JP2015203364A - Muffler for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler for an internal combustion engine, which can reduce the surface temperature of a muffler cover and exhibit a muffling effect while suppressing increase in the number of components.SOLUTION: A muffler 1 of an internal combustion engine comprises: a first expansion chamber 21 provided between an inlet 6 and an oxidation catalyst 4, into which exhaust gas flows; a second expansion chamber 22 defined by a first partition 11 provided on the outflow side of the first expansion chamber 21 and by a protector 12 opposed to the first partition 11, into which the exhaust gas passed through the oxidation catalyst 4 passes; a tail pipe 8 provided adjacent to the second expansion chamber 22 for discharging the exhaust gas, which has passed through the second expansion chamber 22, from an outlet 7; and a third expansion chamber 23 defined by the protector 12 and a muffler cover 3. A gas flow passage P communicating with the third expansion chamber 23 is formed between a protector exhaust pipe 12b of the second expansion chamber 22 and the tail pipe 8.

Description

  The present invention relates to a muffler for an internal combustion engine.

  As described in Patent Document 1, a muffler including an exhaust gas purifier coated with a catalyst is known. The muffler includes a first expansion chamber having an exhaust gas inlet and a second expansion chamber having an exhaust gas outlet. The wall of the second expansion chamber is a double wall surface on the side opposite to the side attached to the engine. It is said. A heat insulating material is filled between the double wall surfaces. Further, both the first expansion chamber side and the second expansion chamber side of the exhaust gas purifier are covered with a cover.

Japanese Patent No. 3517834

  As shown in FIGS. 7 and 8, conventionally, in an internal combustion engine muffler 100 having a muffler body 102 and a muffler cover (outer wall) 103, exhaust gas that has flowed from the engine through the inlet 106 is first expanded. Enter chamber 121. The exhaust gas passes through the oxidation catalyst 104 from the first expansion chamber 121, burns unburned hydrocarbons, reaches a high temperature, and moves to the second expansion chamber 122. The exhaust gas flows through the vent hole 122 a of the second expansion chamber 122 to the third expansion chamber 123 that is inside the muffler cover 103. Then, the exhaust gas is discharged from the tail pipe 108 to the outside. In such a muffler 100 for an internal combustion engine, the exhaust gas passes through the plurality of throttle portions and the expansion chamber, so that the sound is silenced.

  In the muffler 100 for an internal combustion engine as described in FIGS. 7 and 8, the high-temperature gas after passing through the oxidation catalyst 104 heats the muffler cover 103. Due to the radiant heat from the heated muffler cover 103, the exterior component is likely to become high temperature. In this regard, in the muffler described in Patent Document 1, since the double wall surface is provided and the heat insulating material is filled therebetween, it is possible to prevent the muffler cover or the exterior part from becoming high temperature.

  In the muffler described in Patent Document 1, the silencing effect is enhanced by covering both surfaces of the exhaust gas purifier with a cover. However, in such a configuration, the number of parts increases.

  An object of the present invention is to provide a muffler for an internal combustion engine that can exhibit a silencing effect while reducing the surface temperature of the outer wall and suppressing an increase in the number of parts.

  The present invention has a catalyst part (4) inside, and is configured such that exhaust gas flows from the inlet (6), passes through the catalyst part (4), and is then discharged from the outlet (7). In the internal combustion engine muffler (1, 1A), a first expansion chamber (21) provided between the inlet (6) and the catalyst portion (4) and into which exhaust gas flows, and a first expansion chamber (21 ) And the second partition wall (12) facing the first partition wall (11), and the exhaust gas that has passed through the catalyst section (4) passes therethrough. A second expansion chamber (22) and a discharge pipe (8) provided adjacent to the second expansion chamber (22) and exhausting the exhaust gas that has passed through the second expansion chamber (22) from the front discharge port (7) And a third expansion chamber (23) defined by the second partition wall (12) and the outer wall (3), and an outlet of the second expansion chamber (22) Between the (12b) and discharge pipe (8), wherein a gas flow path which communicates with the third expansion chamber (23) (P) is formed.

  According to the muffler (1, 1A) for the internal combustion engine, the exhaust gas passes through the catalyst part (4) and the second expansion chamber (22), and then passes through the discharge port (7) of the discharge pipe (8) to the outside. Discharged. A third expansion chamber (23) is provided between the second expansion chamber (22) and the outer wall (3), and high-temperature exhaust gas does not flow into the third expansion chamber (23). Therefore, the surface temperature of the outer wall (3) can be reduced. Furthermore, in this muffler (1, 1A) for the internal combustion engine, the gas flow path (P) communicating with the third expansion chamber (23) is connected to the outlet (12b) of the second expansion chamber (22) and the discharge pipe (8 ). Therefore, this gas flow path (P) adjusts the role of the third expansion chamber (23) or the role of the resonance chamber, and exhibits a silencing effect. In this case, since only the gas flow path (P) is provided between the outlet part (12b) of the second expansion chamber (22) and the discharge pipe (8), the silencing effect is suppressed while suppressing an increase in the number of parts. Can be demonstrated.

  In the internal combustion engine muffler (1, 1A), the outlet part (12b) of the second expansion chamber (22) is a tubular part at least partially disposed in the discharge pipe (8), and the outlet part ( 12b) and an exhaust pipe (8), an annular gas flow path (P) is formed. When exhaust gas is exhausted from the exhaust pipe (8), the inside of the third expansion chamber (23) Negative pressure compared to outside air. According to this configuration, the silencing effect is further enhanced.

  In the muffler (1A) for the internal combustion engine, the outer wall (3) is provided with a ventilation hole (3b), and outside air is taken into the third expansion chamber (23) through the ventilation hole (3b). According to this configuration, the cooling efficiency inside the muffler (1) for the internal combustion engine is increased.

  In the internal combustion engine muffler (1A), the ventilation hole (3b) is provided on the side opposite to the discharge pipe (8) with respect to the third expansion chamber (23). The outside air near the exhaust pipe is relatively hot. As in this configuration, by providing the ventilation hole (3b) on the side opposite to the exhaust pipe, relatively low temperature outside air can be taken into the third expansion chamber (23).

  In the above-described muffler (1A) for the internal combustion engine, a protective cover (14) that covers the catalyst part (4) is provided between the catalyst part (4) and the second partition wall (12). 14) is provided with another gas flow path (14a). According to this configuration, the protection cover (14) protects against sparks. The flow of exhaust gas from the catalyst part (4) to the second expansion chamber (22) can be created by another gas flow path (14a) formed in the protective cover (14).

  According to the present invention, the silencing effect can be exhibited while reducing the surface temperature of the outer wall (3) and suppressing the increase in the number of parts.

1 is a perspective view showing an muffler for an internal combustion engine according to a first embodiment of the present invention. It is a partially broken perspective view of the muffler for internal combustion engines of FIG. It is sectional drawing which shows the muffler for internal combustion engines of FIG. It is sectional drawing which follows the IV-IV line of FIG. It is sectional drawing which shows the muffler for internal combustion engines which concerns on 2nd Embodiment. It is sectional drawing which follows the VI-VI line of FIG. It is sectional drawing which shows the conventional muffler for internal combustion engines. It is sectional drawing which follows the VIII-VIII line of FIG.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  With reference to FIGS. 1-4, the muffler 1 for internal combustion engines of 1st Embodiment is demonstrated. As shown in FIGS. 1 and 2, an exhaust muffler 1 for an internal combustion engine is fixed to an internal combustion engine such as a portable engine (not shown), for example, and exhaust gas that has been silenced through the exhaust gas of the engine flows in. Exhaust the gas. The muffler 1 for an internal combustion engine includes a bowl-shaped muffler body 2 disposed on the exhaust gas inflow side and a bowl-shaped muffler cover (outer wall) 3 disposed on the exhaust gas discharge side and covering the muffler body 2. . The edge of the muffler body 2 and the edge of the muffler cover 3 are joined together to form the outer shape of the muffler 1 for the internal combustion engine.

  The muffler body 2 has a mounting surface portion 2a that faces the exhaust portion of the engine. The outer surface of the mounting surface portion 2a is a flat surface, and an exhaust gas inlet 6 is formed at the center thereof. A seal member such as a gasket is provided between the mounting surface portion 2a and the exhaust portion of the engine. Two bolt holes 10 are provided on both sides of the inlet 6 around the inlet 6. When a fastening bolt is passed through the bolt hole 10 and tightened with respect to the engine, the muffler cover 3 and the muffler body 2 are fastened together with the exhaust part of the engine, and the muffler 1 for the internal combustion engine is fixed to the engine. .

  As shown in FIGS. 2 and 3, a first partition 11 and a protector (second partition) 12 are fixed inside the muffler 1 for an internal combustion engine. The first partition 11 and the protector 12 are fixed by being sandwiched between the edge of the muffler body 2 and the edge of the muffler cover 3 in a state where the peripheral edges thereof overlap each other. The 1st partition 11 is flat form. The protector 12 is fixed to the muffler cover 3 side of the first partition 11. The protector 12 faces the first partition wall 11 and the oxidation catalyst 4 and has a shape that swells toward the muffler cover 3. The protector 12 faces the muffler cover 3 and is disposed between the first partition wall 11 and the muffler cover 3.

  A cylindrical oxidation catalyst (catalyst portion) 4 is provided inside the muffler 1 for an internal combustion engine. The oxidation catalyst 4 is disposed in a circular opening 11 a formed in the first partition wall 11, and its central axis is attached in a direction substantially parallel to the bolt hole 10. The oxidation catalyst 4 burns unburned hydrocarbons in the exhaust gas by passing the exhaust gas from the engine.

  As described above, the first partition 11 is provided around the oxidation catalyst 4. The first partition 11 partitions the inside of the muffler 1 for an internal combustion engine into an inflow side and an outflow side. A first expansion chamber 21 is provided between the first partition wall 11 and the muffler body 2. That is, the first expansion chamber 21 is provided between the inflow port 6 and the oxidation catalyst 4. Exhaust gas flows into the first expansion chamber 21 through the inlet 6. The exhaust gas that has flowed into the first expansion chamber 21 flows out of the first expansion chamber 21 through the oxidation catalyst 4. That is, the muffler body 2 is provided on the inflow side of the first expansion chamber 21, and the first partition 11 is provided on the outflow side of the first expansion chamber 21.

  A second expansion chamber 22 is provided between the first partition wall 11 and the protector 12. That is, the second expansion chamber 22 is defined by the first partition wall 11 and the protector 12. The first expansion chamber 21 and the second expansion chamber 22 communicate with each other through a large number of pores formed in the oxidation catalyst 4. Exhaust gas that has passed through the oxidation catalyst 4 passes through the second expansion chamber 22.

  As shown in FIGS. 2 and 4, a circular tail pipe (discharge pipe) 8 extending in the illustrated horizontal direction is provided at one end 3 a (lower end shown in FIG. 2) of the muffler cover 3. Yes. The tail pipe 8 is provided adjacent to the second expansion chamber 22 and discharges the exhaust gas that has passed through the second expansion chamber 22 from the discharge port 7.

  More specifically, a tubular protector exhaust pipe (exit part) 12b extending in the horizontal direction in the figure is provided at one end 12a (the lower end shown in FIG. 2) of the protector 12. The protector exhaust pipe 12 b discharges exhaust gas from the protector exhaust port 22 a of the second expansion chamber 22.

  The diameter of the protector exhaust pipe 12b is smaller than the diameter of the tail pipe 8, and the tip of the protector exhaust pipe 12b (the end on the downstream side in the exhaust gas discharge direction) is disposed in the tail pipe 8. The tail pipe 8 and the protector exhaust pipe 12b are arranged concentrically. As shown in FIG. 4, the distal end portion of the protector exhaust pipe 12 b slightly enters the proximal end of the tail pipe 8. In the axial direction of the tail pipe 8 and the protector exhaust pipe 12b, the tip of the protector exhaust pipe 12b overlaps the tail pipe 8, and this overlapped portion is an overlap portion A. With such a configuration, an annular gas flow path P is formed between the tail pipe 8 and the protector exhaust pipe 12b.

  A third expansion chamber 23 is provided between the protector 12 and the muffler cover 3. That is, the third expansion chamber 23 is defined by the protector 12 and the muffler cover 3. The third expansion chamber 23 is provided so as to cover the second expansion chamber 22 from the muffler cover 3 side. The third expansion chamber 23 is configured so that the high-temperature exhaust gas that has passed through the oxidation catalyst 4 and the second expansion chamber 22 does not flow.

  As described above, the protector exhaust pipe 12b of the protector 12 and the tail pipe 8 are separated from each other and are not directly joined. Therefore, the gas flow path P formed around the protector exhaust pipe 12 b communicates with the third expansion chamber 23. In other words, the discharge port 7 communicates with the second expansion chamber 22 via the protector exhaust port 22a, and further communicates with the third expansion chamber 23 via the gas flow path P. When the exhaust gas is discharged from the discharge port 7 of the tail pipe 8, the third expansion chamber 23 is configured to have a negative pressure compared to the outside air.

  According to the muffler 1 for the internal combustion engine, the exhaust gas passes through the oxidation catalyst 4 and the second expansion chamber 22 and is then discharged to the outside from the discharge port 7 of the tail pipe 8. A third expansion chamber 23 is provided between the second expansion chamber 22 and the muffler cover 3, and high-temperature exhaust gas does not flow through the third expansion chamber 23. Therefore, the surface temperature of the muffler cover 3 can be reduced. Further, in the internal combustion engine muffler 1, a gas flow path P communicating with the third expansion chamber 23 is formed between the protector exhaust pipe 12 b of the second expansion chamber 22 and the tail pipe 8. This gas flow path P adjusts the role (that is, function) of the third expansion chamber 23 as an expansion chamber or the role (that is, function) of the resonance chamber, and exhibits a silencing effect. In this case, since the gas flow path P is merely provided between the protector exhaust pipe 12b and the tail pipe 8 of the second expansion chamber 22, it can be configured with the same number of parts as the conventional structure. Therefore, a silencing effect can be exhibited while suppressing an increase in the number of parts.

  Further, when the exhaust gas is discharged from the discharge port 7 of the tail pipe 8, the third expansion chamber 23 has a negative pressure compared to the outside air, so that the silencing effect is further enhanced.

  Since the high-temperature exhaust gas contacts the protector 12, the protector 12 becomes high temperature. However, since the third expansion chamber 23 is provided, transmission of radiant heat from the muffler cover 3 to the exterior component is suppressed. Therefore, the temperature rise of the exterior component can be kept low.

  The silencing effect can be adjusted by changing the shape of the overlap portion A described above. More specifically, the back pressure can be adjusted by adjusting the inner diameter of the protector exhaust pipe 12b. Even if the inner diameter of the protector exhaust pipe 12b is made smaller than before, the increase in the back pressure is suppressed and the influence on the output is small. In the muffler 1 for an internal combustion engine, the exhaust noise can be made equal to or higher than that of the conventional structure while increasing the output.

  Regarding the number of parts, the muffler 1 for an internal combustion engine can be configured with the same number of parts as the conventional structure. Therefore, it does not lead to cost increase.

  Next, a muffler 1A for an internal combustion engine according to a second embodiment will be described with reference to FIGS. The difference between the muffler 1A for the internal combustion engine and the muffler 1 for the internal combustion engine of the first embodiment is that a protective cover 14 that covers the oxidation catalyst 4 is provided, and a ventilation hole 3b is provided in the muffler cover 3. . The protective cover 14 is attached to the protector 12 side (that is, the muffler cover 3 side) of the oxidation catalyst 4. The protective cover 14 is a bottomed cylindrical cover, and the opened edge (the engine-side edge) is joined to the first partition wall 11. A gas channel (another gas channel) 14 a communicating with the second expansion chamber 22 is formed in the protective cover 14.

  As shown in FIG. 6, the ventilation hole 3 b is provided on the side opposite to the tail pipe 8 with the third expansion chamber 23 as a reference. The outside air is configured to be taken into the third expansion chamber 23 through the ventilation hole 3b.

  The effect similar to that of the muffler 1 for the internal combustion engine is also obtained by the muffler 1A for the internal combustion engine of the second embodiment. Furthermore, since the outside air is taken into the third expansion chamber 23 through the ventilation holes 3b, the cooling efficiency inside the muffler 1A for the internal combustion engine is increased.

  The outside air in the vicinity where the tail pipe 8 is provided is relatively hot. In the muffler 1 </ b> A for the internal combustion engine, a relatively low temperature outside air can be taken into the third expansion chamber 23 by providing the ventilation hole 3 b on the side opposite to the tail pipe 8.

  The protective cover 14 protects against sparks. A gas flow path 14 a formed in the protective cover 14 can create a flow of exhaust gas from the oxidation catalyst 4 to the second expansion chamber 22.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, the tail pipe 8 and the protector exhaust pipe 12b may not be concentric. The gas flow path P is not limited to an annular shape. It may be a rectangular ring or may be formed in a part of the periphery of the protector exhaust pipe 12b. The overlap portion A may not be provided. That is, the protector exhaust pipe 12 b does not have to enter the tail pipe 8.

  The aspect of the catalyst portion is not limited to the oxidation catalyst 4 described above. You may employ | adopt the ventilation hole 3b of the muffler cover 3 for the muffler 1 for internal combustion engines of 1st Embodiment. The present invention is not limited to being applied to a portable engine, and can be applied to any engine as long as it is an engine using a muffler using a catalyst. That is, it can be applied to general-purpose engines in general.

  DESCRIPTION OF SYMBOLS 1 ... Muffler for internal combustion engines, 3 ... Muffler cover (outer wall), 3b ... Ventilation hole, 4 ... Oxidation catalyst (catalyst part), 6 ... Inflow port, 7 ... Discharge port, 8 ... Tail pipe (discharge pipe), 11 ... 1st partition, 12 ... protector (second partition), 12b ... protector exhaust pipe (outlet), 14 ... protective cover, 14a ... gas flow path, 21 ... first expansion chamber, 22 ... second expansion chamber, 23 ... Third expansion chamber, P: gas flow path.

Claims (5)

An internal combustion engine having a catalyst part (4) inside, and configured such that exhaust gas flows from the inlet (6), passes through the catalyst part (4), and is then discharged from the outlet (7). For muffler (1,1A)
A first expansion chamber (21) provided between the inlet (6) and the catalyst part (4) and into which the exhaust gas flows;
The catalyst section (4) is defined by a first partition wall (11) provided on the outflow side of the first expansion chamber (21) and a second partition wall (12) facing the first partition wall (11). A second expansion chamber (22) through which the exhaust gas that has passed through;
A discharge pipe (8) provided adjacent to the second expansion chamber (22) and discharging the exhaust gas that has passed through the second expansion chamber (22) from a front discharge port (7);
A third expansion chamber (23) defined by the second partition wall (12) and the outer wall (3),
A gas flow path (P) communicating with the third expansion chamber (23) is formed between the outlet (12b) of the second expansion chamber (22) and the discharge pipe (8). A muffler for an internal combustion engine. The outlet part (12b) of the second expansion chamber (22) is a tubular part at least partially disposed in the discharge pipe (8), and the outlet part (12b) and the discharge pipe (8). An annular gas flow path (P) is formed between
The muffler for an internal combustion engine according to claim 1, wherein when the exhaust gas is exhausted from the exhaust pipe (8), the third expansion chamber (23) has a negative pressure compared to the outside air. The outer wall (3) is provided with a ventilation hole (3b),
The muffler for an internal combustion engine according to claim 1 or 2, wherein outside air is taken into the third expansion chamber (23) through the ventilation hole (3b).   The muffler for an internal combustion engine according to claim 3, wherein the ventilation hole (3b) is provided on a side opposite to the discharge pipe (8) with respect to the third expansion chamber (23). .   A protective cover (14) that covers the catalyst part (4) is provided between the catalyst part (4) and the second partition wall (12). The muffler for an internal combustion engine according to any one of claims 1 to 4, wherein a gas flow path (14a) is formed.

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