JPH033922A - Exhaust device for multi-cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the output torque over the whole ration range by communicating and connecting branch exhaust pipes via two communicating pipes provided with opening/closing valves respectively. CONSTITUTION:Branch exhaust pipes 16-18 connected to exhaust ports 8-10 of cylinders A1-A3 of an internal combustion engine 1 are formed in the same length size, and tips of branch exhaust pipes 16-18 are merged into one and connected to a main exhaust pipe 19 with the cross section area larger than that of them to constitute an exhaust device 15. Branch exhaust pipes 16-18 are communicated and connected to each other at optional portions via communicating pipes 21a-21c and 22a-22c. Opening/closing valves 23a-23c and 24a-24c are provided on communicating pipes 21a-21c and 22a-22c respectively. Opening/ closing valves 23a-23c and 24a-24c are opened or closed in proper rotation ranges by a control means 26 related to a rotation sensor 25 for the internal combustion engine 1. The high output torque can be obtained in each rotation area of the internal combustion engine 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust system for a multi-cylinder internal combustion engine having a plurality of cylinders, which aims to improve the output torque by improving the exhaust system of the engine.

[Conventional technology]

Generally, as is well known, an exhaust system for a multi-cylinder internal combustion engine merges the tips of branch exhaust pipes connected to each of the exhaust ports of each cylinder into one, and has a larger cross section than each of the exhaust pipes. It is connected to the main exhaust pipe of the area, and the main exhaust pipe is opened to the atmosphere via a muffler.

In an exhaust system configured in this way, the length of the exhaust passage from the exhaust valve to each cylinder to the confluence via the intake boat and branch exhaust pipe, the filling efficiency of air to each cylinder, and the There is a certain relationship between the output torque of an internal combustion engine, and if the length of the exhaust passage is set appropriately, the pressure in the exhaust port will change between the intake valve and the exhaust valve in a specific rotation range. It is known that the negative pressure becomes below atmospheric pressure in the overlapping section of (For example, published by Sankaido Co., Ltd., written by Maki Hirao, “Principles of Automotive Engine Planning J, 36~
(See page 38).

[Problem to be solved by the invention]

However, in this case, the output torque can be improved by setting the length of the exhaust passage from the exhaust valve to the confluence via the exhaust port and branch exhaust pipes, but it is possible to This is limited to a specific rotation range in which negative pressure is generated in the exhaust port during the lap section, and in other rotation ranges, there is almost no improvement in output torque, and in other rotation ranges, the pressure in the exhaust port increases. However, due to positive pressure (pressure higher than atmospheric pressure) in the overlap area between the intake valve and the exhaust valve, a phenomenon occurs in which the efficiency of filling air into the cylinder and, by extension, the output torque decreases. be.

Therefore, we created multiple branch exhaust pipes with different lengths that connect the exhaust ports and the main exhaust pipe in each cylinder, and selected these multiple branch exhaust pipes according to the rotational speed of the internal combustion engine. However, configuring a plurality of branch exhaust pipes for each cylinder in this way would significantly increase the size and weight of the exhaust system. It's not a good idea.

The present invention enables the output torque of an internal combustion engine to be distributed over the entire rotation range of the internal combustion engine by devising the intake pipe from the exhaust port of each cylinder, without causing an increase in size or weight. It is an object of the present invention to provide an improved exhaust system.

[Means to solve the problem]

In order to achieve this object, the present invention makes the branch exhaust pipes connected to each exhaust port in each cylinder of a multi-cylinder internal combustion engine the same length, and the tips of the exhaust pipes are merged into one. In an exhaust system connected to a main exhaust pipe having a larger cross-sectional area than each of the branch exhaust pipes, there is a A first part of the arbitrary part near the exhaust port is connected to the first part via the first communication pipe, and the merging part is made of the arbitrary part in the middle of the length of each of the exhaust pipes. communicatively connected via a second communication pipe in a second part near the area, and providing a first on-off valve in each of the first communication pipes and a second on-off valve in each of the second communication pipes, The first on-off valve and the second on-off valve are set according to the rotational speed of the internal combustion engine. When each first on-off valve is opened, each second on-off valve is closed, and when each first on-off valve is closed, each second on-off valve is closed. The configuration was configured to control the opening of the .

〔Example〕

Hereinafter, an embodiment of the present invention will be explained with reference to a drawing (Fig. 1). In the drawing, reference numeral 1 indicates a first cylinder A1, a second cylinder A
It is equipped with three cylinders, the second and third cylinders A3, and the phase between each cylinder is 120 degrees in crank angle, and the ignition order is first cylinder A1 - second cylinder A2 - third cylinder A3. A four-cylinder cylinder internal combustion engine is shown, and each cylinder Al, A2 . A3 has intake valves 5, 6.7
intake boats 2 and 3.4, each equipped with an exhaust valve 11.1
Exhaust ports 8,910 with 2.13 each are provided.

An intake manifold 14 for each of the intake boats 2, 3.4 is joined to one longitudinal side 1a of the internal combustion engine 1, while an exhaust device 15 is connected to the other longitudinal side 1b of the internal combustion engine 1. is attached.

This exhaust system 15 includes branch exhaust pipes 16, 17, 18 connected to each of the exhaust ports 8, 9, 10 in each of the cylinders Al, A2 and A3, and each of these branch exhaust pipes 16, 17.
．． One main exhaust pipe 1 with a cross-sectional area larger than 18
9, and the length of each branch exhaust pipe 16, 17. and the branch exhaust pipe line 18 in the third cylinder A3 (the branch exhaust pipe line 18 is configured to curve in a direction perpendicular to the paper plane of FIG. 20), which is connected to the main exhaust pipe line 19.

and a branch exhaust pipe line 17 in the second cylinder A2;
Branch exhaust pipe 16 in first cylinder AI and third cylinder A3
Each technical exhaust pipe 16,
17. Among arbitrary parts in the middle of the length direction of 18, a first part (r) having an appropriate length Ll from the other side surface 1b of the internal combustion engine 1 is connected to the first part (r) through first communication pipes 21a and 21b. In addition, the internal combustion engine 1 is located at any part in the longitudinal direction of each branch exhaust pipe 16, 17, 18.
A length L whose length from the other side surface 1b is greater than the above L1.
In the second portion (II) of 2, a second communication conduit 22a,
22b for communication connection.

Furthermore, each first communication pipe 2 in the first part (1)
1a and 21b are provided with first on-off valves 23a and 23b, respectively, and second on-off valves 24a and 24b are also provided on each of the second communication pipes 22a and 22b in the second portion (II), respectively. (1) On-off valves 23a, 23b and second on-off valve 24a.

24b is configured to be opened and closed in an appropriate rotation range by a control means 26 associated with a rotation sensor 25 for the internal combustion engine 1.

The present inventors conducted various experiments on the three-cylinder, four-stroke internal combustion engine with a total displacement of 993 cc, and as a result, they arrived at the configuration described above.

That is, first, as shown in Figure 2, the inner diameter is 3011.
The length L2 of each branch exhaust pipe 16, 17.
In the case of an exhaust system configured to be connected to the main exhaust pipe 19, which has a length of 8, as shown in FIG. is connected to the main exhaust pipe line 19, and the second cylinder A
2, a branch exhaust pipe 16 in the first cylinder A1, and a branch exhaust pipe 18 in the third cylinder A3.
and the length L from the other side surface 1b of the internal combustion engine 1
An experiment was conducted to measure the output torque for each rotation speed for both the case of an exhaust system configured such that the second part (n) where 2 is 80 ON is connected through the second communication pipes 22a and 22b. However, the exhaust system was
The output torque curve when configured as shown in the figure is the dotted curve a in Figure 4, whereas the output torque curve when the exhaust system is configured as shown in Figure 3 is curve 4. As shown by the solid curve A in the figure,
It was observed that the output torque was partially improved in a specific rotation range.

In addition, as shown in Fig. 5, the length Ll of each branch exhaust pipe 16, 17, and 18 with an inner diameter of 3 On is 500 x m.
As shown in FIG. 17
．． 18 with a length LO of 1200 m each and connected to the main exhaust pipe 19, and a branch exhaust pipe 17 in the second cylinder A2, a branch exhaust pipe 16 in the first cylinder A1, and a branch exhaust pipe in the third cylinder A3. The length 1 from the other side surface 1b of the internal combustion engine 1 between the pipe line 18 is 500 mm.
The first communication pipes 21a, 21 in the first part (I) of
An experiment was conducted to measure the output torque for each rotation speed for both the case of the exhaust system configured to be connected as shown in Fig. The curve is the dotted line curve in FIG. 7, whereas the output torque curve when the exhaust system is configured as shown in FIG. 6 is as shown by the solid line curve B in FIG. It was observed that the output torque was partially improved in a specific rotation range.

Therefore, when the output torque curve A when the exhaust system is configured as shown in FIG. 3 and the output torque curve B when the exhaust system is configured as shown in FIG. 6 are superimposed, the output l. Since the torque curve is as shown in FIG. 8, the rotational speed (rpm) of the internal combustion engine 1 is
(a) area below 700 and 1700 to 2300
(b) area of , and (c) area of 2300 to 3300,
It is divided into five regions: (d) region of 3,300 to 4,500 and (e) region of 4,500 or more.

Then, the first on-off valves 23a, 23b in each of the first communication pipes 21a, 21b and the second on-off valves 24a, 24b in each of the second communication pipes 22a, 2b are rotated at the rotational speed of the internal combustion engine 1. In order to open and close the opening/closing operation appropriately according to the above, in the region (A), the second on-off valves 24a and 24b are opened, while the first on-off valves 23a and 23b are controlled to be closed. ) region, each first on-off valve 23a,
23b is opened, while each of the second on-off valves 24a, 24b is controlled to be closed.

24b is opened, while each of the first on-off valves 23a, 23b is controlled to be closed. Each of the second on-off valves 243.24b is controlled to close, and in the (e) region, each of the second on-off valves 24a, 24b is opened, as in the (a) region, while each of the first on-off valves is controlled to close. 23a.

23b is controlled to close.

The first on-off valve 23 in each of the first communication pipes 21a and 2Ib
a, 23b, and each second communication pipe 22a.

When the second on-off valves 24a and 24b in 2b are controlled to open and close in this way, the areas (A), (C), and (E)
In the region, each second on-off valve 24a, 24b is open and each first on-off valve 24a, 24b is open.
By closing the on-off valves 23a and 23b, the exhaust system is in the same state as in the case where it is configured as shown in FIG. 3, so in these regions, high output torque along the curve can be obtained.

In addition, in the (b) area and (d) area, each first on-off valve 2
3a and 23b are open and the second on-off valves 24a and 24b are closed, resulting in the same state as when the exhaust system is configured as shown in FIG. High output torque can be obtained.

In addition, in the above embodiment, the first part (N) and the second part (
I[), the branch exhaust pipe 1 in the second cylinder A2
7 and the branch exhaust pipe 16 in the first cylinder IAI and the branch exhaust pipe 18 in the third cylinder A3, but in addition to this, as shown in FIGS. 9 and 10, In addition, a first portion (I
) and the second part (If), the first on-off valve 23C
The present invention is not limited to the case of the three-cylinder internal combustion engine; In the case of a cylinder internal combustion engine, it suffices to apply it to each of the two banks.

[Action/effect of the invention]

As described above, the present invention provides a method for displacing the exhaust gas between each branch exhaust pipe connecting the exhaust boat and the main exhaust pipe in each cylinder at any part in the longitudinal direction of each branch exhaust pipe. A first part closer to the boat is connected to the first part through the first communication pipe, and a second part closer to the confluence part is connected to the second part in the middle of the length of each branch exhaust pipe. a first on-off valve that is connected in communication via a second communication pipe in the first portion and provided in each of the first communication pipes in the first portion; and a second on-off valve provided in each of the second communication pipes in the first portion; By opening and closing appropriately according to the rotation speed of the internal combustion engine, high output torque can be obtained in each rotation range of the internal combustion engine, so the output torque of the internal combustion engine can be improved over the entire rotation range, In addition, since each branch exhaust pipe is connected to each other by a communication pipe, and an on-off valve is provided in each communication pipe,
This has the effect of not causing a significant increase in the size and weight of the exhaust system.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing an embodiment of the present invention, FIGS. 2, 3, 5, and 6 are plan views showing an exhaust system before the present invention, and FIG. is an output torque curve diagram in the case of FIGS. 2 and 3, FIG. 7 is an output torque curve diagram in the case of FIGS. 5 and 6, and FIG. 8 is a diagram showing the case where the output torque curves are overlapped. Figures 9 and 10 are the first
It is a sectional view showing other examples in a first part (I) and a second part (n) in the figure. 1...Internal combustion engine, 2.3.4...Intake boat,
5.6.7...Intake valve, 8,9.10...Exhaust port, 11.12.13...Exhaust valve, 14...
・Intake manifold, 15...Exhaust device, 16.1
718... Branch exhaust pipe line, 19... Main exhaust pipe line, 20... Merging part, (1)... First part,
(II)...Second part, 21a, 21b, 21c
...First communication pipe line, 22a, 22b, 22c...
- Second communication pipe line, 23a, 23b, 23C...first
On-off valve, 24a, 24b, 24cm--second on-off valve,
25... Rotation sensor 26... Control device.

Claims (1)

[Claims] (1) The branch exhaust pipes connected to each exhaust port in each cylinder of a multi-cylinder internal combustion engine are made to have the same length dimension, and the tips of the respective exhaust pipes are merged into one, and each branch exhaust pipe is In an exhaust system connected to a main exhaust pipe having a cross-sectional area larger than that of the pipe, between the branch exhaust pipes, the A first part near the exhaust port is connected to the first part via the first communication pipe, and a second part near the confluence part of any part in the lengthwise direction of each of the branch exhaust pipes is connected to the first part near the exhaust port. A first on-off valve is provided in each of the first communication pipes, a second on-off valve is provided in each of the second communication pipes, and the first on-off valve and When the second on-off valve is opened, each second on-off valve is closed, and when each first on-off valve is closed, each second on-off valve is closed, depending on the rotational speed of the internal combustion engine.
An exhaust system for a multi-cylinder internal combustion engine, characterized by controlling an on-off valve to open.