JPH0826774B2 - Engine exhaust control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine exhaust control device in which exhaust control valves each of which is a butterfly valve are provided in a plurality of exhaust pipes extending from an exhaust port of an engine to an expansion chamber. It is a thing.

(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 volumetric efficiency is increased at a certain rotation speed, the dynamic effect is adversely affected and the volumetric efficiency is significantly reduced at other rotation speeds. 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, an exhaust control valve that changes the exhaust flow passage area is provided near the opening end of the exhaust pipe to the expansion chamber, and the flow passage area is reduced in the rotational speed range where the volumetric efficiency is reduced, and the flow passage area is changed in other rotational speed regions. It is considered to increase.

In this case, if the exhaust control valve is formed of a butterfly valve, a rotational force is generated on the valve shaft due to the exhaust pressure (exhaust pressure) that strikes the valve plate. That is, the valve plate is normally fixed eccentrically from the center of rotation of each valve shaft. Therefore, this rotational force is transmitted to the driving means such as the motor through the transmission system such as the wire. For this reason, problems such as the need to increase the capacity of the drive means such as the drive motor and the occurrence of vibrations easily in the transmission system such as the wire for transmitting the rotation of the motor to the valve shaft may occur.

(Object of the Invention) The present invention has been made in view of such circumstances,
When the exhaust control valve is a butterfly valve, the exhaust pressure cancels the rotational force generated on the valve shaft, and this rotational force is not transmitted to the drive means, enabling a reduction in the capacity of the drive means. It is an object of the present invention to provide an exhaust control system for an engine, in which a transmission system such as a wire for transmitting the rotation of the drive means to a valve shaft is less likely to be vibrated by the rotational force.

According to the present invention, an object of the present invention is to provide a plurality of exhaust pipes, one end of which is connected to an exhaust port of an engine and the other end of which is connected to an expansion chamber.
In an engine including an exhaust control valve, which is provided in each of the exhaust pipes and includes a butterfly valve that changes an exhaust flow passage area of each of the exhaust pipes, a valve shaft that penetrates a part of the exhaust pipes and another exhaust pipe that penetrates the exhaust pipes. The valve shaft and the valve shaft are arranged non-coaxially and substantially parallel to each other,
A valve plate is fixed to each valve shaft for each exhaust pipe, and each valve shaft is interlocked by an interlocking mechanism so that the exhaust force acts on each valve plate and the rotational forces generated on each valve shaft cancel each other out by the interlocking mechanism. This is achieved by an exhaust control system for an engine, which is characterized in that they are adapted to each other.

(Embodiment) FIG. 1 is a front view of an exhaust system of a motorcycle according to an embodiment of the present invention, FIGS. 2 and 3 are side views and a plan view of the same, and FIG. 4 uses this exhaust system. FIG. 5 is a side view of the motorcycle, FIG. 5 is a side sectional view of the exhaust control valve assembly, FIG. 6 is a sectional view taken along the line VI-VI, and FIGS. 7 and 8 are a plan view and a left side view.

In FIG. 4, reference numeral 10 is a 4-cycle 4-cylinder engine, which is mounted near the center of the vehicle body. This engine 10
Is a cylinder 14 that extends diagonally upward and forward from the crankcase 12.
Have. The exhaust system includes four exhaust pipes 16 (16a to 16d) extending from the front surface of the cylinder 14 to the lower side of the crankcase 12.
An exhaust control valve assembly 18 connected to the rear ends of these exhaust pipes 16 to collect exhaust gas, and an expansion chamber 20 of the exhaust control valve assembly 18.
(See FIG. 5) One muffler 22 for guiding the exhaust gas collected in the atmosphere to the atmosphere.

In FIG. 4, 24 is a front wheel, 26 is a steering wheel, 28 is a rear wheel, 30 is a fuel tank, and 32 is a driving seat. Again 34
Is a fairing, which covers the engine 10, the exhaust pipe 16, and the left and right sides and the lower side of the exhaust control component assembly 18.

The exhaust control valve assembly 18 includes a plurality of butterfly type exhaust control valves 36 (36a to 36d) that change the exhaust passage area of each exhaust pipe 16.
That is, this assembly 18 is a body 18a having a circular hole (38a to 38d) communicating with each exhaust pipe 16 and having a center forming a square, a collecting pipe 18b forming the expansion chamber 20, and an upper stage. Two valve shafts 40a, 40b that respectively penetrate the circular holes 38a, 38d and the lower circular holes 38b, 38c non-coaxially and horizontally, a pulley 42 fixed to the left end of the upper valve shaft 40a, and both valves. Axis 40a,
The sector gears 44a and 44b fixed to the left end of 40b are provided.
Both sector gears 44a and 44b constitute an interlocking mechanism A that rotates both valve shafts 40 in synchronization. The lower sector gear 44b hardly projects below the valve shaft 40b, as is apparent from FIGS. A circular valve plate 48 (48a to 48d) located in each circular hole 38 is fixed to the upper side of each valve shaft 40. That is, the valve shaft 40 is chamfered at the upper and lower edges as is clear from FIGS. The chamfered upper surface of the valve shaft 40 is fixed with a screw.
Therefore, the valve plate 48 is displaced upward with respect to the center of the valve shaft 40, and as a result, the exhaust pressure applied to the valve plate 48 gives a rotational force to the valve shaft 40. That is, the sector gear 44 causes the valve plate 48 to rotate in the direction shown by the phantom line in FIG.
Since the valve shafts 40 are deviated upward with respect to the horizontal planes B passing through the center of the valve 40, a rotational force in the clockwise direction in FIG. Therefore, while the sector gear 44a tends to rotate clockwise in FIG. 8, the sector gear 44b
Since they also try to rotate in the same direction, the rotational forces of both gears 44a and 44b are canceled by the transmission mechanism A.

A pulley 42 fixed to the left end of the valve shaft 40a is forcibly rotated in both directions by a servomotor 52 via a wire 50 (see FIG. 3). The servomotor 52 is controlled by the control circuit 56 so as to close each control valve 36 in a rotation region where the volumetric efficiency deteriorates and open it in other rotation regions, for example, based on the engine rotation speed detected from the ignition device 54.

Therefore, when the diameter and length of the exhaust pipe 16 are set so that the volume efficiency of the engine 10 is high in the high speed range,
The control circuit 56 drives the servomotor 52 so as to close the exhaust control valve 36 in the medium / low speed range.

The positive pressure wave generated by opening the exhaust valve of the engine 10 propagates in the exhaust pipe 16 at the speed of sound, and the negative pressure wave generated by the rapid expansion at the open end propagates in the opposite direction at the speed of sound in the exhaust pipe 16. Back to the exhaust valve of engine 10. If the exhaust control valve 36 located near the opening end is closed, the positive pressure wave due to the opening of the exhaust valve is reflected by the exhaust control valve 36 and returns to the exhaust valve as a positive pressure wave at the speed of sound. Therefore, if the exhaust control valve 36 is controlled so that the exhaust flow passage area is halved, the negative pressure wave generated by the open end of the exhaust pipe and returned and the positive pressure wave reflected by the exhaust control valve 34 will be returned. The sum of and becomes zero. At this time, the pulsating effect is canceled out, and a decrease in volumetric efficiency (occurrence of a torque valley) in the medium speed range can be suppressed.

Further, the exhaust control valve 36 can also be used for the purpose of preventing the torque reduction due to the exhaust interference between the cylinders. In this case, the exhaust control valve 36 may be closed in the low speed rotation region where the torque reduction due to the exhaust interference is remarkable. . In this case, the exhaust control valve 34 restricts the area of the exhaust flow passage by 70 to 90% to reduce the opening ratio.
It is possible to use the one that is set to about 30 to 10%.

The outer tube of the wire 50 is held by an outer receiver 58 fixed to the collecting pipe 18b (see FIG. 7). Further, the body main body 18a has a lightening hole 60 of an appropriate size at an appropriate position.
To reduce the thermal deformation of the body 18a (FIG. 6).

In this embodiment, the present invention is applied to a motorcycle, and two exhaust pipes 16a, 16d and 16b, 1 are provided below the engine 10 respectively.
Since the 6c are arranged in the upper and lower stages, the lateral width of the exhaust system below the engine is reduced, and the bank angle of the vehicle body can be increased.

Further, since the pulley 42 is provided on the valve shaft 40a of the upper stage, the position of the wire and the outer receiver of the wire also becomes high, and the sector gear 44b of the lower stage of the interlocking mechanism A does not project downward from the valve shaft 40b. The lateral width of the lower portion of the control valve assembly 18 can be suppressed to be small. Therefore, a large bank angle can be secured even when a fairing that covers them is attached.

9 and 10 are a cross-sectional view and a right side view of an exhaust control valve assembly 18A of another embodiment, respectively. In this embodiment, the exhaust control valve 36 is arranged below the engine of the motorcycle as in the above embodiment, but the interlocking mechanism A is formed by a link mechanism and the upper and lower valve plates 48 are provided. It differs from the embodiment shown in FIGS. 1 to 8 in that the two valve shafts 40 are fixed to different surfaces vertically. That is, since the upper valve plates 48a and 48d are located above the horizontal plane B passing through the center of the valve shaft 40a, the exhaust pressure tends to rotate the valve shaft 40a clockwise in FIG.
On the other hand, since the lower valve plates 48b and 48c are located below the horizontal plane B passing through the center of the valve shaft 40b, the exhaust pressure tends to rotate the valve shaft 40b counterclockwise. The rotational force of both valve shafts 40 is applied to the link 60 of the link mechanism A in the direction of compressing and cancels each other.

Also, if the upper exhaust control valve is offset in the front-back direction relative to the lower exhaust valve, the appropriate exhaust control valve 36 can be shifted back and forth in accordance with the difference in length due to the routing of each exhaust pipe 16. Can be placed in Furthermore, although each exhaust pipe is arranged in a substantially square shape in the embodiment, the present invention is not limited to this, and by changing the arrangement interval in the width direction of each exhaust pipe, it is possible to avoid interference between the engine and the exhaust control valve. The upper degree of freedom increases.

(Effects of the Invention) As described above, the present invention interlocks a plurality of non-coaxial and substantially parallel valve shafts, and the exhaust pressure unevenly strikes the valve plate with respect to the valve shaft center. It is configured such that the rotational force generated in the is canceled by this interlocking mechanism. Therefore, the driving force of the motor or the like for driving the exhaust control valve can be reduced, the driving force of the motor or the like can be reduced, and the capacity of the motor or the like can be reduced. Further, the force applied to the wire or the like for transmitting the rotation of the motor or the like to the valve shaft is reduced, and the possibility that the rotating force of the valve shaft vibrates the wire or the like is reduced.

[Brief description of drawings]

FIG. 1 is a front view of an exhaust system of a motorcycle according to an embodiment of the present invention, FIGS. 2 and 3 are side views and a plan view, and FIG.
Figure is a side view of a motorcycle using this exhaust system, Figure 5 is a side sectional view of an exhaust control valve assembly, Figure 6 is a sectional view taken along the line VI-VI, and Figures 7 and 8 are plan views. It is a side view. 9 and 10 are a sectional view and a left side view of an exhaust control valve assembly of another embodiment. 10 …… Engine, 16 …… Exhaust pipe, 18,18A …… Exhaust control valve assembly, 20 …… Expansion chamber, 36 …… Exhaust control valve, 40 …… Valve shaft, 44 …… Sector gear, 48 …… Valve plate, 60 ... Link, A ... Interlocking mechanism.

Claims (4)

[Claims] 1. A plurality of exhaust pipes, one end of which is connected to an exhaust port of an engine and the other end of which is connected to an expansion chamber, and a butterfly valve which is provided in each of the exhaust pipes and changes an exhaust passage area of each exhaust pipe. In an engine including an exhaust control valve, a valve shaft that penetrates a part of the exhaust pipe and a valve shaft that penetrates another exhaust pipe are arranged non-coaxially and substantially parallel to each other, and the exhaust gas is exhausted on each valve shaft. The valve plate is fixed for each pipe, and each valve shaft is interlocked by the interlocking mechanism so that the exhaust force acts on each valve plate and the rotational forces generated on each valve shaft cancel each other out by the interlocking mechanism. An exhaust control device for an engine. 2. The engine is a motorcycle engine having a cylinder extending obliquely upward and forward from a crankcase, and the plurality of exhaust pipes are juxtaposed so as to extend rearward from a front surface of the cylinder through a lower portion of the crankcase. Is
The engine exhaust control device according to claim 1, wherein the exhaust control valves are disposed below the crankcase. 3. Four exhaust pipes are arranged so that their centers form a substantially square shape below the crankcase, and two exhaust pipes are provided in each of the upper and lower stages.
The two upper and lower valve shafts that penetrate the respective exhaust pipes are interlocked by an interlocking mechanism consisting of a set of sector gears, while each valve plate is fixed on the same upper and lower sides of both valve shafts. An exhaust control device for an engine according to claim 2. 4. The four exhaust pipes are arranged so that their centers form a substantially square below the crankcase, and two exhaust pipes are provided in each of the upper and lower stages.
Two upper and lower valve shafts that penetrate the respective exhaust pipes are interlocked by an interlocking mechanism composed of a link mechanism, while each valve plate is fixed to different side faces of the two valve shafts. The exhaust emission control device for an engine according to the second aspect of the present invention.