JPH1122439A - Two-cycle engine and small planing boat furnished with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly hold a pre-load ratio of a crankcase and to maintain a balancer in a proper lubricating state. SOLUTION: Balancers 18A, 18B to rotate interlocked with a crankshaft 4 and an oil pump 39 to supply lubricating oil to these balancers are provided on a two-cycle engine 3. Additionally, a balancer chamber 40b to store the balancer 18B and a crankcase 42 are communicated to each other through a labyrinth seal 43b provided on an outer periphery of the crankshaft 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke engine for forcibly lubricating a balancer rotating in association with a crankshaft, and a personal watercraft equipped with the engine.

[0002]

2. Description of the Related Art As a two-stroke engine for a personal watercraft, a crankcase compression type in which an air-fuel mixture is compressed in a crankcase and then guided to a combustion chamber is used.
A pair of balancers that rotate in conjunction with the crankshaft and a balancer chamber that stores each balancer are provided, and the mixture introduced into the crank chamber is guided from the crank chamber to the balancer chamber to lubricate the balancer. Are known. However, the lubrication mechanism of the two-stroke engine may have an insufficient lubrication amount. In addition, since the crank chamber communicates with the balancer chamber, the capacity of the crank chamber actually increases, and accordingly, the pre-compression ratio of the compression of the air-fuel mixture in the crank chamber decreases, and the output of the engine decreases.

[0003] Apart from this, there is also known an oil bath type two-stroke engine in which lubricating oil is stored in a balancer chamber. However, in this configuration, since the lubricating oil in the balancer chamber is consumed as it is used, it is necessary to check the liquid level of the lubricating oil in the balancer chamber and replenish the lubricating oil, which requires a lot of maintenance.

There is also known a configuration in which lubricating oil is supplied to a balancer chamber by an oil pump, and the supplied lubricating oil is sequentially returned to the oil pump. However, in this case, air return or dust clogging may occur in the lubricating oil return path, and smooth circulation of the lubricating oil is not easy. As another example, there is one in which a lubricating oil passage is formed in the rotating shaft of an oil pump (Japanese Utility Model Application Laid-Open No. 63-177607), but lubricating oil is not sufficiently supplied to the gear surface of the balancer.

Accordingly, the present invention provides a two-stroke engine capable of appropriately maintaining a preload ratio in a crankcase, smoothly supplying lubricating oil, and maintaining a proper lubrication state, and a personal watercraft equipped therewith. The purpose is to provide.

[0006]

According to a first aspect of the present invention, there is provided a two-stroke engine, wherein a mixture containing fuel and lubricating oil is compressed by a change in the volume of the crank chamber and then introduced into the combustion chamber. A compression-type two-cycle engine, a balancer that rotates in conjunction with a crankshaft;
An oil pump for supplying lubricating oil to the balancer is provided, and a balancer chamber that houses the balancer and a crank chamber communicate with each other via a labyrinth seal provided on the outer periphery of the crankshaft.

According to the two-cycle engine, the lubricating oil supplied from the oil pump and stored in the balancer chamber is introduced into the crank chamber via the labyrinth seal and consumed together with the air-fuel mixture. Since the lubricating oil is secured, the balancer can be maintained in an appropriate lubricating state, and the lubricating oil can be smoothly supplied to the balancer bearing and the interlocking tooth surface with the crankshaft without excessive accumulation of the lubricating oil. The mechanical loss caused by the balancer gear stirring the lubricating oil can also be reduced. Also, since the crank chamber and the balancer chamber are communicated by a labyrinth seal, the crank chamber and the balancer space are substantially airtightly sealed against a sudden change in the pressure of the crank chamber due to the reciprocating motion of the piston. Thus, the preload ratio of the crank chamber can be properly maintained. Furthermore, maintenance such as lubricating oil replenishment and inspection as in the oil bath method is unnecessary,
The structure is also simplified.

[0008] The two-stroke engine according to claim 2 is:
The balancer includes a plurality of balancers that rotate in conjunction with a crankshaft, a balancer chamber that stores the balancers, and an oil pump that supplies lubricating oil to one balancer. A supply passage for sequentially supplying lubricating oil from the chamber to another balancer chamber is formed, and a labyrinth seal is provided between the most downstream balancer chamber and the crank chamber. According to this two-cycle engine, despite having a plurality of balancers, the oil pump only needs to supply lubricating oil to one balancer, so that the structure is simplified and the capacity of the oil pump is reduced.

Further, the two-stroke engine according to claim 3 is:
It is also a crank compression type, including a plurality of balancers rotating in conjunction with the crankshaft, a plurality of balancer chambers accommodating each balancer, and a single oil pump for supplying lubricating oil to each balancer. The balancer chamber and the crank chamber communicate with each other via a labyrinth seal provided on the outer periphery of the crankshaft. According to the two-cycle engine, since the lubricating oil is supplied directly to each balancer from a single oil pump, each balancer can be properly lubricated.

The two-stroke engine of claim 4 is
4. The two-stroke engine according to claim 2, wherein the balancer is spaced apart in an axial direction of the crankshaft. 5. According to the two-cycle engine, the balancer can be arranged compactly, so that the engine can be easily installed in a narrow space.

The two-stroke engine according to claim 5 is
The rotation center of the balancer is located above the crankshaft center. According to the two-cycle engine, the lubricating oil in the balancer chamber easily flows into the crank chamber through the labyrinth seal due to gravity.

The two-stroke engine according to claim 6 is
The number of cylinders is three, and one of the balancers is provided at a position corresponding to a front part and a rear part of a crankshaft. According to this two-cycle engine, the mass of the rotating part around the crankshaft is balanced in a symmetrical arrangement, and the vibrating force in the axial direction of the piston due to the mass of the reciprocating part of the piston or the like becomes the largest vibration source and is located at the front and rear ends. While the vibrating force of the cylinder generates a moment that causes pitching vibration of the entire engine, the balancers that are arranged one after the other in opposite phases are arranged in opposite phases.
Since the same magnitude of moment is generated in the opposite phase to the corresponding cylinder moment, pitching vibration can be canceled, balance is improved, and vibration can be reduced.

[0013] The personal watercraft according to the seventh aspect of the present invention is the second aspect of the present invention.
The two-stroke engine described in 1 above is used for driving a propulsion device, and the crankshaft center of this engine coincides with the front-rear direction of the hull, and the one balancer is located forward of the other balancer along the crankshaft. Are located. According to this personal watercraft, the front of the hull rises while running,
In a two-cycle engine, lubricating oil can be easily supplied from the front balancer chamber to the rear balancer chamber via the communication passage.

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view of a personal watercraft equipped with a two-stroke engine according to an embodiment of the present invention, and FIG. 2 is a plan view showing an installation state of each device except for a deck of the personal watercraft. The hull 2 of the personal watercraft 1 of FIG. 1 is configured by joining a deck 2b on a hull 2a, and the deck 2b is provided with a seat 2c and a floor 2d serving as a footrest. Is provided with a handle 2e in front of.

The two-stroke engine 3 mounted on the personal watercraft 1 shown in FIG. 2 has three cylinders 20 arranged in series.
The engine 3 is mounted on the hull 2 a in a direction in which the axis of the crankshaft 4 coincides with the longitudinal direction of the hull 2. A propulsion machine shaft 6 is connected to a crankshaft 4 of the engine 3 via a coupling 5, and the crankshaft 4, the coupling 5 and the propulsion machine shaft 6
The engine 3 and a propulsion device (water jet pump) 7 arranged at the rear end of the hull 2 are rotationally connected to each other.
, Thereby driving the propulsion device 7 to eject water from the nozzle 8 to obtain a propulsion force. The steering nozzle is not disclosed. Exhaust gas from the engine 3 is guided by an exhaust pipe 10 having a muffler section 9 to a water muffler 11 disposed in the hull 2, and the muffled exhaust gas is discharged to the rear of the hull 2 via a tail pipe 12. You. A fuel tank 13 is arranged in a space in front of the engine 3 in the hull 2.

FIG. 3 is a rear view of the state of the engine of the personal watercraft as viewed from the stern side, and FIG. 4 is a partially cutaway side view of the engine 3 viewed from the port side. As shown in FIG. 4, the engine 3 includes an in-line three-cylinder engine main body 17,
It has two balancers 18A and 18B which are rotationally connected to the crankshaft 4 and suppress the vibration of the engine body 17, and one balancer 18A is located at the front of the crankshaft 4 and has a crank corresponding to the balancer 18A. The other balancer 18B is disposed at the rear of the shaft 4 so as to be spaced apart therefrom. In this way, one balancer 18A is arranged ahead of the other balancer 18B along the crankshaft 4. Further, as shown in FIG. 3, these balancers 18A, 18A
B is arranged such that its rotation center C1 is located above the axis C2 of the crankshaft 4.

In the upper part of the crankcase 19 of the engine body 17, a cylinder 20 extending obliquely upward on one side (in this example, starboard side) from the axis of the crankshaft 4, and an intake air extending obliquely upward on the other side. The introduction device 21 is arranged in a V-shape. The intake air introduction device 21 includes a water trap structure, and an air intake device 23 that takes in air from an obliquely downward intake port 22, a carburetor 24, and an intake reed valve 25.
And the fuel is mixed with the air by the carburetor 24,
On the downstream side, lubricating oil is mixed from a lubricating oil supply passage (not shown), and the mixture is supplied to the crank chamber 42. The air-fuel mixture entering the crank chamber 42 is compressed in the crank chamber 42 by the lowering of the piston, and is sent to a combustion chamber above the piston through a scavenging passage (not shown). That is, the engine 3 is of a crankcase compression type.

An exhaust manifold 14 and an exhaust pipe 10 are arranged between a V-shaped structure composed of a cylinder 20 and an intake introduction device 21. The exhaust manifold 14, the exhaust pipe 10, the water muffler 11 and the tail pipe 12 shown in FIG.

In FIG. 4, a connecting rod 26 and a web 2 are attached to a piston (not shown) reciprocating in the cylinder 20.
The crankshaft 4 connected via the shaft 7 is rotatably supported via a bearing 28 inside the crankcase 19. Further, three intake reed valves 25 corresponding to the respective cylinders are mounted inside the crankcase 19 side by side in the axial direction C2 of the crankshaft 4. The intake reed valve 25 is provided in an intake passage for introducing an air-fuel mixture into the crank chamber 42, and prevents the air-fuel mixture from blowing back from the crank chamber 42, and is provided between a pair of webs 27 corresponding to each cylinder. The mixture is introduced into the crank chamber 42. The two balancers 18A and 18B include balancer weights 28a and 28b, balancer rotating shafts 29a and 29b for supporting these, respectively, and a balancer gear 3
0a and 30b are integrally formed.

The front balancer 18A is disposed further forward than the front end cylinder web 27, and covers the crankcase 19 and a generator that covers the front end face of the crankcase 19 via the front balancer rotation shaft 29a. The pair of bearings 34 held on the cover 33 allows the crankshaft 4
It is rotatably supported in parallel with. Rear balancer 1
8B is disposed further rearward than the web 27 of the rear-end cylinder, and a pair of the rear-end surface of the crankcase 19 and a cover 31 that covers the rear-end surface of the crankcase 19 are held via a balancer rotation shaft 29b at the rear end. With the bearing 32,
It is rotatably supported in parallel with the crankshaft 4.

The front balancer 18A rotates with the crankshaft 4 because the balancer gear 30a meshes with a balancer driving gear 35a integrally formed with a boss 37 fixed to the front end of the crankshaft 4 with bolts 36. Are linked. The balancer 18B at the rear portion has the balancer gear 30b meshed with the balancer driving gear 35b attached to the rear end of the crankshaft 4, and thus the crankshaft 4B
Is rotationally connected. Therefore, both balancers 18
A and 18B rotate in the opposite direction to the crankshaft 4, respectively.

An oil pump 39 for supplying the lubricating oil in the oil tank 38 to the balancer 18A via a supply passage 40 is provided in front of the front balancer 18A.
The oil pump 39 is driven using the balancer rotating shaft 29a as a drive source. The oil tank 38 is disposed above the fuel tank 13 as shown in FIG. The balancer chamber 40a for storing the front balancer 18A and the balancer chamber 40b for storing the rear balancer 18B are:
The communication is established through the communication passage 41. As a result, the lubricating oil supplied to the front balancer 18A and accumulated in the balancer chamber 40a passes through the communication passage 41, and the rear balancer chamber 40b
To lubricate the balancer 18B. In the personal watercraft 1 on which the two-cycle engine 3 is mounted, the front of the hull 2 is raised by traveling, so that lubricating oil is supplied from the front balancer chamber 40a to the rear balancer chamber 40b through the supply passage 41. It will be done smoothly.

As shown in the enlarged view of FIG. 5, the balancer driving gear 35b for driving the rear balancer 18B is located opposite to the outer periphery of the boss, and the balancer chamber 40b of the rear balancer 18B is provided. A labyrinth seal 43b is provided for communicating the crankcase with the adjacent crank chamber. The labyrinth seal 43b is a seal member 4
The seal member 44B is fitted and fixed to a bore of the crankcase 19 and is located closer to the outside of the crank chamber 42 of the bearing 28 than the seal member 44B.

In the two-stroke engine 3 configured as described above, the front balancer 18A is connected to the rear balancer 18A.
The lubricating oil supplied to B is gradually introduced into the crank chamber 42 through the labyrinth seal 43b and the bearing 28 and consumed. In particular, as described above, the balancer 18A,
Since the rotation center C1 of 18B is arranged at a position higher than the axis C2 of the crankshaft 4, lubricating oil is smoothly introduced from the balancer chamber 40b to the crank chamber 42 via the labyrinth seal 43b. Therefore, an appropriate amount of lubricating oil is always stored in the front and rear balancer chambers 40a and 40b, and the balancers 18A and 18B can be maintained in an appropriate lubricating state.

Further, since the lubricating oil does not excessively accumulate in the balancer chambers 40a, 40b, the balancer gears 30a,
30b can also reduce the mechanical loss caused by stirring the lubricating oil. Further, the crank chamber 42 and the balancer chamber 4
0b is communicated with the labyrinth seal 43b, so that a small gas flow is generated in both spaces, but a large gas flow is not generated. Therefore, the pressure between the crank chamber 42 and the balancer chamber 42b is substantially airtightly sealed against the pressure change in the crank chamber 42 due to the reciprocating motion of the piston. As a result, the preload ratio of the crank chamber 42 can be appropriately maintained.

Further, unlike the oil bath method, maintenance such as checking and replenishing the liquid level of the lubricating oil stored in the balancer chambers 40a and 40b becomes unnecessary. Also, two balancers 18A, 18
Despite having B, it is only necessary to supply the lubricating oil from the oil pump 39 to one balancer 18A, so that the lubricating mechanism can be simply configured and the oil pump 39 can be of a small capacity. Further, the engine 3 has a structure in which the two balancers 18A and 18B are compactly arranged at corresponding positions axially separated from each other in the front part and the rear part of the crankshaft 4, so that the bottom of the personal watercraft 1 and the like are provided. Installation of the engine in a narrow space becomes easier.

Since the engine 3 is an in-line three-cylinder engine, the mass of the rotating part around the crankshaft is balanced in a symmetrical arrangement, and the vibrating force in the axial direction of the piston due to the reciprocating mass of the piston or the like is maximized. Moments that act as vibration sources and cause the entire engine to pitch and vibrate due to the vibrating forces of the cylinders located at the front and rear ends are generated. However, the balancers 18A and 18B, which are arranged one after the other and at opposite phase positions,
Since moments of the same magnitude are generated in opposite phases to the moments of the corresponding cylinders, pitching vibrations can be canceled and the balance of the engine 3 is improved.

When three or more balancers are provided, lubricating oil is supplied from the oil pump to the first balancer, and the first balancer chamber and the second, third,... Through the first, second, third ...
The lubricating oil is sequentially supplied to the balancer chambers of the first and second stages, and the lubricating oil is introduced from the most downstream balancer chamber to the crank chamber through the labyrinth seal.

FIG. 6 is a partial longitudinal sectional view of an engine according to another embodiment of the present invention. This embodiment is different from the above embodiment in that the supply of the lubricating oil to the rear balancer 18B does not pass through the communication passage 41 as shown in FIG.
The operation is performed directly from the oil pump 39 via the supply passages 40A and 40B, and a seal member 44A is fitted and fixed to a bore of the crankcase 19 so as to face the outer periphery of the front portion of the crankshaft 4, and this seal is formed. A labyrinth seal 43a for communicating the balancer chamber 40a of the front balancer 18A with the crank chamber 42 adjacent thereto is provided on the inner periphery of the member 44A.

With this configuration, each balancer chamber 40a, 4
0b is supplied directly with lubricating oil from a single oil pump 39, and the lubricating oil stored in each of the balancer chambers 40a, 40b passes through the labyrinth seals 43a, 43b and the bearing 28, and passes through the adjacent front and rear portions. Crank chamber 42
Is gradually introduced and consumed. As described above, since the lubricating oil is directly supplied from the single oil pump 39 to each of the balancers 18A and 18B, each of the balancers 18A and 18B can be maintained in a more appropriate lubricating state.

In the above embodiment, the balancer 18
Although the rotation centers of A and 18B are arranged above the axis of the crankshaft 4, the upper and lower positional relationship is not limited to this, and may be reversed, for example. Also in this case, the lubricating oil accumulated in the balancer chambers 40a and 40b is splashed up by the balancer gears 30a and 30b, and is introduced into the crank chamber 42 from the labyrinth seals 43a and 43b as droplets and mist, so that it is gradually consumed. Will be done.

In each of the above embodiments, a description has been given of the case of an in-line three-cylinder two-cycle engine. However, the same applies to a single-cylinder having one or more balancers or a two-cylinder two-cycle engine other than three cylinders. Applicable to

[0033]

As described above, according to one embodiment of the present invention,
According to the cycle engine, lubricating oil is supplied by an oil pump to the balancer that rotates in conjunction with the crankshaft, and the lubricating oil in the balancer chamber is supplied to the crankcase by a labyrinth seal that connects the balancer chamber that houses the balancer and the crankcase. Since it is introduced and consumed, an appropriate amount of lubricating oil is always secured in the balancer chamber, and the balancer can be maintained in an appropriate lubricating state. Further, the preload ratio of the crank chamber can be appropriately maintained, and maintenance such as replenishment and inspection of lubricating oil is not required. The structure is also simplified.

According to a two-stroke engine according to another configuration of the present invention, lubricating oil is supplied to one of the balancer chambers of a pair of balancers rotating in association with the crankshaft by an oil pump, and the lubricating oil in the balancer chamber is supplied. Is supplied to the other balancer chamber via a supply path, and the lubricating oil accumulated in the other balancer chamber is introduced into the crank chamber through a labyrinth seal provided between the balancer chamber and the crank chamber. While having a plurality of balancers, it is only necessary to supply lubricating oil from the oil pump to one of the balancers, so that the structure is simplified and the capacity of the oil pump is reduced.

According to a two-stroke engine according to still another configuration of the present invention, a single oil pump supplies lubricating oil to each of a plurality of balancers rotating in association with a crankshaft, and stores each balancer. Since the lubricating oil accumulated in each balancer chamber is introduced into the crank chamber via a labyrinth seal interposed between the balancer chamber and the crank chamber, each balancer can be appropriately lubricated.

According to the personal watercraft using the two-stroke engine of the present invention, the crankshaft center of the engine matches the longitudinal direction of the hull, and the one balancer is connected to the other along the crankshaft. Since the front of the personal watercraft rises during traveling, lubricating oil can be easily supplied from the front balancer chamber to the rear balancer chamber.

[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 plan view showing an installation state of each device except for the deck of the personal watercraft.

FIG. 3 is a partially broken front view showing a two-stroke engine installed state of the personal watercraft.

FIG. 4 is a partially broken side view of the two-stroke engine.

FIG. 5 is an enlarged sectional view of a main part of the two-stroke engine.

FIG. 6 is a partial longitudinal sectional view of a two-stroke engine according to another embodiment of the present invention.

[Explanation of symbols]

1 ... personal watercraft, 2 ... hull, 3 ... 2 cycle engine,
4 ... Crankshaft, 7 ... Propulsion device, 18A, 18B ... Balancer, 39 ... Oil pump, 40a, 40b ... Balancer chamber, 41 ... Supply passage, 42 ... Crank chamber, 43a, 43
b ... Labyrinth seal

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 25, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

FIG. 6 is a partial longitudinal sectional view of an engine according to another embodiment of the present invention. This embodiment is different from the above embodiment in that the supply of the lubricating oil to the rear balancer 18B does not pass through the communication passage 41 as shown in FIG.
This is performed directly from the oil pump 39 via the supply passages 4 1 A and 4 1 B, and the seal member 44 A is fitted and fixed to the bore of the crank case 19 facing the outer periphery of the front part of the crank shaft 4. Further, a labyrinth seal 43a for communicating the balancer chamber 40a of the front balancer 18A with the crank chamber 42 adjacent thereto is provided on the inner periphery of the seal member 44A. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 6, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

FIG. 6 is a partial longitudinal sectional view of an engine according to another embodiment of the present invention. This embodiment is different from the above embodiment in that the supply of the lubricating oil to the rear balancer 18B does not pass through the communication passage 41 as shown in FIG.
This is performed directly from the oil pump 39 via the supply passages 4 1 A and 4 1 B, and the seal member 44 A is fitted and fixed to the bore of the crank case 19 facing the outer periphery of the front part of the crank shaft 4. Further, a labyrinth seal 43a for communicating the balancer chamber 40a of the front balancer 18A with the crank chamber 42 adjacent thereto is provided on the inner periphery of the seal member 44A.

Claims (7)

[Claims] 1. A crank compression type two-stroke engine for introducing an air-fuel mixture containing fuel and lubricating oil into a combustion chamber after compressing the air-fuel mixture by a change in volume of the crank chamber, the balancer rotating in association with a crankshaft; A two-stroke engine including an oil pump that supplies lubricating oil to the balancer, wherein a balancer chamber that houses the balancer and a crank chamber communicate with each other via a labyrinth seal provided on an outer periphery of the crankshaft. 2. A two-stroke engine of a crank compression type for compressing an air-fuel mixture containing fuel and lubricating oil by a change in volume of a crank chamber and then introducing the compressed air into a combustion chamber, wherein the plurality of balancers rotate in conjunction with a crankshaft. And a balancer chamber for accommodating each balancer, and an oil pump for supplying lubricating oil to one balancer, and a communication path for sequentially supplying lubricating oil from the one balancer chamber to another balancer chamber is formed, A labyrinth seal is provided between the most downstream balancer chamber and the crank chamber 2
Cycle engine. 3. A two-stroke engine of a crank compression type for introducing an air-fuel mixture containing fuel and lubricating oil into a combustion chamber after compressing the air-fuel mixture by changing the volume of the crank chamber, wherein the plurality of balancers rotate in conjunction with a crankshaft. A plurality of balancer chambers for accommodating each balancer, and a single oil pump for supplying lubricating oil to each balancer. Each of the balancer chambers and the crank chamber is provided via a labyrinth seal provided on the outer periphery of the crankshaft. Two-cycle engine that communicates with 4. The two-stroke engine according to claim 2, wherein the balancer is disposed apart from the crankshaft in the axial direction. 5. The method according to claim 1, wherein
A two-stroke engine, wherein the rotation center of the balancer is located above the crankshaft center. 6. The method according to claim 1, wherein the number of cylinders is three,
A two-stroke engine in which the balancer is provided at a position corresponding to a front part and a rear part of a crankshaft. 7. A two-stroke engine according to claim 2 for driving a propulsion device, wherein the crankshaft center of the engine matches the longitudinal direction of the hull, and the one balancer extends along the crankshaft. Is a small planing boat located ahead of other balancers.