JPH0825504B2 - Vehicle exhaust control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control device which is applied to a vehicle such as a motorcycle equipped with a V-type 4-cylinder engine and has an exhaust control valve attached to an exhaust pipe. is there.

(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 proposed that the exhaust pipe be equipped with an exhaust control valve that changes the exhaust flow passage area so that the flow passage area is reduced in the rotational speed region where volume efficiency decreases and the flow passage area is increased in other rotational speed regions. (Japanese Patent Application No. 60-263752).

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 has been proposed to provide an exhaust control valve for each exhaust pipe and close the control valve in the rotational speed range where adverse effects due to exhaust interference occur to reduce the exhaust flow passage area (Japanese Patent Application No. 60-263753).
issue).

It is also considered to improve combustion by controlling the back pressure of the exhaust pipe or to control the exhaust gas component by controlling self-EGR (exhaust gas recirculation).

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 4-cylinder engine, providing a separate exhaust control valve for each exhaust pipe of each cylinder leads to an increase in the size of the device, making 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 separated from each other, so that the above-mentioned problem becomes more remarkable. .

(Object of the Invention) The present invention has been made in view of such circumstances,
In particular, when a front and rear V-type four-cylinder engine is mounted, the exhaust control device is downsized, the mountability thereof is improved, and particularly when applied to a motorcycle, a large bank angle can be secured. An object is to provide an exhaust control device.

(Construction of the Invention) According to the present invention, the object is to mount a V-shaped member 4 near the center of the vehicle body and to form a substantially V-shaped side view with a front bank and a rear bank.
A cylinder engine, an exhaust pipe connected to each cylinder of the engine, an expansion chamber arranged below the engine and connected to a downstream side of each exhaust pipe, a downstream end of each exhaust pipe, and In a vehicle provided with an exhaust control valve interposed between an expansion chamber and the expansion chamber, two exhaust pipes of the front bank are extended rearward from below the engine, and two exhaust pipes of the rear bank are provided. This is achieved by an exhaust control device for a vehicle, which is lowered from the rear of the engine and connected to the front of the exhaust control valve in upper and lower stages.

(Embodiment) FIG. 1 is a plan view of an exhaust system for a motorcycle according to an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG. 3 is a side view of a motorcycle using the same, and FIG. Is IV-IV in Fig. 2
A line sectional view and FIG. 5 are plan views in which a part of the exhaust control valve is sectioned.

In FIG. 3, reference numeral 10 is a four-cycle four-cylinder V-type engine, which is mounted near the center of the vehicle body. The engine 10 has a crankshaft (not shown) arranged in the width direction of the vehicle body, and has a front bank 12 and a rear bank 12 that form a substantially V-shaped side view.
14 is divided in the front-rear direction to form a so-called front-rear V-type engine. The body frame 18 is provided with a side tube 18a passing through the side of the engine 10, and the front upper portion of the crankcase 16 is attached to the side tube 18a.
The rear part of 6 is attached to the body frame 18.

The exhaust system of the engine 10 extends from the front of the two cylinders of the front bank 12 through the lower part of the crankcase 16 to the rear 2
Exhaust pipes 20a, 20b, exhaust pipes 20c, 20d extending downward from the rear surfaces of the two cylinders of the rear bank 14 and curving rearward of the engine 10 toward the rear of the vehicle body, and these exhaust pipes 20 ( 20a to 20d) is connected to the downstream side of the exhaust control valve assembly 22, an expansion chamber 24 connected to the rear surface of the exhaust control valve assembly 22 to collect the exhaust gas of each exhaust pipe 20, and connected to the expansion chamber 24. An exhaust muffler that extends from the lower right of the vehicle to the rear
25 and. That is, each exhaust pipe 20 is an exhaust control valve assembly.
It is connected to the front of 22 in two steps. The expansion chamber 24 is located below and behind the engine 10.

The exhaust control valve assembly 22 includes a plurality of butterfly type exhaust control valves 26 (26a to 26d) that change the exhaust passage area of each exhaust pipe 20.
That is, the exhaust control valve 22 includes a body 22a having holes (28a to 28d) communicating with the exhaust pipes 20 and forming a square center, and upper holes 28c and 28d and lower holes 28a and 28b.
And two valve shafts 30a and 30b that respectively penetrate horizontally in
A pulley 32 fixed to the left end of the upper valve shaft 30a, a lever 34 fixed to the left end of the valve shaft 30b, the lever 34 and the pulley 32.
And a link 36 for connecting with. That is, the pulley 32,
The lever 34 and the link 36 form a link mechanism A for synchronously rotating both valve shafts 30 (30a to 30b). Each valve shaft 30
A circular valve plate 38 (38a to 38d) located in each hole 28 is fixed to the.

A pulley 32 fixed to the left end of the valve shaft 30a is forcibly rotated in both directions by a servomotor 42 via a wire 40 (see FIGS. 2 and 3). The servomotor 42 is controlled by the control circuit 46 so as to close each control valve 26 in the rotation region where the volume efficiency deteriorates and open it in the other rotation region, for example, based on the engine rotation speed detected from the ignition device 44.

Therefore, when the diameter and length of the exhaust pipe 20 are set so that the engine 10 has high volume efficiency in the high speed range,
The control circuit 46 drives the servo motor 42 so as to close the exhaust control valve 26 in the medium / low speed range. Lower exhaust control valves 26b, 26c
Are controlled by the link mechanism A in synchronism with the upper exhaust control valves 26a and 26d to have substantially the same opening degree within the exhaust gas of about 45 °.

In this embodiment, the flanges 22A and 22B for attaching the exhaust control valve assembly 22 to the exhaust pipe 20 and the expansion chamber 24 are attached to the pulley.
32 side and protect plate between these flanges 22A and 22B.
48 is installed. The protective plate 48 covers the outer sides of the pulley 32 and the link mechanism A and protects them from obstacles on the road surface. The protective plate 48 is omitted and the flanges 22A and 22B are replaced by the pulley 32.
The effect of protecting them from obstacles can be obtained simply by projecting them outwards from the link mechanism A.

In FIG. 3, 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 a driving seat.

Next, the operation of this embodiment will be described. When the diameter and length of the four exhaust pipes 20 are set so that the volumetric efficiency of the engine 10 is high in the high speed range, the exhaust control valve 26 is closed in the low and medium speed range and opened in the high speed range. Driven by a servo motor.

When the exhaust valve of each cylinder of the engine 10 is opened, the positive pressure wave due to this opening propagates in the exhaust pipe 20 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end of the exhaust pipe is generated. 20 propagates in the opposite direction at the speed of sound and returns to the exhaust valve of the engine 10. If the exhaust control valve 26 is closed, the positive pressure wave due to the opening of the exhaust valve is reflected by this exhaust control valve 26 and returns to the exhaust valve as a positive pressure wave at the speed of sound. Therefore, if the exhaust control valve 26 is controlled so that the exhaust flow passage area is halved in the low-medium speed range where the dynamic effect acts in reverse, a negative pressure wave generated by the open end of the exhaust pipe 20 and returned And the positive pressure wave reflected by the exhaust control valve 26 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 26 is used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valve 26 may be closed in a rotation region where the torque reduction due to the exhaust interference is remarkable.

The above embodiment applies the present invention to a motorcycle, and
Since the upper valve shaft 30a of the stepped valve shaft 30 is provided with the pulley 32, the bank angle of the vehicle body is increased. Also one pulley 32
Is driven by the motor 42 and the other valve shaft 30b is linked with the valve shaft 30a by the link mechanism A, so that the drive device of the exhaust control valve 26 is simplified.

FIG. 6 is a side sectional view of another embodiment of the exhaust control valve, and FIG. 7 is a sectional view taken along line VII-VII thereof. This exhaust control valve assembly 1
The reference numeral 22 denotes a valve shaft 130 held between front and rear split surfaces of the body 122a, and the valve shaft 130 has upper and lower circular holes 128c and 128d.
The valve plates 138 (138a to 138d) facing the 128a and 128b are integrally formed.

According to this embodiment, one valve shaft 130 is arranged near the center of the upper and lower exhaust pipes, so that the structure is very simple.

(Effects of the Invention) As described above, the present invention extends the two exhaust pipes of the front bank from the lower side of the engine to the rear side, and lowers the two exhaust pipes of the rear bank from the rear side of the engine. Since this exhaust pipe is connected to the front of an exhaust control valve arranged in the lower rear part of the engine in two stages, the exhaust control valve can be downsized, its mounting space can be reduced, and its drive device can be
In this way, the size and weight of the entire device can be greatly reduced. Further, when applied to a motorcycle, the lateral width near the exhaust control valve can be narrowed to secure a large bank angle of the vehicle body.

[Brief description of drawings]

FIG. 1 is a plan view of an exhaust system for a motorcycle according to an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 is a side view of a motorcycle using the same, and FIG. FIG. 5 is a sectional view taken along line IV-IV in FIG. 5, and FIG. 5 is a plan view in which a part of the exhaust control valve is sectioned. Further, FIG. 6 is a sectional view of another embodiment of the exhaust control valve, and FIG. 7 is a sectional view taken along line VII-VII thereof. 10 …… V type 4 cylinder engine, 12 …… Front bank, 14 …… Rear bank, 20a ～ 20d …… Exhaust pipe, 22,122 …… Exhaust control valve assembly, 24 …… Expansion chamber, 26a ～ 26d …… Exhaust Control valve.

Claims (1)

[Claims] 1. A V-type four-cylinder engine mounted near the center of a vehicle body to form a substantially V-shaped side view with a front bank and a rear bank,
An exhaust pipe connected to each cylinder of this engine,
In a vehicle provided with an expansion chamber, which is disposed below and behind the engine and is connected to a downstream side of each exhaust pipe, and an exhaust control valve interposed between a downstream end of each exhaust pipe and the expansion chamber, The two exhaust pipes of the front bank are extended from the lower side of the engine to the rear side, and the two exhaust pipes of the rear bank are lowered from the rear side of the engine so that two exhaust pipes are provided above and below the front face of the exhaust control valve. An exhaust control device for a vehicle, characterized by being connected in stages.