JPH0825505B2 - Exhaust control device for saddle type motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to exhaust control of a saddle-ride type motorcycle in which exhaust control valves are provided in a plurality of exhaust pipes that pass under the engine near the center of the vehicle body in the front-rear direction. It relates to the device.

(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 specifications of the exhaust system (exhaust pipe length, exhaust pipe system, etc.) are set so that this dynamic effect is optimal in the high speed region, the torque is significantly reduced in the medium speed region (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.

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.

Also, an exhaust control valve is installed in the middle of the exhaust pipe to improve combustion by controlling the back pressure and self EGR (exhaust gas recirculation).
It is also considered to control the exhaust gas to control the exhaust gas component.

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 volumetric efficiency, improvement of combustion, and control of exhaust components.

If this exhaust control valve is installed below the engine in a saddle-ride type motorcycle equipped with a multi-cylinder engine near the center of the vehicle body, this exhaust control valve will greatly protrude downward, and thus There was a problem that the height became small. Therefore, it is conceivable to provide a recess in the oil pan under the engine and dispose the exhaust control valve below this. However, in this case, there arises a problem that the oil pan volume is reduced and the piston pumping loss is increased. Further, particularly in a motorcycle, when the vehicle turns, the vehicle body is tilted to the left or right (banked), so it is necessary to secure a bankable angle (called a bank angle) as large as possible so that the lower part of the vehicle body does not contact the road surface at this time. Further, since the exhaust control valve becomes high in temperature, it is also necessary to improve the cooling property so as not to exert a thermal adverse effect on surrounding members as much as possible.

(Object of the Invention) The present invention has been made in view of such circumstances,
When the exhaust control valve is installed under the engine near the center of the vehicle body, the minimum ground clearance of the vehicle body can be secured large, the oil pan capacity can be secured large, the bank angle can be secured large, and the cooling performance of the exhaust control valve can be improved. Another object of the present invention is to provide an exhaust control device for a straddle-type motorcycle that does not exert a thermal adverse effect on surrounding members as much as possible.

(Structure of the Invention) According to the present invention, it is an object of the present invention to provide a straddle-type operation seat disposed on the upper part of a vehicle body, a multi-cylinder engine mounted near the center of the vehicle body, and a guide from the front of the engine to the lower side of the engine. In a straddle-type motorcycle including a plurality of exhaust pipes and an exhaust control valve assembly that is provided in these exhaust pipes and that changes the exhaust flow passage area, in the lower part of the engine, below the oil pan, near the center in the vehicle width direction. A recess is formed that opens downward in the front-rear direction and has its front and rear ends opened in the front-rear direction. The plurality of exhaust pipes are guided to the recess in the upper and lower two stages from the front, and the oil pan wall surface is inserted in this recess. And an upper portion of the exhaust pipe and the upper portion of the exhaust control valve assembly are accommodated in the recess, and the exhaust control valve assembly includes the above-mentioned exhaust pipe. Top and bottom The upper and lower two valve shafts, each of which crosses the exhaust pipe in the vehicle width direction, are passed through, and the pulley fixed to one end of the lower valve shaft is rotated by a motor via a wire, and the lower valve shaft is also rotated. Is transmitted to an upper stage valve shaft by an interlocking mechanism, and is achieved by an exhaust control device for a saddle-ride type motorcycle.

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

In FIG. 1, 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 starts from the front of the cylinder 14
Four exhaust pipes 16 (16a to 16d) that extend below the lower oil pan 12 and extend rearward, an exhaust control valve assembly 18 that is connected to the rear ends of these exhaust pipes 16 and collects exhaust gas, The exhaust control valve assembly 18 includes one muffler 22 for guiding the exhaust collected in the expansion chamber 20 (see FIG. 5) to the atmosphere. On the lower surface of the oil pan 12, there is formed a recess 12a which opens in the front-rear direction through the vicinity of the center of the vehicle width direction and which opens downward in the front-rear direction (see FIG. 2). The exhaust pipes 16a, 16d and the upper portion of the exhaust control valve assembly 18 are located in the upper part of the exhaust pipe. Here, the exhaust pipe 16 is divided into upper and lower stages and guided in parallel to the recess 12a. Also, the exhaust control valve assembly 18 and the recess 12a
A space through which traveling wind passes is formed between the inner wall surface and the inner wall surface.

In FIG. 1, 24 is a front wheel, 26 is a steering wheel, 28 is a rear wheel, 30 is a fuel tank, and 32 is a straddle type operation seat.
Further, 34 is a fairing, the engine 10, the exhaust pipe
It covers the left and right sides and the bottom of the exhaust valve assembly 16 and the exhaust control valve assembly 18.

The exhaust control valve assembly 18 includes a plurality of butterfly type exhaust control valves 36 for changing the exhaust passage area of each exhaust pipe 16 as shown in FIGS.
(36a to 36d). That is, this assembly 18 is a circular hole (38) which communicates with each exhaust pipe 16 and whose center forms a square.
a body 38a having an a to 38d), a collecting pipe 18b forming the expansion chamber 20, and upper and lower circular holes 38a and 38d and lower circular holes 38b and 38c which are non-coaxially and horizontally penetrating respectively. The pulleys 42 protruding downward from the recess 12a of the oil pan 12 are fixed to the right ends of the book valve shafts 40a and 40b and the lower valve shaft 40b, and the left ends of both valve shafts 40a and 40b are composed of a link mechanism 44. It is connected by the interlocking mechanism. A circular valve plate 48 (48a to 48d) located in each circular hole 38 is fixed to each valve shaft 40.

The pulley 42 fixed to the valve shaft 40b is forcibly rotated in both directions by the motor 52 via the 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 circuit 54. In addition, in this FIG.
A rotation angle detector 52a detects the rotation angle of the motor 52 and feeds it back to the control circuit 56.

The outer tube of the wire 50 is held by an outer receiver 58 fixed to the collecting pipe 18b (see FIGS. 3 and 4). Further, the body main body 18a has a lightening hole 6 of an appropriate size at an appropriate position.
It is desirable to form 0 to reduce thermal deformation of the body 18a (Fig. 6).

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 servomotor 52 rotates the lower valve shaft 40b via the wire 50 and the pulley 42, and this rotation is served by the link mechanism 44 to the upper valve shaft 40a. As a result, each exhaust control valve 36 is synchronously rotated about 45 °.
Within the range (see FIG. 5), the opening is controlled to be the same.

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, when the exhaust control valve 36 is used for the purpose of preventing the torque decrease due to the exhaust interference between the cylinders, the exhaust control valve 36 may be closed in a rotation region where the torque decrease due to the exhaust interference is significant. When the exhaust control valve 36 is closed in the low speed range, the exhaust control valve 34 can be used so that the area of the exhaust flow passage is reduced by about 70 to 90% so that the opening ratio is about 30 to 10%.

The upper part of the exhaust control valve assembly 18 has the upper exhaust pipes 16a, 16d.
At the same time, since it is housed in the recess 12a provided in the oil pan 12, the position of this assembly 18 becomes high, and the distance to the road surface, that is, the minimum ground clearance can be increased.
Further, since the pulley 42 is provided on the lower valve shaft 40b for inputting the rotation for opening and closing each exhaust control valve 36, the lower surface of the oil pan 12a can be lowered without interfering with the valve shaft 40b and the pulley 42. This increases the oil pan volume,
Pumping loss due to vertical movement of the engine piston is also reduced.

Since the present invention applies the present invention to a motorcycle, the bank angle of the vehicle body can be increased and the turning performance can be improved.

Further, by displacing the upper exhaust control valve with respect to the lower exhaust control valve in the front-rear direction, the appropriate exhaust control valve 36 is shifted back and forth in response to the difference in length due to the routing of each exhaust pipe 16. It can be placed at an optimum position, and by changing the position of each exhaust pipe in the width direction, it is possible to avoid the interference between the engine and the exhaust control valve, which increases the degree of freedom in design.

FIG. 7 is a side sectional view of the second embodiment of the exhaust control valve, and FIG.
The figure is a sectional view taken along the line VIII-VIII. In this exhaust control valve assembly 118, the body 118a has a rectangular outer shape, and the openings 138 (138a to 138d) and the valve plates 148 (148a to 148d) of the exhaust control valves 136 (136a to 136d) have a rectangular shape. is there.

According to this embodiment, the body 118a has a square outer shape,
The oil pan 12 fits better into the recess 12a, and the opening 138 is also square, which is more suitable for increasing the minimum ground clearance. In these figures, the same parts as those in FIGS. 5 and 6 are designated by the same reference numerals, and the description thereof will not be repeated.

Although the above embodiment has four exhaust pipes, the present invention has two
It is needless to say that the present invention can be applied to an engine in which three or three exhaust pipes are passed in the upper and lower stages in the front-rear direction below the oil pan, and the present invention also includes such an engine.

(Advantages of the Invention) As described above, the present invention forms a recess on the lower surface of an oil pan, which opens in the front-rear direction in the vicinity of the center of the vehicle width direction and opens downward in the front-rear direction. Is connected to an exhaust control valve assembly arranged so that the upper part enters the recess, and the valve shaft of the exhaust control valve assembly is driven by a motor via a wire. Therefore, it is not necessary to provide a motor under the engine, and the bank angle of the vehicle body can be secured large while increasing the minimum ground clearance of the vehicle body. Further, since this recess is opened in the front-rear direction of the vehicle body and there is a space between the exhaust control valve assembly and the wall surface of the recess, the running wind enters the recess and smoothly flows rearward to cool the exhaust control valve assembly. Good sex. Further, the drive system such as the pulley for driving the lower valve shaft is lowered, the lower surface of the oil pan can be lowered, and the oil pan capacity can be increased. Therefore, the pumping loss of the engine due to the vertical movement of the piston is reduced. On the other hand, since the oil pan originally has a high temperature, and the exhaust control valve assembly itself can be well cooled by the traveling wind passing through the recess, the oil pan is not likely to be thermally adversely affected.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle according to an embodiment of the present invention,
FIG. 2 is a front view of the exhaust system, FIGS. 3 and 4 are side views and a plan view of the same, FIG. 5 is a side sectional view of the exhaust control valve assembly, and FIG. 6 is a sectional view taken along line VI-VI thereof. It is a figure. FIG. 7 is a sectional side view of the second embodiment of the exhaust control valve, and FIG. 8 is its VI.
FIG. 11 is a sectional view taken along line II-VIII. 10 …… Engine, 12 …… Oil pan, 12a …… Concave, 16
...... Exhaust pipe, 18,118,218 …… Exhaust control valve assembly, 32 ……
Straddle-type operation seat, 36 ... Exhaust control valve, 40 ... Valve shaft, 40
b …… Lower valve shaft, 42 …… Pulley, 44 …… Link mechanism as interlocking mechanism, 50 …… Wire, 52 …… Motor.

Claims (1)

[Claims] 1. A straddle-type operating seat disposed on the upper part of a vehicle body, a multi-cylinder engine mounted near the center of the vehicle body, a plurality of exhaust pipes which are guided from the front of the engine to the lower side of the engine, and A straddle-type motorcycle provided with an exhaust control valve assembly that is provided in an exhaust pipe and changes an exhaust flow passage area. A recess is formed such that its front end and rear end are opened in the front-rear direction. The plurality of exhaust pipes are guided from the front to the upper and lower two stages in this recess, and are disposed in this recess through the oil pan wall surface and a space. Connected to the exhaust control valve assembly, the upper exhaust pipe and the upper part of the exhaust control valve assembly are housed in the recess, and the exhaust control valve assembly includes the upper exhaust pipe and the lower exhaust pipe, respectively. Vehicle width Two upper and lower valve shafts traversing in the same direction are passed through, and a pulley fixed to one end of the lower valve shaft is rotated by a motor via a wire, and the rotation of the lower valve shaft is linked by an interlocking mechanism to the upper valve. An exhaust control device for a straddle-type motorcycle, which is characterized in that it is transmitted to a shaft.