CN101619667B

CN101619667B - Motorcycle

Info

Publication number: CN101619667B
Application number: CN2009101587125A
Authority: CN
Inventors: 味户智史
Original assignee: Yamaha Motor Co Ltd
Current assignee: Yamaha Motor Co Ltd
Priority date: 2008-07-03
Filing date: 2009-07-03
Publication date: 2012-08-08
Anticipated expiration: 2029-07-03
Also published as: CN101619667A; ES2373260T3; BRPI0902022B1; ATE524642T1; EP2141330A1; BRPI0902022A2; EP2141330B1; JP2010031852A

Abstract

An exhaust pipe into which an exhaust gas from a single cylinder engine flows is provided with a three way catalyst. The exhaust pipe includes a first pipe inserted into a muffler and a second pipe extending toward the downstream side from the first pipe within the muffler. A narrowed portion having an inner diameter smaller than that of a cylindrical portion of the first pipe is provided in a downstream-end opening of the first pipe. The narrowed portion is inserted into an upstream-end opening of the second pipe. A first expansion chamber that integrally encloses the outer periphery and the downstream-end opening of the second pipe is formed within the muffler. A plurality of holes are formed in a distributed manner in a region, except a downstream region, of a peripheral surface of the second pipe. The length in the axial direction of the downstream region is not less than 1/3 times the inner diameter of the second pipe.

Description

Motorcycle

Technical field

The present invention relates to comprise the motorcycle of venting gas appliance.

Background technique

Traditionally, for the exhaust sound that the exhaust emissions that reduces owing to the motor of automobile causes, various bafflers (for example, referring to JP 60-37287B) have been developed.

Disclosed baffler has perforated pipe and urceolus in JP 60-37287B.Perforated pipe is inserted in the urceolus.Resonant chamber is formed between the inner peripheral surface of outer circumferential face and urceolus of perforated pipe.Expansion chamber is formed on the downstream side of urceolus interior resonance chamber.Resonant chamber and expansion chamber are separated plate separately.The inner space of perforated plate is communicated with resonant chamber through the hole of perforated pipe.In addition, the downstream of perforated pipe is at the expansion chamber inner opening.

The end in the downstream side of outlet pipe narrows down to form small diameter portion.The end of outlet pipe is assemblied in the perforated pipe.The exhaust of discharging from outlet pipe is incorporated into the expansion chamber through perforated pipe, and further is incorporated in the atmosphere through tail pipe.At this moment, exhaust sound reduces through the effect of resonant chamber and expansion chamber.

Simultaneously, baffler also is arranged in the motorcycle.The baffler that requirement is used in motorcycle reduces the exhaust sound that causes owing to the high pressure-temperature exhaust emissions.In addition, the rotational speed of the motor of motorcycle is elevated to 8000rpm at least.Thereby through regulating the extraction flow from engine emission, the baffler that requires in motorcycle, to use brings the engine performance of expectation.

Under the situation of multicylinder engine, a plurality of outlet pipes communicate with each other, and make that the pressure surge in each outlet pipe is absorbed by other outlet pipe.Thereby the pressure surge in each outlet pipe is smaller.On the contrary, under the situation of single-cylinder engine, the pressure surge in the outlet pipe is bigger.

In recent years, also developed vent systems and be provided with catalyzer with motorcycle for purifying exhaust gas.In the case, the temperature of exhaust is raise by catalyzer.This causes velocity of sound to raise, and causes the high fdrequency component of exhaust sound to increase.As a result, when adopting catalyzer in the vent systems at single-cylinder engine, produce the metal exhaust sound that comprises high fdrequency component.

In addition, for motorcycle,, require baffler more carefully shorter than the baffler in the automobile from spatial limitation.

When adopting the muffler structure of automobile in the motorcycle with catalyzer, can not under the situation of the size that does not increase baffler, reduce the high fdrequency component of exhaust sound fully.

Special in comprising the motorcycle of single-cylinder engine, expectation small size baffler brings the output performance of motor fully in the synchronous low exhaust sound of the burning of acquisition and motor.

Summary of the invention

The purpose of this invention is to provide a kind of motorcycle, wherein, in the high fdrequency component that fully reduces exhaust sound, fully bring the output performance of motor.

(1) according to an aspect of the present invention, motorcycle comprises: vehicle body; Single-cylinder engine, it is arranged in the vehicle body; Outlet pipe is in the exhaust inflow outlet pipe from motor; Catalyzer, it is arranged in the outlet pipe; And baffler, it will be discharged to the outside from what outlet pipe flowed out, and wherein, outlet pipe comprises: first pipe, it has the downstream-end opening that is inserted in the baffler; And second the pipe; It has upstream-end opening and downstream-end opening, and in baffler, manages downstream side from first and extend, and in the downstream-end opening of said first pipe narrow is set; It has the little internal diameter of internal diameter than first pipe; And be inserted in the upstream-end opening of second pipe, in said baffler, forming first expansion chamber, it surrounds the periphery and the said downstream-end opening of said second pipe integratedly; And a plurality of holes are formed on the mode of disperseing in the side face of said second pipe in the zone except the downstream zone, and said downstream zone is 1/3 times of said second internal diameter of managing at least along the length of axial direction.

In motorcycle, flow in the outlet pipe from the exhaust that is arranged on the single-cylinder engine in the vehicle body.At this moment, exhaust is purified by catalyzer when getting into the condition of high temperature.This causes velocity of sound to raise, and makes the high fdrequency component of exhaust sound increase.

High-temperature exhaust air flows out first expansion chamber that enters into baffler via the pipe of first in the outlet pipe and second pipe.At this moment, exhaust is pressed into second pipe in by the narrow compression of first pipe, make exhaust pressure (pressure of exhaust) increase.This has prevented that unburned mixed gas from flowing out at the overlapping period of motor.As a result, this has improved the torque of engine producing in low-speed region and the intermediate speed region.

In the case, a part of exhaust in second pipe is expanded through going out to enter into first expansion chamber via orifice flow.In addition, all the other exhausts are expanded through entering into first expansion chamber from the downstream-end opening outflow in second pipe.In the case, first expansion chamber surrounds the periphery and the downstream-end opening of second pipe integratedly and continuously.

A plurality of holes are formed in the side face of second pipe in the zone except the downstream zone.The downstream zone is at least 1/3 times of internal diameter of second pipe along the length setting of axial direction.Thereby the pressure surge that goes out the exhaust that pressure surge and the downstream-end opening from second pipe of the exhaust of second pipe flow out through orifice flow has the different high fdrequency component of phase place respectively.Thereby the high fdrequency component that phase place is different cancels each other out.As a result, the high fdrequency component of exhaust sound is reduced.

In addition, progressively expanded in second pipe and first expansion chamber by the outlet pipe of the narrow compression of first pipe.This makes because the pressure surge that the rapid expanding of exhaust produces is alleviated.As a result, suppressed the generation of the sound that pressure surge causes.

In addition, first expansion chamber surrounds the periphery and the downstream-end opening of second pipe integratedly in baffler.Thereby, can guarantee as the volume of first expansion chamber of same pressure space enough big.As a result, can under the situation of length that does not increase baffler and cross sectional area, reduce the high fdrequency component of exhaust sound fully.

These results bring the output performance of single-cylinder engine fully when being illustrated in the high fdrequency component of abundant reduction exhaust sound.

(2) second pipes can be at engagement position first pipe of the upstream side of narrow.

In the case, second pipe state with cantilever under the situation of not using supporting member is fixed to first pipe reliably.This is avoided producing the vibration and the swing of second pipe.As a result, prevented to produce sound owing to the vibration and the swing of second pipe.

(3) narrow can comprise the tapered portion with the internal diameter that reduces gradually.In the case, can prevent to produce hydrodynamic noise owing to the interference of flowing of exhaust.

(4) second expansion chambers can also be formed on the downstream side of said first expansion chamber in the said baffler, and said first expansion chamber and said second expansion chamber can be separated plate separately, and connecting tube can be set to pass said demarcation strip.

In the case, progressively expanded in second pipe, first expansion chamber and second expansion chamber by the exhaust of the narrow compression of first pipe.This causes the pressure surge that produces owing to the exhaust rapid expanding to be alleviated effectively.As a result, fully suppress owing to pressure surge produces sound.

The volume of (5) first expansion chambers can be greater than the volume of said second expansion chamber.In the case, first expansion chamber surrounds the periphery and the downstream-end opening of second pipe integratedly.Thereby, can under the situation of length that does not increase baffler and diameter, make the volume of the volume of first expansion chamber greater than second expansion chamber.Thereby, in first expansion chamber, can reduce the high fdrequency component of exhaust sound effectively.

(6) in outlet pipe, said first pipe can remain in the said baffler, and said second pipe can not remain in the said baffler.

In the case, there is not supporting member, makes that flowing of the exhaust that goes out from a plurality of orifice flows of second pipe is interference-free at the outer circumferential side of second pipe.This can prevent to produce hydrodynamic noise owing to the interference of flowing of exhaust.

According to the present invention, in the high fdrequency component that reduces exhaust sound fully, bring the output performance of motor fully.

Description of drawings

With reference to the description of accompanying drawing to the embodiment of the invention, other characteristics of the present invention, element, characteristic and advantage will become more obvious from following, in the accompanying drawing:

Fig. 1 is the side view according to the motorcycle of the embodiment of the invention;

Fig. 2 is the stereogram of outward appearance of venting gas appliance of looking from the top;

Fig. 3 is from the look stereogram of outward appearance of venting gas appliance of side direction;

Fig. 4 is the viewgraph of cross-section that the line IV-IV of the baffler in Fig. 2 is got;

Fig. 5 is the amplification cross sectional view of outlet pipe shown in Figure 4;

Fig. 6 is the viewgraph of cross-section of the baffler in the comparative example 1;

Fig. 7 is the measurement result separately that the damping characteristic of baffler and the baffler in the comparative example 1 in the example of the present invention is shown; And

Fig. 8 is the viewgraph of cross-section of the baffler in the comparative example 2.

Embodiment

With reference to accompanying drawing, with embodiment of the invention will be described with reference to drawings.In the following description, be benchmark definition upstream side and downstream side with flowing of exhaust.

(1) structure of motorcycle.

Fig. 1 is the side view according to the motorcycle of the embodiment of the invention.

Motorcycle 100 shown in Figure 1 comprises the vehicle body of being made up of body shell and framework cover 80.Head pipe (not shown) is arranged on the front portion of vehicle body 80, and handgrip 81 is arranged on the upper end of head pipe.Front fork 82 is installed the lower end of pipe to the end.Under this state, front fork 82 can the axis with the head pipe be the center rotation in predetermined angular range.Front-wheel 83 rotatably is supported on the lower end of front fork 82.Trailing wheel 84 rotatably is supported on the rear portion of vehicle body 80.Single-cylinder engine 50 is arranged on the center of vehicle body 80.Trailing wheel 84 rotates through the rotating force of motor 50.

Exhaust is incorporated into the cylinder head 51 that outside venting gas appliance 10 is connected to motor 50.Venting gas appliance 10 comprises outlet pipe 20 and baffler (silencing apparatus) 30.Outlet pipe 20 extends back from the cylinder head 51 of motor 50.Baffler 30 extends from the downstream of outlet pipe 20 towards a side of trailing wheel 84.

(2) structure of venting gas appliance 10

Fig. 2 is the three-dimensional view of outward appearance of venting gas appliance 10 of looking from the top.Fig. 3 is from the look three-dimensional view of outward appearance of venting gas appliance 10 of side direction.

Relief opening connector 22 is arranged on the upstream extremity of outlet pipe 20.The opening of the upstream side of outlet pipe 20 is connected to the relief opening of the cylinder head 51 of motor shown in Figure 1 50 through relief opening connector 22.The downstream 24 of outlet pipe 20 is inserted into the upstream extremity (inlet) of baffler 30.The periphery member for mount 26 at the upstream extremity place of baffler 30 is fastening, makes baffler 30 be fixed to outlet pipe 20.

The downstream 24 of outlet pipe 20 is connected to the upstream extremity of the outlet pipe 40 in the baffler 30.Three-way catalyst 90 is arranged in the outlet pipe 40.Notice that outlet pipe 20 can form with outlet pipe 40.Alternatively, outlet pipe 20 can be connected to each other through another member with outlet pipe 40.Lid 31a and 31b are installed to the outer circumferential face of baffler 30.

The exhaust that is produced in motor shown in Figure 1 50 internal combustion by air is fed in the baffler 30 through outlet pipe 20.Exhaust is discharged in the atmosphere through baffler 30.Thereby the exhaust pathway of motor 50 comprises relief opening, outlet pipe 20 and the baffler 30 of cylinder head 51 in order from the upstream side to the downstream side.

Baffler 30 has the silencing function that is used for before will being discharged to atmosphere, reducing exhaust sound.The structure of the multistage expansion type of stating after in the present embodiment, the inboard of baffler 30 has.That is, the inboard of baffler 30 is separated into a plurality of expansion chambers, makes exhaust expand through a plurality of expansion chambers of flowing through.This causes exhaust decompression.

(3) internal structure of baffler 30

The internal structure of baffler 30 is described with reference to Fig. 4 then.Fig. 4 is the viewgraph of cross-section that the line IV-IV along baffler shown in Figure 2 30 is got.Fig. 5 is the amplification cross sectional view of outlet pipe 40 shown in Figure 4.

As shown in Figure 4, baffler 30 comprises conical head 32, hollow tube-shape body 34 and bowl-shape afterbody 37.Head 32 is assemblied in the opening of upstream side of cylinder 34.In outside 37 openings that are assemblied on the downstream side of cylinder 34.

Near the position of the downstream of cylinder 34 from upstream side arranged in sequence demarcation strip 36 and 38.Thereby the inner space of baffler 30 is separated into first expansion chamber 70, second expansion chamber 72 and the 3rd expansion chamber 74.First expansion chamber 70, second expansion chamber 72 and the 3rd expansion chamber 74 are arranged from the upstream side to the downstream side along the longitudinal direction of baffler 30 in order.

Connecting tube 62 passes demarcation strip 36, and connecting tube 64 passes demarcation strip 38, and tail pipe 66 passes afterbody 37.

Outlet pipe 40 inserts in the head 32.The downstream part of outlet pipe 40 extends in first expansion chamber 70.Exhaust is incorporated in first expansion chamber 70 through outlet pipe 40.

Outlet pipe 40 comprises first pipe 42 of upstream side and cylindrical shape second pipe 44 in downstream side.First pipe 42 has the cylindrical portions may 46 of upstream side and the narrow 47 in downstream side.Narrow 47 has tapered portion 48a and small diameter portion 48b.Small diameter portion 48b has respectively less than the external diameter of cylindrical portions may 46 and the external diameter and the internal diameter of internal diameter.The external diameter of tapered portion 48a and internal diameter external diameter and the internal diameter from the external diameter of the external diameter that equals cylindrical portions may 46 and internal diameter and internal diameter towards external diameter that equals small diameter portion 48b and internal diameter gradually reduce.Thereby, the cross sectional area of the stream of narrow 47 gradually from upstream side downstream side reduce.

The internal diameter R2 of second pipe 44 equals the external diameter of the cylindrical portions may 46 of first pipe 42.The narrow 47 of first pipe 42 is inserted in the upstream-end opening of first pipe 42, makes that the upstream extremity of second pipe 44 is overlapping in the position and the cylindrical portions may 46 in the downstream side of the narrow 47 of first pipe 42.Under this state, the inner peripheral surface welding of the outer circumferential face of the column part 46 of first pipe 42 and second pipe 44 makes second pipe 44 join cylindrical portions may 46 to.Thereby second pipe 44 remains under the state of cantilever in first pipe 42.In addition, between second pipe 44 the inner peripheral surface and narrow 47, form cylindric gap.Tapered portion 48a is at second pipe, 44 inner openings.

First pipe 42 is installed to the inner face of head 32 through supporting bar 35, to be positioned at the center of head 32 and cylinder 34.

The internal diameter R0 of the small diameter portion 48b of narrow 47 is less than the internal diameter R1 of cylindrical portions may 46 (R0＜R1).Second pipe, 44 internal diameter R2 is greater than the internal diameter R0 of the small diameter portion 48b of narrow 47, and less than the internal diameter R3 of first expansion chamber 70 (R0＜R2＜R3).This can alleviate the pressure surge that forms owing to the rapid expanding that flows into the exhaust of first expansion chamber 70 from first pipe 42.

In the case, preferably, second pipe, 44 internal diameter R2 is not too near the internal diameter R3 of expansion chamber 70, and not too near the internal diameter R0 of small diameter portion 48b.This can alleviate the rapid expanding of exhaust and the pressure surge that causes fully by second pipe 44.

Preferably, the internal diameter R2 of second pipe 44 is approximately equal to the cylindrical portions may 46 large diameter R1 of first pipe 42.In the present embodiment, the internal diameter R2 of second pipe 44 equals the external diameter of the cylindrical portions may 46 of first pipe 42.Thereby the internal diameter R2 of second pipe 44 is approximately equal to the internal diameter R1 of first pipe, 42 road cylindrical portions may 46.This fluctuation that can effectively ease off the pressure.

Note, do not receive concrete restriction, and be confirmed as and make the low frequency component of exhaust sound not disappear from the length L of the downstream-end opening 43 of downstream-end opening 49 to second pipes 44 of narrow 47, and guarantee under cantilever position, to keep second manage 44 length.

As shown in Figure 5, second pipe 44 comprises upstream region RU that a plurality of holes 45 are set and the downstream area RD that the hole is not set in fact in order towards the downstream side.A plurality of holes 45 are spaced apart in upstream region RU moderate distance.A plurality of holes 45 for example are punching hole.A plurality of holes 45 pass through to inner circumferential surface from the outer circumferential face of second pipe 44.In the present embodiment, the shape in each hole 45 is circular.

Downstream area RD has the length D from second pipe, 44 downstream-end opening 43 towards upstream side.The length of downstream area RD is at least 1/3 times of second pipe, 44 internal diameter R2.

Downstream area RD can be provided with one or more hole, with 1/3rd opening rate of opening rate with upstream region RU at the most.The opening rate meaning of upstream region RU is the opening area summation in a plurality of holes 45 and the ratio of the area of upstream region RU.The opening rate of the downstream area RD meaning is the ratio of summation and the area of downstream area RD of the opening area in one or more hole.In the case, one or more hole that is arranged among the downstream area RD influences the effect that reduces high fdrequency component hardly, and this will be described below.Thereby downstream area RD is provided with one or more hole and means with 1/3rd the such situation of opening rate of opening rate with upstream region RU at the most the hole is not set in fact in downstream area RD.

Although the ratio of the cross sectional area of the summation of the opening area in a plurality of holes 45 and second pipe, 44 stream (below be called a plurality of holes 45 area than) does not receive concrete restriction, preferably, the area in a plurality of holes 45 is than at least 0.5, at the most 2.0, for example, approximate 1.0.

Notice that internal diameter and the distance between the hole 45 (distance between the center of adjacent holes 45) that can regulate each hole 45 as required make that can obtain the above sound satisfactorily reduces effect.In the case, can select the internal diameter in each hole 45 and the distance between the hole 45 to reduce effect in the sound-inhibiting loss, to obtain sound effectively.

(4) operation of venting gas appliance 10

Operation according to the venting gas appliance 10 of present embodiment then will be described.

Exhaust from the relief opening of motor shown in Figure 1 50 is incorporated in the outlet pipe 40 through Fig. 2 and outlet pipe 20 shown in Figure 3.At this moment, exhaust is purified by three-way catalyst 90 when getting into the condition of high temperature.This causes velocity of sound to raise, and causes the high fdrequency component of exhaust sound to increase.

High-temperature exhaust air flows out first expansion chamber 70 that enters into baffler 30 via first pipe, 42 and second pipe 44 of outlet pipe 40.At this moment, exhaust is extruded in second pipe 44 in by narrow 47 compressions of first pipe 42, makes exhaust pressure (pressure of exhaust) increase.This has prevented that the mixed gas of combustion does not flow out at the overlapping period (period that suction valve and outlet valve are all opened) of motor 50.As a result, this has improved the torque that the motor 50 in low-speed region and the intermediate speed region produces.

Being entered into second pipe 44 by the short exhaust of narrow 47 compressions through outflow expands.As shown in Figure 5, expand through flowing out in first expansion chamber 70 as the exhaust E1 of the part of second exhaust of pipe in 44 via hole 45.In addition, all the other exhaust E2 enter into first expansion chamber 70 and expand through flowing out from second pipe, 44 downstream-end opening 43.In the case, first expansion chamber 70 surrounds the periphery and the downstream-end opening 43. of second pipe 44 integratedly and continuously

As stated, hole 45 is formed among the upstream region RU except downstream area RD.Thereby the pressure surge of flowing out the exhaust E2 that pressure surge and the downstream-end opening 43 from second pipe 44 of the exhaust E1 of second pipe 44 flow out through hole 45 has the different high fdrequency components of phase place respectively.Thereby the high fdrequency component of the high fdrequency component of the pressure surge of exhaust E1 and the pressure surge of exhaust E2 cancels each other out in identical pressure space.Inventor's of the present invention result of study shows high fdrequency component counteracting effectively each other when the length L as downstream region R D is at least 1/3 times of internal diameter R2 of second pipe 44.This causes the high fdrequency component of exhaust sound to reduce.

In addition, progressively expanded in second pipe, 44 and first expansion chamber 70 by the exhaust of narrow 47 compressions of first pipe 42.This causes because the pressure surge that the rapid expanding of exhaust produces is alleviated.As a result, suppress because the sound (the metal sound that especially comprises high fdrequency component) that pressure surge produces.

Exhaust gas in first expansion chamber 70 expands through flowing out entering second expansion chamber 72 via connecting tube 62.Exhaust in second expansion chamber 72 is expanded through flowing out entering the 3rd expansion chamber 74 via connecting tube 64.Exhaust in the 3rd expansion chamber 74 is discharged into the outside through tail pipe 66, and is discharged into atmosphere.

If the distance between the downstream-end opening 43 of second pipe 44 and the upstream-end opening of connecting tube 62 is too little, then erasure effect reduces.If the downstream-end opening 43 and the distance between the demarcation strip 36 of second pipe 44 are too little, then the torque of motor 50 generations reduces.Thereby the length D of downstream area RD is three times at the most of second pipe, 44 internal diameter R2 preferably, more preferably twice at the most.

(5) effect of preferred embodiment

In motorcycle 100, be incorporated into the exhaust of outlet pipe 40 through outlet pipe 20 from single-cylinder engine 50 by narrow 47 compressions of first pipe 42 according to present embodiment.This prevents that unburned mixed gas from flowing out from motor 50.As a result, improved the torque that motor 50 produces in low-speed region and intermediate speed region.

In addition, in second pipe, 44, first expansion chamber 70, second expansion chamber 72 and the 3rd expansion chamber 74, progressively expanded, make the pressure of exhaust progressively be reduced to atmospheric pressure by the exhaust of first pipe, 42 narrow, 47 compressions.This causes exhaust sound to be reduced.

In the case, second pipe, 44 interior exhaust E1 flow out through hole 45 and get into first expansion chamber 70, and all the other exhaust E2 flow out entering first expansion chamber 70 from downstream-end opening 43.Thereby the high fdrequency component of the pressure surge of the high fdrequency component of the pressure surge of exhaust E1 and exhaust E2 is cancelling each other out as in first expansion chamber 70 of same pressure space.This causes by the high fdrequency component of three-way catalyst 90 increased pressure fluctuation and is reduced.Thereby the high fdrequency component of exhaust sound reduces significantly.As a result, can, inhibition obtain the intermittence low exhaust sound synchronous when comprising the metal sound generating of high fdrequency component with the burning of single-cylinder engine 50.

In addition, second pipe 44 is fixed to first pipe 42 at upstream extremity with the state of cantilever.Thereby, do not have supporting member to have the outer circumferential side of second pipe 44, and first expansion chamber 70 surround the outer circumferential face and the downstream-end opening 43 of second pipe 44 integratedly and continuously.Thereby, can guarantee as the volume of first expansion chamber 70 of same pressure space enough big.As a result, can under the situation of length that does not increase baffler 30 and diameter, reduce the high fdrequency component of exhaust sound fully.In addition, this can prevent to produce hydrodynamic noise owing to the interference of exhaust air flow.

Because second pipe 44 is connected to first pipe, 42, the second pipes 44 stably are fixed to first pipe 42 with high tenacity outer circumferential face in the position of the upstream side of narrow 47.This has been avoided second pipe 44 to produce vibration and swing.As a result, this has prevented to have the sound and because the generation of the continuous sound that the vibration of second pipe 44 or swing cause of natural frequency of vibration and the swing of second pipe 44.

(6) other embodiments

Although narrow 47 has tapered portion 48a and small diameter portion 48b in above embodiment, only if the mobile of exhaust is interfered, narrow 47 can have ledge structure.In the case, exhaust pressure is also increased by narrow 47.

Although the shape in a plurality of holes 45 is circular in above embodiment, the invention is not restricted to this.For example, the shape in a plurality of holes 45 can be oval or polygonal.

In addition, although a plurality of hole 45 is spaced apart in the upstream region RU moderate distance except downstream area RD, can arrange a plurality of holes 45 arbitrarily.

Although first pipe, 42 and second pipe 44 has circular cross section respectively in above embodiment, the invention is not restricted to this.For example, first pipe, 42 and second pipe 44 can have non-circular cross-section respectively.In the case, the length of long axis of ellipse is taken as internal diameter.Thereby the length D of second pipe, 44 downstream area RD is set at least 1/3 times of length of long axis of ellipse, is preferably three times at the most of internal diameter R2 of second pipe 44, more preferably the twice at the most of the internal diameter R2 of second pipe 44.In addition, first pipe, 42 and second pipe 44 can have the polygonal cross section respectively.The length of in the case, polygonal long-diagonal is taken as internal diameter.Thereby the length D of second pipe, 44 downstream area RD is set at least 1/3 times of length of polygonal long-diagonal, is preferably three times at the most of internal diameter R2 of second pipe 44, more preferably the twice at the most of the internal diameter R2 of second pipe 44.

Although three-way catalyst 90 is used among the above embodiment, the invention is not restricted to this.For example, three-way catalyst 90 can replace with oxidation catalyst or reducing catalyst.

(7) example

Investigation baffler in example of the present invention and comparative example 1 and 2 reduces the effect of the high fdrequency component of exhaust sound respectively.In example of the present invention, use baffler 30 shown in Figure 4.

Fig. 6 is the viewgraph of cross-section of baffler in the comparative example 1.The structure of other parts that baffler 30a shown in Figure 6 and baffler shown in Figure 4 30 different being, baffler 30a shown in Figure 6 do not have second pipe, 44. baffler 30a shown in Figure 6 is identical with the structure of baffler 30 shown in Figure 4.

In the baffler 30 and the baffler 30a in the comparative example 1 of example of the present invention, the internal diameter R0 of narrow 47 is 16.1mm, and the internal diameter R1 of first pipe 42 is 23.6mm.In addition, the internal diameter of connecting tube 62 and length are respectively 28.6mm and 50mm, and the internal diameter of connecting tube 64 and length are respectively 22.2mm and 50mm, and the internal diameter of tail pipe 66 and length are respectively 22.2mm and 30mm.

In the baffler 30 of example of the present invention, the internal diameter R2 of second pipe 44 is 27.4mm, and the internal diameter in hole 45 is 5mm, and the distance between the hole 45 is 7.5mm.The diameter in hole 45 is 5mm, and is 42mm from the length of the downstream-end opening 43 of the downstream-end opening of narrow 47 49 to second pipes 44.The length D of downstream area RD is 9.5mm.

Measure baffler 30a in baffler 30 and the comparative example 1 in the example of the present invention to each damping characteristic of exhaust sound.

Fig. 7 is the figure of each measurement result of the damping characteristic of the baffler 30a in baffler 30 and the comparative example 1 that illustrates in the example of the present invention.In Fig. 7, transverse axis is represented frequency (Hz), and the longitudinal axis is represented sound pressure level (dB).In identical frequency, sound pressure level is low more, and noise figure is just low more.

At Fig. 7, the damping characteristic of the baffler 30 in the example of the present invention is represented by heavy line L0, and the damping characteristic of the baffler 30s in the comparative example 1 is represented by fine line L1.

In the zone of representing by arrow B 1 and B2, make the sound pressure level of the high fdrequency component in the baffler 30 in the example of the present invention be lower than the sound pressure level among the baffler 30a in the comparative example 1 fully.Be lower than separately among the baffler 30a in baffler 30 in the example of the present invention and the comparative example 1 2000Hz low frequency component damping characteristic about equally.

Thereby, use the baffler 30 feasible sound pressure levels of the high fdrequency component of 2000Hz at least that fully reduce in the example of the present invention.Thereby, find to use the baffler 30 of example of the present invention can suppress to comprise the generation of the metal exhaust sound of high fdrequency component.

Fig. 8 is the viewgraph of cross-section of baffler in the comparative example 2.Baffler 30b shown in Figure 8 and baffler shown in Figure 4 30 be different to be following aspect.In baffler 30b shown in Figure 8, a plurality of holes 45 are identically formed in whole second pipe 44.The structure of other parts of baffler 30a shown in Figure 8 is identical with the structure of baffler 30 shown in Figure 4.

Relatively at the baffler 30 of use example of the present invention and the exhaust sound under the baffler 30a situation in the comparative example 2.The use of the baffler 30 in the example of the present invention suppresses to comprise the generation of the metal sound of high fdrequency component fully.On the other hand, use the baffler 30b in the comparative example 2 to cause generation to comprise the metal sound of high fdrequency component.

The result is illustrated among the upstream region RU except downstream area RD and forms the generation that a plurality of holes 45 can suppress to comprise the metal sound of high fdrequency component.

(8) corresponding relation between the parts among composed component and the embodiment in the claim

In following paragraph, various elements and the above non-restrictive example with reference to the corresponding relation between the various elements of various embodiments of the invention description in claim, described are described.

In the above embodiment, vehicle body 80 is examples of vehicle body, and motor 50 is examples of motor; Outlet pipe 20 and 40 is examples of outlet pipe, and three-way catalyst 90 is examples of catalyzer, and baffler 30 is examples of baffler; First pipe 42 is examples of first pipe, and second pipe 44 is examples of second pipe, and narrow 47 is examples of narrow; First expansion chamber 70 is examples of first expansion chamber, and hole 45 is the examples in hole.

In addition, second expansion chamber 72 is examples of second expansion chamber, and demarcation strip 36 is examples of demarcation strip, and connecting tube 36 is examples of connecting tube, and tapered portion 48a is the example of tapered portion.

Can also use various other elements as in the various elements of describing in the claim each with the structure described in the claim or function.

Although below described the embodiment of the invention, it is to be understood that it is tangible under situation about not departing from the scope of the present invention with spirit, changing and revise for those skilled in the art.Thereby scope of the present invention is only confirmed by claim.

Claims

1. motorcycle comprises:

Vehicle body;

Single-cylinder engine, it is arranged in the said vehicle body;

Outlet pipe flows in the said outlet pipe from the exhaust of said motor;

Catalyzer, it is arranged in the said outlet pipe; And

Baffler, it will be discharged to the outside from what said outlet pipe flowed out,

Wherein, said outlet pipe comprises:

First pipe, it has the downstream-end opening that is inserted in the said baffler; And

Second pipe, it has upstream-end opening and downstream-end opening, and in said baffler, extends to said downstream side from said first pipe,

In the said downstream-end opening of said first pipe, narrow is set, its internal diameter is littler than the internal diameter of said first pipe, and is inserted in the said upstream-end opening of said second pipe,

In said baffler, form first expansion chamber, it surrounds the periphery of said second pipe and the downstream-end opening of said second pipe integratedly, and

A plurality of holes are formed on the mode of disperseing in the side face of said second pipe in the zone except the downstream zone, and the zone of said downstream is 1/3 times of said second internal diameter of managing at least along the length of axial direction.

2. motorcycle according to claim 1, wherein, said second pipe is at said first pipe of the engagement position of the upstream side of said narrow.

3. motorcycle according to claim 1 and 2, wherein, said narrow comprises the tapered portion with the internal diameter that reduces gradually.

4. motorcycle according to claim 1 and 2; Wherein, Also the downstream side of said first expansion chamber in said baffler forms second expansion chamber, and said first expansion chamber and said second expansion chamber are separated plate separately, and connecting tube are set to pass said demarcation strip.

5. motorcycle according to claim 4, wherein, the volume of said first expansion chamber is greater than the volume of said second expansion chamber.

6. motorcycle according to claim 1 and 2, wherein, in said outlet pipe,

The part of said first pipe remains in the said baffler, and said second pipe does not remain in the said baffler.