JPH089356B2 - Exhaust control device for motorcycles - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust control device that is applied to a motorcycle equipped with front and rear V-type multi-cylinder engines and has an exhaust pipe equipped with an exhaust control valve.

(Background of the Invention) In a 4-cycle engine, a 2-cycle engine, etc., it is known that exhaust gas is intermittently guided to an exhaust pipe by opening and closing an exhaust valve, and an inertial effect and a pulsating effect of the exhaust gas are generated in the exhaust pipe. . These effects (called dynamic effects) change depending on the engine speed. Therefore, if the dynamic effect is maximized to increase the volumetric efficiency at a certain rotation speed, the dynamic effect is adversely affected at other rotation speeds, and the volumetric efficiency is significantly reduced. For this reason, when the exhaust system specifications (exhaust pipe length, exhaust pipe diameter, etc.) are set so that this dynamic effect is optimal in the high rotation range, the torque is significantly reduced in the middle speed range (torque valley). There was a problem that occurs.

Therefore, it is conceivable to provide an exhaust control valve in the exhaust pipe to change the area of the exhaust flow passage so that the flow passage area is reduced in the rotational speed range where the volumetric efficiency is reduced and the flow passage area is increased in other rotational speed regions. Has been.

Further, in a multi-cylinder engine, if the downstream side of each exhaust pipe is joined in the expansion chamber, the volume efficiency and torque may be reduced due to exhaust interference between the cylinders. Therefore, it is considered that an exhaust control valve is provided for each exhaust pipe and the exhaust flow passage area is reduced by closing this control valve in a rotational speed range where adverse effects due to exhaust interference occur.

It is also considered to improve combustion and control exhaust components by controlling the back pressure of the exhaust pipe.

Thus, it is conceivable to provide the exhaust pipe with an exhaust control valve for changing the exhaust passage area for various purposes such as improvement of volume efficiency, improvement of combustion, and control of exhaust components.

However, particularly in a vehicle such as a motorcycle equipped with a V-type multi-cylinder engine, providing a separate exhaust control valve for each exhaust pipe of each cylinder causes an increase in the size of the device and makes it difficult to secure a mounting space for the device. In particular, in the front and rear V-type engine in which the crankshaft is arranged in the vehicle width direction, the exhaust pipes of the banks forming the V-shape are connected to the expansion chamber through different routes that are far apart from each other. Become.

(Object of the Invention) The present invention has been made in view of such circumstances,
In particular, it is an object of the present invention to provide an exhaust control device for a motorcycle which is excellent in space efficiency by downsizing the exhaust control valve and its drive device when a front and rear V-type engine is mounted.

According to the present invention, an object of the present invention is to provide a V-type multi-cylinder engine which is mounted near the center of a vehicle body and has a crankshaft in the vehicle width direction,
In a motorcycle including a plurality of exhaust pipes respectively connected to the cylinders of the engine, and an expansion chamber arranged at a lower rear portion of the engine and connected to a downstream side of the exhaust pipes, a downstream of the exhaust pipes Side is introduced substantially parallel to each other from the front to the front of the expansion chamber, and one valve shaft is provided in the substantially parallel portion of each exhaust pipe outside the expansion chamber with one valve shaft. Equipped with an exhaust control valve that controls the area simultaneously,
This is achieved by an exhaust control device for a motorcycle, characterized in that an exhaust passage area is externally controlled by an engine rotation speed.

(Embodiment) FIG. 1 is a plan view of an exhaust system for a motorcycle according to an embodiment of the present invention, and FIG. 2 is a side view of a motorcycle using the same.
3 and 4 are a sectional view taken along the line III-III and a sectional view taken along the line IV-IV in FIG. 1, respectively.

In FIG. 2, reference numeral 10 is a four-cycle two-cylinder V-type engine, which is mounted near the center of the vehicle body. In this engine 10, a crankshaft (not shown) is arranged in the vehicle width direction, and two banks 12 and 14 forming a V-shape are divided in the front-rear direction to form a so-called front-rear V-engine. This engine 10 has a crankcase 16 and an upper end of each bank 12, 14.
The rear end is attached to the body frame 18.

The exhaust system of the engine 10 includes an exhaust pipe 20 extending from the front surface of the front bank 12 to the rear through the lower right portion of the crankcase 16,
Exhaust pipe that extends downward from the rear surface of the rear bank 14 and draws a loop to the right of the vehicle behind the engine 10 while drawing a loop.
An expansion chamber 24 to which the downstream sides of the exhaust pipes 20 and 22 are connected, and two exhaust mufflers 26 and 28 are provided. The expansion chamber 24 is located in the lower rear part of the engine 10. Further, the exhaust mufflers 26 and 28 are integrally connected to each other by a bracket 30 (FIG. 1), the front end of the upper muffler 26 is connected to the right upper surface of the expansion chamber 24 by a connecting pipe 32, and the front part of the lower muffler 28 is connected. The right end of the expansion chamber 24 is directly connected to the left side surface (see FIG. 4). The exhaust pipes 20 and 22 extend into the expansion chamber 24 from the right front portion of the expansion chamber 24 as shown in FIG. Also exhaust pipes 20, 22
Are arranged so as to be parallel to each other before entering the expansion chamber 24, that is, on the upstream side of the expansion chamber 24, and an exhaust control valve 34 is attached to this parallel part.

As shown in FIG. 3, the exhaust control valve 34 includes both exhaust pipes 20,
A two-plate flange fixed to the open ends of the two exhaust pipes 20, 22 so as to be interposed in the middle of 22, a body 36 divided in two between the two flanges, and the flange of the body 36. And butterfly valves 38 and 40 that are axially supported between the split surfaces parallel to and penetrate the exhaust flow paths of both exhaust pipes 20 and 22. That is, the valve shaft 42 of each of the valves 38 and 40 is one for each of the exhaust pipes 20 and 22. The upper end of the valve shaft 42 projects from the body 36, and the pulley 44 is fixed to this projecting end. A wire (not shown) is wound around the pulley 44, and the valve shaft 42 is rotated by a drive device (not shown) such as a servomotor via the wire. As is clear from FIG. 3, the body 36 is obliquely arranged and a large bank angle of the vehicle body is secured.

In FIG. 2, 50 is a front fork, 52 is a front wheel, 54 is a handlebar, 56 is a rear wheel, 58 is a fuel tank, and 60 is an operating seat.

Next, the operation of this embodiment will be described. When the diameter and length of the exhaust pipes 20 and 22 are set so that the volumetric efficiency of the engine 10 is high in the high speed range, the exhaust control valve 34 is closed in the low and medium speed range and opened in the high speed range. It is driven by a servo motor.

The positive pressure wave generated by opening the exhaust valve of the engine 10 propagates in the exhaust pipes 20 and 22 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end reverses the exhaust pipes 20 and 22 at the speed of sound. Propagates in the direction and returns to the exhaust valve of the engine 10. When the exhaust control valve 34 is closed, the positive pressure wave generated by opening the exhaust valve is reflected by the exhaust control valve 34 and returns to the exhaust valve as a positive pressure wave at the speed of sound. Therefore, if the exhaust control valve 34 is controlled so that the exhaust flow passage area becomes appropriate in the low-medium speed range where the dynamic effect acts in reverse, the negative pressure generated by the open ends of the exhaust pipes 20 and 22 and returned. The wave and the positive pressure wave reflected by the exhaust control valve 34 cancel each other out. At this time, the pulsating effect is canceled out, and a decrease in volume efficiency (occurrence of a torque valley) in the medium speed range can be suppressed.

Further, when the exhaust control valve 34 is used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valve 34 may be closed in a rotation region where the torque reduction due to the exhaust interference is remarkable.

The exhaust pipes 20 and 22 are introduced in parallel to the front part of the expansion chamber 24 from the front side, and the common one-shaft exhaust control valve 34, that is, one valve shaft 42, is provided outside the expansion chamber 24 and in the parallel part. Since the exhaust control valve 34 for controlling the exhaust flow passage areas of all the exhaust pipes 20 and 22 at the same time is provided, the size can be reduced as compared with the case where the exhaust control valves are separately provided to the exhaust pipes 20 and 22. Further, since only one drive device such as a servo motor for opening and closing the exhaust control valve 34 is required, the size of the entire device can be greatly reduced.

FIG. 5 is a plan view showing an exhaust system of another embodiment of the present invention,
FIG. 6 is a left side view thereof, and FIG. 7 is a right side view thereof. This embodiment is applied to a motorcycle equipped with front and rear V-type two-cylinder engines similarly to the above embodiments.

The exhaust pipes 20A, 22A of this embodiment are introduced into the right front corner of the expansion chamber 24A from the front in two steps in parallel with each other, and the exhaust control valves 34A are arranged in the mutually parallel portions. This exhaust control valve 34A is provided with a body 36A and butterfly valves 38A, 40A as in the above embodiment, and its valve shaft 42A has exhaust pipes 20A, 22A.
It has become one in common. The exhaust is the expansion chamber 24A
Is led to the upper and lower two-stage mufflers 26A and 28A by the connecting pipe 32A.

The operation of this embodiment is the same as that of the embodiment shown in FIGS. 1 to 4, so the description thereof will not be repeated.

(Effect of the Invention) As described above, the present invention introduces the exhaust pipes into the front part of the expansion chamber in parallel with each other from the front side, and the common uniaxial exhaust gas is provided outside the expansion chamber in the substantially parallel parts to the front side. Since the control valve is provided, the space for mounting the exhaust control valve is smaller than that in the case where the exhaust control valve is individually provided in each exhaust pipe, and only one drive unit is required. Further, since the exhaust control valve is arranged adjacent to the expansion chamber, the occupied space can be centralized and the useless space is eliminated. From the above, the size of the entire apparatus can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a plan view of an exhaust system for a motorcycle which is an embodiment of the present invention, FIG. 2 is a side view of a motorcycle using the same, and FIGS. 3 and 4 are III- in FIG. 1, respectively. It is the III line sectional view and the IV-IV line sectional view. FIG. 5 is a plan view showing an exhaust system of another embodiment of the present invention, FIG. 6 is a left side view thereof, and FIG. 7 is a right side view thereof. 10 ... V type multi-cylinder engine, 20,22,22A, 22A ... exhaust pipe, 24,24A ... expansion chamber, 34,34A ... exhaust control valve, 42,42A ... valve shaft.

Claims (1)

[Claims] 1. A V-type multi-cylinder engine having a crankshaft in the vehicle width direction mounted near the center of a vehicle body, a plurality of exhaust pipes respectively connected to the cylinders of the engine, and a rear rear portion of the engine. A motorcycle provided with an expansion chamber to which the downstream side of each exhaust pipe is connected, wherein the downstream side of each exhaust pipe is introduced into the front portion of the expansion chamber from the front in substantially parallel to each other, and the outside of the expansion chamber. An exhaust control valve that controls the exhaust passage area of each exhaust pipe at the same time in front of the exhaust pipe in this substantially parallel part is controlled by one valve shaft, and the exhaust passage area is controlled from the outside by the engine speed. An exhaust control device for a motorcycle, which is characterized by: