JP2971170B2 - Exhaust system for two-cycle gasoline engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for a two-cycle gasoline engine, and more particularly to an exhaust system suitable for a two-cycle gasoline engine mounted on a motorcycle or the like.

[0002]

2. Description of the Related Art As is well known, a two-stroke gasoline engine mounted on a motorcycle or the like mixes gasoline fuel with lubricating oil and supplies it to a cylinder, and unburned lubricating oil is mixed in exhaust gas. Such lubricating oil in the exhaust causes white smoke in the exhaust discharged from the muffler,
There was a problem that it adhered to the tail pipe or scattered from the tail pipe.

Therefore, an exhaust system for preventing the lubricating oil in the exhaust from being discharged into the atmosphere together with the exhaust has been proposed in Japanese Patent Application Laid-Open No. 62-13721. In this exhaust device, an expansion chamber is provided in an exhaust passage, specifically, a rear portion inside the outer pipe of the silencer, a porous member is provided in the expansion chamber, and an exhaust passage upstream of the expansion chamber is opened facing the porous member. Let it. And connect the tube to the lower part of the expansion chamber,
This tube guides the lubricating oil in the expansion chamber to the chain and lubricates it.

[0004]

However, in the above-described exhaust system of the conventional two-stroke gasoline engine, the outer tube of the silencer has a relatively higher rear height above the ground than other parts. Therefore, even if a tube for discharging lubricating oil is connected to the expansion chamber located at the rear part of the outer tube, there is a problem that the lubricating oil staying inside the outer tube cannot be effectively discharged. In particular, 2
In a cycle gasoline engine, the exhaust system including the silencer extends obliquely upward from the engine to the rear,
The above problem is also remarkable, and a solution has been demanded.

The present invention has been made in view of the above problems, and has as its object to provide an exhaust system for a two-cycle gasoline engine that can effectively discharge lubricating oil from an exhaust system to the outside.

[0006]

In order to achieve the above-mentioned object, the present invention is characterized in that the first and second aspects of the present invention are provided below and behind an engine exhaust port.
Connected to the exhaust pipe extended toward the exhaust pipe and the downstream end of the exhaust pipe
An exhaust expansion pipe extending rearward and upward;
The downstream end (rear end) of the exhaust expansion pipe, which is the upper end of the enlarged diameter section
-Cycle gasoline engine consisting of a muffler connected to the
In the exhaust device, the upstream portion of the exhaust expansion pipe is exhausted.
The height of the passage is the lowest above the ground,
Exhaust to open the exhaust passage inside to the atmosphere at the lowest part of the height
An oil port is provided, and exhaust is provided on the inner wall surface of the exhaust expansion pipe in the exhaust passage.
Guides oil flowing along the inner wall of the passage to the drain port
A barrier is provided.

A second aspect of the present invention relates to an engine exhaust port.
Exhaust pipe extending downward and rearward from the exhaust pipe, and downstream of the exhaust pipe
Exhaust expansion tube extending rearward and upward connected to the end
And below the exhaust expansion pipe, which is the upper end of the expanded part of the exhaust expansion pipe.
2 size consisting of a muffler connected to the flow end (rear end)
In the exhaust system for a gasoline engine, the exhaust expansion pipe
Means that the upstream section has the lowest ground clearance as a whole exhaust passage,
At or near the lowest part of the exhaust expansion pipe above ground level
An open collection chamber is provided, and the collection chamber is located above the exhaust expansion pipe.
Open to the atmosphere through the oil drain located at the lowest part of the height
And at a position near the oil discharge port on the inner wall surface of the exhaust passage.
Mixed with the exhaust flowing through the exhaust passage
It is characterized in that a collecting wall for collecting oil is provided.

[0008] Then, the invention of claim 2 can adopt a mode to configure the collection wall wire mesh, also claim 1 and claim
The invention of Item 2 can adopt a configuration in which a pipe member that opens to the mechanism lubrication section is connected to the oil discharge port.

[0009]

According to the first aspect of the present invention, since the oil discharge port is opened inside the exhaust passage at a portion having the lowest height above the ground, the lubricating oil inside the exhaust passage can be effectively discharged from the oil discharge port. The transmitted lubricating oil can also be guided to the oil discharge port by the barrier, and the amount of lubricating oil discharged together with the exhaust can be extremely reduced.

According to the second aspect of the present invention, the collection chamber is opened in the exhaust passage at a portion having the lowest height above the ground, so that the lubricating oil in the exhaust passage can be effectively collected in the collection chamber.
The collecting wall can collide with the flow of the exhaust gas to collect the lubricating oil in the exhaust gas, and the amount of the lubricating oil in the exhaust gas discharged can be extremely reduced.

According to the second aspect of the present invention, the collecting wall is formed of a wire mesh, so that the lubricating oil in the exhaust gas can be collected more effectively. In the first and second inventions, the lubricating oil inside the exhaust passage can be reused by connecting the pipe member opening to the mechanism lubricating portion to the oil discharge port.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show a second embodiment according to an embodiment of the first invention.
FIG. 1 shows an exhaust system of a cycle gasoline engine.
2 is a side view of a motorcycle to which the exhaust device of the cycle gasoline engine is applied, FIG. 2 is an enlarged side view of the two-cycle gasoline engine, FIG. 3 is a cross-sectional view taken along the arrow 3-3 in FIG. 2, and FIG. It is an expanded sectional view.

In FIG. 1, reference numeral 11 denotes a body frame of a motorcycle, and a head tube 12 is fixed to a front portion of the body frame 11. A front wheel 14F is steerably supported by the head tube 12 by a front fork 13. A rear fork 15 is pivotally supported by a pivot shaft P at a lower rear portion of the body frame 11,
A seat frame 16 extends rearward and upward at the rear. A rear wheel 14 </ b> R is supported on a rear portion of the rear fork 15, and a seat 17 is mounted on an upper portion of the seat frame 16.

Further, a power unit 18 is mounted on a body frame 11 by a hanger 80 with a cylinder portion 19a of a two-cycle gasoline engine 19 projecting forward and upward at the center. As is well known, the power unit 18 is constructed by assembling a two-cycle gasoline engine 19 with a speed change mechanism (not shown in the figure) and the like, and an output shaft 20 is connected to the rear wheel 14R so as to be able to transmit power.

In FIG. 1, 60 is a front screen, 61 is a meter, 62 is a headlamp, 63 is a blinker lamp, 64 is a front cowl, 65 is a gusset, 6
6 is a center cowl, 67 is an ignition coil, 68
Is a high tension cord, 69 is an under cowl, 70 is an air cleaner, 71 is a fuel tank, 72 is a grab rail, 73 is a tail lamp, 74 is a rear fender, 7
5 is a torque rod, 76 is a gusset, 77 is a carburetor, and 78 is a step.

The output shaft 20 is rotatably supported by a case 21 as shown in FIGS.
1 Project outside. A spline portion (mechanical lubrication portion) 20a is formed at a protruding end of the output shaft 20, and a drive sprocket 22 is provided on the spline portion 20a so as to be integrally rotatable. A chain 24 is mounted on the drive sprocket 22 and a driven sprocket 23 fixed to the rear wheel 14R.
The cover 25 is joined with the cover 25.

An oil supply pipe (pipe member) 26 is provided in the upper part of the cover 25, and the end of the oil supply pipe 26 is bent downward in a hook shape, and a spline is formed immediately above the spline portion 20a of the output shaft 20. It opens toward the part 20a. As described below,
The other end of the oil supply pipe 26 is connected to the expansion pipe, and guides the lubricating oil from the expansion pipe to the spline section 20a.

The two-cycle gasoline engine 19 has an exhaust port below the cylinder portion 19a, and an exhaust pipe 27 is connected to the exhaust port. The exhaust pipe 27 is an engine 1
9 extends rearward below and an expansion tube 28 is connected to the rear end.

The expansion tube 28 extends from the lower part of the engine 19 to the right rear of the rear wheel 14R toward the rear upper side, and has a rear end connected to the muffler 29. As is well known, the muffler 29 has a silencing structure inside, and a tail pipe 29a for discharging exhaust gas is connected to a rear portion.

The exhaust pipe 27, the expansion pipe 28 and the muffler 29
Has an exhaust passage 28a therein, and a diffuser portion 28c in which a part of the exhaust passage 28a is enlarged is formed in the expansion pipe 28. As shown in FIG. 4A, the expansion pipe 28 is formed with a drain port 30 that opens to the exhaust passage 28a at a portion where the ground height is the lowest, and a barrier is provided on the inner wall surface downstream of the drain port 30. 31 are formed. Fitted is joint hands 32 to the oil discharge port 30, the oil supply pipe 26 described above is connected to the joint 32. It is desirable that the oil drain port 30 be formed at a position where the height above the ground is the lowest in the entire exhaust system including the exhaust pipe 27 and the like.

The barrier 31 is formed by projecting the wall of the expansion tube 28 into the exhaust passage 28a, and extends over the entire circumference of the expansion tube 28 in the circumferential direction. As shown in FIG. 4A, the lower part of the barrier 31 is located on the downstream side (rear side) of the oil discharge port 30 in the exhaust flow direction and close to the oil discharge port 30, and the upper part extends forward and upward in a side view. Put out.

In this embodiment, the exhaust gas flowing through the exhaust passage 28a of the expansion pipe 28 hits the barrier 31, and the lubricating oil mixed in the exhaust gas is separated and travels down the barrier 31 to hang down. Further, the lubricating oil attached to the inner wall surface of the exhaust passage 28a also travels along the barrier 31 and hangs down. These oils are collected in the portion of the exhaust passage 28a where the ground height is the lowest (see the phantom line in FIG. 4). 2
The lubricating oil separated from the exhaust gas inside 8a can be effectively discharged to the outside.

In this embodiment, the lubricating oil separated from the exhaust gas is guided from the expansion pipe 28 to the spline section 20a of the output shaft 20 of the power unit 18 by the oil supply pipe 26, and is reused for lubrication of the spline section 20a. Therefore, the lubricating oil can be effectively used, and the lubricating oil can be saved. The object to be lubricated is not limited to the spline portion 20a, and various mechanical lubrication portions can be arbitrarily selected.

It is not always necessary to connect the oil supply pipe 26 to the above-mentioned oil discharge port 30, and the present invention can be achieved even if the oil discharge port 30 is directly opened to the atmosphere as shown in FIG. 4B. Needless to say.

FIG. 5 shows a first embodiment of the second invention.
5A is a plan sectional view of a main part, and FIG. 5B is a sectional side view of the same.
In this embodiment and the embodiments described later, the same portions as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 2, in this embodiment, a collection chamber 33 is formed in a portion where the height of the expansion tube 28 is the lowest above the ground, the inner surface of the tube wall is recessed downward and the upper portion is opened to the exhaust passage 28a. I do. The oil supply pipe 26 is connected to the rear of the collection chamber 33 via the joint 32 as in the above-described embodiment.

A barrier (collecting wall) 31 similar to that of the above-described embodiment is formed on the wall of the expansion tube 28. The barrier 31 has a lower part located in front of the collection chamber 33 and close to the front edge of the collection chamber 33, and an upper part extending forward and upward in a side view. The same effect can be obtained even if the lower part of the barrier 31 is located behind the collection chamber 33 and close to the rear edge of the collection chamber 33.

In the first embodiment, since the lubricating oil is collected in the collecting chamber 33 by the barrier 31, the lubricating oil collected in the collecting chamber 33 is not dragged by the flow of the exhaust gas, and the tail oil is collected. Lubricating oil discharged together with exhaust gas from the pipe 29a can be reduced. Then, similarly to the above-described embodiment, since the lubricating oil collected in the collection chamber 33 is guided to the spline portion 20a of the output shaft 20 of the power unit 18 by the oil supply pipe 26, the lubricating oil can be reused.

FIG. 6 shows a second embodiment of the second invention.
Fig. 6a is a plan sectional view of the main part, Fig. 6b is the same side sectional view, and Fig. 6c.
6B is a sectional view taken along the line 6-6 in FIG. 6B. In this embodiment, a wire mesh 35 is attached to an annular holder 34 to form a collecting member (collecting wall, barrier) 36, and this collecting member 36 is attached to the expansion tube 2.
8 in the exhaust passage 28a. As shown in FIG. 6B, the lower portion of the collecting member 36 is located in the vicinity of the collecting chamber 33, and the upper portion extends forward and upward to block the entire surface of the exhaust passage 28a so that the exhaust gas can flow.

In the second embodiment, the collecting member 36
Consists of a wire mesh 35 that covers the entire surface of the exhaust passage 28a.
The lubricating oil in the exhaust gas can be effectively collected, and the resistance to the flow of the exhaust gas is rarely increased. The rest is the same as the first embodiment.

FIGS. 7A and 7B show a third embodiment of the second invention.
FIG. 7A is a side sectional view of a main part, and FIG.
FIG. 7A is a sectional view taken along line 7-7 of FIG. In the third embodiment, the bottom wall surface of the expansion tube 28 is bulged downward to form a concave portion that opens to the exhaust passage 28a.
To form a collection chamber 33 having a relatively large volume.

The partition member 37 has a substantially partial arc shape in cross section, and both sides are fixed to the inner wall surface of the expansion tube 28, and the front edge is raised upward to form a collection wall 37a. This collection wall 37
A gap is formed between the lower part of the expansion chamber 28a and the bottom wall surface of the expansion tube 28.
Communicates with a. In addition, a drain port (not shown) that opens to the collection chamber 33 is formed at the bottom of the concave portion of the expansion pipe 28, and a drain bolt 38 is detachably screwed to the drain port from the outside.

Also in the third embodiment, the lubricating oil in the exhaust gas is collected by the collecting wall 37 a of the partition member 37, and the collected lubricating oil is collected in the collecting chamber 33. Since a considerable amount of lubricating oil can be stored in the collecting chamber 33, the lubricating oil stored in the collecting chamber 33 is discharged at any time, for example, at regular intervals, by removing the drain bolt 38.

FIG. 7c is a sectional side view of a main part of the fourth embodiment of the second invention. In the fourth embodiment, an oil discharge port 30 is formed in front of a barrier 31 in an expansion pipe 28, and a hollow U-shaped pipe 40 is connected to the oil discharge port 39. One end of the U-shaped tube 40 is connected to the oil drain port 30 and opens at the bottom of the exhaust passage 28a, and the other end is open to the atmosphere below the expansion tube 28. This U-shaped tube 4
A drain hole is formed in the lowermost bent portion at 0, and a drain bolt 38 is removably screwed into the drain hole. The inside of this U-shaped tube 40 corresponds to a collection chamber.
The barrier 31 is the same as that of the first embodiment of the present invention (see FIGS. 4A and 4B).

In the fourth embodiment, similarly to the third embodiment, the collected lubricating oil can be stored in the U-shaped pipe 40, and the lubricating oil in the U-shaped pipe 40 is drained. Remove the bolt 38 and discharge it.

[0036]

As described above, according to the first aspect of the present invention, an oil discharge port is formed at a portion of the exhaust passage where the ground height is the lowest, and the oil discharge port is collected by the barrier. Lubricating oil is guided to drain from the oil drain,
The lubricating oil in the exhaust passage can be effectively discharged, and the amount of lubricating oil discharged together with the exhaust from the muffler or the like can be extremely reduced.

According to the second aspect of the present invention,
A collection chamber is provided at an area where the height of the exhaust passage is the lowest above the ground, and lubricating oil collected by the collection wall is guided to the collection chamber and discharged from an oil discharge port opened to the collection chamber. Therefore, the amount of lubricating oil in the exhaust gas discharged can be extremely reduced.

According to the third aspect of the present invention, since the collecting wall is made of a wire mesh based on the second aspect of the present invention, the resistance to the flow of exhaust gas is hardly increased, and the lubricating oil is effectively used. Can be collected.

Further, according to a fourth aspect of the present invention, based on the first or second aspect of the present invention, a pipe member is connected to an oil discharge port, and the collected lubricating oil is mechanically moved by the pipe member. The lubricating oil is saved because it is guided to the lubricating part and reused.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle to which an exhaust device for a two-cycle gasoline engine according to an embodiment of the present invention is applied.

FIG. 2 is a partially enlarged side view of the motorcycle.

FIG. 3 is a sectional view taken along the arrow 3-3 in FIG. 2;

4A and 4B show an exhaust device of a two-stroke gasoline engine according to one embodiment of the first invention, wherein FIG. 4A is a side sectional view of a main part, and FIG. 4B is a side cross sectional view showing another embodiment of the main part.

FIG. 5 shows an exhaust device of a two-stroke gasoline engine according to the first embodiment in the second invention, and FIG.
FIG. 5b is a side sectional view of the main part.

6 shows an exhaust system of a second two-cycle gasoline engine according to a second embodiment of the invention, cross-sectional plan view of FIG. 6 a is a main portion,
6B is a side sectional view of the main part, and FIG. 6C is a sectional view taken along the line 6-6 in FIG. 6B.

FIG. 7 shows a second embodiment according to the third and fourth embodiments of the present invention.
7a shows a cycle gasoline engine, FIG. 7a is a side sectional view of a main part of a third embodiment, FIG. 7b is a cross-sectional view taken along the line 7-7 in FIG. 7a, and FIG.

[Explanation of symbols]

19: two-cycle gasoline engine, 20a: spline part (mechanical lubrication part), 26: oil supply pipe (pipe member), 27: exhaust pipe, 28: expansion pipe, 28a ... Exhaust passage, 29 muffler, 30 oil drain, 31 barrier
33, 37a: collection chamber, 35: wire mesh, 36: collection member (collection wall), 40: U-shaped tube (collection chamber).

Continuation of the front page (72) Inventor Kaoru Hayashi 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Technical Research Institute Co., Ltd. (56) References JP-A-61-179815 (JP, A) JP-A-61-116023 (JP, a) JitsuHiraku Akira 60-145222 (JP, U) JitsuHiraku Akira 62-133916 (JP, U) real public Akira 50-14023 (JP, Y2) (58 ) investigated the field (Int.Cl. ⁶ , DB name) F01N 7/20

Claims (4)

(57) [Claims] 1. An engine exhaust port is provided below and behind.
After connecting to the exhaust pipe extending to the downstream end of the exhaust pipe
Exhaust expansion pipe extending upwardly and upwardly, and expansion of the exhaust expansion pipe.
At the downstream end (rear end) of the exhaust expansion pipe, which is the upper end of the diameter section
Of a two-cycle gasoline engine consisting of a connected muffler
In the exhaust device, the exhaust expansion pipe has the most upstream portion as the whole exhaust passage.
The upper height is low and the lowest part of the exhaust expansion pipe above the ground is inside the exhaust passage.
The provided oil outlet which opens to the atmosphere, on the inner wall surface of the exhaust passage of the exhaust inflation tube is provided with a barrier for guiding the oil flowing transmitted to the inner wall surface of the exhaust passage to the oil discharge mouth
An exhaust system for a two-cycle gasoline engine. 2. An engine according to claim 1, wherein said engine exhaust port is lower and rearward.
After connecting to the exhaust pipe extending to the downstream end of the exhaust pipe
Exhaust expansion pipe extending upwardly and upwardly, and expansion of the exhaust expansion pipe.
At the downstream end (rear end) of the exhaust expansion pipe, which is the upper end of the diameter section
Of a two-cycle gasoline engine consisting of a connected muffler
In the exhaust device, the exhaust expansion pipe has the most upstream portion as the whole exhaust passage.
High above is low, the provided collecting chamber to the lowest portion or opening in the vicinity of the ground clearance of the exhaust inflation tube, the land of the exhaust expansion pipe collecting chamber
Open to the atmosphere from the oil drain port provided at the lowest part of the height
And a collecting wall for collecting oil mixed in the exhaust gas against the exhaust gas flowing through the exhaust passage at a position near the oil discharge port on the inner wall surface of the exhaust passage. Exhaust system for two-cycle gasoline engine. 3. The two-cycle gasoline engine according to claim 2, wherein the front air collecting wall is formed of a wire mesh provided inside the exhaust passage. 4. The two-stroke gasoline engine according to claim 1, further comprising: a pipe member having one end connected to the oil discharge port, and the other end of the pipe member located near a mechanism lubrication unit. An exhaust device for a two-cycle gasoline engine, characterized by being opened.