JPH0264216A - Exhaust variable device for multiple cylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To provide effective use of exhaust gas flowing effect over a wide rotational range by changing over a combination of exhaust pipes grouped at first and changing the effective length of each exhaust pipe. CONSTITUTION:The exhaust pipes 14a, 14d for No.1 and No.4 cylinders are positioned below a car body and above the exhaust pipes 14b, 14c for No.2 and No.3 cylinders below an internal combustion engine. Moreover, at a position where these exhaust pipes 14 are distributed upward and downward is provided a switching valve to change over a combination of aggregation established by collecting pipes 19, 20. To this switching valve 30 an actuator 32 is connected through a wire 31 and a control unit 28 is also electrically connected. This makes it possible to set a combination of exhaust pipes 14a - 14d grouped at first and the effective length of each exhaust pipe in the optimum condition which provides a dynamic effect suited to the number of revolutions of an internal combustion engine at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable exhaust system for a multi-cylinder internal combustion engine that can improve output over a wide rotation range.

[Prior Art] Generally, in an internal combustion engine, it is known that dynamic effects such as inertia and pulsation of exhaust gas flowing in an exhaust pipe affect the volumetric efficiency of the internal combustion engine.

This dynamic effect varies depending on the rotation speed of the internal combustion engine when the shape and dimensions of the exhaust system are constant, and in the rotation range suitable for the set exhaust system, the volumetric efficiency increases due to the dynamic effect. However, in a certain rotation range, there is a difference between the dynamic effect and the exhaust timing, resulting in a decrease in volumetric efficiency. Sometimes I get stuck.

For example, if the shape and dimensions of the exhaust system are set to obtain an effective dynamic effect in the high rotation range, the exhaust timing and dynamic effect will be adjusted when the internal combustion engine reaches the low to medium rotation speed range. A good matching between the engine and the internal combustion engine cannot be obtained, and the volumetric efficiency of the internal combustion engine decreases, resulting in a phenomenon in which the output of the internal combustion engine decreases in the low and medium rotation range.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 60-128921, a technique has been proposed in which the exhaust characteristics are changed by changing the effective cross-sectional area of the exhaust pipe according to the rotational speed to prevent the drop in output. ing.

In addition, in the case of multi-cylinder internal combustion engines,
As disclosed in Japanese Patent No. 25602, a switching valve is provided at the collecting part of the exhaust pipe, and the switching valve is switched according to the rotational condition of the internal combustion engine to change the collecting method of the exhaust system (for example, 4-2 -1 method to 4-1 method, etc.)
A technique has also been proposed that cancels the dynamic effect of the exhaust in the rotation range where the output drops, thereby reducing the phenomenon of the output drop.

[Problems to be Solved by the Invention] However, although the above-mentioned conventional technologies can be expected to have the effect of suppressing the drop in output, it is difficult to actively increase the output in this rotation range. However, there was a drawback that it was not possible to improve the output over a wide rotation range.

The present invention has been made in view of the above-mentioned circumstances, and provides a variable exhaust system for a multi-cylinder internal combustion engine that can effectively utilize exhaust flow effects over a wide rotation range and actively improve output. It is Party B's purpose to

[Means for Solving the Problems] The first invention of the present application is a multi-cylinder internal combustion engine in which a plurality of exhaust pipes extending from a multi-cylinder internal combustion engine are independently extended, and the plurality of exhaust pipes are collected on the downstream side. A variable exhaust system for an internal combustion engine is provided with an exhaust pipe combination switching means for switching the combination of exhaust pipes that are assembled together first, and an exhaust pipe effective cross-sectional area variable means for changing the effective cross-sectional area of the exhaust pipes. Features.

Further, a second invention of the present application provides an exhaust variable exhaust system for a multi-cylinder internal combustion engine in which a plurality of exhaust pipes extending from the multi-cylinder internal combustion engine are independently extended, and the plurality of exhaust pipes are assembled on the downstream side. In addition to the exhaust pipe length variable means for changing the effective length of the exhaust pipe, the exhaust pipe effective cross-sectional area variable means for changing the effective cross-sectional area of the exhaust pipe is also provided.

Furthermore, a third invention of the present application provides an exhaust variable exhaust system for a multi-cylinder internal combustion engine in which a plurality of exhaust pipes extending from the multi-cylinder internal combustion engine are independently extended, and the plurality of exhaust pipes are assembled on the downstream side. In addition to the exhaust pipe combination switching means for switching the combination of exhaust pipes that are brought together first, the exhaust pipe effective length variable means for changing the effective length of the exhaust pipes is further provided, and the exhaust pipe for changing the effective cross-sectional area of the exhaust pipes. It is characterized by comprising effective cross-sectional area variable means.

[Function] The exhaust variable variable device for a multi-cylinder internal combustion engine according to the present invention adjusts the exhaust pipe combination regardless of whether the engine speed is in the low-medium speed range or in the high speed range. By activating the switching means, the combination of the exhaust pipes of the exhaust variable exhaust device that are brought together first is determined to be the optimal combination of exhaust pipes that can obtain a dynamic effect corresponding to the rotational speed of the internal combustion engine at that time. Alternatively, by operating the exhaust pipe effective length variable means, the effective length of the exhaust pipe can be adjusted to the optimum length that provides a dynamic effect corresponding to the rotational speed of the internal combustion engine at that time, and furthermore, the effective cross-sectional area of the exhaust pipe can be varied. By manipulating the means, the effective cross-sectional area of the exhaust and trachea can be set to the optimum cross-sectional area that provides the dynamic effect corresponding to the rotational speed of the internal combustion engine at that time, and has a wide range of speeds from low to high rotational speeds. This means that the output can be actively improved over the period of time.

[Example] The present invention will be described below based on an example shown in FIGS. 1 to 9.

Reference numeral 1 in FIGS. 1 and 2 indicates a motorcycle, which includes a body frame 2, a front fork 3 rotatably attached to a head pipe 2a fixed to the front part of the body frame 2, and A front wheel 4 rotatably attached to the lower end of the front fork 3 and a front fork 3
A multi-cylinder internal combustion engine is mounted approximately in the center of the vehicle body, with a steering handle 5 fixed to the upper end thereof, and a main frame 2b and a down frame 2c constituting the vehicle body frame 2, fixed to each other via a bracket 6. (hereinafter abbreviated as internal combustion engine, and in this example, a parallel 4-cylinder type is exemplified)
7, a rear fork 8 attached to the rear lower part of the vehicle body frame 2 so as to be swingable in the vertical direction, a rear wheel 9 rotatably attached to the swinging end of the rear fork 8, and the rear fork 8. A cushion unit 11 is interposed via a link mechanism 10 between the vicinity of the swing center of the body frame 2 and the body frame 2, a fuel tank 12 is attached to the upper part of the body frame 2, and a cushion unit 11 is installed at the rear of the upper part of the main frame 2b. a seat 13 attached to the extended track rail 2d; a plurality of (four in this embodiment) exhaust pipes 14 (14a = 14d) attached to the end of the surface of the internal combustion engine 7;
A muffler 15 is provided, which is connected to the downstream end of these exhaust pipes 14 (14a=14d).

Moreover, in FIG. 2, the symbol 16 (16a = 16d
) is the piston fitted in each cylinder, and the symbol 17
In this case, the piston 16 is connected to the connecting rod 18 (18a = 1
8d) shows the crankshaft connected via.

Here, each cylinder of the internal combustion engine 7 is numbered 1 to 4 from the first lower side to the upper side (from the front side to the back side in FIG. 2), and the ignition order is set as 1st cylinder to 3rd cylinder. The explanation will be made assuming that the explosions occur in the order No. - No. 4 - No. 2 and are equally spaced.

As shown in FIGS. 1 and 2, each of the exhaust pipes 14 (14a to 14d) is routed from the front end of the internal combustion engine 7 through the vehicle body and below the internal combustion engine 7 to the side of the vehicle body. , exhaust pipe 14a corresponding to the 1st cylinder and the 4th cylinder
14d are collected by the collecting pipe 19, and the exhaust pipes 14b and 14c corresponding to the 2nd and 3rd cylinders are collected by the collecting pipe 2.
0, and these collecting pipes 19.
20 are collected into one by the second collecting pipe 21 and then communicated with the muffler 515.

The inside of each exhaust pipe 14 (14a - 14d) is connected to a collecting pipe 19 (2G) from the connection part to the exhaust boat of the internal combustion engine 7.
The space up to is divided into left and right by a partition wall 22 provided at the center and extending in the vertical direction.

In addition, a part of the partition wall 22 is cut out near the connection part of the exhaust pipe 14 to the internal combustion engine 7, and a plate valve 23 is provided there. When this plate valve 23 is rotated by a predetermined angle as shown in FIG. 7(b) and FIG. 8(b), both the left and right spaces 24x and 24y of the exhaust pipe are used as exhaust flow paths. and when only one of them is used as an exhaust flow path. Plate valve 23 is connected to actuator 27 via power transmission mechanism 25 and wire 26 .

That is, the partition wall 22, the temporary valve 23, the power transmission mechanism 25, the actuator 27, and the control unit 28 connected thereto constitute an exhaust pipe effective cross-sectional area variable means 29 that changes the substantial cross-sectional area of the exhaust pipe 14. are doing.

In addition, exhaust pipes 1 corresponding to the first and fourth cylinders are also provided.
4a-14d indicate exhaust pipes 14 corresponding to the second and third cylinders below the vehicle body and below the internal combustion engine 7.
Located above b-14c, a switching valve 30 for switching the combination of collections set by the collection pipes 19 and 20 is provided in the upper and lower portions of these exhaust pipes 14. It is being As shown in FIG. 3, an actuator 32 is connected to the switching valve 30 via a wire 31, and the control unit 28 is electrically connected to the actuator 32. And this, the switching valve 30,
Actuator 32 and control unit 28
This constitutes an exhaust pipe combination switching means for switching the combination of the exhaust pipes 14a and 14d that are initially assembled, and an exhaust pipe effective length variable means 33 for changing the effective length of the exhaust pipes.

In more detail, the exhaust pipe 1 divided into upper and lower parts
4 is an exhaust pipe corresponding to the No. 1 cylinder (hereinafter referred to as the No. 1 exhaust pipe), and an exhaust pipe corresponding to the No. 2 cylinder (hereinafter referred to as the No. 2 exhaust pipe) is located below 14a, as shown in FIGS. 3 and 6. )
The exhaust pipe corresponding to the 4th cylinder (hereinafter referred to as the 4th exhaust pipe) is located so that the exhaust pipe 14b corresponds to the 3rd cylinder (hereinafter referred to as the 3rd exhaust pipe) is located below +4d. It is arranged in such a way that

The temporary valve 23 is formed in a substantially semicircular shape, and is assembled in the exhaust pipe 14 so that the arcuate portion 23a is located on the upstream side and the upright portion 23b is located on the downstream side. A shaft 35 that rotates together with the plate valve 23 is inserted and fixed into the upright portion 23b, and the shaft 35 has an upper end projected and is rotatably supported by the wall of the exhaust pipe 14. A fork 36 is fixed to the upper projecting end of the shaft 35. The above configuration is also common to the plate valves installed in each of the exhaust pipes 14a and 14d.

A bottle 37 is inserted into the fork 36, and these bottles 3
7 are fixed to one common bar 38.

The bar 38 is supported by a support portion 39 extending from the vehicle body frame so as to be freely slidable in the axial direction. A rack 40a is fixed to one end of the bar 38;
A pinion 40b is engaged with the pinion a, and the wire 26 is wound around the pinion 40b via a wire drum 41. That is, the fork 36, the bottle 37, the bar 38,
The power transmission mechanism 25 is constituted by the rack 40a and the pinion 40b, and when the actuator 27 is operated based on a signal from the control unit 28 according to the rotation speed of the internal combustion engine 7, the power transmission mechanism 25 The valve 23 can be selectively switched between the state shown in FIG. 7(b) and the state shown in FIG. 8(b).

Note that a stopper is attached to the bar support portion 39 to determine the limit position of movement of the bar 38.1. Further, the rack 40a and pinion 40b are covered with a case (not shown) as necessary.

On the other hand, as shown in FIGS. 1 and 2, the switching valve 30 is located below the vehicle body and the internal combustion engine 7 and in the front half of the internal combustion engine 7.
As shown in the drawings and FIG. 6, the valve body 42 includes a cylindrical casing 42a and a valve body 42b fitted inside the cylindrical casing 42a and rotatable around the axis of the casing 42a.

A No. 1 exhaust pipe 14a and a No. 4 exhaust pipe 14d are connected to the casing 42a in a communicating state so that their axes intersect, and a No. 2 exhaust pipe is connected to the casing 42a at the bottom, as shown in FIG. Through holes 46 and 47 are formed through which the exhaust pipe 14b and the third exhaust W14c are communicated. The exhaust pipe 14 and the casing 42a are airtightly connected by welding or the like.

A lid 49 equipped with a bearing 48 is fixed to one end of the casing 42a in the longitudinal direction, and an annular mounting member 50 is fixed to the other end.
A lid body 52 equipped with a bearing 51 is removably attached with bolts 53, and a gasket 54 is interposed between the mounting member 50 and the lid body 52 to airtightly close the space between them.

Furthermore, a cap 55 for sealing the bearing 48 is press-fitted from the outside into a portion of the lid 49 fixed to one end of the casing 42a where the bearing 48 is formed.

The valve body 42b is connected to the casing 4 as shown in FIG.
The inner circumferential surface of 2a is in airtight contact with the entire circumference, and two independent communicating portions are opened in three orthogonal directions in the radial direction at two locations spaced apart in the length direction. 56・
57 is formed, and a partition part 56a/5 continuous with the partition part 22 of the exhaust pipe 14 is formed in the center of the communication part.
7a is formed.

The remaining peripheral wall portions serve as closing portions 58 and 59 for opening and closing the through holes 46 and 47. Each of these closing portions 58 and 59 is formed with four portions 58a and 59a that are continuous with the respective inner circumferential surfaces of the second exhaust pipe 14b and the third exhaust pipe 14c when the respective through holes 46 and 47 are closed. There is.

Furthermore, rods 60 and 61 extending in the axial direction are provided at both ends of the valve body 42b, and these rods 60 and 61
is rotatably fitted into each of the bearings 48 and 51, whereby the valve body 42b is rotatably supported by the casing 42a.

Further, the rod 61 supported by the bearing 51 penetrates the lid 52 and projects to the outside of the casing 42a, and the wire drum 62 around which the wire 31 is wound is attached to the nut 63 at the projecting end. It is removably fixed.

In this embodiment, two wires 26 and 31 are provided,
By being selectively pulled, the plate valve 23 and the valve body 22b are rotated in forward and reverse directions. Further, the wires 31 are guided by a guide plate 64 attached to the lid 52 to maintain a distance therebetween, and are covered by a cover 65.

These guide plates 64 and covers 65
are collinear with the lid body 52 to the mounting member 50 by the bolts 53.

As shown in FIG. 2, the actuator 27 is attached to the lower part of the cross member 2e that connects the main frame 2b and the down frame 2C, and the actuator 32 is attached to the lower part of the seat rail 2d at a position covered by the seat 13. Furthermore, the control unit 28 is attached at a position covered by the seat 13 above the rear end of the seat rail 2d.

Information on the opening degree of the throttle valve C0 of the carburetor C is constantly input to the control unit 28 as an electric signal, and based on this information on the throttle opening degree, when the throttle valve reaches the set opening degree, the actuator A drive signal is output to 27 and 32 to operate them, thereby controlling the operating positions of the plate valve 23 and the switching valve 30.

In the above example, the actuators 27 and 32 are operated by assuming that the change in the opening degree of the throttle valve Co is a change in the rotational speed of the internal combustion engine 7. The rotation speed of the engine 7 may be directly detected and the actuator may be operated based on this.

Therefore, in the exhaust variable exhaust system for a multi-cylinder internal combustion engine of this embodiment configured as described above, when the rotational speed of the internal combustion engine changes, the mode changes in three stages as shown below, and the exhaust system can be made optimal according to the rotational situation at that time (specifically, the change in the opening degree of the throttle valve C8).

That is, when the rotation speed of the internal combustion engine 7 is in a low rotation range, the actuator 27 rotates the temporary valve 23 to position it so that it is inclined at a predetermined angle with respect to the partition wall 22, as shown in FIG. 7(b). Then, one 24x of the left and right spaces 24K and 24y in the exhaust pipe 14 is closed, and only the space 24y on the other side is used as an exhaust flow path. At this time, the plate valve 23 is tilted at an acute angle with respect to the exhaust gas flow, so that the gas flows flowing in both the exhaust flow paths 24X and 24y are merged, and turbulence is unlikely to occur during the merge, making it smooth. This has the advantage of maintaining a steady flow.

Simultaneously with the operation of the plate valve 23, the actuator 32
The valve body 42b is rotated to close its closed portions 58 and 59.
By closing the through holes 46 and 47 of the casing 42a, each exhaust pipe 14 (
14a to 14d) are made independent, and the upper No. 1 exhaust pipe 14a and No. 4 exhaust pipe 14d are maintained in a continuous state along the length from the internal combustion engine 7 to the collecting pipe 19 by the communicating portions 56 and 57. , and the lower No. 2 exhaust pipe 14b and No. 3 exhaust pipe 14c are also connected from the internal combustion engine 7 to the collecting pipe 2.
Maintains continuous state until 0.

In this state, an exhaust flow path with a long equivalent pipe length is secured, and the exhaust gas corresponds to the cylinders that undergo explosion with a 360° phase difference between the 1st and 4th cylinders, and the 2nd and 3rd cylinders. The pipes 14 are grouped together, and the pulsation between the exhaust pipes 14 acts effectively, resulting in an improvement in volumetric efficiency in the low and medium rotation range.

On the other hand, when the rotation speed of the internal combustion engine 7 reaches a medium rotation range, a drive signal is output from the control unit 28 to the actuator 27 based on the information, and the plate valve 23 is rotated by a predetermined angle as shown in FIG. Partition wall 2
In other words, it is arranged on the same plane as the partition wall 22. In this state, both the spaces 24x and 24y on the left and right sides of the exhaust pipe 14 are used as exhaust flow paths, and as the internal combustion engine 7 is in the middle rotation range, the effective cross-sectional area of the exhaust pipe 14 increases. The equivalent length of the tube 14 becomes shorter.

Further, when the rotation speed of the internal combustion engine 7 reaches a high rotation range, a drive signal is output from the control unit 28 to the actuator 32 based on the information, and the valve body 4 of the switching valve 30
2b is rotated 180° as shown in FIG. 9(c).

In this state, the communication portions 56 and 57 of the valve body 42b connect the first exhaust pipe 14a and the second exhaust pipe 14b, and
The No. 4 exhaust pipe 14d and the No. 3 exhaust pipe 14c are communicated,
As a result, the distance between the exhaust pipes 14 to the collecting part is narrowed, thereby forming an exhaust flow path with a shorter equivalent pipe length, and the exhaust pipes 14 corresponding to the cylinders that perform explosion with a phase difference of 180° are collected. As a result, the dynamic effect of the exhaust gas is effectively brought out, and the volumetric efficiency in the high rotation range is improved.

A comparison of the output characteristics of the internal combustion engine 7 in this embodiment equipped with such an exhaust variable device and the output characteristics of a conventional internal combustion engine equipped with an exhaust system of a constant shape and size revealed that It was confirmed that the output was improved over a wide range including the rotation range, and that high output and flat characteristics were obtained.

Note that if the throttle valve C6 is suddenly changed, the state shown in FIG. 7 will change to the state shown in FIG. 9, or vice versa, the state shown in FIG. 9 will change to the state shown in FIG. Since the change in the aspect of is too large, there is a possibility that a phenomenon in which the output temporarily drops may occur. In order to eliminate this phenomenon, when switching from the state shown in Fig. 7 to the state shown in Fig. 8, or when switching from the state shown in Fig. 9 to the state shown in Fig. 8, a certain amount of time has elapsed. In order to switch to the state shown in FIG. 9 or 7 only after
It is preferable to assemble the circuit within the control unit.

It should be noted that the shapes and dimensions of each component shown in the above embodiments are merely examples, and can be changed in various ways based on design requirements and the like.

For example, although this embodiment describes an example in which the exhaust pipe combination switching means and the exhaust pipe effective length variable means are integrated, they may be provided separately, and it is best to connect one of them to the exhaust pipe effective length variable means. The tube effective cross-sectional area variable means may also be included.

Further, in the embodiments described above, an in-line four-cylinder internal combustion engine has been described, but the present invention is not limited to this, and the present invention can also be applied to other types of multi-cylinder internal combustion engines.

"Effects of the Invention" As explained above, according to the present invention, the exhaust pipe combination can be switched regardless of whether the rotational speed of the internal combustion engine is in the low/medium rotational range or in the high rotational range. By activating the means, the combination of the exhaust pipes of the exhaust variable exhaust device that are brought together first is determined to be the optimal combination of exhaust pipes that can obtain a dynamic effect corresponding to the rotational speed of the internal combustion engine at that time. Alternatively, by operating the exhaust pipe effective length variable means, the effective length of the exhaust pipe can be set to the optimal length that provides a dynamic effect corresponding to the rotational speed of the internal combustion engine at that time, and the effective cross-sectional area of the exhaust pipe can also be varied. By manipulating the means, the effective cross-sectional area of the exhaust pipe can be set to the optimum cross-sectional area that provides the dynamic effect corresponding to the rotational speed of the internal combustion engine at that time, and can be adjusted over a wide range from low to high rotational speeds. This means that output can be actively improved over the period of time.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic side view of the motorcycle, Fig. 2 is a plan view thereof, Fig. 3 is a perspective view of the exhaust system, and Fig. 4 is a plate valve and its operating system. FIG. 5 is a perspective view of the switching valve, FIG. 6 is a longitudinal sectional view thereof,
Figures 7 (a) to (c) are explanatory diagrams of the operation of the exhaust system when the internal combustion engine is in the low speed range, and Figures 8 (a) to (c) are exhaust system diagrams when the internal combustion engine is in the middle speed range. Diagram explaining the operation of the system, No. 9
Figures (a) to (c) are explanatory views of the operation of the exhaust system when the internal combustion engine is in a high rotation range. ■...Motorcycle, 2...Body frame, 7...Multi-cylinder internal combustion engine, 14...Exhaust pipe, a... No.1 exhaust pipe, 14b...2nd exhaust pipe, C...3rd exhaust pipe, 14d...
No. 4 exhaust pipe, 20.21...Collecting pipe, ...Partition wall, ...Plate valve, ...Power transmission mechanism, ...Actuator, ... ...control unit, ...exhaust pipe effective cross-sectional area variable means, ...changeover valve, ...actuator, ...exhaust pipe effective length variable means and exhaust pipe combination switching means.

Claims (3)

[Claims] (1) In a variable exhaust system for a multi-cylinder internal combustion engine, in which a plurality of exhaust pipes extending from the multi-cylinder internal combustion engine are installed independently, and the exhaust pipes are brought together on the downstream side, the exhaust pipes are brought together first. An exhaust gas variable device for a multi-cylinder internal combustion engine, comprising an exhaust pipe combination switching means for switching the combination of exhaust pipes, and an exhaust pipe effective cross-sectional area variable means for changing the effective cross-sectional area of the exhaust pipes. . (2) An exhaust variable exhaust system for a multi-cylinder internal combustion engine in which a plurality of exhaust pipes extending from the multi-cylinder internal combustion engine are independently extended, and the plurality of exhaust pipes are assembled on the downstream side, wherein: An exhaust gas variable device for a multi-cylinder internal combustion engine, comprising: an exhaust pipe length variable means for changing an effective length; and an exhaust pipe effective cross-sectional area variable means for changing an effective cross-sectional area of an exhaust pipe. (3) In a variable exhaust system for a multi-cylinder internal combustion engine, in which a plurality of exhaust pipes extending from the multi-cylinder internal combustion engine are installed independently and are brought together on the downstream side, the exhaust pipes are brought together first. The exhaust pipe combination switching means for switching the combination of exhaust pipes, the exhaust pipe effective length variable means for changing the effective length of the exhaust pipe, and the exhaust pipe effective cross-sectional area variable means for changing the effective cross-sectional area of the exhaust pipe. A variable exhaust device for a multi-cylinder internal combustion engine, characterized by comprising: