Engine muffler and engine exhaust pipe

Abstract

Provided is an engine muffler (30) comprising a first chamber (31) and a closed tube (50) that communicates with the first chamber (31) via an opening end (51) and communicates with a second chamber (60) via a first opening (Z1) of a side surface (53). Also provided is an engine exhaust pipe (20) comprising a main pipe and a closed pipe (50) that communicates with the main pipe via an opening end (71) and communicates with a fourth chamber (81) via a third opening (Z3) of a side surface (73).

Description

Engine mufflers and engine exhaust pipes

[0001] The present invention relates to an engine muffler and an engine exhaust pipe.

[0002] A silencer is known in which a gas passage pipe is connected to a curved branch passage whose end is closed and whose length is determined by the resonant frequency (Patent Document 1).

[0003] JP 62-126215 Publication

[0004] In the above-mentioned conventional technology, the length of the branch passage is determined depending on the resonance frequency, and therefore, when silencing low-frequency sounds in particular, the length of the branch passage becomes long, resulting in a problem of an increased size of the silencer.

[0005] The problem to be solved by the present invention is to provide an engine muffler and an engine exhaust pipe that can prevent the silencer from becoming too large.

[0006] The present invention solves the above problems by providing a closed tube that communicates with a first chamber through an open end and with a second chamber through a side opening.

[0007] According to the present invention, it is possible to prevent the noise absorbing device from becoming large.

[0008] 1 is a plan view showing an example of a silencer according to an embodiment of the present invention. FIG. 1 is a left side view of the silencer of FIG. 1. FIG. 2 is a cross-sectional view showing the closed tube and the second chamber of FIG. 1, taken along line A-A in FIG. 1. FIG. 3 is an enlarged cross-sectional view of the periphery of the first opening shown in FIG. 3. FIG. 4 is a cross-sectional view showing the closed tube and the second chamber of FIG. 1, taken along line B-B in FIG. 3. FIG. 5 is a cross-sectional view showing another example of the second chamber according to an embodiment of the present invention. FIG. 6 is a plan view of a main part showing another example of a muffler according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of a main part showing the closed tube and the third chamber of FIG. 7, taken along line C-C in FIG. 7. FIG. 8 is a plan view of another example of a silencer according to an embodiment of the present invention. FIG. 9 is a rear view of a main part showing the closed tube and the chamber of FIG. 9. FIG. 10 is a cross-sectional view of a main part showing the closed tube and the chamber of FIG. 9. FIG. 11 is a cross-sectional view of a main part showing the closed tube and the chamber of FIG. 9, taken along line D-D in FIG. FIG. 12 is a diagram (part 1) showing the operation of the chamber of FIG. 1. FIG. 13 is a diagram (part 2) showing the operation of the chamber of FIG. 1. FIG. 14 is a diagram (part 1) showing the operation of the chamber of FIG. 9. FIG. 10 is a diagram (part 2) showing the operation of the chamber in FIG. 9 .

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the front side of a vehicle engine is defined as the front side. In addition, in the drawings, "front" refers to the front of the vehicle, "rear" refers to the rear of the vehicle, "right" refers to the right side of the vehicle, "left" refers to the left side of the vehicle, "up" refers to the top of the vehicle, and "down" refers to the bottom of the vehicle.

[0010] [Configuration of silencer] Fig. 1 is a plan view showing an example of a silencer according to an embodiment of the present invention, and Fig. 2 is a left side view of the silencer shown in Fig. 1. The silencer is a device that reduces exhaust noise from an engine 10, which is an internal combustion engine that obtains output by burning a combustible air-fuel mixture, and includes an exhaust pipe 20, a muffler 30, and a tail pipe 40. Note that the engine 10 may also be a hybrid engine that combines an internal combustion engine and an electric motor.

[0011] The exhaust pipe 20 is a pipe that introduces exhaust gas (hereinafter simply referred to as exhaust gas) from the engine 10 and sound waves (hereinafter simply referred to as sound waves) of the exhaust sound from the engine 10 into the muffler 30, and is routed under the floor of the vehicle. For example, the exhaust pipe 20 is made by welding together multiple circular pipes made of corrosion-resistant stainless steel (such as SUS409), and is attached to the vehicle by stays that are fixed to the floor via rubber. The base end of the exhaust pipe 20 is attached to the exhaust manifold of the engine 10, and the exhaust gas and sound waves are introduced from the engine 10. Meanwhile, the end of the exhaust pipe 20 is attached to the muffler 30 and communicates with the chamber of the muffler 30.

[0012] The muffler 30 is a device that reduces the temperature of exhaust gases introduced from the exhaust pipe 20 and the sound pressure level of exhaust noise, and has at least one chamber. For example, the muffler 30 is a cylindrical hollow molded product made of corrosion-resistant stainless steel, and its cross-sectional shape may be circular, elliptical, rectangular, or the like. A muffler 30 having a desired shape is manufactured, for example, by pressing and welding a stainless steel plate. The muffler 30 is suspended from the underside of the vehicle floor, for example, via stays provided at both ends in the longitudinal and / or lateral directions. The stays are fixed to the underside of the floor via rubber.

[0013] The tail pipe 40 is a pipe that discharges exhaust gas and sound waves outside the muffler 30 (for example, into the atmosphere). The tail pipe 40 is made of the same material as the exhaust pipe 20, and is attached to the muffler 30 using a joining method such as welding. The shape of the tail pipe 40 is not particularly limited. Note that when the muffler 30 is connected to a different subsequent muffler, the tail pipe 40 discharges exhaust gas and sound waves outside the housing of the muffler 30.

[0014] The muffler 30 is an engine muffler that includes a closed pipe 50 and a second chamber 60 to prevent the noise suppression device from becoming too large and improve its mountability on a vehicle. The closed pipe 50 is a pipe (e.g., a circular pipe) with an open end and a closed end, and cancels sound waves of a desired frequency by waves reflected at the closed end. The closed pipe 50 is made of the same material as the exhaust pipe 20 and is attached to the muffler 30 using a joining method such as welding. Meanwhile, the second chamber 60 is a space separated by a housing, and the housing of the second chamber 60 is made of, for example, corrosion-resistant stainless steel.

[0015] The closed pipe 50 and the second chamber 60 will be described using FIG. 3. FIG. 3 is a cross-sectional view taken along line A-A in FIG. 1. As shown in FIG. 3, the muffler 30 includes a first chamber 31. The shape of the first chamber 31 is not particularly limited as long as it can reduce the sound pressure level of the exhaust noise to within a predetermined range set by regulations. On the other hand, the closed pipe 50 has an open end 51, a closed end 52, and a side surface 53. The closed pipe 50 communicates with the first chamber 31 via the open end 51 and with the second chamber 60 via a first opening Z1 in the side surface 53. In the drawing, the open end is indicated by a dashed line, and the closed end is indicated by a solid line.

[0016] The second chamber 60 is shaped so as not to inhibit the introduction of sound waves into the second chamber 60. Specifically, in a first cross section S1 of the second chamber 60 taken along a plane perpendicular to a first normal line L1, which is a normal to the tube axis X1 of the closed tube 50 and passes through the center Y1 of the first opening Z1, the cross-sectional area of ​​at least one surface within the second chamber 60 (particularly, outside the first opening Z1) (excluding the portion corresponding to the interior of the closed tube 50) is made larger than the first opening area of ​​the first opening Z1. The tube axis X1 of the closed tube 50 refers to the central axis of the closed tube 50. The normal to the tube axis X1 refers to a line perpendicular to the tube axis X1, and in FIG. 3 , is a straight line extending in the vertical direction of the drawing. The outside of the first opening Z1 refers to the side away from the tube axis X1 of the closed tube 50 with respect to the first opening Z1, and in FIG. 3 , refers to the upper side of the first opening Z1. The second chamber 60 is a space that is closed except for the first opening Z1, and does not have any openings other than the first opening Z1.

[0017] The center Y1 of the first opening Z1 is the center of a projection of the first opening Z1 onto a projection plane, and the first opening area is the area of ​​the projection. A method for determining the center Y1 and the first opening area will be described using FIG. 4 . FIG. 4 is an enlarged cross-sectional view of the periphery of the first opening Z1 shown in FIG. 3 , and the first opening Z1 is defined by the end faces E1 and E2 shown in FIG. 4 . As shown in FIG. 4 , the center Y1 of the first opening Z1 is the center of a projection onto a projection plane P that is perpendicular to at least one of the end faces E1 and E2, and the first opening area is the area of ​​the projection onto the projection plane P. Note that the projection plane P shown in FIG. 4 is a plane parallel to the left-right direction (and the front-rear direction) of the vehicle, so the first opening area of ​​the first opening Z1 shown in FIG. 3 corresponds to the area of ​​the first opening Z1 when viewed in a plan view.

[0018] Fig. 5 is a cross-sectional view taken along line B-B in Fig. 3, and is a plan view of the first cross section S1 and the first opening Z1. As described above, the area of ​​the first opening Z1 in a plan view is the same as the first opening area, so the lightly hatched portion in Fig. 5 corresponds to the first opening area T1 of the first opening Z1. The darkly hatched portion in Fig. 5 corresponds to the cross-sectional area of ​​the first cross section S1, so as shown in Fig. 5, the cross-sectional area of ​​the first cross section S1 is larger than the first opening area T1 of the first opening Z1.

[0019] The shape of the second chamber 60 is not particularly limited as long as the cross-sectional area of ​​at least one first cross section S1 is larger than the first opening area T1. For example, to promote the propagation of sound waves to the second chamber 60, the cross-sectional areas of all first cross sections S1 may be larger than the first opening area T1, as in the second chamber 60 shown in Fig. 3. For the same purpose, the cross-sectional area of ​​the first cross section S1 may increase with increasing distance from the first opening Z1 within a range from the first opening Z1 to a position a predetermined distance away from the first opening Z1 along the first normal line L1.

[0020] Fig. 6 is a cross-sectional view taken along line A-A in Fig. 1, similar to Fig. 3, except that the rectangular parallelepiped second chamber 60 shown in Fig. 3 is replaced with a spherical second chamber 60a shown in Fig. 6. In the second chamber 60a shown in Fig. 6, the cross-sectional area of ​​the first cross section S1a increases with increasing distance from the first opening Z1 within a range R extending from the first opening Z1 to a position a predetermined distance away from the first opening Z1 along the first normal line L1. The predetermined distance can be set to any appropriate value within the range in which the second chamber 60a can be mounted on a vehicle.

[0021] The sound waves (specifically, the pressure fluctuations of the sound waves) introduced from the exhaust pipe 20 into the first chamber 31 propagate from the open end 51 into the closed pipe 50, are reflected at the closed end 52, and are output from the open end 51. The waveform of the sound waves changes while the sound waves propagate through the closed pipe 50 and the second chamber 60 (specifically, the phase of the waveform is delayed), and if the reflected wave output from the open end 51 has a waveform that is in the opposite phase to the waveform of the sound waves, the reflected wave will cancel out the sound waves in the first chamber 31.

[0022] The effect of delaying the phase of the waveform of the sound wave becomes greater the longer the length of the closed tube 50 and the easier it is for the sound wave (specifically, the pressure fluctuations of the sound wave) to propagate to the second chamber 60. In other words, the effect of delaying the phase of the waveform becomes greater the larger the first opening area T1, the larger the number of first openings Z1 when the first opening area T1 is constant, the larger the volume of the second chamber 60, and the larger the cross-sectional area of ​​the first cross section S1. Therefore, the specific tube length of the closed tube 50, the first opening area T1, the number of first openings Z1, the volume of the second chamber 60, and the cross-sectional area of ​​the first cross section S1 are set according to the frequency (desired frequency) of the sound wave to be canceled.

[0023] In the silencer shown in FIG. 1 , the closed pipe 50 protrudes outside the muffler 30, but as shown in FIG. 7 , the closed pipe 50 may be disposed inside the muffler 30a. FIG. 7 is a plan view of a main portion showing an example of a muffler 30a equipped with the closed pipe 50 inside. The muffler 30a includes a housing 32 that houses the devices that make up the muffler 30a, and partition plates 33, 34, 35, and 36 that separate the interior of the housing 32. The housing 32 has a substantially rectangular parallelepiped shape, and the top surface of the housing 32 is not shown in FIG. It should be noted that the substantially rectangular parallelepiped is only an example of the shape of the housing 32, and the shape of the housing 32 is not particularly limited.

[0024] 7, the interior of the muffler 30a is divided into multiple chambers by partition plates 33, 34, 35, and 36. The muffler 30a includes a first chamber 31a divided by the partition plate 33, a second chamber 60b divided by the partition plates 33 and 34, the first chamber 31b divided by the partition plates 34 and 35, a third chamber 61 divided by the partition plates 35 and 36, and a first chamber 31c divided by the partition plate 36. In the muffler 30a, the first chambers 31a, 31b, and 31c, the second chamber 60b, and the third chamber 61 are formed by the housing 32 and the partition plates 33, 34, 35, and 36.

[0025] The first chamber 31b communicates with the end of the exhaust pipe 20, and exhaust gas and sound waves are introduced into the first chamber 31b. The muffler 30a includes communication pipes 37 and 38 that directly connect the different chambers. The first chambers 31b and 31c adjacent to the third chamber 61 communicate with each other via the communication pipe 37 located within the third chamber 61. The first chambers 31a and 31c also communicate with each other via the communication pipe 38 that passes through the third chamber 61, the first chamber 31b, and the second chamber 60b. The muffler 30a also includes a tail pipe 40 that discharges exhaust gas to the outside. The tail pipe 40 has an inner end 41 located within the first chamber 31a and communicating with the open end 51 of the closed pipe 50, and an outer end 42 located outside the muffler 30a.

[0026] Exhaust gas (arrow F1) introduced from the exhaust pipe 20 into the first chamber 31b is introduced from the first chamber 31b to the first chamber 31c via the connecting pipe 37 (arrow F2). The exhaust gas introduced into the first chamber 31c moves within the first chamber 31c (arrow F3) and is introduced from the first chamber 31c to the first chamber 31a via the connecting pipe 38 (arrow F4). The exhaust gas introduced into the first chamber 31a moves within the first chamber 31a (arrow F5). The exhaust gas is then introduced into the tail pipe 40 from the inner end 41, passes through the tail pipe 40, and is discharged into the atmosphere from the outer end 42 (arrow F6).

[0027] As indicated by arrows F1 to F6, exhaust gas is not introduced into the second chamber 60b and the third chamber 61. Therefore, a temperature difference occurs between the first chambers 31a, 31b, and 31c, into which exhaust gas is introduced, and the second chamber 60b and the third chamber 61, into which exhaust gas is not introduced. To prevent thermal stress from concentrating on a part of the housing 32 due to this temperature difference, in the muffler 30a, the third chamber 61 may be positioned on the opposite side of the second chamber 60b from the center of the housing 32 in the axial direction of the closed tube 50. For example, if the center of the housing 32 in the axial direction along the tube axis X1 of the closed tube 50 is position Q, the second chamber 60b and the third chamber 61 are disposed on opposite sides of position Q.

[0028] The closed pipe 50 has an open end 51, a closed end 52, and a side surface 53. The closed pipe 50 is in communication with the first chamber 31a via the open end 51 and with the second chamber 60b via a first opening Z1 in the side surface 53. In the muffler 30a, similar to the silencer shown in FIG. 3 , in a first cross section of the second chamber 60b taken along a plane perpendicular to a first normal line normal to the pipe axis X1 of the closed pipe 50 that passes through the center of the first opening Z1, the cross-sectional area of ​​at least one surface outside the first opening Z1 is larger than the first opening area of ​​the first opening Z1. Furthermore, the open end 51 of the closed pipe 50 is positioned closer to the inner end 41 of the tailpipe 40 than the end of the pipe other than the closed pipe 50 that communicates with the inner end 41 of the tailpipe 40. For example, the open end 51 shown in FIG. 7 is positioned closer to the inner end 41 than the end of the connecting pipe 38 located within the first chamber 31a.

[0029] 7 has a second opening Z2 located farther from the open end 51 than the first opening Z1, and is connected to a third chamber 61 via the second opening Z2. To increase the effect of delaying the waveform phase on the side closer to the open end 51, the volume of the third chamber 61 is made smaller than the volume of the second chamber 60b. The volume of the third chamber 61 may be reduced by providing connecting pipes 37, 38 within the third chamber 61.

[0030] FIG. 8 is a cross-sectional view of the main portion of the closed tube 50 and the third chamber 61 of FIG. 7 , taken along line CC of FIG. 7 . In the third chamber 61, similar to the second chamber 60b, the cross-sectional area of ​​at least one surface within the third chamber 61 (particularly, the area outside the second opening Z2) of a second cross section S2 obtained by cutting the third chamber 61 along a plane perpendicular to a second normal line L2, which is a normal to the tube axis X1 of the closed tube 50 and passes through the center Y2 of the second opening Z2, is set larger than the second opening area of ​​the second opening Z2. The center Y2 is determined in the same manner as the center Y1, and the second opening area is determined in the same manner as the first opening area. The third chamber 61 is a closed space except for the second opening Z2, and does not have any openings other than the second opening Z2.

[0031] Returning to FIG. 7 , the lightly hatched areas in FIG. 7 correspond to the second opening area T2 of the second opening Z2, and the heavily hatched areas correspond to the cross-sectional area of ​​the second cross section S2. As shown in FIG. 7 , the cross-sectional area of ​​the second cross section S2 is larger than the second opening area T2 of the second opening Z2. The shape of the third chamber 61 is not particularly limited as long as the cross-sectional area of ​​at least one of the second cross sections S2 is larger than the second opening area T2, and may be the same shape as the second chambers 60, 60a, and 60b. As with the second chamber 60, the length of the closed tube 50, the second opening area T2, the number of second openings Z2, the volume of the third chamber 61, and the cross-sectional area of ​​the second cross section S2 are set according to the frequency (desired frequency) of the sound waves to be canceled.

[0032] In the muffler 30a, the first opening Z1 may be located at a position corresponding to the center of the second chamber 60b in the axial direction along the tube axis X1 of the closed tube 50, and the second opening Z2 may be located at a position corresponding to the center of the third chamber 61 in the axial direction. For example, as shown in FIG. 7 , the first opening Z1 may be located midway between the partition plates 33 and 34 (equidistant from the partition plates 33 and 34), and the second opening Z2 may be located midway between the partition plates 35 and 36 (equidistant from the partition plates 35 and 36). This arrangement suppresses resonance within the chambers (e.g., the second chamber 60b and the third chamber 61). To suppress resonance within the second chamber 60b and the third chamber 61, a sound-absorbing material (e.g., glass wool) may be provided within at least one of the second chamber 60b and the third chamber 61.

[0033] In the silencer shown in Fig. 1 , the closed pipe 50 is connected to the muffler 30, but as shown in Fig. 9 , the sound pressure level of the exhaust noise can also be suppressed when the closed pipe 70 is connected to the exhaust pipe 20. Fig. 9 is a plan view showing another example of the silencer according to this embodiment, and Fig. 10 is a rear view of the main parts showing the exhaust pipe 20, closed pipe 70, and chamber 80 of the silencer shown in Fig. 9. The exhaust pipe 20 shown in Fig. 9 includes a main pipe leading to the muffler 30 and a closed pipe 70 which is a branch pipe branching off from the main pipe. As shown in Fig. 10 , the exhaust pipe 20 and the closed pipe 70 are circular pipes, and the chamber 80 has a cylindrical shape.

[0034] The closed tube 70 and the chamber 80 will be described with reference to Figures 11 and 12. Figure 11 is a plan view of the main parts showing the closed tube 70 and the chamber 80 in Figure 9, and Figure 12 is a cross-sectional view taken along line DD in Figure 9. Note that the upper half of the chamber 80 is not shown in Figure 11.

[0035] 11 , the closed pipe 70 has an open end 71, a closed end 72, and a side surface 73, and the chamber 80 is divided into a fourth chamber 81, a chamber 82, and a fifth chamber 83. The closed pipe 70 communicates with the main pipe via the open end 71, and communicates with the fourth chamber 81 via a third opening Z3 on the side surface 73. The closed pipe 70 also has a fourth opening Z4 located farther from the open end 71 than the third opening Z3, and communicates with a fifth chamber 83 having a smaller volume than the fourth chamber 81 via the fourth opening Z4.

[0036] The shapes of the fourth chamber 81 and the fifth chamber 83 are, like the second chamber 60, shapes that do not inhibit the introduction of sound waves into the chambers. Specifically, as shown in Fig. 12, in a third cross section S3 obtained by cutting the fourth chamber 81 along a plane perpendicular to a third normal line L3 that is normal to the tube axis X2 of the closed tube 70 and passes through the center Y3 of the third opening Z3, the cross-sectional area of ​​at least one surface within the fourth chamber 81 (particularly, outside the third opening Z3) (excluding a portion corresponding to the interior of the closed tube 70) is made larger than the third opening area of ​​the third opening Z3. Furthermore, in a fourth cross section S4 obtained by cutting the fifth chamber 83 along a plane perpendicular to a fourth normal line L4 that is normal to the tube axis X2 of the closed tube 70 and passes through the center Y4 of the fourth opening Z4, the cross-sectional area of ​​at least one surface within the fifth chamber 83 (particularly, outside the fourth opening Z4) (excluding a portion corresponding to the interior of the closed tube 70) is made larger than the fourth opening area of ​​the fourth opening Z4. The centers Y3 and Y4 are determined in the same manner as the center Y1, and the third and fourth opening areas are determined in the same manner as the first opening area.

[0037] Returning to Fig. 11 , of the two lightly hatched portions in Fig. 11 , the left portion corresponds to the third opening area T3 of the third opening Z3, and the right portion corresponds to the fourth opening area T4 of the fourth opening Z4. Furthermore, of the two heavily hatched portions in Fig. 11 , the left portion corresponds to the cross-sectional area of ​​the third cross section S3, and the right portion corresponds to the cross-sectional area of ​​the fourth cross section S4. As shown in Fig. 11 , the cross-sectional area of ​​the third cross section S3 is larger than the third opening area T3 of the third opening Z3, and the cross-sectional area of ​​the fourth cross section S4 is larger than the fourth opening area T4 of the fourth opening Z4.

[0038] The shape of the fourth chamber 81 is not particularly limited as long as the cross-sectional area of ​​at least one third cross section S3 is larger than the third opening area T3, and the shape of the fifth chamber 83 is not particularly limited as long as the cross-sectional area of ​​at least one fourth cross section S4 is larger than the fourth opening area T4. For example, the cross-sectional areas of all third cross sections S3 may be larger than the third opening area T3. Alternatively or additionally, the cross-sectional areas of all fourth cross sections S4 may be larger than the fourth opening area T4. Furthermore, similar to the second chamber 60a shown in FIG. 6 , the cross-sectional area of ​​the third cross section S3 may increase with increasing distance from the third opening Z3 within a range from the third opening Z3 to a position a predetermined distance from the third opening Z3 along the third normal line L3. Alternatively or additionally, the cross-sectional area of ​​the fourth cross section S4 may increase with increasing distance from the fourth opening Z4 within a range from the fourth opening Z4 to a position a predetermined distance from the fourth opening Z4 along the fourth normal line L4.

[0039] The position of the third opening Z3 may be a position corresponding to the center position of the fourth chamber 81 in the tube axis direction of the closed tube 70, and the position of the fourth opening Z4 may be a position corresponding to the center position of the fifth chamber 83 in the tube axis direction of the closed tube 70. For example, the position of the third opening Z3 shown in Fig. 12 is the center position of the fourth chamber 81 in the tube axis X2 direction, and the position of the fourth opening Z4 is the center position of the fifth chamber 83 in the tube axis X2 direction.

[0040] As in the case of the second chamber 60, the length of the closed tube 70, the third opening area T3, the number of third openings Z3, the volume and cross-sectional area of ​​the third cross section S3 of the fourth chamber 81, the fourth opening area T4, the number of fourth openings Z4, and the volume and cross-sectional area of ​​the fourth cross section S4 of the fifth chamber 83 are set according to the frequency (desired frequency) of the sound waves to be cancelled. The fourth chamber 81 is a space that is closed except for the third opening Z3 and has no openings other than the third opening Z3, and the fifth chamber 83 is a space that is closed except for the fourth opening Z4 and has no openings other than the fourth opening Z4.

[0041] Also, an engine silencer may be configured by combining the exhaust pipe 20 having the closed pipe 70 with the muffler 30 having the closed pipe 50. Furthermore, an engine silencer may be configured by combining the exhaust pipe 20 having the closed pipe 70 with a normal muffler, or an engine silencer may be configured by combining a normal exhaust pipe with the muffler 30 having the closed pipe 50.

[0042] 13 and 14, the operation of the second chamber 60 shown in Fig. 3 will be described. The sound wave W propagated from the open end 51 into the closed tube 50 shown in Fig. 13 propagates along the arrows from the first opening Z1 to the second chamber 60 (arrow A1), and then from the first opening Z1 to the closed tube 50 (arrow A1). As the pressure fluctuation of the sound wave indicated by arrow A1 propagates to the second chamber 60, the phase of the sound wave waveform is delayed at the portion indicated by B1. Then, the sound wave that reaches the closed end 52 undergoes free-end reflection.

[0043] 14 propagates from the first opening Z1 to the second chamber 60 (arrow A1) along the arrow, and then from the first opening Z1 to the closed tube 50 (arrow A1). Due to this second propagation of the pressure fluctuation to the second chamber 60, the phase of the waveform of the sound wave is further delayed at the portion indicated by B1. Then, the sound wave that reaches the open end 51 is output to the first chamber 31.

[0044] Next, the functions of the fourth chamber 81 and the fifth chamber 83 shown in Fig. 12 will be described using Fig. 15 and Fig. 16. In Fig. 15, a sound wave W propagates from the open end 71 into the closed tube 70, propagates along the arrows from the third opening Z3 to the fourth chamber 81 (arrow A2), then from the fourth opening Z4 to the fifth chamber 83 (arrow A3), and reaches the closed end 72. During this time, the propagation of pressure fluctuations of the sound wave to the fourth chamber 81 and the fifth chamber 83 causes a phase delay in the waveform of the sound wave at the portions indicated by B2 and B3.

[0045] 16 propagates from the fourth opening Z4 to the fifth chamber 83 along the arrows (arrow A3), then from the third opening Z3 to the fourth chamber 81 (arrow A2), and is then output to the main pipe from the open end 71. During this time, the phase of the sound wave waveform is further delayed at portions indicated by B2 and B3 due to the propagation of pressure fluctuations of the sound wave to the fourth chamber 81 and the fifth chamber 83. In this way, the phase of the sound wave waveform can be delayed while suppressing an increase in the pipe length of the closed pipes 50 and 70.

[0046] [Embodiments of the Present Invention] According to this embodiment, there is provided an engine muffler 30 including a first chamber 31 and a closed pipe 50 that communicates with the first chamber 31 via an open end 51 and communicates with a second chamber 60 via a first opening Z1 in a side surface 53. This makes it possible to prevent the silencer from becoming too large.

[0047] In the engine muffler 30 of this embodiment, in a first cross section S1 obtained by cutting the second chamber 60 along a plane perpendicular to a first normal line L1 that passes through the center Y1 of the first opening Z1 among normal lines to the pipe axis X1 of the closed pipe 50, the cross-sectional area of ​​at least one surface within the second chamber 60 may be larger than the first opening area T1 of the first opening Z1. This makes it possible to prevent the silencer from becoming larger in size.

[0048] In the engine muffler 30a of this embodiment, the closed pipe 50 has a second opening Z2 located farther from the opening end 51 than the first opening Z1, and is in communication with a third chamber 61 having a volume smaller than that of the second chamber 60b via the second opening Z2, and in a second cross section S2 obtained by cutting the third chamber 61 along a plane perpendicular to a second normal line L2 passing through a center Y2 of the second opening Z2 among the normal lines, the cross-sectional area of ​​at least one surface within the third chamber 61 may be larger than the second opening area T2 of the second opening Z2. This makes it possible to further prevent the noise reduction device from becoming large.

[0049] In the engine muffler 30a of this embodiment, the third chamber 61 may include a communication pipe 37 that directly connects multiple different chambers adjacent to the third chamber 61. This allows the internal space of the muffler 30a to be used effectively.

[0050] In the engine muffler 30a of this embodiment, the position of the first opening Z1 may be a position corresponding to the center of the second chamber 60b in the axial direction of the closed pipe 50, and the position of the second opening Z2 may be a position corresponding to the center of the third chamber 61 in the axial direction of the closed pipe 50. This makes it possible to suppress resonance occurring inside the second chamber 60b and the third chamber 61.

[0051] The engine muffler 30a of this embodiment includes a housing 32 having the first chamber, the second chamber, and the third chamber, and the third chamber 61 may be located on the opposite side of the second chamber 60b from the center of the housing 32 in the axial direction of the closed pipe 50. This makes it possible to prevent thermal stress from concentrating on one part of the housing 32.

[0052] The engine muffler 30a of this embodiment includes a tail pipe 40 that discharges exhaust gas from the engine 10 to the outside, and the tail pipe 40 has an inner end 41 that is located in the first chambers 31a, 31b, 31c and communicates with the open end 51, and the open end 51 may be located closer to the inner end 41 than the end of a pipe other than the closed pipe 50 that communicates with the inner end 41. This makes it possible to cancel out exhaust noise immediately before it is output from the muffler 30a.

[0053] The engine muffler 30a of this embodiment includes a housing 32 and partition plates 33 to 36 that separate the interior of the housing 32, and the first chambers 31a, 31b, 31c and the second chamber 60b may be formed by the housing 32 and the partition plates 33 to 36. This allows the silencer to be made smaller.

[0054] In the engine muffler 30 of this embodiment, the cross-sectional areas of all the first cross sections S1 may be larger than the first opening area T1, which promotes the introduction of sound waves into the second chamber 60 (propagation of pressure fluctuations of sound waves).

[0055] In the engine muffler 30 of this embodiment, the cross-sectional area of ​​the first cross section S1 may increase with increasing distance from the first opening Z1 within a range R from the first opening Z1 to a position a predetermined distance away from the first opening Z1 along the first normal line L1. This promotes the introduction of sound waves into the second chamber 60.

[0056] Furthermore, according to this embodiment, there is provided an engine exhaust pipe 20 including a main pipe and a closed pipe 70 that communicates with the main pipe via the open end 71 and with the fourth chamber 81 via the third opening Z3 in the side surface 73. This makes it possible to prevent the silencer from becoming too large.

[0057] In the engine exhaust pipe 20 of this embodiment, in a third cross section S3 obtained by cutting the fourth chamber 81 along a plane perpendicular to a third normal line L3 that passes through the center Y3 of the third opening Z3 among the normal lines to the pipe axis X2 of the closed pipe 70, the cross-sectional area of ​​at least one surface within the fourth chamber 81 may be larger than a third opening area T3 of the third opening Z3. This makes it possible to prevent the silencer from becoming larger.

[0058] In the engine exhaust pipe 20 of this embodiment, the closed pipe 70 has a fourth opening Z4 located farther from the open end 71 than the third opening Z3, and is in communication with a fifth chamber 83 having a smaller volume than the fourth chamber 81 via the fourth opening Z4, and in a fourth cross section S4 obtained by cutting the fifth chamber 83 along a plane perpendicular to a fourth normal line L4 passing through a center Y4 of the fourth opening Z4, the cross-sectional area of ​​at least one surface within the fifth chamber 83 may be larger than a fourth opening area T4 of the fourth opening Z4. This makes it possible to further prevent the silencer from becoming large in size.

[0059] In the engine exhaust pipe 20 of this embodiment, the position of the third opening Z3 may be a position corresponding to the center of the fourth chamber 81 in the axial direction of the closed pipe 70, and the position of the fourth opening Z4 may be a position corresponding to the center of the fifth chamber 83 in the axial direction of the closed pipe 70. This makes it possible to suppress resonance occurring inside the fourth chamber 81 and the fifth chamber 83.

[0060] In the engine exhaust pipe 20 of this embodiment, the cross-sectional areas of all the third cross sections S3 may be larger than the third opening area T3, which promotes the introduction of sound waves into the fourth chamber 81 (propagation of pressure fluctuations of sound waves).

[0061] In the engine exhaust pipe 20 of this embodiment, the cross-sectional area of ​​the third cross section S3 may increase with increasing distance from the third opening Z3 within a range from the third opening Z3 to a position a predetermined distance away from the third opening Z3 along the third normal line L3, thereby facilitating the introduction of sound waves into the fourth chamber 81 (propagation of pressure fluctuations of sound waves).

[0062] According to this embodiment, the second chambers 60, 60a, 60b may be spaces that are closed except for the first opening Z1, the third chamber 61 may be a space that is closed except for the second opening Z2, the fourth chamber 81 may be a space that is closed except for the third opening Z3, and the fifth chamber 83 may be a space that is closed except for the fourth opening Z4. This allows pressure to build up inside the chambers.

[0063] DESCRIPTION OF SYMBOLS 10...Engine 20...Exhaust pipe 30, 30a...Muffler 31, 31a, 31b, 31c...First chamber 32...Housing 33, 34, 35, 36...Partition plate 37, 38...Communicating pipe 40...Tail pipe 41...Inner end 42...Outer end 50...Closed pipe 51...Open end 52...Closed end 53...Side 60, 60a, 60b...Second chamber 61...Third chamber 70...Closed pipe 71...Open end 72...Closed end 73...Side 80, 82...Chamber 81...Fourth chamber 83...Fifth chamber A1, A2, A3...Arrows B1, B2, B3...Parts E1, E2...End surface F1, F2, F3, F4, F5, F6...Arrows P...Projection plane Q...Position R...Range L1...first normal line, L2...second normal line, L3...third normal line, L4...fourth normal line S1, S1a...first cross section, S2...second cross section, S3...third cross section, S4...fourth cross section T1...first opening area, T2...second opening area, T3...third opening area, T4...fourth opening area W...sound wave X1, X2...tube axis Y1, Y2, Y3, Y4...center Z1...first opening, Z2...second opening, Z3...third opening, Z4...fourth opening

Claims

1. A muffler for an engine comprising: a first chamber; and a closed tube communicating with the first chamber through an open end and communicating with a second chamber through a first opening in a side surface.

2. A muffler for an engine as described in claim 1, wherein, in a first cross section obtained by cutting the second chamber along a plane perpendicular to a first normal line that passes through the center of the first opening among normal lines to the axis of the closed tube, the cross-sectional area of ​​at least one surface within the second chamber is larger than the first opening area of ​​the first opening.

3. A muffler for an engine as described in claim 2, wherein the closed tube has a second opening at a position farther from the opening end than the first opening, and communicates with a third chamber having a volume smaller than that of the second chamber via the second opening, and in a second cross section obtained by cutting the third chamber along a plane perpendicular to a second normal line among the normal lines that passes through the center of the second opening, the cross sectional area of ​​at least one surface within the third chamber is larger than the second opening area of ​​the second opening.

4. A muffler for an engine according to claim 3, wherein the third chamber is provided with a communication pipe that directly communicates between a plurality of different chambers adjacent to the third chamber.

5. An engine muffler as described in claim 3 or 4, wherein the position of the first opening corresponds to the center position of the second chamber in the axial direction of the closed pipe, and the position of the second opening corresponds to the center position of the third chamber in the axial direction of the closed pipe.

6. An engine muffler as claimed in any one of claims 3 to 5, comprising a housing having the first chamber, the second chamber and the third chamber, the third chamber being located on the opposite side to the second chamber with respect to the center position of the housing in the axial direction of the closed pipe.

7. A muffler for an engine as claimed in any one of claims 1 to 6, comprising a tail pipe which discharges engine exhaust gas to the outside, said tail pipe having an inner end located in said first chamber and communicating with said open end, said open end being located at a position closer to said inner end than an end of a tube other than said closed tube which communicates with said inner end.

8. An engine muffler as described in any one of claims 1 to 7, comprising a housing and a partition plate that separates the interior of the housing, the first chamber and the second chamber being defined by the housing and the partition plate.

9. A muffler for an engine as set forth in any one of claims 2 to 6, wherein the cross-sectional areas of all of said first cross sections are larger than said first opening area.

10. A muffler for an engine as described in any one of claims 2 to 6, wherein the cross-sectional area of ​​the first cross section increases with increasing distance from the first opening, within a range from the first opening to a position a predetermined distance away from the first opening along the first normal line.

11. An exhaust pipe for an engine, comprising: a main pipe; and a closed pipe communicating with the main pipe through an open end and communicating with a fourth chamber through a third opening in a side surface.

12. An exhaust pipe for an engine as described in claim 11, wherein, in a third cross section obtained by cutting the fourth chamber along a plane perpendicular to a third normal line that passes through the center of the third opening among normal lines to the axis of the closed tube, the cross-sectional area of ​​at least one surface within the fourth chamber is larger than a third opening area of ​​the third opening.

13. An exhaust pipe for an engine as described in claim 12, wherein the closed pipe has a fourth opening at a position farther from the opening end than the third opening, and communicates with a fifth chamber having a volume smaller than that of the fourth chamber via the fourth opening, and a cross-sectional area of ​​at least one surface within the fifth chamber in a fourth cross section obtained by cutting the fifth chamber along a plane perpendicular to a fourth normal line among the normal lines that passes through the center of the fourth opening is larger than a fourth opening area of ​​the fourth opening.

14. An exhaust pipe for an engine as described in claim 13, wherein the position of the third opening corresponds to the center position of the fourth chamber in the axial direction of the closed pipe, and the position of the fourth opening corresponds to the center position of the fifth chamber in the axial direction of the closed pipe.

15. An engine exhaust pipe according to any one of claims 12 to 14, wherein the cross-sectional areas of all of the third cross sections are larger than the third opening area.

16. An engine exhaust pipe as described in any one of claims 12 to 15, wherein the cross-sectional area of ​​the third cross section increases with increasing distance from the third opening, within a range from the third opening to a position that is a predetermined distance away from the third opening along the third normal line.

17. A muffler for an engine as described in any one of claims 1 to 10, wherein the second chamber is a space that is closed except for the first opening.

18. A muffler for an engine as described in any one of claims 3 to 6, wherein the third chamber is a space that is closed except for the second opening.

19. An engine exhaust pipe as claimed in any one of claims 11 to 16, wherein the fourth chamber is a space that is closed except for the third opening.

20. An engine exhaust pipe as set forth in claim 13 or 14, wherein the fifth chamber is a space that is closed except for the fourth opening.

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