JPH09287474A - Crankcase-supercharged engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce adverse effects on an engine by reducing the inflow amount of lubricating oil into a combustion chamber to prevent the increase of oil consumption. SOLUTION: A crankcase-supercharged engine leads fresh air pressurized in a crankcase 21c through a pressurized-air intake passage, an intake port and an intake valve at the end of the intake port into a combustion chamber, and emits exhaust gas from the combustion chamber through an exhaust valve, an exhaust port and an exhaust passage into the atmosphere, while supplying lubricating oil to sliding areas between a cylinder C and a piston 24. A pressurized-fresh air outlet of the crankcase 21c to the pressurized-air intake passage is provided in the upper part of the crankcase 21c, above the lowermost part at the connection between the cylinder C and the crankcase 21c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharged engine in a crankcase in which fresh air is supercharged in a crankcase and the supercharged fresh air is guided from the crankcase to a combustion chamber.

[0002]

2. Description of the Related Art In recent years, for the purpose of improving engine output, a supercharging device having a connecting rod supercharging mechanism for compressing air drawn into a crank chamber by swinging a connecting rod and supplying the compressed air to a combustion chamber. Has been proposed (for example,
See JP-A-6-93869). A supercharging device including this connecting rod supercharging mechanism and a piston supercharging mechanism that compresses air sucked into the crank chamber by reciprocating pistons is called a crank chamber supercharging device.

In such a crank chamber supercharged engine, since the crank chamber cannot have a closed structure, oil can be stored in an oil pan below the crank chamber and circulated as in a so-called four-cycle engine. Instead, a small amount of lubricating oil was supplied directly to the lubrication-needed part in the crank chamber or mixed with fresh air and supplied.

[0004]

In such a crank chamber supercharged engine, when lubricating oil flows from the crank chamber into the combustion chamber through the pressurized intake passage, the lubricating oil is difficult to vaporize and cannot be completely combusted. In this case, the piston ring may become stuck and exhaust emissions may be deteriorated due to incomplete combustion. Further, if the spark plug becomes a tulle and adheres to the spark plug, the spark may be weakened, resulting in misfire and deterioration of engine performance. In the first place, the lubricating oil flowing into the combustion chamber is burned and consumed. Therefore, if the amount of inflow into the combustion chamber increases, the amount of lubricating oil consumed increases, which is not economical. Particularly in a supercharged engine, there is a problem that the amount of fresh air flowing out from the crank chamber is large, the amount of lubricating oil flowing out from the crank chamber is large, and the amount of lubricating oil consumed tends to increase.

The present invention has been made in view of the above circumstances, and first of all, it is possible to reduce the inflow amount into the combustion chamber to prevent the lubricating oil consumption from increasing and to reduce the adverse effect on the engine. Secondly, the lubricating oil consumption is positively reduced by collecting the lubricating oil staying in the crank chamber. Thirdly, the supercharging tank is used to reduce the pressure fluctuation of the pressurized fresh air. A crank that can positively reduce the amount of lubricating oil consumed by functioning as a means for preventing the lubricating oil from flowing into the combustion chamber, and fourthly by collecting the lubricating oil that accumulates in the supercharging tank. It is intended to provide an indoor supercharged engine.

[0006]

In order to solve the above-mentioned problems and achieve the first object thereof, the invention according to claim 1 is
The fresh air pressurized in the crank chamber is guided to the combustion chamber through the pressurized intake passage, the intake port, and the intake valve at the end of the intake port, and is exhausted from the combustion chamber to the atmosphere through the exhaust valve, the exhaust port, and the exhaust passage. In the crank chamber supercharged engine in which the lubricating oil is supplied to the sliding portion between the cylinder and the piston, the pressurized new airflow outlet of the crank chamber to the pressurized intake passage is connected to the cylinder and the crank. It is characterized in that it is provided in the upper part of the crank chamber above the lowermost part of the connecting portion with the chamber.

By providing the pressurized fresh air flow outlet of the crank chamber above the lowermost part of the connecting portion between the cylinder and the crank chamber, the inflow amount from the pressurized fresh air flow outlet to the combustion chamber is reduced. It is possible to prevent the consumption of lubricating oil from increasing and reduce the adverse effect on the engine.

According to a second aspect of the present invention, similarly, in order to achieve the first object, fresh air pressurized in the crank chamber is burned through the pressurized intake passage, the intake port, and the intake valve at the end of the intake port. The exhaust gas from the combustion chamber to the atmosphere through the exhaust valve, the exhaust port and the exhaust passage, while supplying lubricating oil to the crankshaft support bearing and lubricating the crankshaft support bearing. In a supercharged crank chamber engine that lubricates lubrication points in the crank chamber, the pressurized new airflow outlet of the crank chamber to the pressurized intake passage is fed to the crankshaft support bearing by lubricating oil after lubrication. It is characterized in that it is provided in the upper part of the crank chamber above the part that flows into the room.

By providing the pressurized fresh air flow outlet of the crank chamber above the portion where the lubricating oil after the lubrication of the crankshaft support bearings flows into the crank chamber, the lubricating oil flowing into the crank chamber is discharged from the pressurized fresh air flow outlet. It is possible to prevent outflow in the combustion chamber direction, reduce the inflow amount into the combustion chamber, suppress an increase in the lubricating oil consumption amount, and reduce adverse effects on the engine.

In order to achieve the first object, fresh air is introduced into the crank chamber, and the fresh air pressurized in the crank chamber is pressurized by an intake passage, an intake port, and an intake port. Leads to the combustion chamber through the intake valve at the end, exhausts the exhaust gas from the combustion chamber to the atmosphere through the exhaust valve, the exhaust port and the exhaust passage, and lubricates the fresh air at the upstream side of the new airflow inlet of the crank chamber. In a crank chamber supercharged engine in which oil is mixed and lubrication is carried out in the crank chamber by means of this lubricating oil, the pressurized new air flow outlet of the crank chamber to the pressurized intake passage is The feature is that it is provided above the crank chamber above the air flow inlet.

By providing the pressurized new airflow outlet of the crank chamber above the new airflow inlet, it is possible to prevent the amount of inflow from the pressurized new airflow outlet to the combustion chamber and increase the consumption of lubricating oil. The adverse effect on the engine can be reduced.

According to a fourth aspect of the present invention, in order to achieve the first and third objects, a supercharging tank for reducing the pressure change of the pressurized air from the crank chamber in the middle of the pressurized intake passage. Is provided, and the position of the outlet of the pressurized air from the supercharging tank is located above the inlet of the pressurized air to the supercharging tank.

Not only is the supercharging tank used to reduce the pressure fluctuations of the pressurized fresh air, but also the position of the outlet is located above the inlet of the pressurized air, so that It can function as a lubricating oil inflow prevention means to prevent the amount of lubricating oil from flowing into the combustion chamber and increase the amount of lubricating oil consumed, and reduce the adverse effects on the engine.

In order to achieve the first and second objects of the present invention, a lubricating oil return pipe is connected to the lower portion of the crank chamber to circulate the lubricating oil from the lower portion of the crank chamber. It is characterized by having done.

By circulating the lubricating oil and collecting the lubricating oil retained in the crank chamber, the consumption of the lubricating oil can be positively reduced.

In order to achieve the first and fourth objects of the present invention, an oil drain valve is provided in the lower portion of the supercharging tank or a lubricating oil return pipe is provided to circulate the lubricating oil. It is characterized by doing so.

By collecting the lubricating oil accumulated in the supercharging tank, the consumption of lubricating oil can be positively reduced. The configurations of claims 5 and 6 may be adopted at the same time.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a crank chamber supercharged engine of the present invention will be described below with reference to the accompanying drawings. 1 to 6 are views for explaining a scooter type motorcycle equipped with a crank chamber supercharged engine according to an embodiment of the present invention, and FIGS. 1 to 3 are side views of the embodiment, respectively. FIG. 4 is a plan view, a rear view, FIG. 4 is a side view of the scooter-type motorcycle of this embodiment, and FIGS. 5 and 6 are schematic views showing the positional relationship of the supercharger component parts and the air flow.

In this specification, left and right mean left and right as viewed in the vehicle traveling direction. In the figure, reference numeral 1 is a scooter type motorcycle of this embodiment, and a body frame 2 thereof is an underbone type motorcycle, and an upper end of a main frame 2b, which is substantially L-shaped in side view, is connected to a head pipe 2a. The front ends of the pair of left and right side frames 2c, 2c are connected to the lower end of the frame 2b, both side frames 2c are raised upward, and further extended rearward. A front fork 4 which pivotally supports the front wheel 3 at its lower end is pivotally supported to the left and right of the head pipe 2a, and a steering handle 5 is fixed to the upper end of the front fork 4. The periphery of the steering handle 5 is covered with a handle cover 6, and the periphery of the head pipe 2a is covered with a front cover 7 having a two-part structure of a front cover 7a and a rear cover 7b.

A footboard 8 constituting a footrest portion is provided at a connecting portion between the main frame 2b and the side frame 2c.
And side covers 9 are provided on the left and right sides of the side frame 2c. This side cover 9
The seat 10 is disposed on the upper part of the seat 10, and the storage box 11, the fuel tank 12 and the like are mounted below the seat 10. The unit swing type engine unit 15 is mounted near the lower part of the upper bent portion of the left and right side frames 2c.

The engine unit 15 includes an engine body 17 rotatably supported around a pivot shaft 16 by a pivot shaft 16 installed between the side frames 2c, 2c via a bracket 14, and the engine body 17. A rear wheel transmission 18 integrally formed on the left side of the rear wheel so as to extend rearward.
A belt drive type non-throwing speed change mechanism is built in 8, and a rear wheel 19 is pivotally supported at the rear end thereof. Also,
The lower end of the rear suspension 20 is pivotally supported on the upper surface of the rear end of the transmission case 18a of the rear wheel transmission 18, and the upper end of the rear suspension 20 is pivotally supported by the side frame 2c.

The engine body 17 is of a forced air-cooled, 4-cycle, single-cylinder type, in which a cylinder block 22 and a cylinder head 23 are connected to a crankcase 21,
The piston 24 is placed in the cylinder bore of the cylinder block 22.
Is slidably inserted and arranged, and the piston 24 is connected to the crank pin 26a of the crank shaft 26 by the connecting rod 25. Further, a drive pulley (not shown) is mounted on the left end of the crankshaft 26 that rotates counterclockwise (rotation in the direction of the arrow) in FIG. 6, and a forced cooling fan 51 that supplies cooling air to the engine body 17 is mounted on the right end. . The engine body 17 is surrounded by an air shroud 50. When the cooling air a sucked by the cooling fan 51 passes between the engine body 17 and the air shroud 50, the cylinder head 23 and the cylinder block 22. And the like, and is discharged from the outlet 50a. Note that 22a and 23c are a cylinder block cooling fin and a cylinder head cooling fin, respectively, for increasing the heat radiation area.

An exhaust pipe 28 is connected to the exhaust port 23a led out to the lower surface of the cylinder head 23, and a muffler 29 arranged on the right side of the rear wheel 19 is connected to the rear end of the exhaust pipe 28. There is. Further, the intake port 23b led out to the upper surface of the cylinder head 23 is provided with a third pressurizing intake pipe 30 forming a pressurizing intake passage.
And a carburetor 31 arranged on the upper surface of the cylinder block 22 is connected to the upstream end of the third pressurized intake pipe 30. An oil tank 32 is arranged on the right side of the vaporizer 31.

Further, the exhaust port 23a and the intake port 23
b is opened and closed by an exhaust valve 111 and an intake valve 110, and each valve 11
1, 110 are exhaust and intake side tappets 114, 113
It is opened and closed by the cam shaft 112 via the. Then, the engine unit 15 includes a connecting rod supercharging type supercharging device 33.
It has. The supercharging device 33 includes a connecting rod supercharging mechanism 33a, an air cleaner 35 for filtering air to the supercharging mechanism 33a, and compressed air supplied to the cylinder C by storing compressed air from the supercharging mechanism 33a. And a supercharging tank 37 that suppresses the pressure fluctuation. The supercharging device components 35 to 37 are all mounted on the unit swing type engine unit 15 so as to swing together with the unit 15.

The connecting rod supercharging mechanism 33a includes a connecting rod 25 on the inner peripheral wall of the crankcase 21, the left and right walls of the piston notch, and the left and right crank webs 26b.
The crankcase 2 is divided into a suction chamber A and a compression chamber B by making the outer surfaces of the crankcase face to each other in a sealed manner or sliding in contact with each other in order to ensure a tight seal.
1. A suction port 21a which forms a new air flow inlet communicating with the suction chamber A is formed in the lower left part of 1, and a discharge port 21b which forms a pressurized new air flow outlet communicating with the compression chamber B is formed in the upper right part. Has been done. This allows connecting rod 25
A positive displacement supercharging mechanism that compresses the sucked air by swinging the. Incidentally, such a structure is described in the above-mentioned JP-A-6-9.
It is described in detail in Japanese Patent No. 3869.

A lubricating device 100 is connected to the connecting rod supercharging mechanism 33a. This lubricating device 100 is
The lubricating oil from the oil tank 32 is transferred to the oil strainer 10
1 is suctioned and pressurized by the oil pump 102, and the pressurized lubricating oil is supplied to the sliding surfaces such as the piston 24, the connecting rod 25, the crank web 26b and the bearing portion of the crank shaft 26 via the delivery pipe 103, Further, of the supplied lubricating oil, the lubricating oil collected at the bottom of the crankcase 21 is collected by a lubricating oil return pipe 105 having a check valve 104 and is circulated for reuse.

Here, in the connecting rod supercharging mechanism 33a of this embodiment, the compression chamber having a high supercharging pressure is arranged on the upper side and the suction chamber is arranged on the lower side, and the air sucked from below the crankcase 21 is added. It is configured to press and discharge from above. Therefore, the lubricating oil supplied by the lubricating device 100 is easily and reliably separated from the compressed air by its own weight in the crank chamber, and it is possible to suppress the lubricating oil from being mixed into the pressurized air. Further, the separated lubricating oil also functions as a sealant for the sliding surface between the connecting rod or the like and the wall surface in the crankcase 21, improving the airtightness,
The boost pressure is high.

The air cleaner 35 has a substantially triangular shape in a side view, has an air cleaner element 35c therein, and has the cylinder block 22 and the cylinder head 2 in a plan view.
3 is disposed on the left side of the left side wall and at the front of the front wall of the transmission case 18a, and is fixed by bolting to the transmission case 18a and the crankcase 21. The suction port 35a of the air cleaner 35 is opened inside the side cover 9 toward the inside of the vehicle body, and the discharge port 35b is located at the lower part. The discharge port 35b is connected to the suction port 21a of the crankcase 21 by an air introducing pipe 40.

As described above, since the air passing through the air cleaner 35 flows from the top to the bottom and is introduced into the supercharging mechanism, it is possible to prevent the air cleaner element from being contaminated with the lubricating oil due to the blowback of the intake air from the crank chamber. Further, since the discharge port 35b of the air cleaner 35 is located near the suction port 21a of the supercharging mechanism, the passage length of the air introduction pipe 40 can be shortened and the suction resistance can be reduced accordingly. Therefore, the supercharging pressure becomes high, and the engine performance can be improved. Furthermore, since the suction port 35a of the air cleaner 35 is opened to the upper part inside the side cover 9,
It is possible to prevent rainwater or the like from entering the air cleaner 35.

Even if the supply of pressurized fresh air from the supercharger 33 and the outflow of fresh air to the combustion chamber are deviated in timing, the pressurized fresh air is stored in order to reduce the pressure change of the pressurized fresh air. The supercharge tank 37 is arranged between the rear transmission device 18 and the side frame 2c, and is bolted and fixed to the upper surface of the transmission case 18a. As a result, the supercharging tank 37 is located at substantially the same height as the carburetor 31. Supercharge tank 37
Has an inflow port 37a formed in the lower front wall thereof, and the first pressurizing intake pipe 42 is connected to the discharge port 21b of the crankcase 21. The discharge port 21b supplies pressurized air into the crankcase 21. A reed valve 115 for preventing backflow is provided. The first pressurized intake pipe 42 is integrally provided with an air cooling fin 42a which is a cooling unit for cooling the fresh air whose temperature has been increased by compression and compression. An outlet 37b is formed on the upper inner wall of the supercharging tank 37.
7b is connected to the carburetor 31 by a second pressurized intake pipe 45 arranged above the crankcase 21. As described above, since the supercharging tank 37 and the carburetor 31 have substantially the same height, the shape of the second pressurized intake pipe 45 can be simplified and the degree of freedom of the shape can be improved. Further, since the supercharging tank 37 is arranged on the transmission case 18a side, that is, on the side opposite to the muffler 29, even if the lubricating oil accumulated in the supercharging tank 37 oozes out to the plate, the muffler 29 will be splashed. In addition, the generation of white smoke can be prevented.

In the apparatus of this embodiment which operates in this manner, the air cleaner 35 and the supercharging tank 37 which constitute the supercharging device 33 are connected to the unit swing type engine unit 15.
Since the engine unit 15 is arranged and fixed to itself, the component parts 35 to 37 also swing at the same time as the engine unit 15 swings up and down, so that there is no relative movement between the component parts and the component parts 35 to 37.
It is not necessary to provide flexibility in connecting 7 to each other, and the wiring structure can be simplified. In addition, each pipe 4
A material and a shape having rigidity and strength can be adopted for 0, 42 to 45, and the mounting strength of the entire device can be improved.

The transmission case 18 of the air cleaner 35
a and a mounting portion to the crankcase 21 with a vibration proof rubber interposed therebetween, and / or the supercharge tank 37 is fixed to the upper surface of the transmission case 18a via a similar vibration proof rubber, and / or the carburetor 31 is also prevented. In the case of fixing to the cylinder block 22 via a vibrating rubber, the air introduction pipe 40 and / or the first pressurized intake pipe 42 and the second pressurized intake pipe 45,
Alternatively, and / or the second pressurized intake pipe 45 and the third pressurized intake pipe 30 need to have flexibility. But,
The air cleaner 35 and / or the supercharging tank 37 can be made smaller than the flexibility to be given to the air introduction pipe 40 and / or the first pressurized intake pipe 42 and the second pressurized intake pipe 45 when fixing to the side frame 2c. When the air introduction pipe 40 and / or the first pressurized intake pipe 42 and the second pressurized intake pipe 45 are largely deformed (for example, when passing through a large hollow passage), the output may be affected. Not desirable.

Further, since the respective component parts 35 to 37 are mounted on the unit swing type engine unit 15 itself, the air cleaner 35 is provided at the corner portion of the cylinder block 21 and the transmission case 18a, and the supercharge tank 37 is provided at the transmission case. The space around the engine, such as between 18a and the side frame 2c, can be effectively utilized and arranged intensively, and the entire engine including the supercharger can be made compact.

Next, the function and effect of this embodiment will be described.

In the supercharging device 33 of this embodiment, the air filtered by the air cleaner 35 is sucked into the crankcase 21 through the air introduction pipe 40 by the swing of the connecting rod 25 and is compressed, and the compressed air is 1 Pressurized intake pipe 4
It is pressure-fed to the supercharging tank 37 through 2 and stored. The compressed air in the supercharging tank 37 is supplied to the second pressurized intake pipe 4
It is supplied to the carburetor 31 through 5 and becomes a mixture here, and is supplied to the combustion chamber from the third pressurized intake pipe 30. Then, the exhaust gas is discharged from the muffler 29 through the exhaust pipe 28 (see the broken line arrow in FIGS. 1 to 3).

Further, the first pressurizing intake pipe 42 is connected to the air cooling fin 4
It is cooled by 2a, so that the efficiency of filling fresh air introduced into the combustion chamber can be improved and high engine performance can be achieved. Further, the air-cooled fins 42 functioning as cooling means.
Since the first pressurized intake pipe 42 in which a is integrated is arranged on the upstream side of the carburetor 31, the carburetor 31 is less likely to be heated,
Vapor is less likely to be generated in the thin fuel pipe in the carburetor 3l, and the fuel supply shortage due to the vapor is reduced.
The so-called bearer lock is hard to occur.

In this embodiment, as described above, the lubricating oil is supplied to the sliding portion between the cylinder C and the piston 24, which is the pressurized new airflow outlet of the crank chamber 21c to the pressurized intake passage. Since the discharge port 21b is provided above the crank chamber 21c above the lowermost part of the connecting portion between the cylinder C and the crank chamber 21c, the crank chamber 21c
The lubricating oil mixed in the fresh air at c is prevented from flowing out to the combustion chamber from the discharge port 21b, which is the pressurized new airflow outlet, and the inflow amount into the combustion chamber is reduced to increase the lubricating oil consumption amount. Can be suppressed and the adverse effect on the engine can be reduced.

Lubricating oil is supplied to the crankshaft 26 support bearings, and after the crankshaft 26 support bearings are lubricated, they are introduced into the crank chamber 21c so as to lubricate the necessary lubrication points in the crank chamber 21c and pressurize. Since the discharge port 21b, which is a pressurized new air flow outlet of the crank chamber 21c to the intake passage, is provided above the crank chamber 21c above the portion where the lubricating oil after lubricating the crankshaft 26 support bearing flows into the crank chamber 21c. It is possible to prevent the lubricating oil flowing into the crank chamber 21c from flowing out of the discharge port 21b, which is a pressurized new airflow outlet, toward the combustion chamber, reduce the inflow amount into the combustion chamber, and increase the lubricating oil consumption amount. It is possible to suppress the adverse effect on the engine.

Further, a supercharging tank 37 for reducing the pressure change of the pressurized air from the crank chamber 21c is provided in the middle of the pressurized intake passage, and the flow of the pressurized air to the supercharging tank 37 is provided. For the inlet 37a, which is the inlet, the supercharging tank 3
Since the position of the outlet 37b of the pressurized air from 7 is set to the upper side, the supercharging tank 37 is not only used for reducing the pressure fluctuation of the pressurized fresh air, but also prevents the lubricating oil from flowing into the combustion chamber. By functioning as a means, it is possible to reduce the amount of inflow into the combustion chamber and prevent the amount of lubricating oil consumption from increasing, and reduce the adverse effect on the engine.

Further, a lubricating oil return pipe 105 is connected to the lower portion of the supercharger tank 37 to return the oil to the upstream of the oil strainer 10l, the oil pump 102, or the oil tank 32, thereby circulating the lubricating oil and lubricating it. The oil consumption can be reduced. In particular, since the flow velocity of the pressurized fresh air in the supercharging tank 37 decreases, the mist-like lubricating oil in the pressurized fresh air is likely to descend and is easily separated from the pressurized fresh air. An oil drain plug 500, which is a valve for removing oil, may be provided below the supercharging tank 37 so that the accumulated lubricating oil can be collected every time the lubricating oil accumulates.

Further, the check valve 1 is provided below the crank chamber 21c.
A lubricating oil return pipe 105 is connected via 04, and an oil strainer 10l upstream or an oil pump 102 upstream,
Alternatively, by returning the oil to the oil tank 32, the lubricating oil is circulated and the lubricating oil staying in the crank chamber 21c is recovered, whereby the amount of lubricating oil consumed can be positively reduced. Further, the lubricating oil return pipe 105 is connected to the suction chamber A side, and pressurized fresh air is mixed into the lubricating oil supply system (including the oil pump 102 and the delivery pipe 103), resulting in seizure due to insufficient lubricating oil. Can be prevented.

It should be noted that the lubricating oil is mixed into the fresh air on the upstream side of the intake port 21a which is the new air flow inlet of the crank chamber 21c, and the lubricating oil mixes the crank chamber 21c.
You may make it lubricate the lubrication required part inside. Even in this case, the discharge port 21b, which is the pressurized new air flow outlet of the crank chamber 21c to the pressurized intake passage, is provided above the crank chamber 21c above the suction port 21a which is the new air flow inlet, so that the crank chamber 21c To prevent the lubricating oil mixed in the fresh air from flowing out toward the combustion chamber from the discharge port 21b, which is the pressurized new airflow outlet, reduce the inflow amount to the combustion chamber and increase the lubricating oil consumption amount. Can be suppressed and the adverse effect on the engine can be reduced.

A scooter type motorcycle equipped with a supercharged engine of the second embodiment will be described with reference to FIGS. This second
In the embodiment, the supercharging tank 37 and the second pressurized intake pipe 45 of the scooter type motorcycle equipped with the supercharging engine of the first embodiment are removed and the discharge port 21b of the crankcase 21 and the carburetor 31 are directly connected to the first. The pressurized intake pipe 42 is connected.
The first pressurizing / intake pipe 42 has an end portion 42b on the reed valve 115 side whose cross section is larger than other portions.
Of the first pressurized intake pipe 42 and the volume of the third pressurized intake pipe 30 and the volume of the third pressurized intake pipe 30 become a sufficient volume, the pressurized fresh air is stored and the pressurized pressure is increased. The leveling function can be exerted.

Also in this second embodiment, similarly to the above, the discharge port 21b, which is the pressurized new air flow outlet, is formed to prevent the amount of inflow to the combustion chamber from decreasing and the amount of lubricating oil consumption to increase. The adverse effect on the engine can be reduced, and similarly, the lubricating oil return pipe 105 is connected and the lubricating oil staying in the crank chamber can be collected to actively reduce the lubricating oil consumption amount. is there.

Another embodiment of the lubricating device 100 will be described with reference to FIG. The lubricating oil return pipe 205 of this embodiment is
The return inlet 205a is connected to the lower portion of the supercharger tank 37, the return outlet 205b is connected to the oil tank 32, and the lubricating oil is returned to the oil tank 32. The return inlet 205a at the bottom of the supercharging tank 37 is located below the inlet 37a,
A portion below the inflow port 37a functions as an oil reservoir.
Further, the lubricating oil return pipe 205 is provided with a throttle 205c so that a large pressing force does not act on the lubricating device 100 beyond the pressure necessary for returning the lubricating oil. Further, since the return outlet 205b of the lubricating oil return pipe 205 and the return outlet 105a of the lubricating oil return pipe 105 connected to the lower portion of the crank chamber 21c are connected above the oil surface 32a in the oil tank 32, the lubricating device 100 It is possible to prevent fresh air from being mixed in. That is, the oil tank 32 functions as a bubble separating device in the return lubricating oil.

As shown in FIG. 11, the supercharging tank 37 is provided with an oil drain plug 210, which is a valve for removing oil, at the lower portion of the supercharging tank 37 so that the lubricating oil can be collected whenever needed. You may do it.

FIG. 12 illustrates another embodiment of the supercharged engine. The carburetor 3 is installed in the air introduction pipe 40 of the supercharged engine.
1 is arranged. Further, a throttle valve 300 is arranged in the third pressurized intake pipe 30, and the throttle valve 300 is provided in the carburetor 31.
Is opened and closed in synchronization with a throttle valve (not shown). The carburetor 31 has a fuel filter 302 driven by the fuel pump 301.
Lubricating oil mixed gasoline is supplied from the fuel tank 303 via the. Of the supplied lubricating oil, the crankcase 21
What is collected at the bottom of the fuel tank is collected in the fuel tank 303 by the lubricating oil return pipe 105 having the check valve 104 and is circulated.

A bypass passage 350 is provided between the introduction pipe 40b on the downstream side of the carburetor 31 and the first pressurized intake pipe 42, and the bypass valve 351 is provided in the bypass passage 350.
Is arranged. The bypass valve 351 is configured to open when the load is low, open early when the speed is rapidly decelerated, and close when the load is medium or high to reduce the pump loss of the fuel pump 301.

In the above embodiment, the case where the present invention is applied to a scooter type motorcycle has been described as an example, but the present invention is not limited to this, and a motorcycle equipped with a unit swing type engine and an engine unit are provided. It can be applied to any motorcycle such as a motorcycle fixed to a body frame, a motorcycle, or a motorcycle. Further, the present invention can be applied to an outboard motor, a small snowmobile, a water scooter, a general-purpose engine, and the like.

[0050]

As described above, according to the first aspect of the invention, the pressurized fresh air flow outlet of the crank chamber is provided above the lowermost portion of the connecting portion between the cylinder and the crank chamber. It is possible to prevent an increase in the amount of lubricating oil consumed by reducing the amount of inflow from the fresh air outlet to the combustion chamber, and reduce adverse effects on the engine.

According to the second aspect of the present invention, since the pressurized new air flow outlet of the crank chamber is provided at a position higher than the portion where the lubricating oil after the lubrication of the crankshaft supporting bearing flows into the crank chamber.
Prevents lubricating oil flowing into the crank chamber from flowing out from the pressurized new airflow outlet toward the combustion chamber, reducing the amount of inflow into the combustion chamber and suppressing an increase in lubricating oil consumption, which adversely affects the engine. Can be reduced.

According to the third aspect of the invention, since the pressurized new air flow outlet of the crank chamber is provided above the new air flow inlet,
It is possible to reduce the amount of inflow into the combustion chamber from the pressurized fresh air flow outlet, prevent an increase in the amount of lubricating oil consumed, and reduce the adverse effects on the engine.

According to the fourth aspect of the invention, the supercharging tank is
Not only used to reduce the pressure fluctuation of pressurized fresh air,
By setting the position of the outlet to the position above the inlet of the pressurized air, it functions as a means for preventing lubricating oil from flowing into the combustion chamber, reducing the amount of flow into the combustion chamber and reducing the amount of lubricating oil consumed. It is possible to prevent the increase and to reduce the adverse effect on the engine.

According to the fifth aspect of the invention, the lubricating oil is circulated and the lubricating oil staying in the crank chamber is recovered, whereby the consumption of the lubricating oil can be positively reduced.

According to the sixth aspect of the present invention, an oil drain valve is provided in the lower portion of the supercharging tank or a lubricating oil return pipe is provided to circulate the lubricating oil, so that the lubricating oil retained in the supercharging tank is recovered. By doing so, the consumption of lubricating oil can be positively reduced.

[Brief description of drawings]

FIG. 1 is a side view of a rear portion of a scooter type motorcycle equipped with a crank chamber supercharged engine.

FIG. 2 is a plan view of a rear portion of a scooter type motorcycle having a crank chamber supercharged engine mounted therein.

FIG. 3 is a rear view of a scooter type motorcycle equipped with a crank chamber supercharged engine.

FIG. 4 is a side view of a scooter type motorcycle having a crank chamber supercharged engine mounted therein.

FIG. 5 is a schematic cross-sectional rear view of a scooter type motorcycle equipped with a crank chamber supercharged engine.

FIG. 6 is a schematic configuration of a supercharged engine in a crank chamber.

FIG. 7 is a plan view of a rear portion of a scooter type motorcycle equipped with a crank chamber supercharged engine of another embodiment.

FIG. 8 is a rear view of a scooter type motorcycle equipped with a crank chamber supercharged engine of another embodiment.

FIG. 9 is a schematic configuration of a crank chamber supercharged engine of another embodiment.

FIG. 10 is a diagram of a main part for explaining another embodiment of the lubricating device.

FIG. 11 is a view showing a supercharging tank of another embodiment of the lubricating device.

FIG. 12 is a view showing a crank chamber supercharged engine of another embodiment.

[Explanation of symbols]

 21a Inlet port 21b Discharge port 21c Crank chamber 24 Piston 30 Third pressurized intake pipe 31 Vaporizer 37 Supercharge tank 42 First pressurized intake pipe 45 Second pressurized intake pipe C Cylinder

Claims (6)

[Claims] 1. Fresh air pressurized in a crank chamber is introduced into a combustion chamber through a pressurized intake passage, an intake port, and an intake valve at the end of the intake port, and an exhaust valve, an exhaust port and an exhaust passage are introduced from the combustion chamber. In a crank chamber supercharged engine in which exhaust gas is discharged into the atmosphere and lubricating oil is supplied to the sliding portion between the cylinder and the piston, a new pressurized airflow outlet of the crank chamber to the pressurized intake passage. Is provided in an upper part of the crank chamber which is above a lowermost part of a connecting portion between the cylinder and the crank chamber. 2. Fresh air pressurized in the crank chamber is introduced into a combustion chamber through a pressurized intake passage, an intake port, and an intake valve at the end of the intake port, and an exhaust valve, an exhaust port and an exhaust passage are introduced from the combustion chamber. After that, the exhaust gas is exhausted to the atmosphere, and the lubricating oil is supplied to the crankshaft support bearing.After lubricating the crankshaft support bearing, it is introduced into the crank chamber and lubricated where necessary in the crank chamber for lubrication. In the feed type engine, the pressurized fresh air flow outlet of the crank chamber to the pressurized intake passage is provided above the crank chamber above the portion where the lubricating oil after lubrication of the crankshaft supporting bearing flows into the crank chamber. A supercharged engine in the crank chamber. 3. Fresh air is introduced into a crank chamber, and fresh air pressurized in the crank chamber is introduced into a combustion chamber through a pressurized intake passage, an intake port, and an intake valve at an end of the intake port, and exhausted from the combustion chamber. Exhaust gas is exhausted to the atmosphere through the valve, exhaust port and exhaust passage, and the lubricating oil is mixed into the fresh air at the upstream side of the new air flow inlet of the crank chamber. In a crank chamber supercharged engine that lubricates points, a pressurized new air flow outlet of the crank chamber to the pressurized intake passage is provided above the new air flow inlet above the crank chamber. Crank chamber supercharged engine. 4. A supercharging tank for reducing the pressure change of the pressurized air from the crank chamber is arranged in the middle of the pressurized intake passage, and the supercharging tank is connected to the inlet of the pressurized air to the supercharging tank. 4. The crank chamber supercharged engine according to any one of claims 1 to 3, wherein the position of the outlet of the pressurized air from the supercharging tank is set to the upper side. 5. The lubricating oil return pipe is connected to the lower portion of the crank chamber so that the lubricating oil from the lower portion of the crank chamber is circulated. Crank chamber supercharged engine described. 6. A crank chamber supercharging type according to claim 4, wherein an oil drain valve is provided at a lower portion of said supercharging tank or a lubricating oil return pipe is provided to circulate lubricating oil. engine.