Engine exhaust assembly for a motorcycle

Information

  • Patent Grant
  • 6336321
  • Patent Number
    6,336,321
  • Date Filed
    Friday, January 21, 2000
    24 years ago
  • Date Issued
    Tuesday, January 8, 2002
    22 years ago
Abstract
A partitioning member for dividing a connecting pipe into at least two exhaust passageways is provided in the connecting pipe, which is attached to an exhaust side of a silencer. A valve mechanism is operable to vary the passageway area of one of the exhaust passageways. With this structure, for example, when an engine is rotating at low revs, exhaust gas is discharged from the exhaust passageway without the valve mechanism, while when the engine is rotating at high revs exhaust gas is simultaneously discharged from the exhaust passageway having no valve mechanism and a passageway provided with the valve mechanism. Therefore, it is possible to reduce exhaust noise when the engine is rotating at low revs.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to improvements to an engine exhaust assembly. In particular, the present invention relates to an engine exhaust assembly for a motorcycle.




2. Description of Related Art




Engine exhaust assemblies for motorcycles are known, for example, from (1) Japanese Patent Laid-open No. Hei. 10-238334, entitled 4-cycle engine, and (2) Japanese Utility Model Laid-open No. Hei. 2-22617, entitled Engine Exhaust Assembly.




In the above mentioned document (1) according to FIG.


1


and

FIG. 2

of that publication, an exhaust pipe


40


is connected to an exhaust passageway


14


of a cylinder head


4


. Furthermore, a variable valve


41


having a cutaway section


4


la is provided in the exhaust passageway side of the exhaust pipe


40


.




In the above described document (2) according to

FIG. 2

of that publication, the exhaust system is branched into two exhaust systems, with first and second exhaust outlet pipes


5


and


6


being respectively provided in the exhaust systems. Furthermore, an opening and closing valve


7


is provided in the first exhaust outlet pipe


5


of the respective exhaust systems. The opening and closing valves


7


,


7


of the respective exhaust systems are closed when the engine is rotating at low revs, one of the opening and closing valves


7


is closed when the engine is rotating at medium revs, and the opening and closing valves of the respective exhaust systems are open when the engine is rotating at high revs. In this way, it is intended to reduce the sound pressure level of exhaust noise.




However, in the above-described document (1), a variable valve


41


is provided in an inlet of the exhaust pipe


40


, which means that it is not possible to adequately reduce the sound pressure level of the exhaust noise.




Also, in the above-described document (2), the exhaust system is divided into two. A first exhaust outlet pipe


5


and a second exhaust outlet pipe


6


are provided in each of the exhaust systems, and an opening and closing valve


7


is respectively fitted in the first exhaust outlet pipe of each exhaust systems, which means that the structure is made complicated and costs also increase.




SUMMARY OF THE INVENTION




Therefore, the object of the present invention is to provide an engine exhaust assembly for a motorcycle having a simple structure, and which can sufficiently reduce acoustic noise.




In order to achieve the above described object, a first aspect of the present invention has a partitioning member provided in a pipe of a silencer arranged in the engine exhaust assembly for dividing the pipe into at least two exhaust passageways. The partitioning member is provided with a valve mechanism for causing variation in surface area of one of the exhaust passages.




For example, when the engine is rotating at low revs, the valve mechanism is closed, so that exhaust gas is discharged from the exhaust passageway without the valve mechanism. Furthermore, when the engine is rotating at high revs the valve mechanism is open so exhaust gas is discharged simultaneously from the exhaust passageway without the valve mechanism and the exhaust passageway provided with the valve mechanism. Therefore, it is expected that the exhaust noise when the engine is rotating at low revs will be reduced.




Also, by dividing one connecting pipe with a partitioning member and providing a valve mechanism in one of the exhaust passageways formed by the dividing member, the structure of the exhaust assembly is simplified.




A second aspect of the present invention is an engine exhaust assembly, having a valve mechanism for varying opening areas of a connecting pipe for a silencer arranged in the engine exhaust assembly. The valve mechanism is fitted into the connecting pipe of the silencer. One end of a connecting member connects to the valve mechanism, the other end of the connecting member connects to drive means arranged outside the silencer. Furthermore, the valve mechanism is driven by the drive means and the connecting member passes through the silencer.




The valve mechanism is fitted into the connecting pipe of the silencer, one end of a connecting member is connected to the valve mechanism, the other end of the connecting member is connected to drive means arranged outside the silencer, and the valve mechanism is driven by the drive means. Accordingly, by fitting a pipe to the silencer and housing part of the connecting member in the pipe, the connecting member is hidden from the outside of the silencer and the external appearance of the exhaust assembly is improved.




A third aspect of the present invention is a motorcycle exhaust assembly having an engine arranged substantially in the center of a vehicle frame of the motorcycle. An exhaust pipe extending rearwards from the engine, a silencer is connected to the exhaust pipe and a valve mechanism is provided in a connection pipe of the silencer. One end of a connecting member is connected to the valve assembly, the other end of the connecting member is connected to drive means provided on the side of a vehicle frame, and the valve mechanism is driven by the drive means. Furthermore, a central potions of the connecting member is close to the silencer, and is caused to run alongside a member extending out from the vehicle frame.




The valve mechanism is fitted into the silencer, the drive means is attached to the side of the vehicle frame, and the valve mechanism is operated by connecting the valve mechanism to the drive means using the connecting member. The connecting member is close to the silencer, and is caused to run alongside a member extending out from the vehicle frame so that it reaches the side of the vehicle frame. Therefore, a member for supporting the connecting member is omitted and the number of components is reduced.




Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.











BRIEF DESCRIPTION OF THE DRAWINGS




The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:





FIG. 1

is a side view of a motorcycle to which an engine exhaust assembly of a first embodiment of the present invention is attached;





FIG. 2

is a side view of the engine exhaust assembly of a first embodiment of the present invention;





FIG. 3

is front cross sectional view of a silencer of the engine exhaust assembly of the first embodiment of the present invention;





FIG. 4

is a drawing looking in the direction of arrows


4





4


in

FIG. 3

;





FIG. 5

is a side view of a valve mechanism of the engine exhaust assembly of the first embodiment of the present invention;





FIG. 6

is a drawing for describing the operation of the engine exhaust assembly of the first embodiment of the present invention;





FIG. 7

is a side view of the engine exhaust assembly of a second embodiment of the present invention;





FIG. 8

is a schematic drawing of drive means of a separate embodiment to the engine exhaust assemblies of the first and second embodiments of the present invention.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Embodiments of the present invention will now be described with reference to the accompanying drawings. The directions front, rear, left, right, up and down refer to directions as viewed from the point of view of the rider, while Fr represents front side, Rr represents rear side, L represents left side and R represents right side.





FIG. 1

is a side view of a motorcycle to which an engine exhaust assembly of a first embodiment of the present invention is attached. The motorcycle


1


comprises a vehicle frame


2


, a front fork


4


to which a head pipe


3


of the vehicle frame


2


is attached, a front wheel


5


attached to the front fork


4


, a handlebar


6


connected to the front fork


4


, a fuel tank


7


attached so as to straddle an upper front section of the vehicle frame


2


, a seat


8


attached to an upper rear section of the vehicle frame


2


, a power unit


9


(a structure comprising a combination of an engine


11


to the front and a transmission


12


to the rear) attached to a lower front section of the vehicle frame


2


, a swing arm


13


attached to a lower rear section of the vehicle frame


2


, rear suspension


14


suspended between a midpoint of the swing arm


13


and the vehicle frame


2


, a rear wheel


15


attached to a rear end of the swing arm


13


, and an exhaust assembly


40


as an engine exhaust assembly or a motorcycle exhaust assembly extending from the engine


11


to the rear of the vehicle frame


2


.




Reference numeral


24


is a carburetor, reference numeral


25


is a step holder, reference numeral


26


is step holder stay close to the carburetor


26


and extending out from the vehicle frame, reference numeral


27


is a exhaust pipe, reference numeral


28


is a muffler stay close to the silencer and extending out from the vehicle frame, reference numeral


31


is a headlamp, reference numeral


32


is a mirror, reference numeral


33


is a radiator, reference numerals


34


,


34


are seat rails, reference numeral


37


is a drive chain, reference numeral


38


is a cowl stay, and reference numeral


39


is a main stand.




Specifically, the motorcycle


1


is a full cowling type motorcycle having a good external appearance, provided with an upper cowl


17


covering an upper front section of the vehicle frame, a windscreen


18


attached to an upper part of the upper cowl


17


, a side cowl


19


covering a side section of the vehicle frame


2


, a seat cowl


21


covering below a seat


8


to the rear of the vehicle frame


2


, a front mudguard


22


covering the top of the front wheel


5


, and a rear mudguard


23


covering the rear and top of the rear wheel


15


.





FIG. 2

is a side view of the engine exhaust assembly of a first embodiment of the present invention. The exhaust assembly


40


in an exhaust assembly of an engine


11


, has a partitioning member


77


(described later) provided in a pipe


63


of a silencer


42


for dividing the pipe


63


into at least two exhaust passageways


75


,


76


(described later), and provided with a valve mechanism


64


for causing variation in a surface area of one of the exhaust passages


75


and


76


. For example, when the engine


11


is rotating at low revs, by closing the valve mechanism


64


and discharging exhaust gas from the exhaust passageway


75


,


76


without the valve mechanism


64


, the exhaust noise when the engine is rotating at low revs can be reduced. Furthermore, drive means


41


is attached to the side of the vehicle frame


2


, the silencer


42


is attached to the end of the exhaust pipe


27


, and a connecting member


43


for joining the valve mechanism


64


of the silencer


42


to the drive means


41


is also provided.




In more detail, the drive means


41


is joined to one side of a diaphragm


44


by the connecting member


43


, and is connected at the other end to a throttle valve chamber


24


a of carburetor


24


through a bypass controller


45


and a check valve


46


. The drive means drives the diaphragm by applying negative pressure of the throttle valve chamber


24


a to the other end of the diaphragm


44


. Reference numeral


47




a


is an air hose joining the diaphragm


44


and bypass controller


45


, reference numeral


47




b


is an air hose joining the bypass controller and the check valve


46


, and reference numeral


47




c


is an air hose joining the check valve


46


and the throttle valve chamber


24




a.






The bypass controller


45


controls the amount of negative pressure applied from the throttle valve chamber


24




a


to the diaphragm


44


using information from a spark unit (ignition coil)


48


, and causes a reduction in negative pressure bypass amount when the engine


11


(refer to

FIG. 1

) is rotating at low revs and increases the amount of negative pressure applied to the diaphragm


44


, but causes an increase in bypass amount when the engine


1


is rotating at high revs to reduce the amount of negative pressure applied to the diaphragm


44


.




The check valve


46


is a valve for setting the amount of negative pressure to be applied from the throttle valve chamber


24




a


to the diaphragm


44


in a predetermined range. The drive means


41


uses negative pressure of the throttle valve chamber


24




a


as a drive source, enabling the exhaust assembly


40


to have a simple structure.




The silencer


42


will now be described in detail with reference to FIG.


3


.

FIG. 3

is front cross sectional view of a silencer of the engine exhaust assembly of the first embodiment of the present invention. The silencer


42


has an attenuation wall


52


, a front partitioning wall


53


, a rear partitioning wall


54


and an outlet wall


55


attached in that order from an inlet side inside an inner wall tube


51


. A first expansion chamber


56


is formed by the attenuation wall


52


, the front partitioning wall


53


and the inner wall tube


51


. A second expansion chamber


57


is formed by the front partitioning wall


53


, the rear partitioning wall


54


and the inner wall tube


51


. A third expansion chamber


58


is formed by the rear partitioning wall


54


the outlet wall


55


and the inner wall tube


51


. The first expansion chamber


56


and the third expansion chamber


58


are joined by an exhaust inlet pipe


61


. The third expansion chamber


58


and the expansion chamber


57


are joined by a connecting pipe


62


. Furthermore, the second expansion chamber


57


is released to the outside through a connecting pipe


63


. A switching unit


59


is attached to an exhaust side of the connecting pipe


63


via a gasket


63




a


. An extension pipe


66


and a connecting pipe


67


are attached in that order to the outside of the inlet side of the inner wall tube


51


via an intermediary pipe


65


. Furthermore, a tail cover


68


is attached to a circular section


55




a


of the outlet wall


55


. The inner wall tube


51


is covered by an outer wall pipe


69


, and a heat insulating material


71


is interposed between the outer wall pipe


69


and the inner wall tube


51


. Also, a guide pipe


73


is passed through a tapered section


66




a


of the extension pipe


66


, the attenuation wall


52


, the front partitioning wall


53


, the rear partitioning wall


54


and the outlet wall


55


, as a pipe for guiding the connecting member


43


.




The outer wall pipe


69


is provided with a support stay


69




a


for attaching the silencer


42


to a muffler stay


28


(refer to FIG.


1


), and the attenuation wall


52


is provided with a plurality of holes


52




a


in a plate.




The connecting member


43


is for connecting the valve mechanism


64


to the diaphragm


44


, as shown in FIG.


2


. One end of the connecting member is provided with a link holder (see

FIG. 3

) for connecting to the valve mechanism


64


. The connecting member


43


is passed through the guide pipe


73


and the other end runs along a step holder stay


26


and is drawn into the side of the vehicle frame


2


.




In other words, the exhaust assembly


40


shown in

FIG. 2

has an intermediate section of the connecting member


43


housed in a guide pipe


73


provided inside the silencer


42


, and runs along a step holder stay


26


(refer to

FIG. 2

) as a member close to the silencer


42


and extending out from the vehicle frame


2


. The connecting member


43


can be hidden from outside of the silencer


42


, thus improving the external appearance of the exhaust assembly.




Description will now be provided of a switching unit


59


to which the silencer


42


is attached with reference to

FIGS. 4 and 5

.

FIG. 4

is a view in the direction of arrows


4





4


in

FIG. 3

, and illustrates a rear view of the switching unit


59


.

FIG. 5

is a side cross sectional view of a switching unit


59


of the engine exhaust assembly of the first embodiment of the present invention.




The switching unit


59


causes variation in the opening area of the connecting pipe


63


, and is a mechanism for varying the flow amount of exhaust gas. Specifically, a joint pipe


81


is attached to a support plate


78


, a partitioning member


77


is attached to the joint pipe


81


, first and second exhaust passageways


75


and


76


are partitioned off as exhaust passageways, and the valve mechanism


64


is attached to the joint pipe


81


.




The valve mechanism


64


has a support platform


79


attached to the joint pipe


81


, a shaft member


82


is rotatably attached to this support platform


79


, a lever


83


for connecting to a connecting holder


74


is attached to one end of the shaft member


82


, an opening and closing member


84


is attached to a central section of the shaft member


82


, and a return unit


85


for returning the opening and closing member


84


to its initial state is attached to the other end of the shaft member


82


.




In more detail, the return unit


85


comprises a fixed receiving section


85




a


attached to the support platform


79


side, a rotating receiving section


85




b


attached to the shaft member


83


side, and a return spring


86


wound over and between the receiving sections


85




a


and


85




b.






Reference numerals


87


represent bolts attaching the support plate


78


to the outlet wall


55


, reference numeral


88


represents a screw for attaching the opening and closing plate


84


to a central section of the shaft member


83


, and reference numeral


89


represents a nut holding the shaft member


83


on the support platform


79


.




That is, the switching unit


59


is removably attached to the connecting pipe


63


, which means that maintenance of the valve mechanism


64


is made easy, and it becomes possible to use the same structure for various mechanisms. Also, by using the same structure for various mechanisms, it is possible to reduce the mass production costs.




Next, the operation of the exhaust assembly


40


described above will be described.




FIG.


6


(


a


) and FIG.


6


(


b


) are drawings for describing the operation of the engine exhaust assembly of the first embodiment of the present invention.




In FIG.


6


(


a


), when the engine is rotating at low revs, the bypass amount of negative pressure is reduced by the bypass controller


45


, and the amount of negative pressure applied to the diaphragm


44


is increased to pull the connecting member


43


. The opening and closing plate


84


of the valve mechanism


64


is then closed and the first exhaust passageway


75


is blocked off Exhaust gas is discharged from the exhaust passageway


76


to the outside, as shown by the allows labeled {circle around (1)}.




When the engine is rotating at low revs, there is also less exhaust gas, which means that it is possible to sufficiently discharge exhaust gas with only the second exhaust passageway


76


open. Since the first exhaust passageway


75


is blocked off when the engine is at low revs, it is possible to reduce the exhaust noise.




In FIG.


6


(


b


), when the engine is rotating at high revs, the bypass amount of negative pressure is increased by the bypass controller


45


, and the amount of negative pressure applied to the diaphragm


44


is reduced to slacken the connecting member


43


. The opening and closing plate


84


of the valve mechanism


64


is then open and the first exhaust passageway


75


is released. Exhaust gas is discharged from the first exhaust passageway


75


, as shown by the arrows labeled {circle around (2)} and from the second exhaust passageway


76


, as shown by the arrows labeled {circle around (3)} to the outside.




Specifically, when the engine is rotating at high revs, the first exhaust passageway


75


is released, and exhaust gas is discharged from the first and second exhaust passageways


75


and


76


so as not to oppose the engine.





FIG. 7

is a side view of the engine exhaust assembly of a second embodiment of the present invention, and shows an example of a modification to the engine exhaust assembly. Parts that are the same as those in the first embodiment have the same reference numerals, and detailed description will therefore be omitted.




The exhaust assembly


90


, as an engine exhaust assembly or motorcycle exhaust assembly, comprises drive means


41


attached to the side of the vehicle frame


2


, a silencer


92


attached to the end of an exhaust pipe


27


, and a connecting member


95


for linking the valve mechanism


64


of the silencer


92


to the drive means


41


.




The silencer


92


has substantially the same structure as the silencer


42


of the exhaust assembly


40


shown in

FIG. 2

, but a guide pipe


93


is made of a curved pipe, a tip end of the pipe


93


protrudes from a middle section of an outer wall pipe


94


, and the connecting member


95


engages with the vehicle frame


2


side drive means


41


, via a muffler stay


28


close to the silencer


92


and extending out from the vehicle frame


2


.





FIG. 8

is a schematic drawing of drive means of a separate embodiment to the engine exhaust assemblies of the first and second embodiments of the present invention, and shows drive means


96


. Parts that are the same as the drive means


41


of the first embodiment have the same reference numerals and detailed description will therefore be omitted.




Compared to the case where the drive means


41


shown in

FIG. 2

uses a mechanical drive source, making use of the negative pressure of the throttle valve chamber


24




a


, the drive means


96


uses an electrical drive source and has a connecting member


43


linked to the valve mechanism wound around a pulley


97


, a motor


98


for driving the pulley


97


, and a controller


99


for controlling the motor


98


using information from a spark unit (ignition coil)


48


.




Specifically, the drive means


96


is capable of fine control of the valve mechanism


64


according to the speed of rotation of the engine, because the valve mechanism


64


is driven by the motor


98


and the motor is controlled by a controller


99


.




In the embodiments, description has been given for a motorcycle exhaust assembly, but the present invention is not particularly limited to a motorcycle exhaust assembly and can also apply to an engine exhaust assembly.




The connecting member


43


shown in the accompanying drawings can be a wire, a rod, a cable or a wire spring, etc., or any combination of these.




As shown in FIG.


2


and

FIG. 7

, as a member extending out from the vehicle frame


2


, a step holder stay


26


is shown in the first embodiment and a muffler stay


28


is shown in the second embodiment. However, this member is not limited to these components, and any member that extends outward from the vehicle frame


2


can be used.




With the above described structure, the present invention enables the following effects.




In the first embodiment, for example, when the engine is rotating at low revs, the valve mechanism is closed, so that exhaust gas is discharged from the exhaust passageway without the valve mechanism. However, when the engine is rotating at high revs the valve mechanism is open so exhaust gas is discharged simultaneously from the exhaust passageway without the valve mechanism and the exhaust passageway provided with the valve mechanism. Therefore, exhaust noise when the engine is rotating at low revs can be reduced.




Also, by dividing one connecting pipe with a partitioning member and providing a valve mechanism in one of the exhaust passageways formed by the dividing member, the structure of the exhaust assembly can be simplified.




In the second embodiment, the valve mechanism is fitted into the connecting pipe of the silencer, one end of a connecting member is connected to this valve mechanism, and the other end of the connecting member is connected to drive means arranged outside the silencer. When the valve mechanism is driven by the drive means, since a pipe is fitted to the silencer and part of the connecting member is housed in the pipe, the connecting member can be hidden from the outside of the silencer and the external appearance of the exhaust assembly can be improved.




In the above embodiments, in a motorcycle exhaust assembly having an engine arranged substantially in the center of a vehicle frame of the motorcycle, with an exhaust pipe extending rearwards from the engine, a silencer connected to the exhaust pipe and a valve mechanism for varying the exhaust flow amount being provided in a connection pipe of the silencer, the valve mechanism being connected to drive means provided on the side of a vehicle frame via a connecting member, the connecting member is close to the silencer, and is caused to run alongside a member extending out from the vehicle frame, so that it reaches the side of the vehicle frame, which means that, for example, a member for supporting the connecting member can be omitted. Specifically, the number of components of the motorcycle exhaust system can be reduced, bringing about cost reduction as well as making it possible to reduce the weight of the motorcycle.




The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.



Claims
  • 1. An engine exhaust assembly comprising:a valve mechanism for varying opening areas of a connecting pipe of a silencer arranged in the engine exhaust assembly; a connecting member passing through the silencer, said connecting member having a one end connected to the valve mechanism another end of the connecting member connectable to drive means arranged outside the silencer to allow the valve mechanism to be driven by the drive means; and wherein the pipe of the silencer includes a connecting pipe and a joint pipe attached to an end of the connecting pipe, and a partitioning member attached to the joint pipe, said valve mechanism being attached to the joint pipe.
  • 2. The engine exhaust assembly according to claim 1, further comprising:a diaphragm located between the drive means and the connecting member; said drive means connectable to a throttle valve chamber of a carburetor through a bypass controller and a check valve; and wherein the drive means drives the diaphragm by applying negative pressure from the throttle valve chamber thereto, said bypass controller controls the amount of negative pressure applied from the throttle valve chamber, and said check valve sets the amount of negative pressure to be applied from the throttle valve chamber within a predetermined range.
  • 3. The engine exhaust assembly according to claim 1, wherein said valve mechanism includes a support platform attached to the joint pipe, a shaft member rotatably attached to the support platform, a lever for connecting to a connecting holder attached to one end of the shaft member, an opening and closing member attached to a central section of the shaft member, and a return unit for returning the opening and closing member to an initial state attached to another end of the shaft member.
  • 4. The engine exhaust assembly according to claim 1, said drive means further comprising:a pulley, said connecting member being wound around the pulley; a motor for driving the pulley; and a controller for controlling the motor, wherein the valve mechanism is controlled to vary the surface area of said one of the exhaust passages.
  • 5. A motorcycle exhaust assembly comprising:an engine arranged substantially in a center of a vehicle frame of the motorcycle; an exhaust pipe extending rearwards from the engine; a silencer connected to the exhaust pipe; a valve mechanism provided in a connection pipe of the silencer; a connecting member, one end of said connecting member being connected to the valve assembly, the other end of the connecting member being connected to drive means provided on a side of a vehicle frame, and the valve mechanism being driven by the drive means; and wherein a central portion of the connecting member is located close to the silencer, said connecting member extending alongside a member extending out from the vehicle frame.
  • 6. The motorcycle exhaust assembly according to claim 5, wherein said member is a muffler stay.
  • 7. The motorcycle exhaust assembly according to claim 5, wherein said member is a step holder stay.
  • 8. An engine exhaust assembly, comprising:a valve mechanism for varying opening areas of a connecting pipe of a silencer arranged in the engine exhaust assembly, said valve mechanism closing an exhaust passage in a low revolution operating state; a connecting member passing through the silencer, said connecting member having a one end connectable to the valve mechanism and another end of the connecting member connectable to drive means arranged outside the silencer to allow the drive means to drive the valve mechanism; and wherein said drive means further comprises a pulley, said connecting member being wound around the pulley; a motor for driving the pulley; and a controller for controlling the motor, wherein the valve mechanism is controlled to vary the surface area of an exhaust passage between a closed position and a open position.
Priority Claims (1)
Number Date Country Kind
11-014903 Jan 1999 JP
US Referenced Citations (5)
Number Name Date Kind
3523418 Marsee Aug 1970 A
3751921 Blomberg et al. Aug 1973 A
4785626 Shiraishi Nov 1988 A
4795420 Sakurai et al. Jan 1989 A
6220907 Shimizu Apr 2001 B1
Foreign Referenced Citations (2)
Number Date Country
U222617 Feb 1990 JP
A10238334 Sep 1998 JP