JPS63277813A - Collective exhaust pipe for multi-cylinder engine - Google Patents

Abstract

PURPOSE:To attempt improvement of engine characteristics by dividing the inside of a collective exhaust pipe by a separator for forming plural exhaust passages, and forming therein a projected section on the outer wall of the collective exhaust pipe for allowing adjacent exhaust passages to be communicated with each other through said projecting section. CONSTITUTION:A separator 27 is provided inside a collective exhaust pipe 20 connecting exhaust pipes 10 from each cylinder for forming plural exhaust passages inside the collective exhaust pipe 20. The part along the separator 27 of the outer wall 23 of the collective exhaust pipe 20 is expanded for forming a projecting section 40. Plural exhaust passages are thereby communicated through a gap 41 between the projecting section 40 and the separator 27. Exhaust flow in each of exhaust passages is allowed to interfere with each other through the gap 41 during the low speed running of an engine for maintaining exhaust flow at a stable condition. This constitution thereby enables engine characteristics to be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a collective exhaust pipe for a multi-cylinder engine, and can be applied to an exhaust system for a motorcycle equipped with a multi-cylinder engine.

[Conventional technology]

Conventionally, in the exhaust system of a multi-cylinder engine, exhaust from a plurality of cylinders whose firing order is not consecutive is merged in advance to cause the exhaust waves to interfere with each other. In the case of a cylinder engine, cylinder engines with alternating explosion orders at 360 degree intervals are merged into two exhaust streams, which are later merged into one exhaust stream, and generally the 4-2 It is called the -1 set and is often used. According to a collective exhaust pipe using such a collective method, the exhaust efficiency can be increased by causing the exhaust waves to interfere with each other, and the output can be particularly improved during high-speed rotation.

By the way, as for the collective exhaust pipe according to the above-mentioned 4-2-1 set, the inside of the collective pipe is partitioned to provide two exhaust passages, and two of the four exhaust pipes from each cylinder are passed through each exhaust passage. Later, the re-exhaust passages were merged. However, in such an exhaust passage, since the exhaust gas is passed through at intervals of 360 degrees, the flow becomes intermittent during medium and low speed rotations, making the exhaust flow unstable. There is a problem that it is difficult to obtain output.

To solve this problem, in the collective exhaust pipe of a 4-cylinder engine disclosed in Japanese Utility Model Application No. 60-162217,
The partition member that partitions the inside of the collecting pipe to form an exhaust passage is divided into two parts, front and back, and installed in two places, and the exhaust flow flowing through both exhaust passages is made to interfere with each other in the gap between the two partition members, thereby improving the exhaust flow at low rotation speeds. Intermittent parts of the flow are mutually compensated for.

[Problem that the invention attempts to solve]

However, in such a case, the exhaust gas that flows from one side of the exhaust passage to the other through the gap at low rotational speeds flows over the entire width of the exhaust passage, so the flow of the exhaust flow in the exhaust passage is disturbed, and the exhaust flow is disturbed. There was a problem that instability could not be sufficiently resolved.

An object of the present invention is to improve exhaust efficiency at high speeds and stabilize the flow of exhaust gas at low speeds, thereby improving engine characteristics.

[Failure to solve the problem]

The present invention provides a collective exhaust pipe for a multi-cylinder engine formed by collectively connecting a plurality of exhaust vibes from each cylinder of the multi-cylinder engine to one end of the collecting pipe, in which the exhaust pipe is connected to the inside of the collecting pipe. A separator of a predetermined length is provided from one end to the other end, and the separator partitions the inside of the collecting pipe to form a plurality of exhaust passages, and each exhaust pipe is connected to one of these exhaust passages. At the same time, a portion of the outer wall of the collecting pipe along the separator is partially bulged outward to form a bulging portion, and adjacent exhaust passages are made to communicate with each other at this bulging portion. Configures a collective exhaust pipe.

[Effect]

In the present invention, the exhaust gas from each cylinder is passed through the exhaust passage so that, for example, the order of explosion is alternated, and the exhaust pulsation from each exhaust pipe is caused to interfere with each other in each exhaust passage, thereby achieving high-speed rotation. This improves the high-frequency characteristics of the engine by increasing the exhaust efficiency during engine operation. Here, adjacent exhaust passages are communicated with each other at the bulge, but
During high-speed rotation, the time interval between pulsations is short, so there is almost no mutual exchange of exhaust flows. On the other hand, during medium-low speed rotation, the time interval between pulsations is long, and mutual exhaust flows flow, so that the exhaust gas in each exhaust passage is By interfering with each other, a stable exhaust flow is maintained even during medium and low speed rotation. As described above, the present invention improves the output characteristics of the engine in almost all rotational speed ranges from the mid-low range to the high range, thereby achieving the above object.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, the collective exhaust pipe 1 of this embodiment is applied to a 4-stroke parallel 4-cylinder engine 2 for motorcycles, and the exhaust pipe 1 is applied to a 4-cycle parallel 4-cylinder engine 2 for motorcycles, and has a power of 11.112
, I3, I4 four exhaust pipes 10 from each cylinder
The ends 11 of the muffler 30 are assembled and connected to one end of a collecting pipe 20, and a muffler 30 having a noise-reducing structure inside is connected to the other end of the collecting pipe 20.

As shown in FIGS. 2 and 3, the collecting pipe 20 has two upper and lower outer wall members 21 and 22 glued together in a hollow shape.
It is formed by welding the bonded parts 23 on both sides,
An end face member 25 having four openings 24 is attached to the end face of the collecting pipe 20 on the side of the exhaust vibrator 10 which is slightly expanded, and a muffler connecting member 26 for connecting the muffler 30 is attached to the other end. installed.

Furthermore, a plate-shaped separator 27 is provided inside the collecting pipe 20. This separator 27 has both end edges 27A sandwiched between the bonded portion 23 and extends from the end face member 25 to a predetermined position along the bonded portion 23, and the inside of the collecting pipe 20 is partitioned into upper and lower sections in the figure. and two exhaust passages 20A and 20B are formed.

Here, the ends 11 of the four exhaust pipes 10 are connected to each opening 24 of the end face member 25 of the collecting pipe 20, and the periphery thereof is fixed by welding. These four end portions 11 are arranged so that their center axes are approximately square, two each are arranged vertically in two stages, and the explosion order of the cylinders to which each exhaust pipe IO is connected is 111, I2, and 4. , lI3, cylinders with an explosion interval of 360 degrees are grouped together, and the cylinder Ill.

The one connected to I4 is on the upper side, and the cylinder 112.13
Those connected to are placed at the bottom. For this reason, the four exhaust pipes 10 are separated into two exhaust pipes 20A and 20B in the collecting pipe 20 and communicated with each other, and are combined into one pipe at the end of the separator 27, so-called 4- It is configured to be a 2-1 set.

On the other hand, as shown in FIG. 2, the collecting pipe 20 is formed into a substantially S-shape when viewed from above, and is connected to a muffler connecting member 26 with respect to the exhaust pipe 10 located at the center of the motorcycle.
The side is located on the right side of the vehicle body. Further, the collecting pipe 20 is located at a portion on the inside of the substantially S-shaped vehicle body, which is substantially on the extension line of the end portions 11 of the collectively connected exhaust pipes 10, and the bonded portion 23 and the outer wall members 21, 22 in the vicinity thereof are aligned. A bulging portion 40 is formed by bulging outward, and a gap 41 is formed between this bulging portion 40 and the edge 27A of the separator 27. For this reason, the exhaust passages 2OA, 2
The spaces 0B are communicated with each other by a gap 40, and are configured so that gas can mutually flow approximately along the inner surface of the collecting pipe 20.

Furthermore, glass wool 2BB held by punch metal 28A is pasted along the inner surface of the collecting pipe 20, and these punch metal 28A and glass wool 2BB
Therefore, the exhaust noise inside the collecting pipe 20 is absorbed to some extent, and the quietness of the collecting pipe 1 can be improved.

In this embodiment configured in this way, the engine 2
Exhaust gas from cylinders 111, I2, I4, and I3, which explode in the order of rotation, is sent to the collecting pipe 20 through each exhaust pipe 10, and the exhaust gas from cylinders I11 and 114 is sent to the exhaust passage 20A, and from cylinders 112. The exhaust gases 113 are merged with each other in the exhaust passage 20B.

At this time, cylinder H, +14 and cylinder #2゜I
Since the explosion intervals in No. 3 are 360 degrees each, the exhaust gases that merge in the exhaust passages 20A and 20B have a lower exhaust pressure from the other cylinder when exhausting one cylinder than in the case of merging at 180 degrees intervals. lower to reduce exhaust resistance.

Here, when the engine 2 is rotating at high speed, the exhaust flow in each exhaust passage 2OA, 20B is high speed and the time interval of pulsation is short, so there is almost no mutual circulation of the re-exhaust flow in the gap 41, and as described above. Improvement in exhaust efficiency is realized by such a 4-2-1 set.

On the other hand, when the engine 2 is rotating at a medium to low speed, as the interval between exhaust pulsations becomes longer, the re-exhaust flows mutually circulate through the gap 41, and the intermittent parts of the flows are mutually compensated for, resulting in a stable flow. maintain.

Note that, since the flow of exhaust gas flowing through each exhaust passage 20A, 20B through the gap 41 occurs along the inner surface of the collecting pipe 20, the original flow within each exhaust passage 20A, 20B is not disturbed.

According to this embodiment, the following effects can be obtained.

That is, in the high speed range of the engine 2, the exhaust efficiency can be improved by the so-called 4-2-1 set, and
In the medium and low speed range, each exhaust passage is 20A.

As the flow velocity of the exhaust flow in 20B decreases, the re-exhaust flow is caused to mutually circulate through the gap 41, and the intermittent portions of the flow can be mutually supplemented to maintain a stable flow.

Furthermore, instead of providing holes, notches, or gaps in the separator 27, the gap 41 is formed by the bulging portion 40 that bulges the collecting pipe 20 outward, so that the gas flowing through the gap 41 is Since it flows along the inner surface and does not disturb the original exhaust flow in the exhaust passages 2OA and 20B, a stable exhaust flow can be maintained at all times.

Furthermore, in this embodiment, since the gap 41 is arranged approximately on the extension line of the ends 11 of the four exhaust pipes 10 that are collectively connected, the exhaust air from each end 11 is concentrated in the gap 41. Exhaust passage 20A.

Interference between 20B can be performed most effectively.

Therefore, as shown in FIG. 4, the rotational speed N of the engine 2 is
In the case of this embodiment, the output characteristic P according to e is the curve shown by the solid line, and the conventional curve L2 shown by the broken line.
In addition to increasing the maximum output Pso in the high-speed rotation range compared to Can be done.

Further, the gap 41 in this embodiment is formed by the bulging portion 40 of the collecting pipe 20.
and the end edge 27A of the separator 27, the structure is simple and the number of parts does not increase, and the outer wall members 21 and 22 of the collecting pipe 20 can be formed into a predetermined shape in advance. It is also easy to manufacture.

Furthermore, the bulging portion 40 only needs to be provided in a small part in a part of the collecting pipe 20, and the dead space around the collecting exhaust pipe 1 can be effectively used, and the collecting exhaust pipe 1 can be attached to a motorcycle as in this embodiment. When installed, it can be placed inside or facing the bottom of the vehicle to make it difficult to see from the outside, thereby preventing it from degrading the aesthetics.

Note that the present invention is not limited to the above embodiments,
It also includes the following modifications.

That is, the gap 4 that connects the exhaust passages 20A and 20B
1 is not limited to the bulging portion 40 formed by bulging the outer wall members 21, 22 and the bonded portion 23 of the collecting pipe 20, but may use a separate member. For example, as shown in FIG. 5, a portion of the bonded portion 23 of the outer wall members 21 and 22 of the collecting pipe 20 is cut out to form an opening 42, and this opening 42 is sealed with a sealing member 43 having a bulge 40. By stopping, a gap 41 is formed between the edge 27A of the separator 27 and the bulging portion 40, and the exhaust passages 2°A and 20B may be communicated with each other. If it is formed from a cylindrical member instead of a cylindrical member, this example has the advantage of being easier to manufacture. Also, the fifth
In the illustrated example, a pipe or the like may be used instead of the sealing member 43 to allow the re-exhaust passages 2OA and 20B to communicate with each other.

Further, the bulging portion 40 is not limited to one location, but may be provided at two or more locations, and the installation location is not limited to the extension of the four exhaust pipes 10 as in the above embodiment, but is also provided at the end edge 27 of the separator 27.
Other positions along A may also be used. However, it is necessary to set it at an appropriate position taking into consideration the influence of the distance from the end face member 25 on the rotational characteristics of the encoder 20, and it is also desirable to set it at a position that is as difficult to see as possible from the viewpoint of aesthetics.

Further, the engine 2 is not limited to that of the embodiment described above, and may be applied to a six-cylinder engine, for example. Even in the case of a six-cylinder engine, the collective exhaust pipe 1 of the embodiment described above can be applied as is.
Three exhaust pipes 10 for each exhaust passage 2OA and 20B
The exhaust pulsation may be interfered with by connecting them and merging with each other at 240 degree intervals.

Further, exhaust passages 20A, 20 formed in the collecting pipe 20
B is not limited to two, but three or more may be provided. For example, when collecting exhaust gas at 360 degree intervals in a 6-cylinder engine, two separators may be placed in the collecting pipe 2o in a T-shape or 7-shape. Two exhaust pipes may be arranged to communicate with each exhaust passage, and a bulge 40 may be provided along a portion continuous to the inner surface of each collecting pipe 20 to communicate with each other.

〔Effect of the invention〕

As described above, according to the collective exhaust pipe for a four-cylinder engine of the present invention, it is possible to improve exhaust efficiency at high speeds, and stabilize the flow of exhaust gas at low speeds, improving engine characteristics. can be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the main parts of the embodiment, and FIG. 3 is a diagram showing ■-■ in FIG.
FIG. 4 is a graph showing the output characteristics of the embodiment, and FIG. 5 is a partially broken perspective view showing a modification of the present invention. DESCRIPTION OF SYMBOLS 1...Collection exhaust pipe, 2...Engine, 10...Exhaust pipe, 20...Collection pipe, 20A, 20B...Exhaust passage, 21.22...Outer wall member, 40... Bulge. Agent: Patent attorney Minoru Kinoshita (one idiot) Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a collective exhaust pipe for a multi-cylinder engine formed by collectively connecting a plurality of exhaust pipes from each cylinder of the multi-cylinder engine to one end of the collecting pipe, the exhaust pipe is connected to the inside of the collecting pipe. A separator of a predetermined length is provided from one end to the other end, the separator partitions the inside of the collecting pipe to form a plurality of exhaust passages, and each of the exhaust pipes is communicated with one of these exhaust passages. and a part of the outer wall of the collecting pipe along the separator is partially bulged outward to form a bulged part, and adjacent exhaust passages are made to communicate with each other in this bulged part. A collective exhaust pipe for a cylinder engine.