JP4671899B2 - Internal combustion engine with intake silencer - Google Patents

Description

  The present invention relates to an internal combustion engine including an intake device including an intake silencer that forms an expansion chamber, and the internal combustion engine is used in, for example, an outboard motor.

An intake device for an internal combustion engine is known that includes an intake silencer that forms an expansion chamber in order to reduce intake noise (see, for example, Patent Documents 1 and 2). An intake device for an internal combustion engine that includes an intake silencer provided with a resonance chamber in addition to the intake silencer is also known (see, for example, Patent Document 3).
JP 2001-165012 A JP 2000-145594 A JP-A-2-49963

  If the intake silencer that forms the expansion chamber (hereinafter referred to as “expansion silencer” for the sake of convenience) alone does not provide a sufficient silencing effect for intake noise in a specific frequency range, a resonance chamber is further formed. An intake silencer (hereinafter referred to as “resonance silencer” for convenience) is also used. However, if the expansion silencer and the resonance silencer are provided separately, the intake silencer becomes large. For this reason, it is difficult to compactly arrange the intake silencer in a machine that is being made compact to the limit, such as an outboard motor.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the size of an intake silencer that combines expansion-type noise reduction and resonance-type noise reduction. . A second object of the present invention is to obtain an intake device that can be applied to reduce intake noise in various frequency ranges, and to enhance the silencing effect by resonance-type silencing when using an expansion chamber. Further, an object of the present invention is to enhance the silencing effect without complicating the shape of the intake silencer.

The invention according to claim 1 is an air having an intake silencer that forms an expansion chamber into which air from an intake inlet flows in, an inflow port through which the air in the expansion chamber flows in, and an outflow port through which the air toward the combustion chamber flows out. In an internal combustion engine including an intake device including a passage forming body that forms a passage, the passage forming body includes a passage wall that partitions the expansion chamber and the air passage in the intake silencer, and the passage wall includes A communication hole for communicating the expansion chamber and the air passage in order to cause the expansion chamber to function as a resonance chamber; and the intake inlet of the intake silencer and the inflow port of the passage forming body are: Each of the openings opens side by side on a substantially parallel virtual plane, and the inflow direction of air to the intake inlet and the inflow inlet is substantially opposite, and the flow of air flowing into the expansion chamber from the intake inlet is the flow of the air. Flows into the entrance An internal combustion engine, characterized in that it is formed to be bent once in the expansion chamber until.

  According to this, since the expansion chamber can be used as a resonance chamber by the communication hole provided in the passage wall that partitions the expansion chamber and the air passage, it is not necessary to provide the expansion chamber and the resonance chamber separately, and the expansion type The silencing effect of the intake noise is improved by the combination of silencing and resonance type silencing.

  According to a second aspect of the present invention, in the internal combustion engine according to the first aspect, the passage forming body is connected to the intake silencer, extends from the connection portion in the expansion chamber, and the inflow port. And the passage wall is a tube wall of the inner tube portion, and the inner tube portion has a communication hole at a central portion of the expansion chamber with respect to the connection portion. It has a curved pipe part bent in the approaching direction.

  According to this, since the inner pipe portion is bent in the expansion chamber, the length of the inner pipe portion arranged in the expansion chamber can be increased while maintaining the compactness of the intake silencer. By adjusting the pipe length, it is possible to diversify the frequency range of the intake noise that can provide a silencing effect. In addition, since the communication hole is arranged close to the center of the expansion chamber by utilizing the bending of the inner pipe portion, the air passage at the connection portion that is also the intake outlet in the intake silencer The expansion chamber can be effectively used as a resonance chamber regardless of the position.

According to a third aspect of the present invention, in the internal combustion engine according to the second aspect, the bent pipe portion is bent at an angle of approximately 90 ° with respect to the connecting portion.
According to this, since the intake noise is transmitted to the expansion chamber after hitting the bent pipe portion bent at approximately 90 °, the number of bent intake pulsations in the intake silencer is increased by the amount of the bent pipe portion. Intake noise emitted from the intake inlet is reduced.

According to invention of Claim 1, the following effect is show | played. In other words, since the silencer by the resonance type silencer can be performed by using the intake silencer that forms the expansion chamber, a compact intake silencer in which the noise reduction effect of the intake noise is enhanced can be obtained.
According to the second aspect of the present invention, the degree of freedom in adjusting the pipe length of the inner pipe portion arranged in the expansion chamber is increased, and the intake noise in various frequency ranges can be reduced while maintaining the compactness of the intake silencer. An applicable intake device is obtained. In addition, since the inner tube portion is bent, the communication hole can be disposed near the center portion of the expansion chamber, so that the effect of resonance-type silencing using the expansion chamber can be enhanced and the silencing effect is improved.
According to the third aspect of the present invention, since the number of bendings of the intake pulsation can be increased using the inner pipe portion, the silencing effect can be enhanced without complicating the shape of the intake silencer.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIG. 1, an internal combustion engine to which the present invention is applied is provided in an outboard motor S as a marine propulsion device. The outboard motor S supports the internal combustion engine E with an internal combustion engine E having a crankshaft 26 having a rotation center line oriented in the vertical direction, a power transmission device for transmitting the power of the internal combustion engine E to the propeller 12, and an upper end portion. Mount case 1, an extension case 3 coupled to the mount case 1 via an oil case 2 coupled to the lower end of the mount case 1, a gear case 4 coupled to the lower end of the extension case 3, and a vertical direction The under cover 5 that covers the periphery from the lower part of the internal combustion engine E to the upper part of the extension case 3 including the mount case 1 and the oil case 2, and the engine that is coupled to the upper end of the under cover 5 and covers the internal combustion engine E from above A cover 6.
In the embodiment, the up, down, front, back, left, and right are up, down, front, back, left, and right when the outboard motor S is mounted on the hull 18.

  The power transmission device includes a drive shaft 9 coupled to the lower end portion of the crankshaft 26 so as to be integrally rotatable with the flywheel 8, a forward / reverse switching device 10 housed in the gear case 4 and having a bevel gear mechanism, and a propeller 12 And a propulsion shaft 11 attached thereto. The drive shaft 9 extends downward from the mount case 1 through the extension case 3 and reaches the gear case 4, and is connected to the propulsion shaft 11 via the forward / reverse switching device 10 at the lower end thereof. The forward / backward switching of the hull 18 by the forward / reverse switching device 10 is performed by rotating a shift rod 13 inserted through a swivel shaft 14 described later. The power of the internal combustion engine E is transmitted to the propeller 12 through the crankshaft 26, the drive shaft 9, the forward / reverse switching device 10 and the propulsion shaft 11, and the propeller 12 is rotationally driven.

  The mounting device provided in the outboard motor S includes a swivel shaft 14 provided with an operation portion 14a, a swivel case 15 that rotatably supports the swivel shaft 14, and a tilt shaft that rotatably supports the swivel case 15. And a bracket 17 that holds 16 and is fixed to the rear end of the hull 18. The swivel shaft 14 is fixed to the mount case 1 via a mount rubber 19a at its upper end, and is fixed to the extension case 3 via a mount rubber 19b at its lower end. The outboard motor S attached to the hull 18 by this attachment device can swing in the vertical direction about the tilt shaft 16 and can swing in the left-right direction about the swivel shaft 14.

  Referring also to FIG. 2, an internal combustion engine E, which is an in-line four-cylinder four-stroke internal combustion engine, includes a cylinder block 20 in which four cylinders 20 a are integrally formed, and a crankcase 21 that is coupled to the front end of the cylinder block 20. The engine body includes a cylinder head 22 coupled to the rear end portion of the cylinder block 20 and a head cover 23 coupled to the rear end portion of the cylinder head 22.

  Pistons 24 fitted to the respective cylinders 20a so as to be able to reciprocate are connected to a crankshaft 26 via connecting rods 25. The cylinder head 22 is formed with a combustion chamber 27 that faces the piston 24 and an intake port and an exhaust port that open to the combustion chamber 27. An intake valve and an exhaust valve that are driven to open and close by an overhead camshaft type valve gear that includes a camshaft 28 that is rotationally driven by the crankshaft 26 via a transmission mechanism 28, respectively, the intake port and the exhaust port are connected to the crankshaft. Opens and closes in synchronization with 26 rotations.

  In the internal combustion engine E disposed in the engine room 7 covered and formed by the under cover 5 and the engine cover 6, the intake device K that guides the combustion air to the combustion chamber 27 and the air-fuel mixture in the combustion chamber 27 are combusted. And an exhaust system provided with passages H1 and H2 for guiding the generated combustion gas to the outside of the outboard motor S. Then, the intake air flowing through the intake passage provided in the intake device K is mixed with fuel supplied from a fuel injection valve as an air-fuel mixture forming means attached to the cylinder head 22 to form an air-fuel mixture. After the air is sucked into the combustion chamber 27 through the intake port, it is ignited by the spark plug and burned. The piston 24 driven by the pressure of the generated combustion gas and reciprocatingly drives the crankshaft 26 via the connecting rod 25. The combustion gas flows out from the combustion chamber 27 through the exhaust port to the exhaust passage H1 provided in the cylinder head 22 and the cylinder block 21 as exhaust gas, and further in the mount case 1, the extension case 3, and the gear case. 4 and through the exhaust guide passage H2 provided in the boss of the propeller 12, it is discharged to the outside of the outboard motor S.

  The intake device K disposed in the engine room 7 sucks a part of the outside air that has flowed into the engine room 7 from an air intake port 6 a provided in the engine cover 6 as combustion air. The intake device K forms an air passage 45 having an intake silencer 30 that forms an expansion chamber 33 as a silencer chamber into which air from the intake inlet 34 flows, and an inlet 46 into which air in the expansion chamber 33 flows. A connecting pipe 40 as a passage forming body, one throttle valve device 50 connected to the intake silencer 30 via the connecting pipe 40, and connected to the throttle valve device 50 at the upstream end and at the downstream end An intake manifold 60 connected to the cylinder head 22 having an inlet port of the intake port. The intake manifold 60 has one collecting portion 60a connected to the throttle valve device 50, and four branch pipes 60b branched from the collecting portion 60a and connected to the intake port belonging to each cylinder 20a.

  Referring to FIGS. 2 to 7, an intake silencer 30 provided with an intake port 34 which is an intake port for outside air in the intake device K includes a first case 31 and a second case 32 which are divided into left and right parts. , 32 and the hollow columnar coupling portions 31b and 32b located substantially at the center are integrally coupled by thermal welding. Both the cases 31 and 32 constituting the wall of the intake silencer 30, that is, the chamber walls W 1 and W 2 of the expansion chamber 33, are composed of thin members made of synthetic resin, and are provided on the inner surface of the reinforcing ribs that intersect each other. Reinforced by 231c and 32c. The intake silencer 30 is attached to the crankcase 21 at a plurality of attachment portions 31e provided on the case 31 by a fastening structure or a locking structure using bolts.

  Referring to FIGS. 2, 3, 5, and 6, the throttle valve device 50 is arranged in the intake body 55 and a throttle body 51 as a body in which an intake passage 55 through which air from the air passage 45 flows is formed. The throttle valve 52 that controls the intake air amount and the throttle operation mechanism 53 that opens and closes the throttle valve 52 are provided. The throttle valve 52 is constituted by a butterfly valve having a valve shaft 52a rotatably supported by the throttle body 51 and a valve body 52b attached to the valve shaft 52a. The throttle operating mechanism 53 includes an operating lever 53b that operates an operating arm 53a fixed to the valve shaft 52a, and a return spring 53c that biases the throttle valve 52 in the valve closing direction. When the driver operates the throttle lever, the operating arm 53a is operated via the operating lever 53b that rotates in conjunction with the throttle lever, and the throttle valve 52 is opened and closed. The opening degree of the throttle valve 52 is detected by a throttle opening degree sensor 54 and used for controlling the amount of fuel supplied from the fuel injection valve.

  3 to 7, the intake silencer 30 is provided with a first portion 30 </ b> U in which an intake inlet 34 is provided, a fitting portion 35 to which a connection pipe 40 is connected, and an inner pipe portion 42 to be described later. Second portion 30D. In this embodiment, the first part 30U and the second part 30D are arranged in an expansion chamber 33 having an intake inlet 34 and are made of a wire mesh having a flame extinguishing function to prevent backfire from reaching the intake inlet 34. It is divided by frame arrester F.

A first portion 30U formed on the case 31 and positioned above the intake silencer 30 constitutes a protruding portion in the intake silencer 30, and is the same as the direction in which the throttle body 51 protrudes from the intake silencer 30. In the direction, it protrudes substantially parallel to the intake passage 55. Therefore, the first portion 30U is provided using a space formed by the throttle body 51 protruding from the intake silencer 30. The first portion 30U forms a columnar space having an axis substantially parallel to the center line Lt or the left-right direction of the intake passage 55, and communicates with the second portion 30D through an opening that opens in the direction of the axis. The intake inlet 34 provided at the lower portion of the first portion 30U opens to a flat plate-like chamber wall portion W1a substantially parallel to the center line Lt of the intake passage 55 in the radial direction of the intake passage 55. The chamber wall portion W1a that constitutes the bottom wall of the first portion 30U has a bottom surface W1a1 (see FIG. 3) formed of an inclined surface facing slightly forward, and faces the throttle body 51 in the radial direction and has an inlet 46. Is almost parallel to. The intake port 34 that opens to the bottom surface W1a1 is open obliquely downward and forward.
In the specification or claims, the radial direction means a radial direction centering on the center line L of the air passage 45 and the center line Lt of the intake passage 55, and the circumferential direction means the center line L. , Lt in the circumferential direction. In this embodiment, the center lines Lb, Lc, Lt are substantially parallel to the left-right direction.

  The second portion 30D formed by the cases 31 and 32 includes a fitting portion 35 as a connection portion with the connection pipe 40 in the intake silencer 30 and a peripheral member disposed in the vicinity of the intake silencer 30. The case 31 is provided with recesses 36 and 37 that avoid interference with the crankcase 21 and the throttle operation mechanism 53.

  The fitting portion 35 located below the intake silencer 30 and below the first portion 30U is a circular opening provided in a flat chamber wall portion W1c that is substantially parallel to the vertical direction and substantially orthogonal to the horizontal direction. It is comprised from the peripheral part of the chamber wall part W1c which prescribes | regulates the fitting hole 35a which consists of. The fitting hole 35a and the fitting portion 35 substantially coincide with the center line Lt of the intake passage 55 and the center lines Lb and Lc of the air passage portions 45b and 45c formed by the connecting portion 41 and the outer tube portion 43 described later. The center line is substantially located on a plane orthogonal to the center line Lb.

Referring to FIGS. 3, 4, and 7, the intake silencer 30 includes the first portion 30 </ b> U and the fitting portion as viewed from the directions of the center lines Lb, Lc, and Lt (hereinafter referred to as “center line direction”). 35 an area 30 ₁ which is housed the inner tube portion 42 is provided with a main chamber 33a, which accounts for more than half of the volume of the expansion chamber 33 with recesses 36 and 37 is a portion that protrudes toward the expansion chamber 33 is provided The region 302 is divided into _two in the front-rear direction. The recesses 36 and 37 extend substantially along a direction in which the first portion 30U and the fitting portion 35 are arranged in parallel (hereinafter referred to as “arrangement direction”, which is the vertical direction in this embodiment). Yes. Of these, the recess 36 is for avoiding interference with the crankcase 21 (see also FIG. 2), and the recess 37 is for avoiding interference with the rotating throttle arm (FIG. The position of the throttle lever when the throttle valve 52 is fully opened is indicated by a two-dot chain line) (see also FIG. 2). Further, in a part region 30 _2, protrusion 38 which protrudes from the recess 36 like eaves is partitioned from the first portion 30U by the partition walls W1d (see also FIG. 5) as well as adjacent to the first portion 30U Provided. The protrusion 38 increases the volume of the second portion 30D and enhances the silencing effect of the expansion chamber 33.

  Of the chamber wall W1, a step wall W1e, which is a chamber wall portion formed by the recess 36, is substantially parallel to the arrangement direction when viewed from the center line direction (in this embodiment, in a plane perpendicular to the front-rear direction). (Substantially parallel) and extends in the center line direction from the chamber wall portion W1c to the center of the inlet 46 and the straight pipe portion 42b described later (see FIG. 5). A part of the step wall W1e constitutes a guide wall W1e1. The guide wall W1e1 is a portion of the stepped wall W1e that extends beyond the inlet 46 and the inlet 34 in the arrangement direction. The air flowing in from the intake port 34 is restricted from flowing toward the recesses 36 and 37 away from the inflow port 46 by the guide wall W1e1 located upstream from the inflow port 46. Guided.

Referring to FIGS. 2 to 7, a circular connecting pipe 40 integrally formed of an elastic material having rubber elasticity, for example, synthetic rubber, is disposed between the intake silencer 30 and the throttle valve device 50, and both are connected. At the same time, an air passage 45 that guides the air in the expansion chamber 33 to the intake passage 55 is formed. The connecting pipe 40 is inserted into the fitting hole 35a to be fitted into the fitting part 35, and the inner pipe part 42 extending from the connecting part 41 in the expansion chamber 33 with the connecting part 41 as a boundary. And an outer tube portion 43 extending from the connection portion 41 outside the expansion chamber 33. An upstream end portion 51a of the throttle body 51 is fitted into a downstream end portion 43a as a connecting portion with the throttle valve device 50 in the outer pipe portion 43, and an outer periphery of the downstream end portion 43a is clamped by a clamp 49 as a fixture. The connecting pipe 40 and the throttle body 51 are connected by being tightened. On the outer peripheral surface of the connecting pipe 40, a reinforcing rib 40c1 along the circumferential direction and a reinforcing rib 40c2 along the center line L are provided. Further, the downstream end 43a forms an outlet 47 of the air passage 45, and air flowing from the outlet 47 to the combustion chamber 27 through the intake passage 55 and the intake manifold 60 flows out.
The intake passage of the intake device K is a passage formed by the connecting pipe 40, the throttle body 51, and the intake manifold 60, and the air passage 45 and the intake passage 55 constitute a part of the intake passage.

  The connecting portion 41 that fits inside the fitting portion 35 has an annular shape as a pair of side wall portions that form an annular fitting groove 41c that is a groove into which the fitting portion 35 fits on the outer peripheral surface thereof. The flanges 41a and 41b and a pair of engaging portions 41e as positioning portions for setting the circumferential position of the connecting portion 41 with respect to the intake silencer 30 are provided. The pair of annular flanges 41a and 41b are constituted by an internal flange 41a and an external flange 41b arranged inside the expansion chamber 33 and outside the expansion chamber 33, respectively.

  On the outer rod 41b, which is one of the rods 41a and 41b, both engaging portions 41e are formed as a pair of projecting portions projecting radially at positions facing each other in the diametrical direction. On the other hand, the intake silencer 30 is provided with a pair of engaging portions 39 that engage with the engaging portions 41e. Each engaging portion 39 as a positioning portion in the intake silencer 30 is formed by a pair of protruding portions 39a and 39b protruding from the outer surfaces of the chamber walls W1 and W2 so that the engaging portion 41e is fitted. Consists of recesses. Each engaging portion 39 is open in the insertion direction of the connecting pipe 40 into the fitting hole 35a when the connecting pipe 40 is connected to the intake silencer 30.

  Then, by engaging the corresponding engaging portions 41e and 39, the position of the connecting portion 41 in the circumferential direction with respect to the intake silencer 30 is set, and the position in the bending direction described later with respect to the intake silencer 30 is set. In addition, the connection pipe 40 is prevented from rotating in the circumferential direction with respect to the intake silencer 30. Therefore, both the engaging portions 41e and 39 are also a rotation stop portion of the connecting pipe 40.

  In the second portion 30D, the inner pipe portion 42 bent in the direction in which the inlet 46 approaches the intake inlet 34 with respect to the connection portion 41 has an inlet 46 at an angle of approximately 90 ° from the connection portion 41. The curved pipe portion 42a is bent in a direction approaching 34, and the straight pipe portion 42b extends linearly from the upstream end of the curved pipe portion 42a in a tangential direction substantially parallel to the chamber wall portion W1. The pipe wall 42w of the inner pipe part 42 is a passage wall that partitions the expansion chamber 33 and the air passage 45 in the intake silencer 30, and the pipe wall 42w expands to function as the resonance chamber 33 as a resonance chamber. A communication hole 44 for communicating the chamber 33 and the air passage 45 is provided. The inflow port 46 is formed by the upstream end portion 42b1 (see FIG. 6) of the straight pipe portion 42b.

  The inlet 46 and the intake inlet 34 are aligned in the bending direction of the inner pipe portion 42 (see FIG. 4), and the inlet 46 and the intake inlet 34 that open on a plane substantially parallel to each other are straight pipes. The air passage 45 in the portion 42b is in a close position in the direction of the center line La of the air passage portion 45a1 or in the direction of the main flow of air flowing into the inlet 46. Further, the direction of the main flow of air between the intake inlet 34 and the inlet 46 is almost opposite. Therefore, the intake air pulsation from the intake passage 55 is bent once at the curved pipe portion 42a in the connection pipe 40, and is bent once between the inlet 46 and the first portion 30U in the second portion 30D. By bending once toward the intake inlet 34 at 30U, it is bent at least three times before reaching the intake inlet 34 from the air passage 45, so that intake noise emitted from the intake inlet 34 is reduced.

  The communication hole 44 opens toward the main chamber 33a, and is closer to the intake inlet 34 in the radial direction of the center line Lb than the center line Lb of the air passage portion 45b, which is the air passage 45 in the connection portion 41. In this embodiment, the air passage portion 45b is closer to the intake port 34 in the radial direction. For this reason, the curved pipe portion 42a bends in a direction in which the communication hole 44 approaches the central portion of the expansion chamber 33 with respect to the connection portion 41. The air passage portion 45 c is a passage through which the air in the expansion chamber 33 flows out of the intake silencer 30, and is also an intake outlet in the intake silencer 30.

  The communication hole 44 is provided in the reinforcing ribs 40c1 and 40c2 constituting the thick part of the connecting pipe 40, and at the intersection of both rib ribs 40c1 and 40c2, so that the connecting pipe 40 is made of the elastic material, The strength reduction of the connecting pipe 40 due to the provision of the communication hole 44 is prevented. The communication hole 44 provides a silencing effect that combines expansion-type silencing and resonance-type silencing in the expansion chamber 33 that also serves as a resonance chamber in one intake silencer 30.

Further, the tube length or passage length of the outer tube portion 43 is shorter than the tube length or passage length of the inner tube portion 42. Therefore, the throttle body 51 can be disposed in the vicinity of the intake silencer 30. Further, the passage length of the air passage portion 45a formed by the inner pipe portion 42 is set so that an intake pulsation node causing the intake noise is located at or near the inlet 46 in order to reduce intake noise in a specific frequency range. Set to be located.
Here, the pipe length or the passage length is the length on the center line of the intake passage.

  Since the connection part 41 and the outer pipe part 43 are composed of a continuous straight pipe part 42b, the connection part 41 and the outer pipe part 43 have center lines Lb and Lc made of the same straight line as the center line Lt of the intake passage 55, and are arranged coaxially. . Therefore, when the engaging portions 41e and 39 that also serve as the rotation stop portions are not provided, the connection pipe 40 is rotated at the fitting portion 35 of the intake silencer 30 to thereby connect the connection pipe 40 to the intake silencer 30. Even if the bending direction is changed, the position of the throttle body 51 with respect to the connecting pipe 40 is kept unchanged. Therefore, in this case, the connection pipe 40 can change the position of the connection portion 41 in the circumferential direction with respect to the intake silencer 30 without changing the relative position of the throttle body 51 with respect to the intake silencer 30. Accordingly, the position of the inlet 46 in the expansion chamber 33 can be adjusted, and the bending direction can be set to a position where the silencing effect is optimal.

  When connecting the intake silencer 30 and the connection pipe 40, first, the fitting hole is deformed so that the straight pipe portion 42b having substantially the same outer diameter as the fitting hole 35a is slightly reduced in diameter. After that, the inner tube portion 42 is inserted into the expansion chamber 33 until the fitting groove 41c and the fitting portion 35 are fitted. Then, the connecting portion 41 is fitted into the fitting portion 35 in a slightly elastically deformed state, and the connection is completed. Further, when removing the connection pipe 40 from the intake silencer 30, the connection part 41 is deformed so as to reduce the diameter, and after the fitting state with the fitting part 35 is released, the connection part 41 and the inner pipe part 42 are removed. Is pulled out from the fitting hole 35a. In this way, the connection part 41 is detachably connected to the intake silencer 30 at the fitting part 35.

Next, operations and effects of the embodiment configured as described above will be described.
In the intake device K, the connecting pipe 40 has a pipe wall 42w as a passage wall that partitions the expansion chamber 33 and the air passage 45 in the intake silencer 30, and the pipe wall 42w includes an inlet 46, an expansion chamber 33, and the like. In order to allow the expansion chamber 33 and the air passage 45 to communicate with each other, the expansion hole 33 can be used as a resonance chamber by the communication hole 44. Are not separately provided, and the effect of silencing intake noise is improved by a combination of expansion-type silencing and resonance-type silencing. As a result, it is possible to mute by resonance mute using the intake muffler 30 that forms the expansion chamber 33, so that a compact intake muffler 30 with improved noise muffling effect can be obtained.

  The connection pipe 40 has a connection part 41 connected to the intake silencer 30 and an inner pipe part 42 extending in the expansion chamber 33, and the inner pipe part 42 has a communication hole 44 with respect to the connection part 41. By having the bent pipe part 42a bent in the direction approaching the center part of 33, the inner pipe part 42 is bent in the expansion chamber 33, so that the compactness of the intake silencer 30 is maintained and the inside of the expansion chamber 33 is maintained. The length of the inner pipe portion 42 arranged in the inner pipe portion 42 can be increased, and the frequency range of the intake noise that can provide a silencing effect by adjusting the tube length of the inner pipe portion 42 can be diversified. In addition, since the communication hole 44 is disposed close to the central portion of the expansion chamber 33 by utilizing the bending of the inner pipe portion 42, the air passage portion at the connection portion 41 that is also the intake outlet in the intake silencer 30 Regardless of the position of 45b in the intake silencer 30, the expansion chamber 33 can be effectively used as a resonance chamber. As a result, the degree of freedom of adjustment of the pipe length of the inner pipe portion 42 disposed in the expansion chamber 33 is increased, and the intake silencer 30 can be applied to reduce intake noise in various frequency ranges while maintaining compactness. An intake device K is obtained. Moreover, since the inner pipe portion 42 is bent, the communication hole 44 can be disposed near the center of the expansion chamber 33, so that the effect of resonance-type noise reduction using the expansion chamber 33 can be enhanced, and the noise reduction effect can be achieved. improves.

  Since the bent pipe portion 42a is bent at an angle of about 90 ° with respect to the connection portion 41, intake noise is transmitted to the expansion chamber 33 after hitting the bent pipe portion 42a bent at about 90 °. In addition, the number of times the intake pulsation bends in the intake silencer 30 increases by the amount of the curved pipe portion 42a, and intake noise emitted from the intake inlet 34 is reduced. As a result, the number of bends of the intake pulsation can be increased by using the inner pipe portion 42, so that the silencing effect can be enhanced without complicating the shape of the intake silencer 30.

  In the intake device K, the connection pipe 40 connecting the intake silencer 30 and the throttle body 51 is formed of an elastic material having rubber elasticity, and the connection pipe 40 is internally fitted to the fitting portion 35 of the intake silencer 30. A connecting part 41, an inner pipe part 42 extending in the expansion chamber 33 with the connection part 41 as a boundary, and an outer pipe part 43 extending outside the expansion chamber 33, to which the throttle body 51 is connected. The pipe length of the outer pipe portion 43 is shorter than the pipe length of the inner pipe portion 42, so that the connection pipe 40 made of an elastic material having rubber elasticity is connected to the intake silencer 30 from the engine body via the throttle valve device 50. Is suppressed, and the vibration of the intake silencer 30 is reduced. Further, since the pipe length of the outer pipe portion 43 is shorter than the pipe length of the inner pipe portion 42, the intake silencer 30 and the throttle valve device 50 can be disposed close to each other. And the passage length of the inner pipe portion 42 in the intake silencer 30 can be increased, and the enlargement of the intake device K by increasing the passage length of the intake passage is avoided. Is done. As a result, the noise caused by the vibration of the intake silencer 30 is reduced, and the intake silencer 30 and the throttle valve device 50 can be compactly arranged. In addition, the intake silencer is avoided while increasing the size of the intake device K. This can be applied to increase in engine output by adjusting the passage length of the inner pipe portion 42 in the vessel 30 and to reduce intake noise in various frequency ranges.

  The inner pipe part 42 is bent in a direction approaching the intake inlet 34, and the inner pipe part 42 is bent because the inlet 46 and the intake inlet 34 of the air passage 45 are arranged in the bending direction of the inner pipe part 42. Therefore, it is possible to increase the length of the passage while maintaining the compactness of the intake silencer 30 as compared with the case where the pipe extends linearly in the intake silencer 30, and further, the intake inlet 34 in the bending direction. Therefore, the air flow from the inlet port 34 to the inlet port 46 becomes relatively simple, and the ventilation resistance in the intake silencer 30 is reduced. As a result, while maintaining the compactness of the intake silencer 30, the degree of freedom in adjusting the passage length of the inner pipe portion 42 for increasing the engine output and reducing the intake noise can be increased, and the intake efficiency is further improved. Can be improved.

  The connection portion 41 has an inner flange 41a and an outer flange 41b that form a fitting groove 41c into which the fitting portion 35 is fitted on the outer peripheral surface thereof, and the outer flange 41b has a connection portion 41 to the intake silencer 30. In order to connect the intake silencer 30 and the connecting pipe 40 by providing an engaging portion 41e which is a positioning portion for setting the position in the bending direction with respect to the intake silencer 30 by setting the position in the circumferential direction This eliminates the need for a fastener such as a clamp and reduces costs. In addition, by using the external flange 41b that forms the fitting groove 41c, the bending direction of the inner pipe portion 42 with respect to the intake silencer 30 can be easily set to an optimal position from the viewpoint of intake noise, etc. The effect of reducing the intake noise can be optimized by setting the bending direction of the connecting pipe 40 within 30.

  By using the space formed by the throttle body 51 projecting from the intake silencer 30, the first portion 30U is provided, so that the space between the intake silencer 30 and the throttle valve device 50 is utilized. Since the volume of the expansion chamber 33 can be increased, this also contributes to the improvement of the silencing effect while maintaining a compact arrangement of the intake silencer 30 and the throttle valve device 50.

  Since the intake silencer 30 can be arranged close to the engine body and the throttle operation mechanism 53 by the recesses 36 and 37 provided in the intake silencer 30, the intake silencer 30 can be compactly arranged in the outboard motor S.

  By the guide wall W1e1 formed by using a part of the step wall W1e formed by the recess 36, the air from the intake inlet 34 is guided to flow toward the inlet 46 of the inner pipe portion 42. Since the air flowing in from the intake inlet 34 is deflected toward the inlet 46, the intake efficiency is improved.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
The throttle valve device may be a carburetor as an air-fuel mixture forming means including a throttle valve.
The positioning part may have only a positioning function for setting the bending direction of the inner tube part 42 without also serving as a locking part. In this case, both positioning parts are arranged around the connection part 41. It may be configured by a combination of a scale and a mark indicating a position in the direction, and position adjustment in the bending direction may be possible.
The positioning part may be provided on the inner rod 41a.
The connecting pipe is formed of an integrally molded member, but may be formed of a member integrated by combining a plurality of members.
When the connecting pipe is not formed from the elastic body, at least the inner pipe portion 42 may be integrally formed with the intake silencer, and in that case, a part of the air passage may be formed by the chamber wall.
The connection pipe has two or more curved pipe parts so that it bends at least twice in the air passage before reaching the intake inlet from the air passage and bends three times or more in the expansion chamber until it reaches the intake inlet. And an air silencer may be configured.
The internal combustion engine may be provided in a marine propulsion device other than the outboard motor or a machine (for example, a vehicle) other than the marine propulsion device.

1 is a schematic right side view of an outboard motor including an internal combustion engine to which the present invention is applied. It is principal part sectional drawing in the II-II line | wire of FIG. FIG. 3 is a right side view of a main part as viewed in the direction of arrow III in FIG. It is principal part sectional drawing in the IV-IV line of FIG. It is principal part sectional drawing in the VV line | wire of FIG. It is principal part sectional drawing in the VI-VI line of FIG. (A) is principal part sectional drawing in the VII-VII line of FIG. 6, (B) is bb sectional view taken on the line of (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mount case, 2 ... Oil case, 3 ... Extension case, 4 ... Gear case, 5 ... Under cover, 6 ... Engine cover, 7 ... Engine room, 8 ... Flywheel, 9 ... Drive shaft, 10 ... Forward / reverse switching device 11 ... Propeller shaft, 12 ... Propeller, 13 ... Shift rod, 14 ... Swivel shaft, 15 ... Swivel case, 16 ... Tilt shaft, 17 ... Bracket, 18 ... Hull, 20 ... Cylinder block, 21 ... Crankcase, 22 ... Cylinder head, 23 ... Head cover, 24 ... Piston, 25 ... Connecting rod, 26 ... Crankshaft, 27 ... Combustion chamber, 28 ... Transmission mechanism, 29 ... Camshaft, 30 ... Intake silencer, 31, 32 ... Case, 33 ... Expansion Chamber 34, intake inlet 35, fitting portion 36, 37 recess, 38, protrusion 40, connection pipe 41, connection portion 42, inner tube portion 43, outer tube portion 44, communication hole , 45 ... Air passage, 46 ... Inlet, 47 ... Outlet, 49 ... Clamp, 50 ... Slot Water valve device, 51 ... Throttle body, 52 ... Throttle valve, 53 ... Throttle operation mechanism, 54 ... Throttle opening sensor, 55 ... Intake passage, 60 ... Intake manifold,
S ... Outboard motor, E ... Internal combustion engine, K ... Intake device, H1, H2 ... Passage, F ... Flame arrester, L, La, Lb, Lc, Lt ... Center line.

Claims (3)

An air intake silencer (30) that forms an expansion chamber (33) into which air from the intake air inlet (34) flows, and an air flow toward the inlet (46) and the combustion chamber into which the air (33) in the expansion chamber flows In an internal combustion engine comprising an intake device comprising a passage forming body that forms an air passage (45) having an outlet (47) that flows out,
The passage forming body has a passage wall (42w) that partitions the expansion chamber (33) and the air passage in the intake silencer (30), and the passage wall (42w) includes the expansion chamber (33 ) To function as a resonance chamber, a communication hole (44) for communicating the expansion chamber (33) and the air passage (45) is provided ,
The intake inlet (34) of the intake silencer (30) and the inlet (46) of the passage forming body are opened side by side on a substantially parallel virtual plane, and the intake inlet (34) The inflow direction of air to the inflow port (46) is almost opposite, and the flow of air that has flowed into the expansion chamber (33) from the intake port (34) flows into the inflow port (46). An internal combustion engine formed so as to be bent once in the expansion chamber (33) .   The passage forming body includes a connection portion (41) connected to the intake silencer (30), and extends from the connection portion (41) in the expansion chamber (33) and the inflow port (46). A connecting pipe (40) having an inner pipe part (42) provided, the passage wall (42w) is a pipe wall of the inner pipe part (42), and the inner pipe part (42) is the communication hole. 2. The internal combustion engine according to claim 1, wherein the bent portion has a curved pipe portion that is bent in a direction approaching a central portion of the expansion chamber with respect to the connection portion.   The internal combustion engine according to claim 2, wherein the bent pipe portion (42a) is bent at an angle of approximately 90 ° with respect to the connecting portion (41).

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