JPH0619796Y2 - Exhaust system for 4-cylinder engine - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an exhaust system for a four-cylinder engine suitable for implementation in a traveling vehicle such as a two-wheeled vehicle, a three-wheeled vehicle, or a four-wheeled vehicle.

[Conventional technology]

Even in traveling vehicles such as motorcycles and 3- and 4-wheeled vehicles,
In response to a request for improved performance, it will be equipped with 4 engines.
In many cases, a multi-cylinder engine such as a cycle 4-cylinder engine is adopted.

In such an exhaust system of a multi-cylinder engine, that is, in an exhaust system having a plurality of exhaust pipes connected to each of a plurality of cylinders, exhaust pipes are connected or assembled to each other to generate a pulsating wave in an exhaust pipe of another cylinder. It is known that the filling efficiency of each cylinder can be improved by utilizing the same.

As one example, as described in Japanese Utility Model Publication No. 58-36808, two exhaust pipes from four cylinders are used.
There is used a structure in which the exhaust pipes are collected one by one and collected into two exhaust pipes, and a silencer is connected to the rear ends of these two exhaust pipes.

Such an exhaust pipe collecting system is called a 4into2to2 system because the number of exhaust passages changes from four exhaust pipes → two exhaust pipes → two silencers.

[Technical issues to be solved by the device]

However, in this 4into2to2 system, the pulsating waves of the other cylinders that can be used by each cylinder are only for one of the cylinders that join at the 4into2 meeting point, and there is a limit in improving the charging efficiency.

Therefore, as an exhaust device that joins the exhaust from all four cylinders, all four exhaust pipes from four cylinders are combined into one exhaust pipe, and a silencer is connected to the rear end of this one exhaust pipe. A configuration, that is, a 4into1to1 system is proposed.

This 4into1to 1 type exhaust device is, for example,
No. 2-55545.

However, in this 4 into 1 to 1 system, the volume of the silencer and the exhaust system as a whole becomes insufficient, and a sufficient silencing effect cannot be obtained, and since there is only one silencer The problem remains that the appearance becomes unbalanced on the left and right when it is carried out, and further, the torque dent is likely to occur in the engine performance curve.

The present invention has been made in view of such a technical problem, and by utilizing the pulsating waves of all four cylinders, the charging efficiency can be effectively increased and the silencing effect can be sufficiently achieved. Further, it is possible to provide an exhaust system for a four-cylinder engine which can prevent the dent of the torque of the engine performance curve and can also solve the left-right unbalance in appearance when applied to a motorcycle or the like. To aim.

[Means for solving problems]

The exhaust system for a four-cylinder engine according to the invention of claim 1 has four
Four front exhaust pipes connected to the exhaust ports of each of the four cylinders are gathered into one intermediate exhaust pipe, and a horizontal partition plate is provided at the gathering portion from the four front exhaust pipes to one intermediate exhaust pipe. By providing a partition region of a predetermined length divided into two upper and lower pipelines, the one intermediate exhaust pipe is branched into two rear exhaust pipes, and further, the rear exhaust pipe is provided from the latter half of the intermediate exhaust pipe. Attach a sound absorbing material to the inner surface of the pipe to the middle part of the pipe, and
By configuring the silencer to be connected to the rear end of each of the rear exhaust pipes, the filling efficiency can be effectively increased by utilizing the pulsating waves of all four cylinders, and the torque dent in the engine performance curve can be improved. Can be achieved, and the sound deadening effect can be sufficiently achieved, and the left and right imbalance in appearance when applied to a motorcycle or the like can be eliminated. 4
An exhaust system for a cylinder engine is provided.

In addition to the above configuration, the exhaust system for a four-cylinder engine according to the invention of claim 2 is configured such that two exhaust pipes are arbitrarily selected from the four front exhaust pipes, and the exhaust pipes are connected by a communication pipe. The present invention provides an exhaust system for a four-cylinder engine that can further improve the charging efficiency.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of an embodiment of an exhaust system for a 4-cylinder engine according to the present invention, and FIG. 2 is a side view of the exhaust system of FIG.

In FIG. 1 and FIG. 2, four exhaust pipes (front exhaust pipes) 11 connected to the exhaust ports of each cylinder of a four-cylinder engine
A, 11B, 11C and 11D are collected into one intermediate exhaust pipe 13 via the manifold 12, and the intermediate exhaust pipe 1
3 again through the manifold 14 at the rear end
After the book, it is branched into exhaust pipes 15A and 15B.

At the rear ends of the two rear exhaust pipes 15A and 15B,
The silencers 16A and 16B are connected.

FIG. 3 is a partially cutaway plan view showing the structure of the manifold 12, the intermediate exhaust pipe 13, and the manifold 14, and FIG. 4 is a partially broken longitudinal section taken along line IV-IV in FIG. 5 is a front view of the manifold 12 as seen from the line VV in FIG. 4, and FIG. 6 is a line in FIG.
FIG. 6 is a sectional view taken along line VI-VI.

3 to 6, at the front end of the manifold 12, there are four connecting portions 12A, 12B, 1 at the upper and lower sides and 1 at the left and right sides.
It is partitioned into 2C and 12D, and four exhaust pipes 11A, 11B, 11C and 11D are connected to these connecting portions one by one.

In the illustrated example, the exhaust pipes 11A and 11D are connected to the upper left and right connecting portions 12A and 12D, and the exhaust pipes 11B and 11C are connected to the lower left and right connecting portions 12B and 12C.

Inside the manifold 12, a U-shaped horizontal partition plate 20 having a U-shaped tip and two U-shaped vertical partition plates 18 extending rearward of the connecting portions 12A, 12B, 12C, and 12D for connecting the exhaust pipes, Divided by 19.

In the illustrated example, the horizontal partition plate 20 extends rearward from the vertical partition plates 18 and 19, so that the four exhaust pipes 11A, 11B, 11C, and 11D are
After the two 1A and 11D and the two 11B and 11C are assembled into two upper and lower passages, one horizontal passage (intermediate) is formed after the rear end of the horizontal partition plate 20. Collected in the exhaust pipe 13).

The manifold (bifurcated portion) 14 is integrally formed at the rear end portion of the intermediate exhaust pipes 13 that are gathered into one, and the manifold 14 has left and right rear exhaust pipes 15A, 1A.
5B is connected.

By the way, in the above exhaust system, depending on operating conditions such as the exhaust pipe length and engine speed of each cylinder, when the positive pressure portion of the exhaust pipe pulsating wave from each cylinder just overlaps, the exhaust pipe internal pressure rises. As a result, the amount of exhaust gas from the combustion chamber may decrease, and the charging efficiency may decrease.

However, generally, it is possible to prevent the filling efficiency from decreasing by designing (such as selecting each exhaust pipe length) so as to avoid overlapping of the positive pressure portions. Furthermore, each partition plate 1
By selecting the shape and length of 8, 19, and 20, it is also possible to improve the filling efficiency by utilizing the interaction of the exhaust pipe pulsating waves.

Thus, the U-shaped partition plates 18, 19, 20
Is for eliminating the above-mentioned exhaust interference and preventing a decrease in the intake efficiency of the engine intake (a depression of the torque in the performance curve) by selecting the length and shape thereof.

In the illustrated example, the manifold 12 for assembly is formed by the front end portions of the first pipe member 31 and the second pipe member 32, and the intermediate exhaust pipe 13 is formed in the middle of the second pipe member 32. The manifold 14 for branching is formed in the rearward portion of the second conduit member 32, but each of these portions can be freely determined in consideration of the manufacturing process.

Further, the first conduit member 31 and the second conduit member 3
The front and rear end connecting portions of 2 are connected in an airtight state by a suitable connecting means such as welding or a clamp.

FIG. 7 is a graph schematically showing the pressure fluctuation in the exhaust passage based on the time when the exhaust valve is opened in a general exhaust device, and the upper side of the horizontal axis shows the time after the exhaust valve is opened. A positive pressure area is formed in the negative pressure area and a negative pressure area is formed below the positive pressure area.

Although the cycle (wavelength) of the pressure in the exhaust passage changes depending on the engine speed, a pulsating wave as shown in FIG. 7 is generated.

FIG. 8 is a graph schematically showing a state of occurrence of peaks and troughs of charging efficiency (output torque) with respect to engine speed in a general engine.

In FIGS. 7 and 8, there is a timing (overlap) when the intake valve opening and the exhaust valve opening overlap in the four-cycle engine, and this overlapping occurs at the positive pressure peaks P ₁ , P ₃ , and P _{5 in} FIG. 7. At a rotational speed substantially equal to, the intake / exhaust flow tends to become stagnant, the charging efficiency decreases, and M in FIG.
Torque troughs such as ₁ , M ₃ and M ₅ will occur.

On the other hand, at the rotational speed at which the above-mentioned overlap substantially coincides with the negative pressure peaks P ₂ , P ₄ , and P _{6 in} FIG. 7, the negative pressure tends to draw intake air and exhaust gas, and the filling efficiency is improved. Torque peaks as shown by M ₆ , M ₄ , and M ₂ in the figure occur.

In the structure as shown in FIGS. 1 to 6, the position and internal structure of the collecting portion (manifold 12) of the exhaust pipes 11A, 11B, 11C and 11D, and the vertical or horizontal partition plates 18, 19, The period and pressure value of the exhaust pipe pulsating wave can be adjusted by the shape and length of 20, etc., and the sound deadening effect due to the pressure decrease (the degree of expansion) is influenced by the volume of the exhaust passage.

In that case, as much as possible with eliminating the influence of the exhaust interference due to the positive pressure _{P 1, P 3, P 5} of the exhaust pipe pulsating, by utilizing as much as possible the pulsation effect of the negative pressure _{P 2, P 4, P 6} , It is possible to increase the efficiency of charging intake air and improve the output.

Further, the sound deadening effect can be enhanced by sufficiently securing the expansion coefficients of the collecting portion (rear portion of the manifold 12) and the branching portion (manifold 14) and further the expansion coefficients of the silencers 16A and 16B.

Therefore, according to the embodiment described with reference to FIGS. 1 to 6, four front exhaust pipes 11A, 11B, 11C, and 11D connected to the exhaust ports of the four cylinders are connected to each other through the manifold 12. The exhaust pipe pulsating waves of all four cylinders can be fully utilized because they are collected in the intermediate exhaust pipe 13 of the U-shaped vertical partition plates 18 and 19 and the horizontal partition plate in the front part of the intermediate exhaust pipe 13. The provision of 20 makes it possible to improve the efficiency of filling intake air and the sound deadening effect of the above-mentioned assembly while preventing exhaust interference.

Further, the intermediate exhaust pipe 13 is again provided with two rear exhaust pipes 15.
Branches to A and 15B, two silencers 16A and 16B on the left and right
Since the structure is used, the total volume of the silencers 16A and 16B can be easily and sufficiently secured, and the silencer effect can be maintained.

At the same time, in a motorcycle, the silencer 16A, 1
Since 6B can be mounted on both left and right sides, it was possible to maintain an excellent appearance with a balanced left and right.

FIG. 9 is a plan view showing another embodiment of the exhaust system for a four-cylinder engine according to the present invention, and FIG. 10 is a side view of the exhaust system of FIG.

Also in the present embodiment, four exhaust pipes (front exhaust pipes) 11A, 11 connected to the exhaust ports of each cylinder of the four-cylinder engine
B, 11C and 11D are gathered into one intermediate exhaust pipe 13 via the manifold 12, and the intermediate exhaust pipe 13 is again provided with two rear exhaust pipes 15A and 15B via the manifold 14 at the rear end. Has been branched into.

At the rear ends of the two rear exhaust pipes 15A and 15B,
The silencers 16A and 16B are connected.

The structure of this embodiment is the same as the structure of FIGS. 1 and 2 except that the second exhaust pipe 11B and the third exhaust pipe 11C are used.
Connected by a communication pipe 21 upstream of the gathering point, and
The partition plates provided in the manifold 12 and the intermediate exhaust pipe 13 are formed in a rectangular shape, and the manifold 14 and the left and right rear exhaust pipes 15A are arranged from the latter half of the intermediate exhaust pipe 13.
The sound absorbing material is modified so that it is attached to the inner surface of the conduit up to the middle portion of 15B.

The other parts of this embodiment are substantially the same as in the case of FIGS. 1 and 2.

11 is a horizontal sectional view of the manifold 12, the intermediate exhaust pipe 13 and the manifold 14 of the exhaust system of FIGS. 9 and 10, and FIG. 12 is a vertical sectional view taken along the line XII-XII in FIG. FIG. 13 is a diagram, and FIG. 13 is a line XIII in FIG.
-XIII is a front view of the manifold 12, FIG. 14 is a cross-sectional view taken along the line XIV-XIV in FIG. 12, and FIG. 15 is an exhaust pipe inner view viewed from the line XV-XV in FIG. 16 is a sectional view taken along line XVI-XVI in FIG.

In the present embodiment, first, the second exhaust pipe 11B and the third exhaust pipe 11C are connected to each other by the communication pipe 21 on the upstream side of the collecting portion at the rear part of the manifold 12.

By thus connecting the exhaust pipes 11B and 11C to each other at the position before the assembly, it is possible to further effectively utilize the exhaust pipe pulsating wave and improve the filling efficiency.

11 to 14, at the front end portion of the manifold 12, there are four connecting portions 12A, 12 at upper, lower, left and right.
It is divided into B, 12C, and 12D, and four exhaust pipes 11A, 11B, 11C, and 11D are connected to these connecting portions one by one.

Further, a horizontal partition plate 25 is used as a member for partitioning the interior of the manifold 12 into upper and lower parts.

In this embodiment, the partition plate 25 has a substantially rectangular shape.

Also in the illustrated example, as in the case of the above-described embodiment, the exhaust pipe 11
A and 11D are connected to the upper left and right connecting portions 12A and 12D, and the exhaust pipes 11B and 11C are connected to the lower left and right connecting portions 12B and 12C.

The four exhaust pipes 11A, 11B, 11C and 11D are
Behind the manifold (collecting portion) 12, they are completely assembled in one passage (intermediate exhaust pipe 13).

The manifold (bifurcated portion) 14 is formed at a rear end portion of the intermediate exhaust pipes 13 which are assembled into one,
Left and right rear exhaust pipes 15A and 15B are provided in the manifold 14.
Are connected.

By the way, in the present embodiment, a rectangular horizontal partition plate 26 is provided at an intermediate portion of the intermediate exhaust pipe 13 in the front-rear direction, and a part of the intermediate exhaust pipe 13 is vertically divided.

Also in this embodiment, as in the case of the above-described embodiment, by selecting the position and length of each of the rectangular partition plates 25 and 26, the exhaust interference as described above is eliminated, and the engine intake air charging efficiency is eliminated. Can be prevented (a depression of the torque in the performance curve).

That is, in the exhaust system, depending on the operating conditions such as the exhaust pipe length of each cylinder and the engine speed, when the positive pressure portion of the exhaust pipe pulsating wave from each cylinder just overlaps, the exhaust pipe internal pressure rises. The filling efficiency may be reduced, but by designing (such as selecting each exhaust pipe length) so that the positive pressure portions do not overlap, the reduction of the filling efficiency can be prevented. By selecting the shapes and lengths of 25 and 26, the filling efficiency can be improved by utilizing the interaction of the exhaust pipe pulsating waves.

In this embodiment, the manifold 12 for assembly is formed in the front half of the first pipeline member 31, and the rear half of the first pipeline member 31 and the front portion of the second pipeline member 32 are joined together. An intermediate exhaust pipe 13 is formed, and a manifold 14 for branching is formed at a rear portion of the intermediate exhaust pipe 13 of the second conduit member 32. However, each of these parts can be freely formed in consideration of a manufacturing process. It can be decided.

Further, the front and rear connecting portions of the first and second conduit members 31, 32 can be connected by any suitable means such as welding or clamping as long as they can be joined in an airtight state.

Further, in this embodiment, as shown in FIGS. 11 and 12, the inside of the second conduit member 32, that is, the latter half of the intermediate exhaust pipe 13 to the manifold 14 are shown.
Further, the sound absorbing material 27 is attached to the inner surface of the pipe path up to the intermediate portion of the left and right rear exhaust pipes 15A and 15B.

As the sound absorbing material 27, for example, if it is a heat resistant sound absorbing material such as glass wool or steel fiber,
Various ones can be used.

As shown in FIG. 15 and FIG. 16, the sound absorbing material 27 is formed in a layer having a predetermined thickness so as to cover the inner surface of the conduit 28, and a steel plate having a large number of holes formed therein. Further, it is held in a joined state on the inner surface of the conduit 28 by a punching plate 29 made of a stainless steel plate, a wire mesh or the like.

In this way, after the sound is silenced at the rear portion (collection portion) of the manifold 12, the sound absorbing material 27 is further silenced to improve the sound deadening effect.

It should be noted that the arrangement range of the sound absorbing material 27 is not limited to the illustrated example and can be freely selected.

Further, also in the embodiment shown in FIGS.
According to the embodiment of FIGS. 16 to 16, the sound absorbing material 2 as described above is used.
An item equivalent to 7 can be attached, and a similar silencing effect can be achieved.

According to the embodiment described with reference to FIGS. 9 to 16 above, the four front exhaust pipes 11A, 11B, 11C and 11D connected to the exhaust ports of the four cylinders are connected to each other through the manifold 12. Since they are collected in the intermediate exhaust pipe 13, the exhaust pipe pulsation waves of all four cylinders can be fully utilized, and further, the rectangular horizontal partition plate 2 is provided in the manifold 12.
5, and by providing a rectangular horizontal partition plate 26 in the intermediate portion of the intermediate exhaust pipe 13, it is possible to prevent exhaust interference and improve the intake charging efficiency and the sound deadening effect by the assembly. did it.

Further, the intermediate exhaust pipe 13 is again provided with two rear exhaust pipes 15.
Branches to A and 15B, two silencers 16A and 16B on the left and right
Since the structure is used, the total volume of the silencers 16A and 16B can be easily and sufficiently secured, and the silencer effect can be maintained.

At the same time, in a motorcycle, the silencer 16A, 1
Since 6B can be mounted on both left and right sides, it was possible to maintain an excellent appearance with a balanced left and right.

Furthermore, since a layer of the sound absorbing material 27 is provided on the inner surface of the conduit 28 on the downstream side of the collecting manifold 12, after the sound is silenced in the collecting portion (rear part of the manifold 12), the conduit 28 portion However, I was able to mute the sound and further improve the muffling effect of the exhaust.

In the above-described embodiment, the second and third exhaust pipes 11B and 11C are connected by the communication pipe 21, but this may connect the first and fourth exhaust pipes 11A and 11D or optionally. Two exhaust pipes can be selected and connected by a communication pipe.

It is also possible to select four exhaust pipes, two exhaust pipes each, and use two communication pipes together.

FIG. 17 is a perspective view of the present invention having the configuration of FIGS.
It is a graph which compares and shows the characteristic curve of the engine output with respect to rotation speed of the exhaust device of into1to2 system, and the conventional exhaust device of 4into2to2 system.

As is apparent from the graph of FIG. 17, by applying the present invention, the exhaust gas is discharged in a region (a low-speed region and a high-speed region in the illustrated example) where the charging efficiency is reduced (torque depression) due to exhaust interference. The influence of interference could be reduced or eliminated, and a significant performance improvement commensurate with it could be realized.

FIG. 18 is a graph showing a comparison of engine output characteristic curves with respect to engine speed of the 4into1to2 type exhaust device of the present invention having the configurations of FIGS. 9 to 16 and the conventional 4into2to2 type exhaust device. is there.

As apparent from the graph of FIG. 18, by applying the configuration of the present invention in which the communication pipe 21 (FIG. 9) is added,
In the region where the filling efficiency is reduced (torque dent) due to the exhaust interference (in the example of the figure, the region of medium-low speed and high speed), the influence of the exhaust interference can be further reduced or eliminated, and accordingly, the effect becomes much larger. We were able to improve performance.

[Effect of device]

As is clear from the above description, according to the exhaust system for a four-cylinder engine of claim 1, the four front exhaust pipes connected to the exhaust ports of the four cylinders are combined into one intermediate exhaust pipe. A partition area of a predetermined length, which is divided into two upper and lower pipelines by a horizontal partition plate, is provided at a gathering portion from the four front exhaust pipes to one intermediate exhaust pipe, and the one intermediate exhaust pipe is The rear exhaust pipe is branched into two rear exhaust pipes, and a sound absorbing material is attached to the inner surface of the pipe passage from the latter half of the intermediate exhaust pipe to the middle portion of the rear exhaust pipe. Since the silencer is connected to, the filling efficiency can be effectively increased by using the pulsating waves of all four cylinders, and the torque dent in the engine performance curve can be prevented and the noise reduction effect can be sufficiently achieved. It can be applied to motorcycles etc. Left and right unbalance in the appearance of the case is also the exhaust system of a four-cylinder engine capable of solving is provided.

According to the exhaust system for a four-cylinder engine of claim 2, in addition to the above configuration, two exhaust pipes are arbitrarily selected from the four front exhaust pipes, and the exhaust pipes are connected by a communication pipe. In addition to the above effects, an exhaust system for a four-cylinder engine that can further improve the charging efficiency is provided.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an exhaust system for a 4-cylinder engine according to the present invention, FIG. 2 is a left side view of the exhaust system of FIG. 1, and FIG. 3 is an assembly of exhaust pipes in FIG. 4 is a vertical sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a manifold 12 viewed from line VV in FIG. 4. Front view of Fig. 6 is line VI- in Fig. 4
Fig. 7 is a cross-sectional view along VI, Fig. 7 is a graph showing general pressure fluctuations in the exhaust passage, Fig. 8 is a graph showing engine output characteristics showing a decrease in filling efficiency (torque depression) due to exhaust interference, 9 is a plan view showing another embodiment of the exhaust system according to the present invention, FIG. 10 is a left side view of the exhaust system of FIG. 9,
11 is a plan sectional view showing the structure of the collecting portion and the branching portion of the exhaust pipe in FIG. 9, and FIG. 12 is a line XII-X in FIG.
Fig. 13 is a longitudinal sectional view taken along line II, and Fig. 13 is a line XIII- in Fig. 12.
A front view of the manifold 12 as seen from XIII, FIG. 14 is a sectional view taken along line XIV-XIV in FIG. 12, and FIG.
The front view which shows the inner surface of the pipe line seen from the line XV-XV in FIG. 1, FIG. 16 is sectional drawing along the line XVI-XVI in FIG.
FIG. 7 and FIG. 18 are graphs showing engine output characteristics of the exhaust system in which the present invention is implemented and the conventional exhaust system, respectively, for comparison. 11A, 11B, 11C, 11D ... Front exhaust pipe, 12 ...
... Manifold for forming exhaust pipe collecting portion, 13 ...
... intermediate exhaust pipe, 14 ... manifold for forming exhaust pipe branch portion, 15A, 15B ... rear exhaust pipe, 16A,
16B ... muffler, 18, 19, 20 ... partition plate, 2
1 ... Communication pipes 25, 26 ... Partition plate, 27 ... Sound absorbing material.

Claims (2)

[Scope of utility model registration request] 1. The four front exhaust pipes connected to the exhaust ports of each of the four cylinders are combined into one intermediate exhaust pipe, and
The front exhaust pipe of one book to the one intermediate exhaust pipe is provided with a partition region of a predetermined length divided into two upper and lower pipe lines by a horizontal partition plate, and two intermediate exhaust pipes are provided. To the rear exhaust pipe, and further, a sound absorbing material is attached to the inner surface of the pipe path from the latter half of the intermediate exhaust pipe to the middle portion of the rear exhaust pipe to muffle sound at the rear end of each of the two rear exhaust pipes. An exhaust system for a four-cylinder engine, characterized in that the exhaust system is connected. 2. The exhaust system for a four-cylinder engine according to claim 1, wherein two exhaust pipes are arbitrarily selected from the four front exhaust pipes, and the exhaust pipes are connected by a communication pipe.