JPH0759891B2 - Vehicle exhaust control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control device that is applied to a vehicle such as a motorcycle equipped with a multi-cylinder engine 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. (Japanese Patent Application No. 60-263752).

On the other hand, instead of separating the exhaust control valve for each exhaust pipe, a common one exhaust control valve is used to simultaneously control the exhaust flow passage areas of two or more exhaust pipes to reduce the size and weight of the device. (Japanese Patent Application No. 61-288480).

By the way, in a vehicle such as a motorcycle, particularly when a front and rear V-type engine in which the crankshaft is arranged in the vehicle width direction is mounted, the exhaust pipes of each bank forming the V-type are connected to the expansion chamber through different routes. Therefore, the length of the exhaust pipe becomes uneven.

In such a case, even if it is attempted to control the exhaust flow passage areas of all the exhaust pipes by using one common exhaust control valve as described above, the engine speed at which the torque valley is generated differs for each cylinder. It has been difficult to sufficiently suppress the occurrence of torque and sufficiently increase the torque. In addition to the above-described exhaust pipe length, the diameter of the exhaust pipe and the difference in cooling conditions may be considered as factors that cause the difference in engine characteristics between cylinders.

(Object of the Invention) The present invention has been made in view of such circumstances, and even when the lengths and diameters of the exhaust pipes are different among the cylinders or the combustion characteristics of the cylinders are not uniform, one common An object of the present invention is to provide an exhaust control device for a vehicle, which is capable of sufficiently increasing the output for each cylinder by using an exhaust control valve.

(Structure of the Invention) According to the present invention, the object is to connect a multi-cylinder engine mounted on a vehicle body, a plurality of exhaust pipes connected to each cylinder of the engine, and a downstream side of each exhaust pipe. A vehicle provided with an expansion chamber is provided with one common exhaust control valve which is disposed near the downstream opening end of each exhaust pipe and controls the exhaust flow passage area of each exhaust pipe with a phase difference. It is achieved by the exhaust control device of the vehicle.

(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 a motorcycle using the same, and FIG. 3 and FIG. III-III line sectional view and IV-IV line sectional view in the figure, and FIG. 5 is a perspective view of the valve body, FIG.
The figure is an operating characteristic diagram of the exhaust control valve.

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. This engine
10, a crankshaft (not shown) is arranged in the vehicle width direction,
The two banks 12 and 14 forming the V-type are divided in the front-rear direction to form a so-called front-rear V-type engine. The engine 10 is attached to the vehicle body frame 18 by the upper ends of the banks 12, 14 and the rear end of the crankcase 16.

The exhaust system of the engine 10 extends from the front of the front bank 12 to the rear through the lower right of the crankcase 16 and to the rear, from the rear of the rear bank 14 to the lower, and further to the right of the vehicle behind the engine 10. Exhaust pipe 22 that extends backward while drawing
And the expansion chamber to which the downstream sides of these exhaust pipes 20 and 22 are connected.
24 and two exhaust mufflers 26, 28. Front bank 12
The exhaust pipe 20 is longer than the exhaust pipe 22 of the rear bank 14, and the diameter of the exhaust pipe 20 is larger than the diameter of the exhaust pipe 22. The expansion chamber 24 is located in the lower rear part of the engine 10. Also exhaust muffler 26,
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 muffler 28 is expanded to the front left side surface. The right end of chamber 24 is directly connected (see Figure 3). As shown in FIG. 1, the exhaust pipes 20 and 22 extend from the right front portion of the expansion chamber 24 into the expansion chamber 24. Exhaust pipes 20 and 22 are arranged in the vicinity of the open ends of the expansion chambers 24 in parallel and adjacent to each other, and an exhaust control valve 34 is arranged at these open ends.

The exhaust control valve 34 includes a crank-shaped valve body 36, and both ends of the valve body 36 are held by bearing plates 38 and 40 fixed to the front wall and the rear wall of the expansion chamber 24. The middle part of the valve body 36 is the third
As shown in the figure, the exhaust pipe is formed in an arc shape in cross section.
The open ends of 20 and 22 are cut out in an arc shape so as to closely face and face the intermediate portion. Further, the lower edge of the intermediate portion of the valve body 36 is obliquely cut out at a half portion facing the open end of the exhaust pipe 22 as shown in FIGS. One end of the valve element 36 penetrates the bearing plate 38 and projects forward, and the pulley 42 is fixed to this projecting end. A wire (not shown) is wound around the pulley 42, and the pulley 42 and the valve body 36 are wound through the wire by a noise device such as a servo motor (not shown).
Is rotated counterclockwise as shown by the arrow in FIG.
As a result, the exhaust flow passage area at the downstream open ends of the exhaust pipes 20 and 22 is controlled. Since the lower half of the lower edge of the valve body 36 is obliquely cut out here, each exhaust pipe 20 with respect to the rotation angle θ of the valve body 36,
The opening A of 22 changes with a phase difference as shown in FIG. In the figure, 20A and 22A face exhaust pipes 20 and 22, respectively.

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 due to the opening of 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. If the exhaust control valve 34 is closed, the positive pressure wave due to the opening of 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 approximately 1/2 in the low and medium speed range where the dynamic effect acts in reverse, the exhaust pipes 20 and 22 generate and turn back. The negative pressure 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.

Since the lower edge of the valve body 36 is notched at a half portion thereof, the opening areas of the exhaust pipes 20 and 22 change with a phase difference as shown in FIG. That is, the opening movement of the exhaust pipe 20 is delayed with respect to the opening movement of the exhaust pipe 22. As a result, the optimal exhaust control valve opening can be set for each cylinder due to the difference in the length and diameter of the exhaust pipes 20, 22 for each bank 14, 16 of the engine 10, and the effect of the exhaust control valve can be maximized. .

Further, since the exhaust pipes 20 and 22 are controlled by the common one exhaust control valve 34, the size and weight can be reduced as compared with the case where the exhaust control valves are separately provided to the exhaust pipes 20 and 22, respectively. Further, only one drive device such as a servo motor for opening and closing the exhaust control valve 34 is required, and the size and weight of the entire device can be greatly reduced.

In this embodiment, the exhaust control valve 34 is formed by using the crank-shaped valve body 36 facing the open ends of the exhaust pipes 20 and 22.
The present invention is not limited to this, for example, when using a butterfly-type valve having a plurality of disc-shaped valve plates fixed to the valve shaft penetrating each exhaust pipe, the fixing angle of each valve plate to the valve shaft is The phase can be shifted by changing it. Also, when a notch is provided in a zigzag valve element that crosses between the exhaust pipes and a valve of the type in which the opening area is controlled by the rotation of this valve element is used, the phase of the notch must be changed. Good. Furthermore, when using an exhaust control valve by utilizing a valve plate that traverses the open end of each exhaust pipe and utilizing the change in the amount of overlap between the notch provided in this valve plate and each exhaust pipe, Just change the position of the notch.

Further, the present invention is particularly effective in the case where the exhaust pipe length and diameter greatly differ depending on the cylinder such as a V-type engine, but in an in-line multi-cylinder engine, combustion becomes non-uniform due to a difference in cooling property between cylinders. It is also effective for compensation, and the present invention includes such a thing.

(Advantages of the Invention) As described above, according to the present invention, the exhaust control valve provided in the vicinity of the downstream end of each exhaust pipe changes each exhaust passage area with a phase difference for each cylinder. Even if the length and diameter of each cylinder differ between cylinders, or if the combustion characteristics of each cylinder are uneven, the exhaust flow passage area can be controlled in the optimum phase for each cylinder, and the engine output can be increased sufficiently. Can be made.

Moreover, since the exhaust passage area of each cylinder is controlled by one common exhaust control valve, the exhaust control valve mounting space is smaller than that in the case where a separate control valve is provided for each exhaust pipe, and its drive device is also 1 Since this is sufficient, the size and weight of the entire device can be greatly 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. A sectional view taken along the line III and a sectional view taken along the line IV-IV, FIG. 5 is a perspective view of the valve element, and FIG. 6 is an operation characteristic diagram of the exhaust control valve. 10 …… V type multi-cylinder engine, 20,22 …… exhaust pipe, 24 …… expansion chamber, 34 …… exhaust control valve, 36 …… valve body.

Claims (1)

[Claims] 1. A vehicle including a multi-cylinder engine mounted on a vehicle body, a plurality of exhaust pipes connected to respective cylinders of the engine, and an expansion chamber connected to a downstream side of each exhaust pipe, An exhaust control device for a vehicle, comprising one common exhaust control valve which is disposed near the downstream opening end of each exhaust pipe and controls the exhaust flow passage area of each exhaust pipe with a phase difference.