JPH07111138B2 - Exhaust control device for motorcycles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust control device applied to a motorcycle equipped with a V-type four-cylinder engine and having an exhaust control valve attached to an exhaust pipe.

(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 and the volume efficiency is increased at a certain rotation speed, the dynamic effect is adversely affected at other rotation speeds, and the volume 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). In this case, it is desirable that the exhaust control valve is provided at the downstream end of the exhaust pipe, that is, near the opening end to the expansion chamber, so that positive and negative pressure waves of the exhaust are effectively canceled as will be described later.

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 the exhaust interference of the cylinder pipes. 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, especially in a motorcycle equipped with a V-type 4-cylinder engine, connecting the exhaust pipe of each cylinder to one expansion chamber is
This causes the expansion chamber to become large in size, making it difficult to secure a space for mounting the expansion chamber and reducing the degree of freedom in designing the layout. Further, when the exhaust control valve is provided in the expansion chamber, there is a problem that the heat generated in the expansion chamber is considerably increased and the cooling property of the expansion chamber is deteriorated.

Further, in a front-rear V-type engine in which each V-shaped bank (cylinder row) is tilted back and forth, the combustion conditions are not uniform due to differences in the cooling characteristics and exhaust characteristics of the front bank and the rear bank. For this reason, it is desirable that the control of the exhaust control valve be different for each bank.

(Object of the Invention) The present invention has been made in view of the above circumstances, and in particular, when a front and rear V-type four-cylinder engine is mounted and an exhaust control valve is provided in an expansion chamber connected to a downstream end of an exhaust pipe. In addition, the degree of freedom in designing the expansion chamber can be increased, and its cooling performance can be improved at the same time. Furthermore, suitable control for each bank can be performed in response to uneven combustion conditions in the front and rear banks. It is an object of the present invention to provide an exhaust control device for a motorcycle capable of performing the following.

(Construction of the Invention) According to the present invention, a purpose is to mount a V-type four-cylinder engine having a front bank and a rear bank forming a V-shape in a side view in the vicinity of the center of a vehicle body, and to arrange the V-cylinder engine below and behind the engine. In a motorcycle including an expansion chamber to which the exhaust gas of each cylinder is guided and an exhaust control valve that controls the exhaust flow passage area of each exhaust pipe, the expansion chamber is divided into two left and right parts, each of which is formed independently. Two exhaust pipes of the bank to one expansion chamber, two of the rear bank
While connecting the exhaust pipe of the book to the other expansion chamber,
An exhaust control valve for controlling the exhaust flow passage area of these two exhaust pipes is provided in each of the expansion chambers, and the opening degree of each exhaust control valve is controlled by a drive device according to the engine rotation speed. This is achieved by the exhaust control device of the motorcycle.

(Embodiment) FIG. 1 is a plan view in which an embodiment of the present invention is partially sectioned, and FIG.
The figure is a side view thereof, FIG. 3 is a side view of a motorcycle using the same, FIG. 4 is a plan view of this exhaust system, and FIG. 5 is a side view of the same.

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. This engine
10, a crankshaft (not shown) is arranged in the vehicle width direction,
A front bank (front cylinder row) 12 and a rear bank (rear cylinder row) 14 that form a V-shape in a side view are separated in the front-rear direction to form a so-called front-rear V-type engine.

The exhaust system of the engine 10 includes exhaust pipes 20, 22 extending from the front of the front bank 12 to the rear through the lower left of the crankcase 16.
And the exhaust pipes 24 and 26 extending from the rear surface of the rear bank 14 to the lower rear of the engine 10 and the exhaust pipes of the left and right cylinders of the rear bank 14.
The left expansion chamber 28 to which the downstream sides of 24 and 26 are connected, the right expansion chamber 30 to which the downstream sides of the exhaust pipes 20 and 22 of the left and right cylinders of the front bank 12 are connected, and the expansion chambers 28 and 30, respectively. Two exhaust mufflers 32, 34 connected to each other. The expansion chamber 28,
The 30 is located below and behind the engine 10 in left and right sections.

An exhaust control valve 36 facing the open ends of the exhaust pipes 24, 26 is disposed in the expansion chamber 28. An exhaust control valve 38 desired at the open ends of the exhaust pipes 20 and 22 is arranged in the expansion chamber 30. The left and right exhaust control valves 36, 38 are symmetrical, so the left-hand side exhaust control valve 36 will be described below with reference to FIGS.

The exhaust control valve 36, as shown in FIG.
And bearing plates 42 mounted on the left and right side surfaces of this body 40,
44, and these bearing plates 42, 44 and a crank-like valve-like member 46 rotatably held. The valve body 46 includes an exhaust pipe 24,
A portion of the 26 facing the open end is formed in an arcuate cross section. The left shaft of the valve body 46 penetrates the bearing plate 42 and projects outward,
A pulley 48 is attached to this protruding end. Wires 50 are attached to the pulleys 48, 48 of the left and right exhaust control valves 36, 38, respectively.
(Fig. 5) is wound around the valve body 46 through this wire 50.
Is independently rotated by a drive device such as a servomotor 52. The motor 52 is controlled by the control device 56 in accordance with the engine rotation speed detected by the ignition device 54.

In FIG. 3, 58 is a front fork, 60 is a front wheel, 62 is a handlebar, 64 is a rear arm that is pivotally mounted by a pivot shaft 66, 68 is a rear wheel that is attached to the rear end of the rear arm 66, 70 is a cushion unit, 72 is a fuel tank, and 74 is an operation seat.

Next, the operation of this embodiment will be described. When the diameter and length of the exhaust pipes 20 to 26 are set so that the volumetric efficiency of the engine 10 is high in the high speed range, the exhaust control valves 36 and 38 are closed in the low and medium speed range and opened in the high speed range. Is driven by the servo motor 52.

The positive pressure wave due to the opening of the exhaust valve of the engine 10 propagates in the exhaust pipes 20 to 26 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end reverses the exhaust pipes 20 to 26 at the speed of sound. Propagates in the direction and returns to the exhaust valve of the engine 10. If the exhaust control valves 36 and 38 are closed, the positive pressure wave due to the opening of the exhaust valve is reflected by the exhaust control valves 36 and 38 and returns to the exhaust valve as a positive pressure wave at the speed of sound. Therefore, in the low-medium speed range where the dynamic effect works in reverse, if the exhaust control valves 36 and 38 are controlled so that the exhaust flow passage area is almost halved, the exhaust pipes 20 to 26 generate the open ends. Then, the negative pressure wave returning 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.

When the exhaust control valves 36, 38 are used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders, the exhaust control valves 36, 38 are used in the rotation region where the torque reduction due to the exhaust interference is remarkable.
You can close 38. As the exhaust control valves 36 and 38, it is possible to use a valve in which the exhaust passage area is reduced to about 10 to 30% in this closed state.

In the present invention, the two exhaust pipes 20 and 22 in the front bank are connected to the expansion chamber 30 on the right side, and the two exhaust pipes 24 and 26 in the rear bank are connected to the expansion chamber 128 on the left side. Therefore, since the two exhaust pipes connected to each expansion chamber belong to the same bank and the conditions are the same, it is easy to give a phase difference to the opening / closing timing of each exhaust control valve 36, 38, and the front bank and the rear bank. Fine control is possible in response to unbalance due to different combustion conditions of the banks or different lengths and diameters of the exhaust pipes 20 to 26.

In the exhaust control valves 36 and 38 of the above embodiment, the valve body having an arc-shaped cross section is used.
Although 46 faces the opening of the exhaust pipe, the invention can use valves of other constructions, such as butterfly valves.

Of course, it is possible to drive the two exhaust control valves independently by two drive devices such as servo motors, but one drive device drives the two exhaust control valves with a phase difference, for example. You may Eg 1
The movement of one drive device is transmitted to the exhaust control valve via separate wires, and the movement of the drive device is transmitted to the pulley arranged between both expansion chambers, while the movement of this pulley is linked by a linking means. It is possible to transmit to the left and right exhaust control valves via the.

(Effects of the Invention) As described above, the present invention divides the expansion chambers disposed below and behind the engine into left and right parts independently of each other, and forms the exhaust pipe of the front bank in one expansion chamber, Since the exhaust pipe of the rear bank is connected to the other expansion chamber, and each expansion chamber is equipped with an exhaust control valve, the degree of freedom in layout design is greater than that of a single expansion chamber. Increase. Further, by dividing the expansion chamber into two, the ratio of the surface area to the volume is increased, and the cooling performance by the outside air is improved. Further, each exhaust control valve can set the opening / closing timing, the opening degree, and the like separately in consideration of the difference in the combustion conditions between the front and rear banks, so that suitable control can be performed for each bank.

[Brief description of drawings]

FIG. 1 is a plan view in which an embodiment of the present invention is partially sectioned, and FIG.
The drawing is a sectional view thereof, FIG. 3 is a side view of a motorcycle using the same, FIG. 4 is a plan view of this exhaust system, and FIG. 5 is a side view of the same. 10 …… V-type 4-cylinder engine, 12 …… Front bank, 14 …… Rear bank, 20-26 …… Exhaust pipe, 28,30 …… Expansion chamber, 36,38 …… Exhaust control valve, 52 …… Drive Servo motor as a device.

Claims (1)

[Claims] 1. A V-type four-cylinder engine mounted in the vicinity of the center of a vehicle body, in which a front bank and a rear bank form a V-shape in side view, and an expansion chamber arranged below and behind the engine to guide exhaust gas of each cylinder. And an exhaust control valve for controlling the exhaust passage area of each exhaust pipe, the expansion chamber is divided into two left and right parts, each of which is formed independently of the other exhaust pipe of the front bank. , Two exhaust pipes of the rear bank are respectively connected to the other expansion chambers, and exhaust control valves for controlling the exhaust flow passage areas of these two exhaust pipes are provided in the expansion chambers, respectively. An exhaust control device for a motorcycle, wherein an opening of an exhaust control valve is controlled by a drive device according to an engine speed.