JP3730350B2 - 4-cycle engine and small planing boat equipped with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a four-cycle engine and a personal watercraft provided with the same.
[0002]
[Prior art]
In a small planing boat that slides on the water, it is conceivable to mount a four-cycle engine as shown in Japanese Patent Laid-Open No. 7-237587 as a propulsion engine.
[0003]
[Problems to be solved by the invention]
However, since the 4-cycle engine is larger than the 2-cycle engine having the same output, how to arrange the 4-cycle engine in the space within the small planing boat is a problem.
That is, in the personal watercraft, the volume of the engine room is limited. In particular, in a small planing boat in which a person rides on a seat, the width of the seat is limited from the standpoint of physique, and therefore the width of the engine room corresponding to the lower portion of the seat is extremely narrow. For this reason, it is not easy to accommodate the 4-cycle engine in the engine room.
[0004]
An object of the present invention is to solve the above-mentioned problems and provide a compact four-stroke engine that is suitable for a small planing boat and a small planing boat equipped with the four-cycle engine.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the four-cycle engine according to claim 1, the exhaust pipes of the plurality of cylinders extend obliquely upward from the exhaust port at the upper part of the combustion chamber, are further bent and extend downward, and are assembled. It is connected to a collective exhaust pipe located on the side of the engine body, each exhaust pipe has a cooling water passage on the outer peripheral side, and each cooling water passage communicates with the uppermost part of the exhaust pipe. A thermostat valve for opening and closing the cooling water passage according to the cooling water temperature is provided, and the thermostat valve has a bypass hole for removing air mixed in the cooling water.
According to the four-cycle engine, the amount of the exhaust pipe having a length necessary to obtain a desired exhaust passage length is suppressed as much as possible, and the entire engine can be made compact.
[0006]
Further, since the thermostat valve is provided at the uppermost part of the cooling water passage, air mixed in the cooling water gathers in the vicinity of the thermostat valve, so that air can be easily vented.
[0007]
A four-cycle engine according to a second aspect is the relief valve according to the first aspect, wherein the relief valve is opened at the uppermost portion of the exhaust pipe and is opened when the pressure of the cooling water excessively increases to prevent the pressure from becoming excessive. Is provided.
According to this four-cycle engine, when the cooling water pressure is going to rise excessively, the relief valve opens to open the cooling water passage, thereby suppressing the increase in water pressure.
[0008]
Further, four-cycle engine according to claim 3, in claim 1, comprising an engine rotational shaft extending in the front-rear direction, the intake pipe system is connected to the intake port of the combustion chamber through the one side from above the engine body The intake port at the tip of the intake pipe device opens downward or obliquely downward close to the upper side of the exhaust pipe located on the other side of the engine body.
According to this four-cycle engine, since the intake pipe device extends from the upper side of the engine body to one side, compared to the case where the entire intake pipe device is arranged on one side of the engine body, Does not increase the width so much. In addition, since the intake port of the intake pipe device is covered with the exhaust pipe, even when there is water in the surroundings, the intake of water together with air is reduced.
[0009]
Further, four-cycle engine according to claim 4, in claim 3, wherein the intake pipe system, an intake pipe connected to each of the plurality of cylinders, a single set suction pipe connected to the upstream end of the intake pipe And an air intake pipe for introducing air into the collective intake pipe, and the collective intake pipe is disposed above the engine body.
According to this four-cycle engine, the air sucked from the air intake pipe is supplied into each cylinder through the intake pipe provided for each cylinder through the one collective intake pipe, so that the silencing effect is enhanced. In addition, since the collective intake pipe is disposed above the engine body, the width of the intake pipe device protruding to the side of the engine is suppressed, and the lateral width of the entire engine can be reduced.
[0010]
Further, four-cycle engine according to claim 5, in claim 4, wherein the air intake pipe, with respect to the spark plug attached to an upper portion of the engine body, are arranged at positions displaced in the longitudinal direction.
According to this four-cycle engine, since the air suction pipe is located between the spark plugs, the spark plug can be attached and detached without removing the air suction pipe.
[0011]
According to a sixth aspect of the present invention, in the four-cycle engine according to any one of the third to fifth aspects, an oil tank is integrally formed on one side of the engine main body and below the intake pipe device. .
According to this four-cycle engine, the oil tank for the dry sump is located below the intake pipe device on one side of the engine body with sufficient space, and is integrated with the crankcase. Compared with the case where the engine is separately provided, the entire engine becomes compact, and connection piping to the oil tank is not required.
[0012]
A small planing boat according to a seventh aspect includes the four-cycle engine according to any one of the first to sixth aspects for driving a propulsion device, and the engine has a rotating shaft that matches a longitudinal direction of the hull. It is installed in the hull.
According to this small planing boat, since a compact four-cycle engine is installed vertically on the hull, a small planing boat equipped with a four-cycle engine without difficulty in space can be realized.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view of a personal watercraft equipped with an in-line four-cylinder double overhead camshaft (DOHC) four-cycle engine according to an embodiment of the present invention, and FIG. 2 is taken along line II-II in FIG. FIG. 3 is a plan view of the four-cycle engine. FIG.
In FIG. 1, the hull 2 is constructed by joining a deck 2b on a hull 2a, and the deck 2b is provided with a seat 2c and a footrest (floor surface) 2d on the left and right. 2e is a handle.
[0014]
4-cycle engine (hereinafter "engine" hereinafter) E, as shown in FIG. 2, is supported via a damper on a mount (not shown) provided on the hull 2a constituting the hull 2, engine E The crankshaft 3 which is the rotation axis of the hull 2 is attached in a direction that matches the front-rear direction of the hull 2 and at a position that substantially matches the center line of the hull 2.
[0015]
As shown in FIG. 1, a water jet propulsion device 42 disposed at the rear part of the hull 2 is driven through a shaft 41 connected via a coupling 40 to a crankshaft 3 that is an engine rotation shaft of the engine E. The water is ejected from the nozzle 43 to obtain a driving force. The exhaust gas of the engine E is guided to the water muffler 45 disposed in the hull 2 by the exhaust pipe 44, and the silenced and cooled exhaust gas is discharged from the rear end portion of the hull 2a through the exhaust pipe 46. The steering nozzle is not shown.
[0016]
As shown in FIG. 2, the engine body 1 has a crankcase 5 that supports the crankshaft 5, a cylinder 4 in which a piston slides, and a cylinder head 11. The cylinder 4 is mounted upright on the crankcase 5, and a piston reciprocates in the cylinder 4 in the vertical direction. The cylinder having the intake / exhaust valves 6, 7, the spark plug 8 disposed therebetween, and the cams 9, 10 provided on the camshafts 9 s, 10 s to drive the intake / exhaust valves 6, 7. The head 11 is disposed, and the cams 9 and 10 are rotationally driven by the timing chain 12 to open and close the intake / exhaust valves 6 and 7.
[0017]
The intake pipe device 13 is disposed above the cylinder head 11 and four intake pipes 14 extending obliquely upward one side (in this example, starboard side: left side in FIG. 2) from the intake valve 6 of each cylinder 4. And a single intake manifold 15 to which the intake pipes 14 are connected. Further, as shown in FIG. 3, the intake pipe 15 passes through the front and rear of the ignition plug 8 from the other side (in this example, as shown in FIG. 3). One air intake pipe 16 extending on the port side (right side in FIG. 2) is provided. Thus, since the air suction pipe 16 is located between the spark plugs 8, the spark plug 8 can be attached and detached without removing the air suction pipe 16.
[0018]
Further, each intake pipe 14 is provided with an injector 18 for injecting fuel in the vicinity of the connection portion with the cylinder head 11 in FIG. 2, that is, in a portion where the intake pipe 14 is bent toward the cylinder head 11 side. . Thus, since the intake pipe device 13 extends from the upper side of the engine body 1 to one side, the intake pipe device 13 is compared with the case where the entire intake pipe device 13 is arranged on one side of the engine body 1. The width of the entire engine E including the device 13 can be reduced. In addition, the silencing effect is enhanced by the large-capacity collective intake pipe 15.
[0019]
Further, the opening 16 a of the air intake pipe 16 opens obliquely downward at a position close to the upper side of the exhaust pipe 17 disposed on the other side of the engine E. As a result, the front of the opening 16a is covered with the exhaust pipe 17, so that water that has entered the ship is less likely to be sucked together with air.
[0020]
Further, as shown by a partially enlarged portion in FIG. 2, a water drain hole 15 a is provided in the bottom wall of the collective intake pipe 15, and even if water is sucked together with air from the air suction pipe 16, It is discharged by its own weight from the hole 15a.
[0021]
An exhaust pipe 17 disposed on the other side of the engine E extends obliquely upward from each exhaust port 19 at the upper part of the combustion chambers of the four cylinders 4 and is further bent downward, with 2 at its lower end (exit). Collected in one exhaust passage. Accordingly, a desired length from each cylinder 4 to the collection point of the exhaust passage, that is, the outlet of the exhaust pipe 17 (to be described later) while suppressing the exhaust pipe 17 from protruding greatly upward and laterally from the engine body 1. D1, D2) can be secured.
[0022]
4 is a diagram showing the configuration of the exhaust pipe device viewed from the other side of the engine E (X1 direction in FIG. 2), FIG. 5 is a sectional view of each part of the exhaust pipe device, and FIG. 5B is a cross-sectional view taken along the line bb in FIG. 4, FIG. 5C is a cross-sectional view taken along the line cc in FIG. 5 (d) is a bottom view taken along the line dd of FIG. 5 (b). A collective exhaust pipe 20 having two exhaust passages shown in FIG. 5C and an exhaust joint pipe 21 following the exhaust pipe 17 are connected to the exhaust pipe 17 and further arranged behind the engine E in FIG. Connected to a water muffler 45.
[0023]
The exhaust port 19 of each cylinder 4 in FIG. 2 is connected to the two exhaust passages on the outside (No. 1 and No. 4 in this example) and the inside (No. 2 and No. 3 in this example) by the exhaust pipe 17 in FIG. The two exhaust passages are combined into one to form two exhaust passages. As shown in FIGS. 5A and 5B, the inner two exhaust passages No. 2 and No. 3 are greatly curved outward, whereas the outer two exhaust passages No. 1 and No. .4 has a small curvature. For this reason, the length D1 until the two outer exhaust passages No. 1 and No. 4 gather together, and the two inner exhaust passages No. 2 and No. 3 gather together. Since the lengths D2 can be configured to have almost the same desired length, the output of the engine can be increased. Further, as shown in FIG. 2, the exhaust flange 31 of the cylinder head 11 to which the exhaust pipe 17 is attached is inclined upward, so that the exhaust pipe 17 can be easily attached and detached.
[0024]
The two exhaust passages are connected to the exhaust pipe 17 and the exhaust joint pipe 21 connected to the exhaust pipe 17 in FIG. A cooling water passage 22 is formed on the outer peripheral side of the exhaust pipe 17 and the collective exhaust pipe 20, and the cooling water taken from the water jet propulsion device 42 (FIG. 1) driven by the engine E will be described later. After passing through the oil cooler, the engine oil is cooled, the exhaust pipe 20 is cooled, and thus the cooling water is preheated, and then the engine body 1 (FIG. 2) is cooled. An exhaust temperature sensor 37 is provided at the top of the exhaust passage No. 4 in FIG.
[0025]
Further, as shown in FIGS. 5A and 5B, the thermostat valve (two in the example: see FIG. 4) 24 and the relief valve 26 are arranged at the top of the cooling water passage 22 of the exhaust pipe 17. , And communicate with each other via a passage 32 (FIG. 3). A water temperature sensor 38 for detecting the cooling water temperature is provided at the uppermost part of the cooling water passage 22. The four cooling water passages 22 of each exhaust pipe 17 are in communication with each other in the vicinity of the uppermost portion. Therefore, air mixed in the cooling water is accumulated in the thermostat case 25 shown in FIG. Air easily escapes from the bypass hole (not shown) of the thermostat valve 24 exposed at the top.
[0026]
The relief valve 26 provided at the uppermost portion of the exhaust pipe 17 shown in FIG. 5B is opened when the pressure of the cooling water in the cooling water passage 22 rises excessively. For example, when the thermostat valve 24 is closed because the cooling water temperature of the engine E is low, when the small planing boat jumps into the air and the water jet propulsion device 42 (FIG. 1) moves away from the water surface, the water jet propulsion is performed. When the cooling water supplied from the machine 42 is stopped, and then the water is landed and the supply of the cooling water is resumed, the water pressure of the cooling water tends to increase instantaneously because the thermostat valve 24 is closed. As a result, the relief valve 26 opens to open the cooling water passage 22 and suppress an excessive increase in water pressure.
[0027]
FIG. 6 is a conceptual diagram showing a cooling water flow path, and FIG. 7 is a flowchart thereof. The cooling water taken from the water jet propulsion device 42 (FIG. 1) first passes through the oil cooler 23 disposed on the other side of the crankcase 5 and the collective exhaust pipe 20 connecting the exhaust pipe 17 and the exhaust joint pipe 21. The thermostat valve 24, the thermostat case 25 (and the relief valve) provided on the uppermost part of the exhaust pipe 17 through the exhaust port 19 of the cylinder head 11 through the cylinder 4 from the upstream side. 26), enters the downstream side of the exhaust pipe 17 from the tube 35, cools the exhaust pipe 17, enters the upstream side of the exhaust joint pipe 21 through the thermostat case 25 (near the thermostat 24), and passes through the water muffler 45. It is discharged out of the ship along with the exhaust gas. As described above, the cooling water is preheated by the oil cooler 23 and the collective exhaust pipe 20 and then supplied to the cylinder 4, whereby the rotation of the engine E is stabilized.
[0028]
Further, part of the cooling water that has cooled the exhaust pipe 17 is discharged to the side of the hull from a water inspection port (not shown) provided in front of the hull 2 via the tube 33 (FIGS. 3 and 4). The pilot can confirm that the cooling water is being passed through the engine E by the discharge of the cooling water.
[0029]
2 is an oil tank for dry sump integrally formed on one side of the crankcase 5 and stores engine oil cooled by the oil cooler 23. The crankshaft 3, the cylinder 4 and the cams 9, 10 are stored in the oil tank. The oil is supplied to the intake / exhaust valve opening / closing mechanism such as the timing chain 12. Reference numeral 28 denotes a starter, which is arranged at a position where a part of the oil tank 27 is cut away. In FIG. 3, 29 is a generator cover, and 30 is an oil drain passage from the cylinder head 11 to the crankcase 5.
[0030]
In this way, the oil tank 27 for dry sump is located below the intake pipe device 13 on one side of the engine body 1 with sufficient space, and is integrated with the crankcase. Compared to the case where it is provided separately, the entire engine is compact, and piping to the oil tank is not required. In addition, since the oil tank 27 having a large volume and the heavy starter 28 are arranged on one side of the crankcase 5, the cooling water passes through and the exhaust systems 17, 20, and 21 having a heavy weight have left and right sides. Weight balance can be achieved.
[0031]
【The invention's effect】
As described above, according to the 4-cycle engine according to one aspect of the invention, each of the exhaust pipes of the plurality of cylinders, extends obliquely upward from the exhaust port of the combustion chamber top, extends downward is further bent, is set The exhaust pipes are connected to a collective exhaust pipe located on the side of the engine body, each exhaust pipe has a cooling water passage on the outer peripheral side, and each cooling water passage communicates with the uppermost portion of the exhaust pipe. A thermostat valve that opens and closes the cooling water passage according to the cooling water temperature is provided in the upper part, and the thermostat valve has a bypass hole that extracts air mixed in the cooling water, so it is necessary to obtain a desired exhaust passage length The entire length of the engine can be made compact by suppressing as much as possible the amount of the exhaust pipe having a long length protruding upward and laterally of the engine body.
[0032]
In the four-cycle engine according to another configuration of the present invention, the intake pipe device is connected to the intake port of the combustion chamber through one side from the upper side of the engine body, and the intake air at the tip of the intake pipe device The intake pipe device extends from the upper side of the engine body to one side because the opening opens downward or obliquely downward near the exhaust pipe located on the other side of the engine body. Therefore, compared with the case where the whole intake pipe device is arranged on one side of the engine, the lateral width of the engine is not increased so much. In addition, since the intake port of the intake pipe device is covered with the exhaust pipe, even when there is water in the surroundings, the intake of water together with air is reduced.
[0033]
Moreover, according to the small planing boat according to the present invention, since the compact four-cycle engine is installed vertically on the hull, it is possible to realize a small planing boat on which the four-cycle engine is mounted without difficulty in space.
[Brief description of the drawings]
FIG. 1 is a side view of a personal watercraft equipped with a (DOHC) 4-cycle engine according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an installed state of the engine along the line II-II in FIG.
FIG. 3 is a plan view of a four-cycle engine according to an embodiment.
4 is a view showing an exhaust pipe device as viewed from the other side of an engine E according to an embodiment. FIG.
5A is a cross-sectional view taken along the line aa in FIG. 4, FIG. 5B is a cross-sectional view taken along the line bb in FIG. 4, and FIG. 5C is a cross-sectional view taken along the line cc in FIG. Sectional drawing along (d) is a bottom view along the dd line of FIG.5 (c).
FIG. 6 is a conceptual diagram illustrating a cooling water flow path according to an embodiment.
FIG. 7 is a flowchart of FIG. 6;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Hull, 2a ... Hull, 2b ... Deck, 3 ... Engine rotating shaft (crankshaft), 4 ... Cylinder, 5 ... Crankcase, 6 ... Intake valve, 7 ... Exhaust valve, 8 ... Spark plug 9, 10 ... cam, 11 ... cylinder head, 12 ... timing chain, 13 ... intake pipe device, 14 ... intake pipe, 15 ... collective intake pipe, 16 ... air intake pipe, 17 ... exhaust pipe, 18 ... injector, 19 ... exhaust port, 20 ... collective exhaust pipe, 21 ... exhaust joint pipe, 22 ... cooling water passage (water jacket),
23 ... Oil cooler, 24 ... Thermostat valve, 25 ... Thermostat case, 26 ... Relief valve, 27 ... Oil tank, 28 ... Starter, 29 ... Generator cover, 30 ... Oil drain passage, 31 ... Exhaust flange, 32, 33 Tube 42 ... water jet propulsion machine, 44 ... water muffler, E ... 4 cycle engine.

Claims (7)

Each of the exhaust pipes of the plurality of cylinders extends obliquely upward from the exhaust port at the top of the combustion chamber, is further bent and extends downward, and is assembled and connected to a collective exhaust pipe located on the side of the engine body ,
Each exhaust pipe has a cooling water passage on the outer peripheral side, and each cooling water passage communicates with the uppermost portion of the exhaust pipe, and a thermostat valve that opens and closes the cooling water passage according to the cooling water temperature is provided at the uppermost portion. A four-cycle engine provided with a bypass hole through which the thermostat valve extracts air mixed in the cooling water . The four-stroke engine according to claim 1, wherein a relief valve is provided at the uppermost portion so as to be opened when the pressure of the cooling water is excessively increased to prevent the pressure from becoming excessive. In Claim 1, it has an engine rotating shaft extending in the front-rear direction, and the intake pipe device is connected to the intake port of the combustion chamber through one side from above the engine body,
A four-cycle engine in which an intake port at a tip of the intake pipe device is opened downward or obliquely downward close to an upper part of an exhaust pipe located on the other side of the engine body. 4. The intake pipe device according to claim 3, wherein the intake pipe device is connected to each of the plurality of cylinders, a single collective intake pipe connected to an upstream end of the intake pipe, and air is introduced into the collective intake pipe. An air suction pipe,
A four-cycle engine in which the collective intake pipe is disposed above the engine body. 5. The four-stroke engine according to claim 4, wherein the air intake pipe is disposed at a position displaced in the front-rear direction with respect to a spark plug attached to an upper portion of the engine body. The four-cycle engine according to any one of claims 3 to 5 , wherein an oil tank is integrally formed at one side of the engine body, below the intake pipe device. A small-sized planing equipped with the four-cycle engine according to any one of claims 1 to 6 for driving a propulsion device, wherein the engine is installed in a ship body with a rotation axis thereof aligned with a longitudinal direction of the ship body. Boat.

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