JPH04358718A - Exhaust device of internal combustion engine - Google Patents

Abstract

PURPOSE:To increase output of an engine by smoothing flow of exhaust gas in a manifold chamber so as to reduce pressure loss of exhaust gas, in the exhaust device of a straight type internal combustion engine. CONSTITUTION:The tapered inlet port 31 of a catalyst converter 30 is provided so as to be projected in a manifold chamber 22. A branch pipe 23-4 provided most backward (T2 direction) is inclined forward (Y1 direction) and it is inserted in and mounted on the manifold chamber 22. Exhaust gas 45-4 outputted from the branch pipe 23-4 is branched away in right and left according to the shape of the inlet port 31, and it flows in a loop shape as shown by an arrow (B). It is thus possible to smooth flow of exhaust gas 45-1 to 45-4 in the manifold chamber 22.

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 an internal combustion engine, and more particularly to an exhaust system for an internal combustion engine that discharges exhaust gas in the axial direction of the crankshaft of an in-line internal combustion engine.

0002

2. Description of the Related Art FIG. 8 shows a configuration diagram of an example of a conventional exhaust system for an internal combustion engine.

In the figure, reference numeral 10 indicates an in-vehicle engine in which an exhaust system 2 is installed directly under the exhaust port (not shown in the figure) of an in-line four-cylinder engine body 1 to achieve miniaturization. . The exhaust system 2 includes a manifold flange 3 that connects the engine body 1 and the exhaust system 2, a branch pipe 4 to which exhaust ports and pipes are connected via the manifold flange 3, and exhaust gas from each branch pipe 4. It is composed of a manifold chamber 5 where the exhaust gases are collected, a catalytic converter 6, a second muffler 7, and an outlet pipe 8 that conveys exhaust gas to the atmosphere.

[0004] Each cylinder of the engine body 1 (not shown)
Exhaust gas is discharged through each exhaust port and branch pipe 4 to a manifold chamber 5, which is a first muffler, and then passes through a catalytic converter 6, a second muffler 7, and an outlet pipe 8. , the sound is muffled and toxic gases are removed before being released into the atmosphere.

[0005] The exhaust system 2 shown in the figure is an engine main body 1.
The engine 10 is configured to discharge exhaust gas in the Y2 direction, which is the axial direction of the crankshaft of the engine 10, so that the axial direction of the crankshaft is aligned with the longitudinal direction of the vehicle, and the outlet pipe 8 is extended toward the rear of the vehicle. This is a vertically mounted vehicle engine mounted on a vehicle (in contrast to the above-mentioned vertically mounted engine, a horizontally mounted engine is one that is mounted so that the axial direction of the crankshaft is perpendicular to the longitudinal direction of the vehicle).

[0006]

[Problem to be solved by the invention] FIG. 9 is a diagram illustrating a problem in the exhaust system 2 shown in FIG. 8, and schematically represents the flow of exhaust gases 11-1 to 11-4 in the manifold chamber 5. It is a diagram.

In the case of the vertically installed engine, as shown in the figure, the exhaust gases 11-1 to 11-4 discharged from the branch pipes 4-1 to 4-4 are directed toward the catalytic converter 6. This requires a 90 degree turn. Furthermore, the flow velocity of the exhaust gases 11-1 to 11-4 at the outlet portions of the branch pipes 4-1 to 4-4 is set at a high speed of about 100 m/s.

For this reason, the exhaust gas 11-4 from the branch pipe 4-4 closest to the inlet port 6a of the catalytic converter 6 cannot completely turn toward the inlet port 6a, and as shown in the figure, the exhaust gas 11-4 is The liquid flows through the front surface of the inlet port 6a of No. 6. Since the exhaust gases 11-1 to 11-3 from the other branch pipes 4-1 to 4-3 are far from the catalytic converter 6, their direction is changed relatively smoothly and flows toward the inlet port 6a. try Therefore, the exhaust gas 11-4 from the branch pipe 4-4 is separated from the other exhaust gas 11-4 in the section A shown by the dotted line in the figure.
1 to 11-3 from flowing into the inlet port 6a, increasing the pressure loss within the manifold chamber 5. Therefore, the exhaust pressure loss in the entire exhaust system 2 increases, causing a decrease in the output of the engine 10.

[0009]The present invention was made in view of the above-mentioned problems, and includes a guide member in the manifold chamber that guides the exhaust gas, which obstructs the smooth flow of the exhaust gas in the manifold chamber, so that the entire exhaust gas flows smoothly. An object of the present invention is to provide an exhaust system for an internal combustion engine, which makes the flow of exhaust gas within a manifold chamber smooth as a whole, reduces exhaust pressure loss in the manifold chamber, and increases the output of the engine.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an expansion chamber directly below an exhaust port of an in-line internal combustion engine in which exhaust gases from a plurality of exhaust ports gather, and In an exhaust system for an internal combustion engine, the expansion chamber is provided with an opening for discharging gas in the axial direction of the crankshaft of the internal combustion engine, wherein exhaust gas is discharged in a direction that disturbs the smooth flow of exhaust gas to the opening in the expansion chamber. A guide member is provided in the expansion chamber so as to face an exhaust port that exhausts gas (hereinafter referred to as a specific port), and the guide member changes the flow of exhaust gas exhausted from the specific port, and This structure maintains the smooth flow of the exhaust gas.

[0011]

[Operation] By providing a guide member in the expansion chamber to face a specific port, exhaust gas from the specific port can be
The flow direction is changed to prevent disturbing the smooth flow of exhaust gas from each exhaust port to the opening in the expansion chamber. As a result, the pressure loss in the exhaust gas expansion chamber is reduced.

0012

[Embodiment] Fig. 1 is a block diagram of a first embodiment of an exhaust system for an internal combustion engine according to the present invention, and Fig. 2 is a cross-sectional view of the exhaust system shown in Fig. 1 installed in the engine. , II-I
A cross-sectional portion taken along line I is shown. FIG. 3 is a perspective view of the entire exhaust system including the exhaust device shown in FIG. 1.

In each figure, an exhaust system 20 is an example of an exhaust system installed in the above-mentioned vertically mounted four-cylinder in-line engine (hereinafter simply referred to as engine) 50. In each figure,
21 is a manifold flange that is a joint with the engine body 24, and 22 is a manifold chamber that is a first muffler. 23-1 to 23-4 are manifold flanges 2
1 and the manifold chamber 22, and conveys exhaust gas from the exhaust port to the manifold chamber 22. Branch pipe 23-1~
One end of 23-4 is connected to each exhaust port (
(not shown in the figure) via the manifold flange 21, and branch pipes 23-1 to 23-
The distal end portion of No. 4 on the side opposite to the exhaust port is provided to extend into the manifold chamber 22 .

The second muffler 25 adjacent to the manifold chamber 22 has a plurality of expansion chambers and exhaust gas circulation holes therein, and efficiently muffles exhaust noise. Further, 26 is an outlet pipe that conveys exhaust gas to the outside.

The manifold chamber 22 and the second muffler 25 are provided with split flanges 27a and 27b, respectively, and are directly connected by bolts 28 with the split flanges 27a and 27b in contact with each other. The catalytic converter 30 is connected between the manifold chamber 22 and the second muffler 25, which are connected to each other in this way.
It is attached to the inner periphery of the The position of the catalytic converter 30 in the Y1-Y2 direction, which is the longitudinal direction of the vehicle, is such that the central portion of the catalytic converter 30 is exactly where the dividing flanges 27a and 27b are located. Therefore, the tapered inlet port 31 of the catalytic converter 30 is provided to protrude into the manifold chamber 22, and the other outlet port 32 is also provided to protrude into the second muffler 25.

In addition, in order to fix the exhaust system 20 in which the heavy catalytic converter 30 is installed as described above to the engine body 24, as shown in FIGS. 36 to the engine body 24, and the other end thereof is fastened together with the bolt 28 when the split flanges 27a and 27b are tightened. Further, 33 and 34 respectively indicate exhaust gas flowing into the catalytic converter 30 and the catalytic converter 3.
This is an oxygen (O2) sensor that detects the amount of oxygen in exhaust gas from which toxic components have been removed.

In FIG. 2, 24a is an oil pan of the engine body 24, and as can be seen from the arrangement of this oil pan 24a, the engine 50 of this embodiment is laid down approximately on its side, as shown in FIG. It is mounted on the vehicle in the same condition. With the engine 50 arranged in this manner, the floor of the vehicle can be lowered.

Further, in FIG. 3, 37 is a muffler bracket that fixes the second muffler to the vehicle, 38 is a flexible pipe that is a vibration isolation device, 39 is a tail pipe that conveys exhaust gas to the rear outside of the vehicle, 40, 42 are support brackets provided on the pipe side and the vehicle side, respectively;
1 is support rubber.

Next, the flow of exhaust gas in the exhaust system 20 will be explained.

Exhaust gas discharged from each cylinder (not shown) of the engine body 24 passes through each exhaust port and branch pipes 23-1 to 23-4, and enters the manifold chamber 22, which is a first muffler. is ejected to and expanded here. This expansion action attenuates the exhaust gas pulsation,
Furthermore, since the exhaust gas from each exhaust port is mixed, exhaust interference between each cylinder can be reduced.

[0021] In the exhaust system 20 of this embodiment, the inlet port 31 of the catalytic converter 30 is provided so as to protrude into the manifold chamber 22, as described above. Furthermore, this inlet port 31 is
The O2 sensor 33 is narrowed in the vicinity of the O2 sensor 33 so that it can accurately detect the amount of O2, and has a tapered shape as shown in FIG.

Therefore, the exhaust gas 45-4 from the branch pipe 23-4 on the rearmost side of the manifold chamber 22, which has been a problem in the past, is removed from the inlet port as shown by arrow B in FIGS. It can be divided into left and right by the outer peripheral shape having 31 inclined surfaces. As a result, the exhaust gas 45-4 does not pass through the front face of the inlet port of the inlet port 31, and the exhaust gas 45-4 does not pass through the front surface of the inlet port of the inlet port 31, and the exhaust gas 45-4 does not pass through the front surface of the inlet portion of the inlet port 31, and the exhaust gas 45-4 does not pass through the front surface of the inlet portion of the inlet port 31, and the exhaust gas 45-4 does not pass through the front surface of the inlet portion of the inlet port 31.
1 to 45-3 can flow into the inlet port 31 of the catalytic converter 30 without being obstructed by the exhaust gas 45-4.

Furthermore, in the exhaust system 20 of this embodiment, the branch pipe 23-4 at the rearmost side (in the Y2 direction) is inclined forward (in the Y1 direction) as shown in FIG. It is attached to 22. Therefore, the exhaust gas 45 from the branch pipe 23-4
-4 is not only distributed to the left and right sides of the inlet port 31 as described above, but also hits the upper surface 22a of the manifold chamber 22 in the figure at an appropriate angle, thereby being guided forward, and furthermore, It is smoothly guided by the curved part 22b formed in the part and turns downward.

Furthermore, this exhaust gas 45-4 is located at the farthest position from the inlet port 31 and at the rear (
The direction in which the exhaust gas 45-1 enters the inlet port 31 in the axial direction of the catalytic converter 30 by merging with the flow of the exhaust gas 45-1 from the branch pipe 23-1 attached to the manifold chamber 22 while being inclined toward the Y2 direction) side. Eventually, it flows in a loop as shown by arrow B in FIG.

[0025] Also, the branch pipes 23-1, 23
The exhaust gases 45-2, 45-3 from the branch pipes 23-2, 23-3 between -4 follow the flow of the exhaust gases 45-1, 45-4 that flow straight into the inlet port 31. and flows into the inlet port 31 relatively smoothly.

As described above, according to the exhaust system 20 of this embodiment, each of the exhaust gases 45-1 to 45-4 smoothly flows inside the manifold chamber 22 without colliding at the front of the inlet port as in the conventional case. and flows into the inlet port 31 of the catalytic converter 30.

FIG. 4 shows an engine 10 equipped with the conventional exhaust system 2 shown in FIG. 8, and an engine 10 equipped with the conventional exhaust system 2 shown in FIG.
3 is a graph showing experimental data comparing the outputs of engines 50 equipped with 0.

In the figure, the torque value T1 is indicated by a dashed line.
, output value P1 are performance values of the engine 50, and torque value T2 and output value P2 shown by solid lines are performance values of the engine 10. As is clear from the figure, the engine 50 of this embodiment exhibits higher torque and output values, demonstrating the effectiveness of the exhaust system having the above configuration. The difference is especially clear in the high engine speed range. This is due to the measurement result that the pressure loss of the exhaust device 20 is about 12% smaller than that of the exhaust device 2 in the measurement of the pressure loss of the exhaust devices 2 and 20, which was conducted separately from the above experiment. It is natural that this is the result of this.

As described above, according to the exhaust system 20 of this embodiment, the pressure loss of exhaust gas can be reduced compared to the conventional exhaust system 2, so that the output of the engine 50 equipped with the exhaust system 20 can be reduced. can be increased. Also, by reducing pressure loss, the manifold chamber 22
The silencing effect is also increased.

In addition to the above effects, the manifold chamber 22 and the second muffler 25 are directly coupled as described above,
By providing an integrated exhaust system 20 with a catalytic converter 30 therein directly under the exhaust port of the engine body 24, the exhaust system 20 alone and the engine 50 equipped with the exhaust system 20 can be made smaller. be able to.

Therefore, in the entire exhaust system including the exhaust device 20 shown in FIG. 3, the muffler and catalytic converter are removed from the tail pipe 39, and as a result, an extra space is created under the vehicle underfloor, for example, the fuel tank, Can be used for parts such as undercarriage. ■Improves the aerodynamic characteristics of the vehicle underfloor. ■The number of support points from the exhaust pipe 26 to the tail pipe 39 can be significantly reduced, and the conventionally installed catalyst case is no longer required, resulting in a significant cost reduction in terms of the number of parts and man-hours, and a reduction in weight. reduction is possible. Effects such as this can be obtained.

Furthermore, in the exhaust system 20 of this embodiment, since the distance between the exhaust port and the catalytic converter 30 is shortened, the emission performance, that is, the efficiency of removing toxic components from the exhaust gas by the catalytic converter 30 is improved.

FIG. 5 shows a configuration diagram of a second embodiment of an exhaust system for an internal combustion engine according to the present invention.

In the figure, 61 is a manifold chamber, and 62 is a manifold chamber.
-1 to 62-4 are branch pipes, and 63 is an outlet pipe. The exhaust system 60 of the second embodiment has branch pipes 62-3 and 6 near the outlet pipe 63.
A guide pipe 64-3 is further inserted into the manifold chamber 61 from the connection part with the manifold chamber 61 of 2-4.
, 64-4 are arranged in series.

One guide pipe 64-4 guides the exhaust gas 65-4 obliquely upward so that the exhaust gas 65-4 flows in a loop shape as indicated by arrow C in the figure. the result,
The exhaust gas 65-4 flows in a loop shape and flows approximately straight in the axial direction of the outlet pipe 63. Exhaust gas (not shown) from the branch pipe 62-3 is also guided by the other guide pipe 64-3 in the same manner as the exhaust gas 65-4, and flows approximately straight in the axial direction of the outlet pipe 63. Furthermore, the exhaust gases 65-1 and 65-2 from the branch pipes 62-1 and 62-2 have a distance from the outlet pipe 63 and flow straight into the branch pipe 62 in the axial direction of the outlet pipe 63. By joining the flow of exhaust gas from -3 and 62-4, it smoothly flows into the outlet pipe 63.

In this way, the exhaust system 60 of the second embodiment
Also, the exhaust gas 65 in the manifold chamber 61
The flow from -1 to 65-4 becomes smooth, pressure loss can be reduced compared to the conventional one, and the same effects as in the first embodiment can be obtained.

FIG. 6 shows a configuration diagram of a third embodiment of an exhaust system for an internal combustion engine according to the present invention.

In the figure, an exhaust system 70 is an exhaust system in which a catalytic converter 72 is disposed inside a manifold chamber 71, and a guide pipe 74-- which was explained in the second embodiment above.
1 to 74-4 are all branch pipes 73-1 to 73-
4 and is provided within the manifold chamber 71. These guide pipes 74-1 to 74-4 direct exhaust gas from each branch pipe 73-1 to 73-4,
As shown by the arrow in the figure, it is guided so that it flows smoothly into the inlet port 72a of the catalytic converter 72.

Further, by having the catalytic converter 72 installed inside the manifold chamber 71, the exhaust system 70 can be made smaller, and the rear guide pipe 74-3 can be
, 74-4 is dispersed on the outer peripheral surface of the catalytic converter 72, and the exhaust gas emitted from the front guide pipes 74-1, 74-
Since collision with the exhaust gas coming out from the manifold chamber 71 is prevented, the flow of the exhaust gas inside the manifold chamber 71 is made smoother. Therefore, in the third embodiment as well, the pressure loss within the manifold chamber 71 can be reduced compared to the prior art, and the same effects as in the first embodiment can be obtained.

Further, like the exhaust system 70, each branch pipe 73-1 to 73-4 has a guide pipe 74-1 to 74-4, respectively.
74-4, the exhaust pressure loss in the manifold chamber 71 can be easily minimized by adjusting the shape of each guide pipe 74-1 to 74-4.

FIG. 7 shows a configuration diagram of a fourth embodiment of an exhaust system for an internal combustion engine according to the present invention.

In the figure, an exhaust system 80 has a structure in which the guide pipe described in the third embodiment is not provided inside a manifold chamber 81 at all. In the exhaust system 80 having the above configuration, the ceiling plate 81a below the outlet pipe 82
However, the rear (Y2 direction) branch pipes 83-3, 8
It acts as a guide member for the exhaust gases 84-3 and 84-4 from the exhaust gases 84-3 and 84-4, and guides the exhaust gases 84-3 and 84-4 forward while diffusing them. As a result, each branch pipe 83
The exhaust gas from -1 to 83-4 flows smoothly in the manifold chamber 81 as shown by the arrows in the figure, and the pressure loss of the exhaust gas in the manifold chamber 81 is also reduced in the fourth embodiment compared to the conventional one. be able to.

[0043]

As described above, according to the present invention, exhaust gas from a specific port is prevented from disturbing the smooth flow of exhaust gas from each exhaust port to the opening in the expansion chamber. The pressure loss of exhaust gas in the chamber can be significantly reduced compared to the conventional method, and as a result, the output of the internal combustion engine can be improved compared to the conventional method. Further, by reducing the pressure loss, the sound deadening effect in the expansion chamber can be improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a first embodiment of an exhaust system for an internal combustion engine according to the present invention.

2 is a cross-sectional view of the exhaust system shown in FIG. 1 installed in an engine, showing a cross-sectional portion taken along line II-II in FIG. 1;

FIG. 3 is a perspective view of the entire exhaust system including the exhaust device shown in FIG. 1;

4 is a graph showing data from an experiment comparing the outputs of an engine equipped with the conventional exhaust system shown in FIG. 8 and an engine equipped with the exhaust system of the present embodiment shown in FIG. 1;

FIG. 5 is a configuration diagram of a second embodiment of an exhaust system for an internal combustion engine according to the present invention.

FIG. 6 is a configuration diagram of a third embodiment of an exhaust system for an internal combustion engine according to the present invention.

FIG. 7 is a configuration diagram of a fourth embodiment of an exhaust system for an internal combustion engine according to the present invention.

FIG. 8 is a configuration diagram of an example of a conventional exhaust system for an internal combustion engine.

9 is a diagram illustrating problems in the conventional exhaust system shown in FIG. 8. FIG.

[Explanation of symbols]

10, 50 Engine 20, 60, 70, 80 Exhaust device 21 Manifold flange 22, 61, 71, 81 Manifold chamber 22a
Upper surface 22b Curved portions 23, 62, 73, 83 Branch pipe 24 Engine body 25 Second muffler 26, 63, 82 Outlet pipes 27a, 27
b Split flange 28, 36 Bolts 30, 72 Catalytic converter 31, 72a Inlet port 32 Outlet port 35 Manifold support bracket 45, 65, 8
4 Exhaust gas 64, 74 Guide pipe 81a Ceiling plate

Claims (1)

[Claims] 1. Directly below an exhaust port of an in-line internal combustion engine, an expansion chamber is provided where exhaust gas from a plurality of exhaust ports collects, and an opening for discharging the exhaust gas in the axial direction of the crankshaft of the internal combustion engine. In the exhaust system for an internal combustion engine, the exhaust system is provided in the expansion chamber, and the exhaust port is opposed to an exhaust port (hereinafter referred to as a specific port) that discharges exhaust gas in a direction that disturbs the smooth flow of exhaust gas to the opening in the expansion chamber. A guide member is provided in the expansion chamber, and the guide member changes the flow of exhaust gas discharged from the specific port to maintain the smooth flow of exhaust gas in the expansion chamber. An exhaust system for an internal combustion engine characterized by: