JPH08100704A - Breather device of engine unit for vehicle - Google Patents

Abstract

PURPOSE: To prevent lubricating oil of a gear case from leaking into a crank case while keeping internal pressure of the gear case, to reduce costs with a simple structure, and to prevent a breather pot from being dropped. CONSTITUTION: A breather chamber 66 provided with the bottom wall 67 inclined downward toward the inside of a gear case is integrally formed on the side wall of the gear case 57, and a breather pot 70 provided with an air passage 77 is attached above this breather chamber. The breather pot is provided with a small-diameter throttle passage 79 on the communication part with the breather chamber, and a bent and narrow communication passage 86 for communicating the air passage with the outside air on the end opposite to the throttle passage. Moreover, the gear case is integrally provided with a guard part 88 for surrounding the breather pot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine unit used in a vehicle such as a motorbike, and more particularly to a breather device for maintaining a constant internal pressure of a gear case.

[0002]

2. Description of the Related Art A speed reducer for decelerating and extracting the power of a motor or an engine includes a gear case containing a plurality of gears meshing with each other. In this gear case,
Lubricating oil for lubricating the meshing portion of the gear is stored, and a part of the gear is immersed in this lubricating oil.

By the way, when a worm gear is used as the gear, the worm gear has a large amount of slippage and a large amount of heat is generated at the meshing portion, so that the temperature rise in the gear case becomes remarkable. When the temperature inside the gear case rises, the air pressure inside the gear case rises, and part of the lubricating oil floats in the gear case in the form of a mist. There is a problem such as leakage from the outside.

Therefore, the speed reducer in which lubricating oil is enclosed is
A breather device is provided to keep the pressure inside the gear case constant. An example of this breather device is shown in FIG.

FIG. 7 shows a speed reducer 1 with a built-in motor. The speed reducer 1 includes a gear case 2.
A gear chamber 3 is formed inside the gear case 2. A worm shaft 4 and a worm wheel 5 that mesh with each other are housed in the gear chamber 3. Lubricating oil 6 is stored in the bottom of the gear chamber 3, and a part of the worm wheel 5 is immersed in the lubricating oil 6.

Both ends of the worm shaft 4 are connected to the gear box 2
Are supported on the left and right side walls 2a, 2b of the bearing via bearings 8. One end of the worm shaft 4 penetrates the side wall 2a and is led out to the outside. The outwardly drawn portion of the worm shaft 4 also serves as the input shaft 9 of the speed reducer 1. The sealing material 1 is provided on the side wall 2a where the worm shaft 4 penetrates.
0 is attached, and the sealing material 10 maintains the airtightness of the gear chamber 3.

The gear case 2 integrally includes a support frame 13 that supports the motor 12. The support frame 13 is the motor 1
Two stators 14 are supported, and the input shaft 9 is introduced inside the stators 14. The rotor 15 of the motor 12 is fixed on the input shaft 9.

In such a speed reducer 1, a breather device 17 is attached to the upper wall 16 of the gear case 2. The breather device 17 includes a bellows-shaped container 18 that can expand and contract. The container 18 is communicated with the gear chamber 3 through a communication hole 19 formed in the upper wall 16.

Therefore, when the temperature of the gear chamber 3 rises due to the heat generation of the worm shaft 4 and the worm wheel 5 and the internal pressure of the gear chamber 3 rises, this pressure is transmitted to the communicating hole 19.
Acts on the container 18 via. Then, the container 18 expands in the axial direction and apparently the internal volume of the gear chamber 3 increases, so that the pressure increase in the gear chamber 3 is absorbed and relaxed, and the gear chamber 3 is absorbed.
It is possible to prevent oil from leaking.

[0010]

By the way, a bicycle with a motor having a bicycle type frame is disclosed in, for example, Japanese Unexamined Patent Publication No. 60-33183.
An engine unit in which a two-cycle engine and a speed reducer are integrated is used. In this type of engine unit, the crankcase of the two-cycle engine and the gear case of the speed reducer are integrally formed. The crank chamber in the crankcase and the gear chamber in the gear case are airtightly partitioned by a partition wall, and one end portion of the crankshaft penetrates the partition wall. A seal material is attached to a portion of the partition wall that penetrates the crankshaft, and the seal material ensures airtightness between the crank chamber and the gear chamber.

In such an engine unit,
Since the reducer is adjacent to the engine cylinder,
The speed reducer tends to be heated to a high temperature by heat conduction or radiant heat from around the cylinder. Therefore, compared with the speed reducer 1 with a built-in motor, the pressure in the gear chamber increases significantly.

Moreover, since the two-cycle engine uses the crank chamber as a primary compression chamber of intake air, when the engine enters the intake stroke, the crank chamber has a negative pressure. Therefore, when the internal pressure of the reduction gear increases, if the crank chamber becomes negative pressure, the lubricating oil in the gear chamber may leak from the penetrating portion of the crankshaft in the partition wall to the crank chamber. When the leaked lubricating oil mixes with the fuel in the crank chamber, there arise problems such as deterioration of combustion performance and increase of exhaust smoke.

As described above, in the engine unit in which the two-cycle engine and the speed reducer are integrated, there are severe conditions for leakage of lubricating oil into the crank chamber. Therefore, even if the breather device 17 used in the conventional speed reducer 1 with a built-in motor is applied, the breather device 17 cannot release the internal pressure of the gear chamber to the outside air. Can not absorb enough,
On the contrary, the internal pressure of the gear chamber may increase.

Therefore, the bellows type breather device 1
In No. 7, the internal pressure of the speed reducer integrated with the engine cannot be kept constant, and the guarantee of lubricating oil leakage into the crank chamber becomes insufficient.

As another means for keeping the internal pressure of the speed reducer constant, a check valve that opens when the internal pressure of the speed reducer reaches a predetermined value can be considered.

However, since this check valve has a complicated structure and a high unit price, there is a problem that the cost is too high for a low-priced vehicle such as a motorbike, and there is room for further improvement in this respect. Is left.

The present invention has been made under such circumstances, and it is possible to prevent the lubricating oil of the gear case from leaking into the crankcase while keeping the internal pressure of the gear case which is affected by the heat of the engine constant. Moreover, it is an object of the present invention to provide a breather device for an engine unit for a vehicle, which has a simple structure and can reduce the cost, and can prevent the breather pot from falling off.

[0018]

In order to achieve the above object, the present invention is premised on a vehicle engine unit in which a crankcase of a two-cycle engine and a gear case of a speed reducer in which lubricating oil is stored are integrated. I am trying.

A breather chamber protruding outward is integrally formed on the side wall of the gear case, and the breather chamber has a bottom wall inclined downward toward the inside of the gear case. At the upper part of the breather chamber, a hollow cylindrical breather pot having an air passage communicating with the breather chamber is attached, and this breather pot has a throttle passage having a diameter smaller than that of the breather chamber or the air passage in a communicating portion with the breather chamber. While having, at the end opposite to the throttle passage, has a bent narrow communication passage that communicates the air passage and the outside air, and in the gear case, a guard portion that surrounds the breather pot. It is characterized by being formed integrally.

[0020]

According to this structure, when the temperature of the gear case rises with the operation of the two-cycle engine, the internal pressure of the gear case rises. Therefore, the air inside the gear case is guided from the breather chamber through the throttle passage to the air passage of the breather pot, and is discharged from there through the communication passage to the outside of the speed reducer. Therefore, the air in the gear case can be released to the outside, and the internal pressure of the gear case can be balanced with the external atmospheric pressure.

Since lubricating oil is stored inside the gear case, mist-like lubricating oil is mixed with the air inside the gear case. If this oil mist is discharged to the outside of the speed reducer together with the air, the amount of lubricating oil consumed will increase.

However, according to the above configuration, when the air in the gear case flows into the air passage from the breather chamber,
Since the flow of the air is forcibly throttled in the throttle passage, the oil mist in the air is captured by coming into contact with the inner surface of the throttle passage and separated and removed from the air. Moreover, since the air passage of the breather pot connected to the throttle passage is wider than the throttle passage, the flow velocity of the air decreases when the air flows into the air passage. Therefore, the oil content heavier than air is separated and removed from the air in the air passage, and adheres to the wall surface of the breather pot.

The oil mist separated from the air becomes a liquid and is returned from the wall surface of the breather pot through the inner surface of the throttle passage to the breather chamber. The bottom wall of this breather room is
Since it is inclined downward toward the inside of the gear case, the oil component returned to the breather chamber is directly returned to the gear case without staying on the bottom wall of the breather chamber.

Therefore, the lubricating oil contained in the air is
It is separated and removed from the air inside the breather pot, and the air from which the lubricating oil has been removed is discharged to the outside through the communication passage.

Further, even if the lubricating oil in the gear case flows into the communication passage from the air passage of the breather pot due to a large inclination of the vehicle, etc., this communication passage is a narrow and bent passage, so this communication passage Is closed by the surface tension of the lubricating oil. Therefore, the outflow of lubricating oil can be prevented in advance.

Furthermore, since the breather pot is a simple hollow cylindrical container, it has a simple structure and can be provided at a low cost. In addition, since the breather pot is surrounded by the guard portion, the breather pot can be protected from the lateral external force by the guard portion, and the breather pot can be prevented from dropping from the gear case.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 6 applied to a bicycle with a motor. Figure 6
In FIG. 1, the bicycle with a motor indicated by reference numeral 31 includes a bicycle-type frame 32. This frame 32
The head pipe 33 at the front end of the
The front wheel 35 is supported via the. This front wheel 35
Steering operation is performed by the bar handle 36.

A down tube 37 is connected to the head pipe 33 and extends obliquely downward and rearward. As shown in FIG. 5, a bottom support pipe 38 is connected to the lower end of the down tube 37. Bottom support pipe 38
A crankshaft 39 is rotatably supported by the crankshaft 39, and left and right pedal arms 41a and 41b having pedals 40 are attached to both ends of the crankshaft 39.

A saddle support pipe 43 extending upward and a rear fork 44 extending rearward are connected to the bottom support pipe 38. Saddle support pipe 43
A saddle 45 is supported by the. Rear fork 44
A rear wheel 47 is rotatably supported at the rear end portion via a rear axle 46. A chain 50 is stretched between the drive sprocket 48 attached to the crankshaft 39 and the driven sprocket 49 attached to the rear wheel 47.

Therefore, when the crank shaft 39 is rotated by pedaling the pedal arm 41 with the foot, this rotation is transmitted to the rear wheel 47 through the drive sprocket 48, the chain 50 and the driven sprocket 49, and the motor-equipped bicycle 31. Can be driven manually.

By the way, as shown in FIGS. 5 and 6, an engine unit 53 is supported on the rear axle 46. The engine unit 53 includes an air-cooled two-cycle engine 54 and a speed reducer 55.

The two-cycle engine 54 has a structure similar to that of a conventionally known one, and has a crankcase 56 accommodating a crankshaft (not shown). The crank chamber in the crank case 56 also serves as a primary compression chamber for intake air.

The speed reducer 55 has a gear case 57 as shown in FIG. Inside the gear case 57,
A gear chamber 58 is formed. The gear chamber 58 accommodates a plurality of gears (not shown) that mesh with each other. Lubricating oil for lubricating the gear is stored in the bottom of the gear chamber 58, and a part of the gear is immersed in the lubricating oil. The rear axle 46 is housed in the gear chamber 58. The rear axle 46 also works as an output shaft of the speed reducer 55 in association with the gear.
Are arranged so as to penetrate the gear case 57. A boss portion 57a that supports the rear axle 46 is formed on the side wall of the gear case 57.

The gear case 57 and the crank case 56 are integrated with each other. The gear chamber 58 of the gear case 57 and the crank chamber of the crank case 56 are hermetically partitioned by a partition wall (not shown). And
One end of the crankshaft penetrates the partition wall and the gear chamber 58
The crankshaft lead-out portion also serves as the input shaft of the speed reducer 55.

Therefore, when the two-cycle engine 54 is started, the power taken out by the crankshaft of the engine 54 is transmitted to the speed reducer 55, and the rear wheels 47 are driven via the rear axle 46. Has become.

In FIG. 6, reference numeral 59 is a vaporizer,
Reference numeral 60 is an air cleaner, and 61 is an exhaust silencer. As shown in FIG. 2, the gear case 57 has a hollow cylindrical convex portion 65 protruding laterally. The internal space of the convex portion 65 forms a breather chamber 66, and the breather chamber 66 is located above the boss portion 57a.
The breather chamber 66 is open toward the gear chamber 58, and the bottom wall 67 of the breather chamber 66 is inclined downward toward the gear chamber 58.

A flat mounting seat 6 is provided on the upper surface of the convex portion 65.
8 is integrally formed. The mounting seat 68 has a mounting hole 69 continuous with the breather chamber 66, and a breather pot 70 is mounted in the mounting hole 69.

The breather pot 70 is provided with a hollow cylindrical pot body 71 having upper and lower ends opened, and a cap 72 for closing the upper end opening of the pot body 71. The pot body 71 and the cap 72 are made of a synthetic resin material such as polypropylene.

As shown in FIG. 3, on the outer peripheral surface of the upper portion of the pot body 71, a projection 73 extending in the circumferential direction is formed. Further, the cap 72 has a peripheral wall 74 covering the upper outer peripheral surface of the pot body 71, and the inner surface of the peripheral wall 74 is
A fitting groove 75 is formed. Therefore, the cap 72
The outer peripheral surface of the pot main body 71 is covered with the peripheral wall 74, and the projection 73 is fitted into the fitting groove 75 of the peripheral wall 74, so that the upper end of the pot main body 71 is airtightly stopped.

The pot body 71 has an air passage 7 inside.
Have 7. A lower end portion of the pot main body 71 forms a neck portion 78 having a small diameter, and inside the neck portion 78, a throttle passage 79 having a diameter smaller than that of the air passage 77 is formed. A rubber grommet 80 is fitted around the neck 78. Grommet 80
The breather pot 70 is fitted into the mounting hole 69 together with the neck portion 78, so that the breather pot 70 is attached to the gear case 5.
7 is elastically supported in a cantilever manner.

On the inner surface of the cap 72, a cylindrical wall portion 8 is formed.
2 is projected. The wall portion 82 is inserted into the upper end opening of the pot body 71, and forms a circumferentially continuous gap 83 with the inner surface of the upper portion of the pot body 71. The gap 83 is connected to the upper end of the air passage 77.

A notch 85 is formed in a part of the upper end of the pot body 71. The notch 85 is open to the upper edge facing the upper end opening of the pot body 71 and the outer peripheral surface continuing to the upper edge, and the notch 85 is covered by the cap 72. And these notches 8
A gap 86 narrower than the air passage 77 is formed between the No. 5 and the cap 72. The gap 86 has one end connected to the outside of the pot body 1 and the other end connected to the gap 83. Therefore, the gap 86 is
A communication passage 87 that communicates the air passage 77 with the outside of the breather pot 70 is formed in cooperation with the gap 83. The communication passage 87 is formed at the upper end of the breather pot 70 as shown in FIG. It is bent in an inverted U shape.

As shown in FIGS. 2 and 4, a guard portion 88 for protecting the breather pot 70 is integrally formed on the side surface of the gear case 57. Guard part 88
Is a bifurcated first guard rib 89 that allows the breather pot 70 to slide in from the front-rear direction, and the breather pot 70.
And a second guard rib 90 extending vertically along. These first and second guard ribs 8
The reference numerals 9 and 90 surround the breather pot 70 from three directions.

Next, the operation of the above configuration will be described.
When the motor-equipped bicycle 31 is powered by the engine unit 53, when the temperature of the gear case 57 rises due to the heat effect from the two-cycle engine 54 and the heat generation of the gears in the gear case 57, the internal pressure of the gear chamber 58 increases. To rise. Then, since the gear chamber 58 is connected to the air passage 77 of the breather pot 70 via the breather chamber 66, the air in the gear chamber 58 flows from the breather chamber 66 to the throttle passage 79 as shown by the arrow in FIG. Through the communication passage 87, and is discharged to the outside of the speed reducer 55.

Therefore, when the internal pressure of the gear chamber 58 rises, the air in the gear chamber 58 can escape to the outside, and the internal pressure of the gear chamber 58 can be balanced with the external atmospheric pressure. Therefore, even if the crank chamber adjacent to the gear chamber 58 has a negative pressure, such as when the two-stroke engine 54 reaches the intake stroke, the lubricating oil in the gear chamber 58 flows from the penetrating portion of the crankshaft to the crank chamber. 2 without leaking
It is possible to maintain good combustion performance of the cycle engine 54 and prevent an increase in exhaust smoke.

When the temperature of the gear case 57 decreases and the internal pressure of the gear chamber 58 decreases, on the contrary, the outside air flows into the air passage 77 from the communication passage 87 and is introduced into the gear chamber 58 through the throttle passage 79.

The lubricating oil stored in the gear chamber 58 is agitated by the gears and floats in the gear chamber 58 in the form of mist. Therefore, in the air guided to the breather pot 70, the oil mist is dispersed. Are mixed together. If this oil mist is discharged to the outside of the speed reducer 55 together with the air, there arises a problem that the consumption amount of the lubricating oil increases.

However, according to the above configuration, since the air passage 77 of the breather pot 70 and the breather chamber 66 are communicated with each other through the small diameter throttle passage 79, the air in the gear chamber 58 containing the oil mist is When the air flows into the air passage 77 from the breather chamber 66, the air flow is forcibly throttled. Therefore, the oil mist in the air is captured by the contact with the inner surface of the throttle passage 79, and is separated and removed from the air. Then, the supplemented oil mist becomes liquid, flows down the inner surface of the throttle passage 79, and is returned to the breather chamber 66.

Further, the air passage 77 connected to the throttle passage 79.
Is wider than the throttle passage 79, the flow velocity of the air decreases when the air flows into the air passage 77.
Therefore, the oil content heavier than the air is separated and removed from the air in the air passage 77 and adheres to the inner surface of the pot body 71. The oil separated from the air flows downward along the inner surface of the air passage 77 and the inner surface of the throttle passage 79,
Returned to the breather chamber 66.

As a result, the oil contained in the air is separated and removed from the air inside the breather pot 70, and the air from which the oil has been removed is communicated from the communication passage 87 to the outside of the speed reducer 55. Is discharged to. Therefore, it is possible to prevent the lubricating oil from being carried on the air flow and discharged to the outside of the speed reducer 55, and it is possible to suppress the consumption amount of the lubricating oil to be small.

The bottom wall 67 of the breather chamber 66 to which the separated lubricating oil is returned is inclined downward toward the gear chamber 58, so that the lubricating oil does not stay in the breather chamber 66. The lubricating oil can be reliably returned to the bottom of the gear chamber 58.

Moreover, since the breather pot 70 is a simple hollow cylindrical body made of synthetic resin, the breather pot 70 has a simple structure and can be provided at a lower cost than conventional check valves. Therefore, even in a vehicle whose vehicle price can be kept low, such as the motor-equipped bicycle 31, there is no problem in terms of cost.

Furthermore, the outward communicating portion of the breather pot 70 is constituted by a narrow communicating passage 87 bent in an inverted U shape. Therefore, even if the motor-equipped bicycle 31 is greatly inclined and the lubricating oil in the gear chamber 58 flows into the air passage 77 of the breather pot 70 and is guided to the communication passage 87 from this, the communication passage 87 is formed. Is closed by the surface tension of the lubricating oil. Therefore, the outflow of the lubricating oil can be prevented in advance.

In addition, in the case of the above structure, the breather pot 70 is only held in a cantilever state by the elasticity of the grommet 80, so the breather pot 70
When a horizontal force is applied to the breather pot 70, the breather pot 70 may fall down and come out of the mounting hole 69.

However, since the gear case 57 integrally includes the guard portion 88 that surrounds the breather pot 70 from three directions, the breather pot 70 can be protected from external lateral force, and the breather pot 70 does not drop off. There is an advantage that it can be prevented. It should be noted that the engine unit according to the present invention is not specified for a bicycle with a prime mover, and can be similarly implemented for other vehicles.

[0056]

According to the present invention described in detail above, even if the internal pressure of the gear case increases due to the heat effect from the two-cycle engine, the air in the gear case can be released to the outside, and The internal pressure can be balanced with the external pressure. Therefore, even if the inside of the crankcase adjacent to the gear case has a negative pressure such as when the two-cycle engine reaches the intake stroke, the lubricating oil in the gearcase does not leak into the crankcase, and It is possible to maintain good combustion performance and prevent an increase in exhaust smoke.

Moreover, since the oil contained in the air is separated and removed from the air inside the breather pot, it is possible to prevent the oil from being carried on the air flow and discharged to the outside of the speed reducer. The consumption of lubricating oil can be reduced.
The bottom wall of the breather chamber where the separated lubricating oil is returned is inclined downward, so this lubricating oil does not stay in the breather chamber, and the lubricating oil must be reliably returned to the bottom of the gear case. You can

Since the breather pot is a simple cylindrical body made of synthetic resin, it has a simple structure and can be provided at a lower cost than conventional check valves. Therefore, even in a vehicle in which the vehicle price is kept low, no problem occurs in terms of cost.

Further, since the air passage of the breather pot is communicated to the outside through a narrow curved communication passage, the lubricating oil in the gear case is communicated from the air passage to the communication passage even if the vehicle is greatly inclined. Even if it is led to, the communication passage will be closed by the surface tension of the lubricating oil, and the outflow of the lubricating oil can be prevented.

In addition, the breather pot can be protected from the lateral external force by the guard portion of the gear case,
There is an advantage that the breather pot can be prevented from falling off while traveling.

[Brief description of drawings]

FIG. 1 is a side view showing a mounting portion of a breather pot in an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view of a breather pot.

FIG. 4 is a plan view of a mounting seat of the gear case.

FIG. 5 is a plan view of the mounting portion of the engine unit.

FIG. 6 is a side view of a motorbike equipped with an engine unit.

FIG. 7 is a cross-sectional view of a speed reducer with a built-in motor having a conventional breather device.

[Explanation of symbols]

 53 ... Engine unit 54 ... Two-cycle engine 55 ... Reduction gear 56 ... Crankcase 57 ... Gear case 66 ... Breather chamber 67 ... Bottom wall 70 ... Breather pot 77 ... Air passage 79 ... Throttling passage 86 ... Communication passage 88 ... Guard section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mihide Nakatani No. 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Nagoya Machinery Works

Claims (1)

[Claims] 1. A vehicle engine unit in which a crankcase of a two-cycle engine and a gear case of a speed reducer in which lubricating oil is stored are integrated, and a breather chamber protruding outward from a side wall of the gear case. This breather chamber has a bottom wall that is inclined downward toward the inside of the gear case, and a hollow cylindrical breather pot that has an air passage communicating with the breather chamber at the top of the breather chamber. The breather pot has a throttle passage having a diameter smaller than that of the breather chamber or the air passage in the communicating portion with the breather chamber, and the air passage and the outside air are provided at the end opposite to the throttle passage. Has a bent narrow communication passage for communicating with each other, and a guard portion surrounding the breather pot is integrally formed in the gear case. A breather device for a vehicle engine unit, which is characterized in that: