assembled.

In the small planing boat, the first
The power transmission mechanism is attached to the crankshaft so as to rotate integrally with the crankshaft, the driven sprocket attached to the intermediate shaft so as to rotate integrally, and the drive sprocket and the driven sprocket. It may be constituted by a drive chain wound between them.

In the small planing boat, the intermediate shaft may be rotatably supported on the cylinder block side. In such a structure, if the first power transmission mechanism is composed of a gear pair, When replacing the piston of the engine or disassembling the crankcase portion, the cylinder block and the cylinder head side can be disassembled from the crankcase side as an integrated assembly.
Therefore, the structure is easy to disassemble and reassemble.

Further, in the small planing boat, the intermediate shaft may be rotatably supported on the crankcase side.

In the small planing boat, when an oil pump for lubricating the engine oil is arranged on the intermediate shaft, power transmission for transmitting power from the crankshaft to the shaft of the oil pump. The mechanism and its related parts can be omitted, resulting in a rational structure. In addition, in such a structure, if the intermediate shaft is obstructed on the crankcase side, the oil pump can be arranged under the engine, The suction pressure of the pump is reduced, and the oil can be efficiently supplied to the engine.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a jet propulsion type small planing boat according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a rear view showing the structure of an engine of a small planing boat according to an embodiment of the present invention, and FIG. 2 is a side sectional view of the engine shown in FIG. 1 taken along a crankshaft.
4 is an overall side view of the jet propulsion type small planing boat according to the embodiment of the present invention, and FIG. 5 is an overall plan view of the small planing boat shown in FIG.

4 and 5, A is a hull, and this hull A is composed of a hull H and a deck D covering the hull H, and the connecting line connecting the hull H and the deck D over the entire circumference is a gunnel line. In this embodiment, this gunnel line G is located above the waterline L of the small planing boat.

As shown in FIG. 5, a portion of the deck D slightly rearward from the center is formed with a substantially rectangular opening 16 in a plan view extending in the longitudinal direction on the upper surface of the hull A. As shown in FIG. 5, a riding seat S is disposed above the opening 16.

The engine E is disposed in a space 20 having a "convex" cross section surrounded by the hull H and the deck D below the seat S. The engine E is a multi-cylinder (four cylinders in this embodiment) fuel injection type four-cycle engine E, and as shown in FIG.
Is mounted so as to extend along the longitudinal direction of the hull A, and the output end of the crankshaft 26 is, via the propeller shaft 27, the pump shaft 21S side of the water jet pump P to which the impeller 21 is attached. , And is rotatably connected integrally. And this impeller 21
Has its outer periphery covered with a pump casing 21C,
A pump that takes in water taken in through a water intake 17 provided on the bottom surface of a small planing boat through a water intake passage, pressurizes and accelerates it with a water jet pump P, and the water passage cross-sectional area becomes smaller as it goes backward. It is configured so as to pass through the nozzle (spout portion) 21R and be discharged from the jet port 21K at the rear end to obtain a propulsive force.

Further, in FIG. 4, 21V is a stationary blade for rectifying the water passing through the water jet pump P. Further, in FIGS. 4 and 5, reference numeral 24 denotes a steering wheel which is steering operation means.
The steering nozzle 18 at the rear of the pump nozzle 21R is swung to the left and right via the cable 25 by operating the water jet pump P.
When the boat is in operation, the boat can be steered in a desired direction. A throttle lever Lt for controlling the rotation speed of the engine E is arranged near the grip on the right side of the handle 24.

Further, as shown in FIG. 4, a bowl-shaped reverse deflector 19 is provided above and behind the steering nozzle 18 so as to be pivotable downward about a horizontally disposed pivot shaft 19a. By oscillating the deflector 19 to the lower position behind the steering nozzle 18, the water discharged rearward from the steering nozzle 18 is turned forward and can be moved backward.

4 and 5, reference numeral 22 denotes a rear deck, which is provided with an opening / closing hatch cover 29, and a storage box (not shown) having a small capacity is provided below the hatch cover 29. ) Has been formed. Further, in FIG. 4 or 5, 23 is a front hatch cover,
Below the hatch cover 23, a box (not shown) for storing equipment and the like is provided.

By the way, the engine E is shown in FIGS.
Power is transmitted from the crankshaft 1 provided at the lower end of the engine E to the camshaft 2 located at the upper end of the engine E via an intermediate shaft 3 provided therebetween, as shown in FIG. Is configured. That is, the crankshaft 1 is rotatably supported by the crankcase 4 at the lower end of the engine E via the bearing 4A. The intermediate shaft 3 is rotatably supported by a cylinder block 5 located above the crankshaft 1 via a bearing 5A. Further, the cylinder head 6 at the upper end of the engine E has the camshaft 2
(2A, 2B) are rotatably supported via a bearing 6A.

The crankshaft 1 and the intermediate shaft 3 have a gear 13 made of the same product, which meshes with each other.
Power is transmitted from the crankshaft 1 to the intermediate shaft 3 by attaching (13A, 13B) in pairs. In the case of this embodiment, power is transmitted from the crankshaft 1 to the intermediate shaft 3 at a rotation ratio of 1: 1. The intermediate shaft 3 has a sprocket S.
k3, the sprocket Sk2 is attached to the camshaft 2 (2A, 2B), and the chain 7 is wound between the sprocket Sk2 and Sk3. (2
The power is transmitted to A, 2B). The diameter (number of teeth) of the sprocket Sk3 of the intermediate shaft 3
Is 1/2 of the diameter (the number of teeth) of the sprocket Sk2 of the camshaft 2 (2A, 2B). Therefore, the rotation speed of the camshaft 2 (2A, 2B) is equal to the rotation speed of the intermediate shaft 3. Power is transmitted in a state of being decelerated so as to be halved. In the case of the engine E according to this embodiment, as shown in FIG. 1, since it is a so-called DOHC (double overhead cam) type engine, a total of two cams of the exhaust system and the intake system are provided. A pair of shafts 2A and 2B are arranged on the engine E so as to be parallel to the crankshaft 1 on the left and right. In the embodiment shown in FIGS. 1 and 2, the crankshaft 1 is further provided with a sprocket Sk1. A rotary shaft 8 of the oil pump Po is arranged in the crankcase 4 so as to be parallel to the crankshaft 1, and a sprocket Sk8 is arranged on the rotary shaft 8. Further, a chain 9 is arranged between the sprocket Sk1 and the sprocket Sk8, and the rotation shaft 8
Are configured to be driven by the crankshaft 1. This oil pump Po is a scavenge pump portion Po1 shown in FIG.
And a feed pump portion Po2 for sucking oil from the oil tank side to supply oil to a required portion of the engine E,
It has a structure in which a pair of front and rear sides are formed with a partition wall.

In FIG. 1, Ts is a tensioner for maintaining the chain 7 at a constant tension, Im is an intake pipe for supplying air to the intake port of the engine E, and Sb is a throttle for adjusting the intake amount. It is a body.
Further, in FIG. 2, 11 is a spark plug, 13 is a generator, 14 is a connecting rod, and 15 is a propeller shaft 2.
It is one member of the coupling for connecting to the 7 side. 1 and 2, reference numeral 12 is a cylinder head cover.

However, the small planing boat equipped with the present engine having the above-described structure has the following effects. That is, if the piston Ep of the engine E is to be replaced, the bolts 10 connecting the cylinder block 5 and the crankcase 4 below the cylinder block 5 may be removed, and the gear 13B of the intermediate shaft 3 and the crankshaft 1 may be removed. Since the gear 13A is simply meshed with the gear 13A, the cylinder block 5 can be easily removed from the crankcase 4. At this time, the four pistons Ep remain attached to the crankcase 4 side together with the connecting rod 14 and the crankshaft 1. Then, after replacing the necessary piston Ep, the cylinder block 5 is attached to the crankcase 4 side while inserting the respective pistons Ep into the respective cylinder liners Cy of the engine E, and in a state where they are substantially in close contact with each other. By tightening the bolts 10 respectively, it becomes possible to easily reassemble them.

In the case of this engine E, the intermediate shaft 3
Since the rotation ratio is reduced to 1/2 and transmitted from the camshaft 2 to the camshaft 2, a gear having a large diameter can be adopted as the gear 13A attached to the crankshaft 1 if necessary. Therefore, the diameter of the crankshaft 1 itself is
The required shaft diameter (large diameter) can be adjusted according to the rotational torque to be transmitted, etc., increasing the degree of freedom in design and
It is not necessary to use an expensive material having high strength for the crankshaft 1.

By the way, in the above embodiment, the oil pump Po is arranged on the side of the crankshaft 1. However, as shown in FIG. 3, the oil pump Po may be provided at the end of the intermediate shaft 3, In such a case, the oil pump Po
Can be attached to the engine E in a compact manner, and the intermediate shaft 3 can be shared as the rotary shaft of the oil pump Po and the transmission mechanism and the like, which is a preferable embodiment in that the number of parts can be reduced as a whole. Become. Note that FIG.
In FIG. 2, the same or corresponding structures as those in FIGS. 1 and 2 are designated by the same reference numerals.

Further, in place of the transmission of power by the gears 13A and 13B in the embodiments shown in FIGS. 1, 2 and 3, sprockets are respectively arranged on the crankshaft and the intermediate shaft (not shown), The structure may be such that power is transmitted by a chain between the sprockets.

Alternatively, when it is sufficient to make only the shaft diameter of the crankshaft a desired shaft diameter, the intermediate shaft may be rotatably supported on the crankcase side.

[0033]

According to the small planing boat of the present invention, the crankshaft diameter of the engine can be freely determined according to the rotational torque to be transmitted. Therefore, it is not necessary to use a strong and expensive material for the crankshaft. Also, when replacing the piston or the piston ring, it is possible to easily remove only the crankcase side from the cylinder block. Therefore, it is possible to realize a small planing boat equipped with an engine excellent in maintainability.

[Brief description of drawings]

FIG. 1 is a rear view showing a configuration of an engine of a small planing boat according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the engine shown in FIG. 1 taken along a crankshaft.

[FIG. 3] The intermediate shaft is shared with the rotary shaft of the oil pump,
FIG. 3 is a partial enlarged cross-sectional view showing a configuration of an intermediate shaft portion of an engine according to another embodiment different from FIGS. 1 and 2.

FIG. 4 is an overall side view of a jet propulsion type small planing boat according to an embodiment of the present invention.

5 is an overall plan view of the small planing boat shown in FIG.

[Explanation of symbols]

E ... Engine 1 ... crankshaft 2 ... Camshaft 3 ... Intermediate axis 7 ... Chain 13 ... Gear Sk2, Sk3 ... Sprocket

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Claims (6)

[Claims] 1. An overhead cam type four-cycle engine and a water jet pump driven by the engine, wherein a crankshaft of the engine is arranged along a longitudinal direction of the boat, and a crankshaft of the engine is disposed through the crankshaft. The pump shaft of the water jet pump is configured to be driven, and the water pressurized and accelerated by the water jet pump is configured to be jetted from a jet port opened rearward and propelled by its reaction. In the small planing boat, the engine includes an intermediate shaft between a crankshaft and a camshaft located at a cylinder head, and power is transmitted from the crankshaft to the intermediate shaft via a first power transmission mechanism. The camshaft is transmitted from the intermediate shaft via a second power transmission mechanism. By power is transmitted, personal watercraft, characterized in that said cam shaft is configured to be driven. 2. A drive gear, wherein the first power transmission mechanism is attached so as to rotate integrally with a crankshaft, and a driven gear which is attached so as to rotate integrally with an intermediate shaft and meshes with the drive gear. 2. The small planing boat according to claim 1, wherein the small planing boat comprises: 3. The first power transmission mechanism includes a drive sprocket attached to a crankshaft so as to rotate integrally with the crankshaft, and a driven sprocket attached to an intermediate shaft so as to rotate integrally with the crankshaft, The small planing boat according to claim 1, wherein the small planing boat comprises a drive sprocket and a drive chain wound between the driven sprockets. 4. The intermediate shaft is rotatably supported on the cylinder block side.
The small planing boat according to any one of 1 above. 5. The small planing boat according to claim 1, wherein the intermediate shaft is rotatably supported on the crankcase side. 6. The small planing boat according to claim 1, wherein an oil pump for lubricating engine oil is arranged on the intermediate shaft.