JP2999448B2 - Forced lubrication two-stroke engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a two-stroke engine having a function of forcibly lubricating an auxiliary machine rotating in conjunction with a crankshaft and an auxiliary machine driving gear.

[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.
Auxiliary equipment such as balancers and magneto rotors that rotate in conjunction with the crankshaft, and auxiliary equipment driving gears such as starter gears,
A storage chamber for accommodating these auxiliary equipment and auxiliary equipment driving gears is provided, and the air-fuel mixture introduced into the crank chamber is guided from the crank chamber to the storage chamber to lubricate the auxiliary equipment and auxiliary equipment driving gears. Things are known. However, the lubrication mechanism of the two-stroke engine may have an insufficient lubrication amount. Further, since the crank chamber communicates with the storage chamber, the volume of the crank chamber is substantially increased, and accordingly, the precompression ratio of the compression of the air-fuel mixture into the crank chamber is reduced, and the output of the engine is reduced.

[0003] Separately, an oil bath type two-stroke engine for storing lubricating oil in a storage chamber is also known.
However, in this configuration, since the lubricating oil in the storage chamber is consumed with use, it is necessary to check the liquid level of the lubricating oil in the storage chamber and replenish the lubricating oil, which requires a lot of maintenance. Also, depending on the mounting condition of the engine, the level of the lubricating oil may not be easily confirmed.

In these two-cycle engines,
In particular, since lubrication of the bearings at the ends of the crankshaft and the large end bearings, which require high lubricity, is normally lubricated by an air-fuel mixture, these parts cannot be maintained in an appropriate lubricating state.

Further, there is known a configuration in which lubricating oil is supplied to a storage 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 rotary shaft of an oil pump (Japanese Utility Model Application Laid-Open No. 63-177607), but lubricating oil is not sufficiently supplied to gear surfaces of auxiliary machines and the like.

In order to solve the problem of the conventional lubrication mechanism, the present applicant first supplies lubricating oil to the storage chamber by an oil pump, and at the same time through a labyrinth seal provided on the outer periphery of the crankshaft. (Japanese Patent Application No. Hei 9-175964) proposes that the storage chamber communicates with the crank chamber to allow the lubricating oil accumulated in the storage chamber to flow into the crank chamber via the labilance seal when the crank chamber is in a negative pressure state. . However, in this prior application, when water enters the crankcase, the water may flow into the storage chamber through the labyrinth seal and mix with the lubricating oil.

Accordingly, the present invention provides a two-stroke engine capable of properly maintaining a precompression ratio in a crankcase, smoothly supplying lubricating oil, and maintaining an appropriate lubrication state of an auxiliary device and an auxiliary device driving gear. It is intended to provide.

[0008]

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 chamber compression type, a housing chamber for housing the auxiliary or accessory drive gear rotates is gear connected to the crankshaft, the accessory or accessories in the housing chamber
An oil pump for supplying lubricating oil for lubricating the machine drive gear; a communication passage provided in a partition wall between the housing chamber and the crank chamber to communicate the crank chamber with the housing chamber; A check valve that allows only the lubricating oil to flow from the chamber into the crank chamber.

According to this two-stroke engine, excess lubricating oil supplied from the oil pump and accumulated in the storage chamber is introduced into the crank chamber through the communication passage of the partition when the crank chamber is in a negative pressure state, and the mixture is mixed. Is consumed with
An appropriate amount of lubricating oil is always ensured in the storage chamber, and auxiliary equipment such as balancers and auxiliary equipment driving gears such as balancer driving gears can be maintained in an appropriate lubricating state. Absent. Therefore, it is possible to reduce a mechanical loss and a rise in lubricating oil temperature caused by stirring the lubricating oil by the auxiliary device and the auxiliary device driving gear. Further, since the check valve closes when the crank chamber is in the positive pressure state, the pre-compression ratio of the air-fuel mixture in the compression of the crank chamber is not reduced, and the output of the engine is not reduced. Further, even if water enters the crank chamber, the action of the check valve prevents the water from entering the housing chamber and mixing with the lubricating oil. Further, maintenance such as lubricating oil replenishment and inspection as in the oil bath method is not required, and the structure is simplified.

[0010] 2-cycle engine according to claim 2, also a crankcase compression type, a housing chamber for housing the auxiliary or accessory drive gear rotates is gear connected to the crankshaft, the said accommodating chamber Auxiliary equipment or auxiliary gear drive gears
An oil pump that supplies lubricating oil that slides, a communication path that communicates the two chambers through respective outer walls of the housing chamber and the crank chamber, and a communication path that is provided in the communication path and that transfers the lubricating oil from the storage chamber to the crank chamber A check valve that allows only inflow is provided. According to this two-stroke engine, in addition to the same operation and effect as in the first aspect, since the housing chamber and the crank chamber communicate with each other through their outer walls, there is an advantage that the communication path can be simply configured.

Further, the two-stroke engine according to claim 3 is:
3. The communication path according to claim 1, wherein, among the gears housed in the housing chamber and constantly rotating during the rotation of the engine, the communication path is arranged at a position higher than the lowermost part of the lowest gear. According to this two-stroke engine, even if lubricating oil flows from the housing chamber to the crank chamber through the communication passage, the level of the lubricating oil in the housing chamber does not become lower than the lowest part of the lowest gear. Therefore, the lubricating oil accumulated in the storage chamber can be reliably scraped up by the gear, and the auxiliary equipment and the auxiliary drive gear in the storage chamber can be appropriately lubricated.

Further, the two-stroke engine of claim 4 is
Oite to claim 1, bearing portion of the crankshaft provided in the partition wall, the bearing to the crank chamber side of the bearing portion, an oil seal is arranged in the housing chamber side, a space is provided between the two The other end of the communication passage having one end opened to the storage chamber is opened to the space. According to this two-stroke engine, since the lubricating oil flowing from the housing chamber into the crank chamber passes through the bearing part of the crankshaft, it is possible to keep the bearing part of the crankshaft, which requires high lubrication, in an appropriate lubricating state. it can.

Further, the two-stroke engine according to claim 5 is:
In any one of claims 1 to 3, further comprising an intake passage through which the air-fuel mixture flows from the outside of the crankcase toward the large end of the connecting rod in the crankcase, a reed valve is disposed in the intake passage, The other end of the communication passage, one end of which opens to the storage chamber, opens to a flow passage from the reed valve to the crank chamber in the intake passage. According to this two-stroke engine, the lubricating oil flowing from the housing chamber into the crank chamber is supplied to the large end of the crankshaft via the intake passage, so that the large end of the connecting rod that requires high lubrication is required. The bearing can be kept in an appropriate lubrication state.

[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 a first embodiment of the present invention, and FIG. 2 is a plan view showing an installation state of each device except for the 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 24 arranged in series.
The engine 3 is mounted on the hull 2 a in such a direction that the axis of the crankshaft 4 coincides with the longitudinal direction of the hull 2. A propulsion shaft 6 is connected to the crankshaft 4 of the engine 3 via a coupling 5, and is disposed at the rear end of the engine 3 and the hull 2 via the crankshaft 4, the coupling 5 and the propulsion shaft 6. A propulsion device (water jet pump) 7 is rotatably connected to the propulsion device 7, and the propulsion device 7 is rotationally driven by the engine 3 to eject water from the nozzle 8 to obtain a propulsion force. The steering nozzle is not disclosed.

The exhaust gas from the engine 3 is supplied to a muffler section 9.
The exhaust gas guided to the water muffler 11 arranged in the hull 2 by the exhaust pipe 10 having
2 and is discharged to the rear of the hull 2. 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 personal watercraft when the engine is installed as viewed from the stern side, and FIG. 4 is a partially cutaway side view of the engine 3 as viewed from the port side. As shown in FIG. 4, the engine 3 includes an in-line three-cylinder engine main body 21,
There are front and rear storage chambers 55a and 55b for storing auxiliary equipment and auxiliary equipment driving gears rotatably connected to the crankshaft 4. The balancer 22A and the magnet rotor 57 are provided as accessories in the front storage chamber 55a, and the balancer driving gear 43a and the starter gear 6 are provided as accessory driving gears.
2 are provided. In the rear storage chamber 55b, a balancer 22B paired with the front balancer 22A is provided as an accessory, and a balancer driving gear 43b is provided as an accessory driving gear. The two balancers 22A and 22B suppress vibration of the engine body 21. As shown in FIG. 3, these balancers 22A and 22B are arranged such that the rotation center C1 is located above the axis C2 of the crankshaft 4.

On the upper part of the crankcase 23 of the engine body 21, the cylinder 24 extending obliquely upward on one side (in this example, on the starboard side) from the axis C2 of the crankshaft 4;
An intake introduction device 25 extending diagonally upward on the other side is arranged in a V-shape. The intake air introduction device 25 has a water trap structure, has an air intake device 27 that takes in air from a diagonally downwardly directed intake port 26, a carburetor 28, and an intake reed valve 29. The fuel is mixed, the lubricating oil is mixed downstream from a lubricating oil supply passage (not shown), and the mixture is supplied to the crank chamber 54. The air-fuel mixture entering the crank chamber 54 is compressed in the crank chamber 54 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 disposed between a V-shaped structure composed of a cylinder 24 and an intake introducing device 25. 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 30 and a web 3 are attached to a piston (not shown) reciprocating in the cylinder 24.
The crankshaft 4 connected via 1 is rotatably supported inside the crankcase 23 via a plurality of bearings 65. In addition, three intake reed valves 29 corresponding to the respective cylinders are mounted inside the crankcase 23 side by side in the axial direction of the crankshaft 4. The intake reed valve 29 is provided in an intake passage 49 for introducing the air-fuel mixture from the outside to the inside of the crank chamber 54.
The air-fuel mixture is introduced into the crank chamber 54 from between a pair of webs 31 corresponding to the respective cylinders. Therefore, the air-fuel mixture that has passed through the intake passage 49 goes to the large end 50 of the connecting rod 30 located between the pair of webs 31. The two balancers 22A, 22
B includes balancer weights 36a and 36b and balancer rotating shafts 37a and 37b for supporting these respectively.
And the balancer gears 38a and 38b are integrally formed.

The front balancer 22A is disposed further forward than the front-end cylinder web 31 and covers the crankcase 23 and a generator that covers the front end face of the crankcase 23 via the front balancer rotation shaft 37a. The pair of bearings 41 held by the cover 40 allows the crankshaft 4
It is rotatably supported in parallel with. Rear balancer 2
2B is disposed further rearward than the web 31 of the rear end cylinder, and a pair of a pair of cylinders 23 held by the crankcase 23 and a cover 39 covering the rear end face of the crankcase 23 via a balancer rotation shaft 37b at the rear end. With the bearing 42,
It is rotatably supported in parallel with the crankshaft 4.

The front balancer 22A rotates on the crankshaft 4 because the balancer gear 38a meshes with a balancer driving gear 43a integrally formed on a boss 45 fixed to the front end of the crankshaft 4 with bolts 44. Are linked. The balancer 22B at the rear portion has the balancer gear 38b meshed with the balancer driving gear 43b attached to the rear end of the crankshaft 4, so that the crankshaft 4B
Is rotationally connected. Therefore, both balancers 22
A and 22B rotate in the opposite direction to the crankshaft 4, respectively.

The boss 45 has a balancer driving gear 4
3a are provided integrally, and a magneto rotor 57 is further mounted. Behind the boss 45, a starter gear 62 is rotatably mounted on the crankshaft 4 via a bearing (not shown). The starter gear 62 is gear-connected to a starter S mounted outside the crankcase 23 at the time of start. The generator cover 40 includes
A stator 58 is provided at a position concentric with the magneto rotor 57, and a generator 59 is formed by the magneto rotor 57 and the stator 58.

An oil pump 52 for supplying the lubricating oil LO in the oil tank 51 to the front and rear storage chambers 55a and 55b via the supply passages 53a and 53b is provided in front of the front balancer 22A. This oil pump 52 is
It is driven using the balancer rotating shaft 37a as a drive source. The oil tank 51 is disposed above the fuel tank 13 as shown in FIG. Storage chamber 5 of supply passages 53a, 53b
Openings 60a and 60b to 5a and 55b are provided above the balancers 22A and 22B, as shown in FIG. As a result, the lubricating oil LO supplied into the storage chambers 55a and 55b via the supply passages 53a and 53b is poured into the balancers 22A and 22B, and then is supplied to the storage chambers 55a and 55B.
accumulates at the bottom of b.

A partition 64a for partitioning the front housing chamber 55a and the adjacent crank chamber 54 shown in FIG. 4 is provided with a bearing 64a. The bearing portion 64a includes a bearing 65 and an oil seal 66, and a space 67 therebetween.
, The bearing 65 is located on the crank chamber 54 side, and the oil seal 66 is located on the housing chamber 55a side. The front end of the crankshaft 4 is rotatably supported with respect to the crankcase 23 by the bearing portion 64a.

A communication passage 68a is formed in the partition wall 63a to communicate the inside of the housing chamber 55a with the crank chamber 54. One end of the communication passage 68a opens to the accommodation chamber 55a,
The other end is open to the space 67 of the bearing portion 64a. In the communication passage 68a, there is provided a check valve 69 that allows only the fluid to flow from the storage chamber 55a to the crank chamber 54. This check valve 69 is, as shown in FIG.
For example, a ball-shaped valve body 69a and a spring 69b for urging the valve body 69a against a valve seat 69c located on the side of the storage chamber 55a
And

Further, as shown in FIG. 3, the communication passage 68a is housed in the front housing chamber 55a and constantly rotates during operation of the engine, that is, the gears 38a and 43a excluding the starter gear 62. , The lowest gear 43a
Is located at a position higher than the lowermost portion (lower tooth portion). Thus, even if the lubricating oil LO in the front housing chamber 55a flows into the crank chamber 54 from the communication passage 68a, the level of the lubricating oil LO in the housing chamber 55a is the lowest.
a is not lower than the lowermost part of the gear 43a.
As a result, the lubricating oil LO in the storage chamber 55a can be reliably scraped up, and the lubrication of the auxiliary equipment and the auxiliary device driving gears in the storage chamber 55a can be guaranteed.

As in the case of the front partition 63a, a bearing portion for supporting the rear end of the crankshaft 4 is also provided on the partition 63b separating the rear storage chamber 55b and the adjacent crank chamber 54 shown in FIG. 64b is provided, and the partition 63b includes:
A communication passage 68b is formed, one end of which opens into the accommodation chamber 55b and the other end opens into the space 67 of the bearing portion 64b. This communication passage 68b is also arranged at a position higher than the lowermost part of the lowermost gear 43b in the rear storage chamber 55b, and a check valve 69 is provided in the communication passage 68b. Thus, the lubricating oil LO stored in the rear storage chamber 55b can be reliably scraped up by the gear 43b.

In the two-stroke engine 3 configured as described above, the lubricating oil LO supplied to the front storage chamber 55a and the rear storage chamber 55b by the oil pump 52 causes auxiliary equipment such as the balancers 22A and 22B and the balancer The accessory driving gears such as the driving gears 43a and 43b and the starter gear 62 are lubricated. Further, the level of the lubricating oil LO accumulated in the storage chambers 55a and 55b is
When the opening heights of the a and 68b reach the storage chambers 55a and 55b, the check valve 69 in the communication passages 68a and 68b is opened when the piston rises and the crank chamber 54 is in a negative pressure state. The bearing portions 64 from the storage chambers 55a and 55b
a and 64b are sucked into the crank chamber 54. Further, the sucked lubricating oil LO mixes with the air-fuel mixture in the crank chamber 54 to lubricate the crankshaft 4, the piston, the sliding portion of the cylinder, and the like. When this occurs, it is pumped to the combustion chamber above the piston together with the air-fuel mixture and consumed.

As described above, when the amount of the lubricating oil LO in the storage chambers 55a and 55b exceeds an appropriate amount, the lubricating oil LO is sucked into the crank chamber 54 and consumed. It is possible to prevent the temperature of the lubricating oil LO from rising due to the stirring of the driving gear and the like, and to prevent the mechanical loss of the auxiliary driving gear and the like from increasing. Further, since the lubricating oil LO is injected into the crank chamber 54 via the bearing portions 64a and 64b of the crankshaft 4, the bearing portions 64a and 64b at both shaft ends of the crankshaft 4 where high lubricity is required are appropriately adjusted. Can be lubricated. Also, unlike the oil bath method, the accommodation room 5
Since the lubricating oil LO in 5a and 55b can be maintained at an appropriate amount,
Maintenance such as checking and replenishing the liquid level of the lubricating oil LO becomes unnecessary.

The crank chamber 54 and the storage chambers 55a, 55
5b is communicated with and interrupted by a check valve 69 in the communication passages 68a and 68b, the inside of the crank chamber 54 is in a positive pressure state,
That is, when the pressure is higher than the pressure in the accommodation chambers 55a and 55, which is the atmospheric pressure, the pressure is shut off, so that the preload ratio of the crank chamber 54 can be appropriately maintained. Moreover, even if water enters the crank chamber 54 from the intake passage 49 or the like, the water does not enter the storage chambers 55a and 55b through the communication passages 68a and 68b because the check valve 69 is provided. Furthermore, the engine 3 has a structure in which the two balancers 22A and 22B 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 part of the personal watercraft 1 and the like are provided. Installation of the engine in a narrow space becomes easier.

The engine 3 is an in-line three-cylinder engine, and the phases of the cylinders are different by 120 °, so that the mass of the rotating part around the crankshaft is balanced in a symmetrical arrangement, and the piston shaft due to the reciprocating mass of the piston or the like. The vibrating force in the direction of the center becomes the largest vibration source, and the vibrating force of the cylinders located at the front and rear ends generates a moment that causes the entire engine to pitch and vibrate. (The phase of the weight part is different by 180 °) Balancer 2
Since the 2A and 22B generate moments of the same magnitude in opposite phases to the moments of the corresponding cylinders, pitching vibrations can be canceled and the balance of the engine 3 is improved.

FIG. 6 shows a partial longitudinal sectional view (a sectional view taken along the line AA in FIG. 7) of the engine according to the second embodiment of the present invention.
In this embodiment, in the engine of the previous embodiment,
For example, it is located at a position separated from the bearing portion 64a of the partition wall 63a that separates the front housing chamber 55a and the crank chamber 54 from the bearing portion 64a, and is substantially the same as the crankshaft 4 as shown by a chain line in FIG. A communication passage 68a is formed at the height position in the horizontal direction. At a position separated from the bearing portion 64a toward the outer peripheral side, as shown in FIG. 6, the thickness of the partition wall 63a is thin, so that the communication passage 68a can be short.
On the crank chamber 54 side, there is provided a check valve 73 comprising an elastic spring piece 73a for opening and closing the opening of the communication passage 68a. A similar communication passage 68b is also formed in a partition 63b that partitions the rear housing chamber 55b and the crank chamber 54. Other configurations are the same as those of the first embodiment.

According to this configuration, as in the case of the first embodiment, the space 6 of the bearing portions 64a and 64b of the crankshaft 4 is formed.
7 does not open one ends of the communication passages 68a, 68b,
The formation of the communication passages 68a, 68b to the partition walls 63a, 63b is facilitated. Further, since it is not necessary to secure the space 67 in the bearing portions 64a and 64b, the axial dimension of the bearing portions 64a and 64b can be shortened.

FIG. 8 is a partial longitudinal sectional view of an engine according to a third embodiment of the present invention, and FIG. 9 is a rear view of the installed state of the engine viewed from the stern side. In this embodiment, in the engine of the first embodiment, for example, the opening on the crank chamber 54 side of the communication passage 68a formed in the partition 63a separating the front housing chamber 55a and the crank chamber 54 is indicated by a chain line in FIG. As shown by the arrow, the air-fuel mixture flows in a direction from the intake reed valve 29 to the crank chamber 54 in the adjacent crank chamber 54 in which the air-fuel mixture flows in the direction toward the large end 50 of the connecting rod 30. The provision of the check valve 69 in the communication passage 68a is the same as in the first embodiment. The same applies to the case of the communication passage 68b formed in the partition wall 63b that separates the rear storage chamber 55b and the adjacent crank chamber 54.

For the center crank chamber 54, the crank chamber 54 and one of the housing chambers, for example, the rear housing chamber 5
8 through the outer walls of both chambers 54 and 55b, as shown by broken lines in FIG. 8, through a communication pipe 78 outside the engine instead of the communication passages 68a and 68b in the previous embodiment. 78 may be opened in the flow path from the central intake reed valve 29 to the crank chamber 54. Providing the check valve 69 in the communication pipe 78 is equivalent to providing the communication passages 68a and 68 formed in the partition walls 63a and 63b.
This is the same as in the case b.

According to this configuration, since the lubricating oil LO flowing from the housing chamber 55a into the crank chamber 54 passes through the large end 50 of the connecting rod 30, the large end bearing that requires high lubricity is properly lubricated. it can.

In each of the above embodiments, the accommodation chamber 55
communication passages 68a, 68b formed in partition walls 63a, 63b separating the adjacent crank chambers 54a, 55b from each other.
However, instead of this, as shown in FIG. 10, a communication pipe 7 horizontally arranged outside the engine is used.
In step 9, the crank chamber 54 may communicate with the storage chamber 55a. In this case, the nipples 83 and 84 are connected to the outer walls 81 and 82 of the two chambers, and the ends of the communication pipe 79 are fitted into the nipples 83 and 84 and fastened with the clamps 85, thereby connecting the communication pipe 79 to the outer walls 81 and 82. Attach to 82. The check valve 69 includes, for example, one nipple 83
Provided within. FIG. 10 shows both the front housing chamber 55a and the adjacent crank chamber 54, but the same applies to the rear housing chamber 55b and the adjacent crank chamber 54. As for the center crank chamber 54 shown in FIG.
5a or 55b can be communicated with a similar structure.

According to this configuration, the accommodation chambers 55a, 55b
And the crank chamber 54 are communicated by the external communication pipe 79, so that the check valve 69 can be easily attached, and the assembling and maintenance are easier than in the case where communication paths are formed in the partition walls 63a and 63b.

Further, as a structure for communicating the storage chamber 55a or 55b and the crank chamber 54, as shown in FIG. 11, the opposed portions of the outer walls 81, 82 straddling both chambers are made thick,
In this thick portion, a communication passage 89 that connects the two chambers may be formed.

T-shaped passages 91 and 92 are formed in the thick portions of the outer walls 81 and 82, and the crankshaft 4 of each passage 91 and 92 is formed.
Are aligned at the joint end surfaces of the outer walls 81 and 82. Outer portions of the passage portions 91b and 92b penetrating the outer walls 81 and 82 of the passages 91 and 92 are closed by blind members 93, respectively, so that the communication passage 89 has an overall U-shape. Check valve 6 in communication passage 89
The provision of 9 is the same as in the first and third embodiments. A similar structure is used for communication between the rear storage chamber 55b and the rear crank chamber adjacent thereto.

According to this configuration, since there is no need to provide a pipe outside the crankcase 23, the communication passage 89 can be formed compactly.

In the above embodiments, the lubricating oil LO is supplied to the front and rear storage chambers 55a and 55b,
Although the case where the communication passages 5a and 55b communicate with the crank chamber 54 adjacent thereto is shown, the supply of the lubricating oil LO to the rear storage chamber 55b may be omitted in some cases.

[0044]

As described above, according to the two-stroke engine of the present invention, the lubricating oil LO supplied from the oil pump and stored in the storage chamber passes through the communication passage of the partition when the crank chamber is in a negative pressure state. As it is injected into the crank chamber and consumed together with the air-fuel mixture, an appropriate amount of lubricating oil LO is always secured in the storage chamber, and auxiliary equipment such as the balancer and gears for driving the auxiliary equipment are maintained in an appropriate lubricating state. As a result, the lubricating oil LO does not accumulate excessively. Therefore, it is possible to reduce a mechanical loss and an increase in lubricating oil LO temperature caused by stirring the lubricating oil LO by the auxiliary machine and the auxiliary driving gear. Even if water enters the crank chamber, the check valve provided in the communication passage prevents the water from entering the housing chamber and mixing with the lubricating oil. Further, the lubricating oil L as in the oil bath system
Maintenance such as O replenishment and inspection is unnecessary, and the structure is simplified.

[Brief description of the drawings]

FIG. 1 is a side view showing a personal watercraft equipped with a two-stroke engine according to a first 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 rear view showing the 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 a second embodiment of the present invention.

FIG. 7 is a partially cutaway rear view of the two-stroke engine.

FIG. 8 is a partially broken side view of a two-cycle engine according to a third embodiment of the present invention.

FIG. 9 is a partially cutaway rear view of the two-stroke engine.

FIG. 10 is a partially enlarged sectional view of a two-stroke engine according to a fourth embodiment of the present invention.

FIG. 11 is a partially enlarged sectional view of a two-stroke engine according to a fifth embodiment of the present invention.

[Explanation of Signs] 3 ... 2-cycle engine, 4 ... Crankshaft, 22A, 2
2B: balancer (auxiliary equipment), 29: intake reed valve, 43
a, 43b: Balancer driving gear (accessory driving gear),
49: intake passage, 50: large end, 52: oil pump,
54: crank chamber, 55a, 55b: accommodation chamber, 57: magneto rotor (auxiliary equipment), 62: starter gear (auxiliary equipment driving gear), 63a, 63b: partition, 64a, 64b: bearing part, 65: bearing, 66 ... oil seal, 67 ... space,
68a, 68b, 89 ... communication passage, 69, 73 ... check valve,
78, 79: communication pipe (communication passage), OL: lubricating oil.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Takada 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Inside the Akashi factory (56) References JP-A-5-71326 (JP, A) 62-191608 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01M 3/00 F02B 67/00-67/04

Claims (5)

(57) [Claims] 1. A two-stroke engine of a crankcase compression type wherein a mixture containing fuel and lubricating oil is compressed by a change in volume of a crankcase and then introduced into a combustion chamber. An accommodating chamber for accommodating the machine or accessory driving gear, and lubricating the accessory or the accessory driving gear in the accommodating chamber .
An oil pump for supplying lubricating oil, a communication passage provided in a partition wall between the housing chamber and the crank chamber, and communicating with the crank chamber and the housing chamber;
A two-stroke engine including a check valve that allows only the lubricating oil to flow. 2. A two-stroke engine of a crankcase compression type wherein a mixture containing fuel and lubricating oil is compressed by a change in the volume of the crankcase and then introduced into the combustion chamber. An accommodating chamber for accommodating the machine or accessory driving gear, and lubricating the accessory or the accessory driving gear in the accommodating chamber .
An oil pump for supplying a lubricating oil, a communication passage communicating the two chambers through respective outer walls of the housing chamber and the crank chamber,
A two-stroke engine including a check valve that allows only the lubricating oil to flow. 3. The communication path according to claim 1, wherein the communication path is arranged at a position higher than a lowermost part of a lowest gear among gears housed in the housing chamber and constantly rotating during engine operation. Two-stroke engine. 4. Oite to claim 1, a bearing portion of the crank shaft is provided in the partition wall, bearing in the crank chamber side of the bearing portion, an oil seal is arranged in the housing chamber side, both A two-stroke engine in which a space is provided therebetween, and the other end of the communication passage having one end opened to the accommodation chamber is open to the space. 5. The intake passage according to claim 1, further comprising an intake passage through which an air-fuel mixture flows from the outside of the crankcase toward the large end of the connecting rod in the crankcase. A two-stroke engine in which a valve is disposed, and one end of the communication passage having one end opened to the storage chamber is opened to a flow passage from the reed valve to the crank chamber in the intake passage.