JPH09315383A - Propulsion engine for small type planing boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a propulsion engine for a small type planing boat which has a simple lubricating structure, and reduces the mechanical loss of a valve system due to the stirring of oil, and effectively lubricates the whole of an engine including reduction gears with an engine oil. SOLUTION: An oil return passage 23 which communicates from a cam shaft chamber 9 above an engine 6 extending over a crankcase 6c and an oilpan 6d is provided on the stern side, and at the same time as the above passage, gears 22, 18, 20 are accommodated at the middle spot in the oil return passage 23. The sprocket 24 of a cam chain 25 is unitedly rotatably attached at an end on the bow side of a crank shaft 6j, and a cam chain tunnel 26 to communicate with the cam shaft chamber 9 is formed above the sprocket 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OHC four-cycle (stroke) engine for driving propulsion means of a small planing boat equipped with propulsion means such as a water jet pump and a screw on the stern side. The present invention relates to an engine speed reducer and its lubrication structure (whether a wet sump system or a dry sump system is used).

[0002]

2. Description of the Related Art A small-sized planing boat gliding on water is generally equipped with a two-cycle propulsion engine which has the advantages of small size and light weight. A 4-cycle engine with a relatively low level and good exhaust gas conditions has begun to be mounted on small planing boats.

This example is described in, for example, Japanese Unexamined Patent Publication No. 7-237587.
No. 6,086,045. The four-cycle engine described in the publication is equipped with a reduction gear consisting of a ring gear connected to a coupling with an impeller shaft of a water jet pump at the stern and a gear inscribed therein, and an output coaxial with the crankshaft. The internal gear is attached to the shaft. Further, the engine is an OHC engine having a camshaft on its top, the camshaft is rotated by a cam chain, and the cam chain is connected to the crankshaft end immediately in front of the internal gear via a sprocket. . Furthermore, the dry sump system is adopted as the lubrication system for the entire engine including the reduction gear.The oil tank for engine lubrication is located above the coupling, and the oil pan is installed in the lower part of the engine via an oil pump. It is in communication.

[0004]

However, in the engine lubrication system described in the above publication, an oil tank separate from the crankcase is provided, which may cause an increase in weight by itself, and two types of pumps. (Scavenging pump that sends lubricating oil from the crankcase to the tank,
An external pipe is required to connect the oil feed tank that feeds oil from the tank to the engine) and the oil tank, which complicates the pipe, increases the pipe resistance, increases mechanical loss, and lowers the hydraulic pressure rise response. Further, it requires a tank mounting space and mounting parts, which causes an increase in manufacturing cost and an increase in weight.

Since the oil return passage is only in the cam chain tunnel at one end (stern side) of the engine, the oil sent to the top of the engine (camshaft chamber) is difficult to return to the crankcase and the oil pan, and after the camshaft is lubricated. The oil stays in the top of the engine, the mechanical loss of the valve train due to the oil agitation increases, and the lubrication efficiency decreases, but such inconvenience becomes more remarkable as the number of cylinders of the engine increases. Further, since the reduction gear is displaced from the position of the cam chain tunnel, the reduction gear may not be sufficiently lubricated.

In order to double the deceleration rate of the camshaft, it is necessary to reduce the number of teeth on the crankshaft side sprocket to half that of the camshaft side sprocket. For this purpose, the number of teeth is small. For example, in order to facilitate mounting of a sprocket having a small outer diameter, the outer diameter of the crankshaft must be reduced, which may deteriorate the durability of the crankshaft.

The present invention has been made in view of the above problems, and mechanical loss of a valve train due to oil agitation is reduced, and the entire engine including a speed reducer can be efficiently lubricated with engine oil. The object is to provide an engine for propulsion of a small planing boat, which is simple.

[0008]

In order to achieve the above object, a propulsion engine for a small planing boat of the present invention is a propulsion engine for a small planing boat equipped with propulsion means such as a water jet pump and a screw on the stern side. In the OHC four-cycle engine for driving the means, the engine is placed vertically, the speed reducer is arranged on the propulsion means side (stern side), and the cam drive mechanism such as a cam chain is arranged on the opposite side (stern side). ing. In addition to the cam chain, the cam drive mechanism includes a pulley, a belt, and a combination of a plurality of gears meshed in series.

According to the propulsion engine for a small-sized planing boat of the present invention having the above-mentioned structure, the speed reducer is arranged between the output shaft for driving the propulsion means and the crankshaft on the stern side of the engine, and the cam is provided on the bow side. Since a cam drive mechanism such as a chain is arranged, for example, in the case of a cam chain, even if the outer diameter of the crankshaft end is reduced to install the sprocket, the crankshaft on the side where the reduction gear is installed (output shaft side) The outer diameter of the end does not have to be small. Therefore, durability is improved over the entire length of the crankshaft.

According to a second aspect of the present invention, an oil return passage is provided on the opposite side (stern side) of the cam drive mechanism tunnel of the engine from the camshaft chamber at the top of the engine to the crankcase or the oil pan. desirable.

In the propulsion engine for a small planing boat according to a second aspect of the present invention, oil return passages (one is a cam drive mechanism tunnel such as a cam chain tunnel) are formed at both front and rear ends of the engine. Oil is not accumulated and mechanical loss due to oil agitation is reduced, and oil is smoothly returned to the crankcase and oil pan, and oil is sufficiently supplied to the friction sliding parts in the engine, and lubrication over the entire engine is performed. The action is done efficiently.

It is more preferable that the reduction gear of the reduction gear is arranged in the middle of the oil return passage.

In the propulsion engine for a small planing boat according to a third aspect of the invention, the oil that drops from the engine top through the oil return passage comes into contact with the reduction gear and is sufficiently lubricated.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a propulsion engine for a small planing boat according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a small planing boat and a 4-cycle engine mounted thereon, FIG. 2 is a schematic plan view showing an engine and an exhaust system of the small planing boat shown in FIG. 1, and FIG. 3 is a hull and an engine. FIG. 4 is a vertical cross-sectional view showing a principal part in a cross section with a part cut away, as viewed from the rear, and FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3 showing a four-cycle engine.

The small planing boat 1 is a water vehicle. As shown in FIG. 1, a deck 3, a seat 4, a handle 5 and the like are mounted on a bottom hull 2 so that one to three persons can board the boat. . As a propulsion means, a water jet pump 7 is provided in the lower rear part of the hull, and the water jet which is pressurized and jetted by the water jet pump 7 obtains a propulsive force to slide on the water surface. A pump 7 for forming a water jet is driven by an engine 6, which is a space inside the hull surrounded by a hull 2 of the bottom, a deck 3 and a seat 4 at approximately the center in the longitudinal direction of the hull ( It is installed in the engine room) 8. The output of the engine 6 is transmitted to the impeller shaft 9 via an elastic joint, and the impeller shaft 9 rotates the pump 7 (the impeller thereof).

Further, as shown in FIG. 2, an exhaust pipe (exhaust manifold) 15, a silencer (silencer) 15b, a water muffler 15c, etc. are connected to the exhaust port of the engine 6. The rear end of the exhaust pipe 15 is inserted into the center of the silencer 15b. The silencer 15b is shown in FIG.
As described above, it is connected to the front end of the water muffler 15d which is fixedly provided adjacent to the left side thereof by the connection pipe 15c whose one end is connected to the lower portion of the front end thereof. Silencer 15b
The cooling water of the engine 6 flows into the inside, and the exhaust gas flows from the exhaust pipe 15 into the inside. The cooling water and the exhaust gas flowing into the silencer 15b are sent from the connection pipe 15c to the water muffler 15d. Although illustration is omitted, the inside of the water muffler 15d is partitioned into a plurality of chambers, and the cooling water is discharged together with the exhaust gas by the exhaust outlet pipe 15e inserted in the rear end portion.

As the engine 6, as shown in FIG.
It is equipped with a cycle / in-line 4-cylinder engine. This engine 6 has a support pipe (not shown) provided on the bottom hull 2 via a damper 11 as shown in FIG. Then, the engine 6 is attached to the support pipe (a plurality of pipes are arranged in the longitudinal direction) with a slight inclination to the right. Further, as shown in FIG. 4, a cylinder head 6a is provided above the engine 6, and a cylinder 6b, a crankcase 6c and an oil pan 6d are provided below the cylinder head 6a. The cylinder head 6a includes an intake port 6e and an exhaust port 6
2 and the valves for opening and closing the respective ports 6e and 6f, in the DOHC engine as shown in FIG. 3, two camshafts 10 are installed in parallel in the camshaft chamber 9 immediately above the cylinder head 6a. There is. Intake port 6e
Intake silencer 13 and carburetor 14 upstream of the
The exhaust device is connected to an intake device, four exhaust pipes 15 are connected to the downstream side of the exhaust port 6f, the exhaust pipes 15 are integrally formed, and a water jacket 16 is provided around the exhaust pipe 15 as a whole. It is installed so as to cover.

Inside each cylinder 6b, a piston 6k connected to a crankshaft 6j is arranged so as to be vertically slidable, and the crankshaft 6j is supported by a crankcase 6c via a bearing. Has been. An oil pan 6d, which collects oil, is attached to the lowest part of the crankcase 6c, and the oil pan 6d is installed in the oil pan 6d.
An oil pump 17 is arranged as shown in FIG. From the discharge portion of the oil pump 17, the upper end of the oil supply hose 17a is connected to the upper camshaft chamber 9 as shown in FIG.
The oil in the oil pan 6d is pumped to the camshaft chamber 9.

As shown in FIG. 4, a reduction gear 18 is integrally rotatably attached to an end of the crankshaft 6j on the stern side, and an output shaft 19 is rotatably supported immediately above the output shaft 19 by a bearing 19a. A large-diameter reduction gear 20 attached to 19 so as to be integrally rotatable is meshed with the reduction gear 18. A coupling 21 for connecting with the impeller shaft 9 (FIG. 1) is attached to one end of the output shaft 19 so as to be integrally rotatable. The oil pump 17 is provided on the side of the reduction gear 18.
The drive gear 22 is disposed and meshes with the reduction gear 18. As shown in FIGS. 3 and 4, an oil return passage 23 that communicates from the upper camshaft chamber 9 to the crankcase 6c and the oil pan 6d is provided, and at the same time, the gears 22, 18, and 20 arranged in series from the bottom are used to return the oil. Passage 2
It fits in the middle of 3.

On the other hand, a generator 28 is attached to the end of the crankshaft 6j on the bow side, and the sprocket 24 of the cam chain 25 is attached to the end of the crankshaft 6j adjacent to the generator 28 so as to be integrally rotatable. A cam chain tunnel 26 communicating with the cam shaft chamber 9 is formed above the sprocket 24, and the two cam shafts 1
No. 0 (FIG. 3), a large diameter sprocket 27 having a large number of teeth is integrally rotatably attached to the upper two sprocket 27 and a lower small sprocket 27 having a small diameter (small number of teeth) sprocket 24 in series. I am crossing over 25.

Next, the operation and circulation action of the propulsion engine 6 of the small planing boat 1 according to the present embodiment constructed as described above will be described.

Regarding the reduction gear device: When the engine 6 is in operation, the rotation of the crankshaft 6j is reduced in speed and transmitted to the output shaft 19 via the reduction gear 18 and the large diameter reduction gear 20, and is further transmitted via the coupling 21 to the impeller shaft. 9 (FIG. 1), the pump 7 (FIG. 1) is rotated to propel the small planing boat 1 (FIG. 1). The rotation of the crankshaft 6j is transmitted to the oil pump 17 via the reduction gear 18 and the drive gear 22 to drive the oil pump 17. Further, the two camshafts 10 (FIG. 3) are decelerated and rotated by the rotation of the crankshaft 6j via the sprocket 24, the cam chain 25, and the sprocket 27 on the opposite side (the bow side). At the same time, the generator 28 also rotates with the rotation of the crankshaft 6j.

Lubrication: In this example, the wet sump system is adopted as described above, and the oil pan 6
The oil accumulated in d is pumped by the oil pump 17 to the upper camshaft chamber 9 through the oil supply hose 17a, and at the same time, is supplied to each friction sliding portion. The oil pumped into the camshaft chamber 9 returns to the inside of the crankcase 6c from both sides of the stern side oil return passage 23 and the bow side cam chain tunnel 26 after lubricating the valve operating mechanism. The oil does not stay in. Also, when oil drops in the oil return passage 23,
As shown in FIG. 4, the reduction gears 20, 18, and 22 are brought into contact with each other and sufficiently lubricated. Further, the oil falling in the cam chain tunnel 26 is also absorbed by the sprocket 24 and the cam chain 25.
Contact and lubricate thoroughly.

Lubricating structure: By tilting the engine 6 to one side, the position of the crankcase 6c is lowered and the center of gravity of the engine 6 is also lowered. Also, unlike the dry sump method, a separate oil tank and pump for tank feeding are not required, and the structure is simplified.
Further, by tilting the engine 6 to one side, the position of the crank shaft 6j is also lowered, and the output shaft 19 can be provided above the crank shaft 6j and at the same time, and at the same time, the output shaft 19 can be provided. Since the sprocket 24 is attached to the end of the crank shaft 6j on the opposite side to the end, the outer diameter of the end of the crank shaft 6j on the output shaft 19 side can be made sufficiently large, and the durability is improved.

Although one embodiment of the present invention has been described above, the engine of the present invention can be implemented in a similar manner with a cylinder other than four cylinders (a single cylinder is also possible). When the number of cylinders is large, it is preferable to provide an oil return passage not only on both sides of the engine but also at an intermediate position in the longitudinal direction.

Further, although the above embodiment is a wet sump type engine, it can be applied to a dry sump type engine.

Further, not only the DOHC engine but also the SO
It goes without saying that it can be applied to HC (single overhead cam).

[0029]

As is apparent from the above description,
The propulsion engine of the small planing boat of the present invention has the following effects.

1) Since a reduction gear having a small diameter for driving the camshaft is attached to the end of the crankshaft opposite to the output shaft,
Since the outer diameter of the crankshaft end on the output shaft side can be increased,
The crankshaft has increased durability over its entire length.

2) In the propulsion engine for a small planing boat according to claim 2, the oil does not stay on the top of the engine, mechanical loss due to oil agitation is reduced, and the oil is smoothly returned to the crankcase and the oil pan. Lubrication of the entire engine is efficiently performed.

3) In the propulsion engine for a small planing boat according to claim 3, since the engine oil that drops from the engine top through the oil return passage comes into contact with the reduction gear and sufficiently lubricates it, a dedicated oil for lubricating the reduction gear is used. Is unnecessary, and the lubrication structure is simple.

[Brief description of drawings]

FIG. 1 is an overall schematic side view showing the inside of a hull of a small planing boat equipped with a four-cycle engine according to an embodiment of the present invention as seen through.

FIG. 2 is a schematic plan view showing an engine and an exhaust system of the small planing watercraft of FIG.

FIG. 3 is a vertical cross-sectional view of a ship body, an engine, and the like, as viewed from the rear, with a part cut away to show a main part in a cross section.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3 showing a 4-cycle engine according to the present embodiment.

[Explanation of symbols]

 1 Small Planing Boat 6 4 Cycle Engine 8 Engine Room 9 Cam Shaft Chamber 10 Cam Shaft 17 Oil Pump 18 ・ 20 ・ 22 Reduction Gear 19 Output Shaft 23 Oil Return Passage 24 ・ 27 Sprocket 25 Cam Chain 26 Cam Chain Tunnel

Claims (3)

[Claims] 1. An OHC four-cycle engine for driving a propulsion unit of a small planing boat equipped with a propulsion unit such as a water jet pump or a screw on the stern side. A propulsion engine for small planing boats, in which a reduction gear is arranged and a cam drive mechanism such as a cam chain is arranged on the opposite side. 2. An engine for propulsion of a small planing boat according to claim 1, wherein an oil return passage communicating from a camshaft chamber at the top of the engine to a crankcase oil pan is provided on the opposite side of the cam drive mechanism tunnel of the engine. . 3. A propulsion engine for a small planing boat according to claim 2, wherein the reduction gear of the reduction gear is arranged in the middle of the oil return passage.