JP2542198B2 - Exhaust control device for saddle type motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a straddle type vehicle in which an exhaust control valve is provided in an exhaust pipe that extends from the front of an engine mounted near the center of a vehicle body to the rear of the engine. The present invention relates to an exhaust control device for a motorcycle.

(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.

In this way, it is conceivable to provide an exhaust control valve in the exhaust pipe to change the exhaust flow passage area for various purposes such as improving volumetric efficiency, improving combustion, and controlling exhaust components. Since the exhaust pipe is arranged below the engine in the front-rear direction, there is a problem that the minimum ground clearance is reduced when the exhaust control valve is provided below the engine. In particular, in a motorcycle, the vehicle body is tilted to the left or right when turning (banked), and therefore it is also 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 necessary not only to improve the cooling performance, but also to prevent the exhaust control valve from exerting a thermal adverse effect on other members in the vicinity 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 bank angle can be secured large, the exhaust control valve can be cooled well, and the surrounding members can be heated as much as possible. An object of the present invention is to provide an exhaust control device for a saddle-ride type motorcycle that does not have an adverse effect.

(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 which opens downward in the front-rear direction and whose front end and rear end open in the front-rear direction is formed, and one exhaust control valve assembly is disposed in this recess through the oil pan wall surface and space. The downstream ends of the plurality of exhaust pipes, which are guided to the recess from the front in two stages from top to bottom, are connected to one common expansion chamber of the exhaust control valve assembly, and the exhaust pipes are provided near the opening end to the expansion chamber. Exhaust control valve assembly car A saddle-ride type motorcycle characterized in that an exhaust passage area of each exhaust pipe is simultaneously changed corresponding to an engine rotation speed by rotating a valve shaft traversing the body width direction through a wire. This is achieved by the exhaust control device.

(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) which extend below the lower oil pan 12 and extend rearward, an exhaust control valve assembly 18 which 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 one 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
A space through which the traveling wind passes is formed between the inner wall surface of the recess 12a and the inner wall surface of the recess 12a.

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 (36a to 36d) that change the exhaust passage area of each exhaust pipe 16 near the opening end of each exhaust pipe 16 to the expansion chamber 20. That is, the 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. Circular holes 38a, 38d
And two valve shafts 40a, 40b that respectively penetrate the lower circular holes 38b, 38c in a non-coaxial and horizontal direction, and pulleys 42 (42a, 42b) fixed to the right ends of the valve shafts 40a, 40b, respectively. Prepare Each valve shaft 40 has a circular valve plate 48 located in each circular hole 38.
(48a-48d) are fixed.

Pulleys 42 fixed to both valve shafts 40 are forcibly rotated in both directions by a motor 52 via a wire 50 (see FIG. 3). Note that 50a and 50b are distributors that distribute and transmit the movement of the wire 50 to the two pulleys 42. This servomotor 52 controls each control valve in the rotation region where the volumetric efficiency deteriorates based on the engine rotation speed detected from the ignition circuit 54, for example.
It is controlled by the control circuit 56 to close 36 and open in the other rotation areas. In FIG. 3, reference numeral 52a denotes a rotation angle detector, which 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 FIG. 6). 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).

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 exhaust control valves 36 are synchronously controlled to the same opening within a range of about 45 ° (see FIG. 5).

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 exhaust control valve assembly 18 has a recess 12 formed in the oil pan 12.
Since it is housed in a, 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 recess 12a is opened in the front-rear direction of the vehicle body, the running wind can flow well in the recess and the assembly 18 can be cooled well. Since the oil pan 12 itself is heated by high temperature lubricating oil, the exhaust control valve assembly
There is no risk that the oil pan 12 will be adversely affected by the heat of this assembly 18 even if the temperature of 18 rises.

Since the present invention is applied to a motorcycle in this embodiment, the bank angle of the vehicle body can be increased and the turning performance can be improved.

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. It is also possible to avoid the interference between the engine and the exhaust control valve by changing the axial position of each exhaust pipe, which increases the degree of freedom in design.

(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. The upper and lower parts of the engine are guided to the recess from the front and connected to the exhaust control valve assembly arranged in the recess. Further, the valve shaft of the exhaust control valve assembly is driven by a motor via a wire, so that There is no need to install a motor in the vehicle, and it is possible to secure a large bank angle of the vehicle while increasing the minimum ground clearance of the vehicle. 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. The property is improved. Furthermore, since the oil pan itself is naturally high in temperature and the exhaust control valve assembly itself can be well cooled by the traveling wind passing through the recessed portion, even if the exhaust control valve assembly becomes high in temperature or high in temperature. There is no danger of being adversely affected by heat.

[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 the line VI-VI. It is a figure. 10 …… Engine, 12 …… Oil pan, 12a …… Concave, 16 …… Exhaust pipe, 18 …… Exhaust control valve assembly, 32 …… Cross-seat operation seat, 36 …… Exhaust control valve, 40 …… Valve shaft, 50 ... Wire, 52 ... Motor.

Claims (1)

(57) [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 which is provided in an exhaust pipe and changes an exhaust flow passage area, in which a lower part of an engine is provided on a lower surface of an oil pan, passing through a vicinity of a center of a vehicle width direction in a front-rear direction and downward. The front end and the rear end of the opening are formed with a recess whose front and rear ends open in the front-rear direction, and one exhaust control valve assembly is disposed in this recess through the oil pan wall surface and a space, and the recess is provided with two upper and lower stages from the front. The downstream ends of the plurality of exhaust pipes that are guided to the exhaust control valve assembly are connected to one common expansion chamber of the exhaust control valve assembly, and the exhaust control valve assembly is installed in the vehicle width direction near the opening end of the exhaust pipe to the expansion chamber. The valve axis across An exhaust control device for a straddle-type motorcycle, wherein the exhaust flow passage area of each exhaust pipe is simultaneously changed in accordance with the engine rotation speed by being rotated by a motor via a gear.