JP4025763B2 - Silencer - Google Patents

Description

  The present invention relates to a silencer that is connected to an exhaust system of an engine for a vehicle or the like and reduces exhaust noise.

As a conventional example of a silencer provided with an inlet pipe for introducing exhaust gas from the engine into the silencer chamber and an outlet pipe for discharging the introduced exhaust gas to the outside of the silencer chamber, one described in Patent Document 1 can be cited. In the silencer described in this Patent Document 1, the outlet pipe includes a first outlet pipe that constantly discharges exhaust gas in the silencer chamber to the outside of the silencer chamber, and an exhaust pressure in the silencer chamber increases to a predetermined value or more. And a second outlet pipe that exhausts the exhaust gas in the silencer chamber to the outside of the silencer chamber when the valve is opened, and exhausts the exhaust gas to the exterior of the silencer chamber only through the first outlet pipe in the low-speed rotation region of the engine. However, in the high-speed engine rotation range, exhaust gas in the muffler chamber is discharged outside the muffler chamber via both outlet pipes, improving the noise reduction performance in the engine low-speed rotation range and reducing the output loss in the high-speed rotation range. We are trying to reduce it.
Japanese Patent Laid-Open No. 11-153019 (paragraphs 0018 to 0020, FIG. 1)

  When the engine is stopped, the high-temperature exhaust gas is cooled in the silencer, and moisture contained in the exhaust gas may condense and accumulate at the bottom of the silencer. In order to solve this problem, a silencer having the above structure employs a method in which a hole is formed in the bottom of the outlet pipe, and water is sucked and discharged from the hole by negative pressure in the pipe. The present invention relates to a technique for draining the water in the silencer using the negative pressure in the outlet pipe, and provides a silencer that is superior in drainage efficiency of water accumulated in the silencer as compared with the prior art. The purpose is that.

In order to solve the above-mentioned problems, the present invention provides a silencer provided with an inlet pipe for introducing exhaust gas into the silencer chamber of the silencer body and an outlet pipe for exhausting exhaust gas inside the silencer chamber to the outside of the silencer body. a vessel, the outlet pipe has a curved portion formed bay songs, and the upstream-side straight portion formed at the upstream end of the curved portion, is formed on the downstream end side of the bending portion, the upstream parallel to the straight portion, and a downstream-side straight portion located obliquely downward of the upstream-side straight portion, Ri Tsurana the outer peripheral surface side of the curved portion, from the axial direction of the upstream-side straight portion and the downstream-side straight portion As seen , the silencer is provided with a drain pipe that faces the bottom surface of the silencer body on the outermost portion of the downstream straight portion that intersects the virtual line that connects the two axes .

  Regarding the flow velocity of the exhaust gas flowing through the curved portion, the flow velocity of the exhaust gas flowing along the outer peripheral surface by the action of centrifugal force is faster than that of the exhaust gas flowing along the inner peripheral surface. Therefore, the outer side surface of the downstream straight portion connected to the outer peripheral surface side of the curved portion becomes a portion that satisfies the two conditions that the centrifugal force is not applied and the exhaust gas flow rate is high. By providing the pipe, a large negative pressure can be obtained, and the water suction efficiency (drainage efficiency) can be increased.

  Further, according to the present invention, the outlet pipe has a first outlet pipe that constantly exhausts the exhaust gas in the muffler chamber to the outside of the muffler chamber, the pressure of the exhaust gas in the muffler chamber reaches a predetermined value or more, and the open / close valve in the muffler chamber has The silencer is provided with a second outlet pipe that discharges the exhaust gas in the silencer chamber to the outside of the silencer chamber only when the valve is opened, and the drain pipe is a silencer provided on the first outlet pipe side.

  According to this silencer, in the low-speed rotation region of the engine, all exhaust gas in the silencer chamber flows only into the first outlet pipe set to the low-speed pipe diameter, so the exhaust gas flow rate becomes relatively high. As a result, water can be efficiently sucked up from the drain pipe by the large negative pressure. In the high-speed rotation range, the exhaust gas in the muffler chamber flows into both the first outlet pipe and the second outlet pipe, so that a large flow path area can be secured for the high-pressure exhaust gas. Therefore, passage resistance of the exhaust gas can be reduced, and water can be efficiently sucked from the drain pipe while reducing output loss in the high speed rotation region of the engine.

  According to this invention, it becomes a silencer excellent in the drainage efficiency of the water accumulated in the silencer compared with the conventional silencer.

  1 is a cutaway perspective view of a silencer embodying the present invention, FIG. 2 is an explanatory plan view of the silencer, FIGS. 3 to 5 are AA sectional view, BB sectional view, and C- C sectional view and FIG. 6 are plan explanatory views of the first outlet pipe.

  The silencer 1 is interposed in an exhaust system of an internal combustion engine such as an automobile. As shown in FIGS. 1 and 2, an elliptical cylindrical shell 11 having both end surfaces opened and both end surfaces of the shell 11. The silencer main body 10 as a hermetically sealed housing is constituted by the end walls 12 and 13 that close the wall. The silencer 1 is attached to a vehicle body (not shown) such that the short diameter side of the silencer main body 10 faces substantially in the vertical direction, the end wall 12 is positioned on the front side of the vehicle, and has a forwardly inclined shape.

  A partition wall 14 is press-fitted and fitted to the silencer body 10 substantially parallel to the end walls 12 and 13, and an upstream chamber U is provided between the partition wall 14 and the end wall 13, and between the partition wall 14 and the end wall 12. The downstream chambers D are respectively defined. The upstream chamber U and the downstream chamber D form a silencing chamber CM. As shown in FIG. 3, a gap c is formed between the lowermost part of the partition wall 14 and the bottom surface of the shell 11, and as described above, the silencer body 10 is attached to the vehicle body so as to be lowered forward. The water accumulated in the vessel body 10 flows from the upstream chamber U to the downstream chamber D in FIG.

  The upstream chamber U is set to have a larger volume than the downstream chamber D, and is located on the front side of the vehicle by a support plate 15 press-fitted into the silencer body 10 so as to be parallel to the partition wall 14. A chamber U1 and a second chamber U2 located on the vehicle rear side are defined. The support plate 15 is provided with a plurality of communication holes 15a made up of a number of punching holes, and the first chamber U1 and the second chamber U2 communicate with each other through these communication holes 15a. That is, in the first chamber U1 and the second chamber U2, free circulation of exhaust gas is allowed through the plurality of communication holes 15a, and the first chamber U1 and the second chamber U2 are substantially one upstream. It functions as a chamber U. As shown in FIG. 4, a gap c is also formed between the lowermost part of the support plate 15 and the bottom surface of the shell 11, and as described above, the silencer body 10 is attached to the vehicle body in a front-down manner, Water accumulated in the silencer main body 10 flows from the second chamber U2 to the first chamber U1 in FIG. 1 through the gap c.

  In FIG. 1 and FIG. 2, the end wall 12 and the partition wall 14 are welded through an inlet pipe 16 extending in the front-rear direction of the silencer body 10 across the end wall 12 and the partition wall 14. The inlet pipe 16 guides exhaust gas from the engine into the silencing chamber CM, and its front end, that is, the upstream end, is connected to an exhaust pipe (shown by a phantom line in FIG. 1) communicating with the exhaust port of the engine. The rear end, that is, the downstream end, is connected to the first chamber U1 of the upstream chamber U.

  Further, an outlet pipe 17 is accommodated in the upstream chamber U. In the present embodiment, the upstream pipe U includes a first outlet pipe 18 and a second outlet pipe 19 that are arranged in parallel with each other. The first outlet pipe 18 has a function of always exhausting the exhaust gas in the muffler chamber CM to the outside of the muffler chamber CM, and the second outlet pipe 19 is used when the exhaust pressure in the muffler chamber CM rises to a predetermined value or more. Only when the opening / closing valve 25, which will be described later, is opened, the exhaust gas in the silencing chamber CM is discharged from the silencing chamber CM. Hereinafter, a specific structure of the first and second outlet pipes 18 and 19 will be described.

  As shown in FIGS. 1 and 2, the first outlet pipe 18 is formed in a U-shape so that the upstream straight portion 18a, the curved portion 18b, and the downstream side parallel to the upstream straight portion 18a are formed. It is comprised from the linear part 18c. The first outlet pipe 18 includes an upstream straight portion 18a and a downstream straight portion 18c along the front-rear direction (axial direction) of the silencer body 10, and the curved portion 18b, the upstream straight portion 18a, and the downstream side. The upstream straight portion 18a and the downstream straight portion 18c penetrate through the support plate 15 and are supported by welding so that a predetermined portion of the straight portion 18c is located in the first chamber U1. Accordingly, the upstream opening 18d of the upstream linear portion 18a and the downstream opening 18e (FIG. 2) of the downstream linear portion 18c both face the second chamber U2. Further, as can be seen from FIG. 5, the upstream straight portion 18a is located near the side of the shell 11, and the downstream straight portion 18c is located near the bottom of the shell 11 below the position of the upstream straight portion 18a. positioned.

   As shown in FIGS. 1 and 2, the upstream linear portion 18 a is supported by a plate 20 that is fixed to the partition wall 14 and extends in a cantilever manner. The plate 20 has a function of reinforcing the upstream linear portion 18 a and a function of increasing the rigidity of the partition wall 14.

  On the other hand, the second outlet pipe 19 is formed in a straight line, and is positioned above the downstream straight portion 18c of the first outlet pipe 18 so as to be substantially parallel thereto. The front end portion of the second outlet pipe 19 passes through and is welded to the partition wall 14, and the upstream opening 19 a faces the downstream chamber D. Further, the periphery of the rear end portion of the second outlet pipe 19 passes through the support plate 15 and is welded thereto, and the downstream opening portion 19b (FIG. 2) faces the second chamber U2. The intermediate portion of the second outlet pipe 19 and the rear end portion of the inlet pipe 16, that is, the free end portion, are integrally connected by a connecting piece 21 so that they are reinforced together. This prevents the cantilever portion of the inlet pipe 16 from swinging.

  In the second chamber U2, the downstream opening 18e (FIG. 2) of the downstream straight portion 18c in the first outlet pipe 18 and the downstream opening 19b (FIG. 2) of the second outlet pipe 19 are It is connected to the upstream side (bifurcated entrance). The downstream side of the collecting pipe 22 passes through the end wall 13 and is connected to the tail pipe 23 (FIG. 1) outside the silencer body 10.

  Next, the partition wall 14 is formed with a valve port 24 (FIGS. 2 and 3) for communicating the first chamber U1 and the downstream chamber D of the upstream chamber U, and around the valve port 24 on the downstream chamber D side. An opening / closing valve 25 is provided. As an example of the opening / closing valve 25, a conventionally known reed valve (for example, one described in JP-A-2001-123817) can be cited. The structure of the opening / closing valve 25 will be briefly described. In FIG. 2, the opening / closing valve 25 includes a base 26 fixed to the partition wall 14 so as to surround the valve opening 24, and a plate-like valve fixed at one end to the base 26. 27, a stopper 28 fixed to the base 26 and restricting the opening degree of the plate valve 27, and fixed to the stopper 28, abutting against the plate valve 27 and urging the plate valve 27 in the valve closing direction. When the pressure of the exhaust gas in the upstream chamber U is less than a predetermined value, the plate valve 27 closes the valve port 24 by the urging force of the leaf spring 29, so that the upstream chamber U The one chamber U1 and the downstream chamber D are in a non-communication state. When the pressure of the exhaust gas in the upstream chamber U exceeds the predetermined value, the pressure of the exhaust gas exceeds the urging force of the leaf spring 29, and the pressure of the exhaust gas opens the plate valve 27. As a result, the first chamber U1 and the downstream chamber D of the upstream chamber U are in communication with each other.

  With respect to the silencer 1 configured as described above, a series of exhaust gas flows will be described with reference to FIG. First, exhaust gas discharged from the engine flows into the upstream chamber U through the inlet pipe 16. Since the pressure of the exhaust gas discharged from the engine is low in the low speed rotation region of the engine, the pressure of the exhaust gas in the upstream chamber U is also low. When the pressure is less than the predetermined value, the biasing force of the leaf spring 29 Accordingly, the plate valve 27 closes the valve port 24, and the first chamber U1 and the downstream chamber D of the upstream chamber U are not in communication. Therefore, in this case, all the exhaust gas in the upstream chamber U flows into the first outlet pipe 18 through the upstream opening 18d, and is discharged to the atmosphere through the collecting pipe 22 and the tail pipe 23 (FIG. 1). Since all the exhaust gas flows into the first outlet pipe 18 in this manner, the flow area of the exhaust gas is reduced, and as a result, it flows through a long path, so that the silencer effect of the silencer 1 in the low-speed rotation region of the engine. Will increase.

  Since the pressure of the exhaust gas discharged from the engine is high in the high-speed rotation region of the engine, the pressure of the exhaust gas in the upstream chamber U also increases, and when the pressure exceeds the predetermined value, the leaf spring The plate valve 27 opens the valve port 24 against the urging force of 29, and the first chamber U1 of the upstream chamber U and the downstream chamber D are in communication. Therefore, in this case, a part of the exhaust gas in the upstream chamber U flows into the first outlet pipe 18 through the upstream opening 18d, and the rest flows into the downstream chamber D through the valve port 24. To the second outlet pipe 19 through the upstream opening 19a. The exhaust gas flowing into the first outlet pipe 18 and the second outlet pipe 19 merges at the collecting pipe 22 and is released to the atmosphere via the tail pipe 23 (FIG. 1). In this way, by allowing the exhaust gas to flow into both the first outlet pipe 18 and the second outlet pipe 19, it is possible to ensure a large flow path area for the high-pressure exhaust gas. Therefore, the passage resistance of the exhaust gas can be reduced, and the output loss in the high speed rotation region of the engine can be reduced.

  When the engine is stopped, the high-temperature exhaust gas is cooled in the silencer 1, and moisture contained in the exhaust gas may condense and accumulate at the bottom of the shell 11. The gap c (FIGS. 3 and 4) described above is for allowing water accumulated at the bottom of the shell 11 to pass therethrough. The present invention relates to a technique for draining the water accumulated at the bottom of the shell 11 using the negative pressure in the outlet pipe 17 (first outlet pipe 18 in the present embodiment), and is shown in FIGS. 5 and 6. As described above, in the first outlet pipe 18, the outer surface 18 f of the downstream linear portion 18 c connected to the outer peripheral surface 18 g (FIG. 6) side of the curved portion 18 b faces the bottom surface of the shell 11 (FIG. 5) of the silencer body 10. The main feature is that a water drain pipe 30 is provided.

  In FIG. 6, regarding the flow rate of the exhaust gas flowing through the curved portion 18b, the flow rate of the exhaust gas flowing along the outer peripheral surface 18g is faster than that of the exhaust gas flowing along the inner peripheral surface 18h due to the action of centrifugal force. . Here, assuming that the drain pipe 30 is provided on the outer peripheral surface 18g of the curved portion 18b, centrifugal force is acting on the exhaust gas flowing along the outer peripheral surface 18g. The predetermined negative pressure effect cannot be expected. On the other hand, the outer side surface 18f of the downstream linear portion 18c connected to the outer peripheral surface 18g side of the curved portion 18b is a portion that does not receive the action of centrifugal force and satisfies the two conditions of high exhaust gas flow velocity. A large negative pressure can be obtained by providing the drain pipe 30 on the outer surface 18f, and the water suction efficiency (drainage efficiency) can be increased.

  Specifically, the outer surface 18f to which the drain pipe 30 is attached is, as shown in FIG. 5, an imaginary line 31 connecting the axes of the upstream linear portion 18a and the downstream linear portion 18c when viewed from the axial direction. A portion of the outermost portion 33 that intersects with is preferable. In the present embodiment, the drainage pipe 30 is attached to the outermost portion 33 so as to be orthogonal to the axial direction of the downstream straight portion 18c, bent in the middle, and extended downward to form the shell 11. It faces the water accumulated on the bottom.

  As for the attachment part of the drainage pipe 30 in the axial direction of the downstream straight part 18c, the part immediately after the end of the formation of the curved part 18b, that is, around the upstream end of the downstream straight part 18c has the highest exhaust gas flow velocity. Since it becomes a part immediately after becoming faster, it is preferable to attach the drain pipe 30 around the upstream end of the downstream straight portion 18c.

  As described above, in the outlet pipe 17 (first outlet pipe 18), the outer surface 18f of the downstream straight portion 18c that is continuous with the outer peripheral surface 18g (FIG. 6) of the curved portion 18b faces the bottom surface of the silencer body 10. If the drainage pipe 30 is provided, a large negative pressure can be generated in the drainage pipe 30, and the bottom surface of the silencer body 10 can be compared with the conventional structure in which a hole is formed in the bottom of the outlet pipe 17. It is possible to improve the efficiency of sucking up the water accumulated in the water.

  1 and 2, as in the present embodiment, the outlet pipe 17 always discharges the exhaust gas in the silencing chamber CM to the outside of the silencing chamber CM, and the silencing chamber CM. A second outlet pipe 19 that exhausts the exhaust gas in the silencing chamber CM to the outside of the silencing chamber CM only when the pressure of the exhaust gas reaches a predetermined value or more and the opening / closing valve 25 in the silencing chamber CM opens. If the drain pipe 30 is provided in the first outlet pipe 18, all the exhaust gas in the muffler chamber CM is only in the first outlet pipe 18 set to the pipe diameter for low speed in the low speed rotation region of the engine. Since it flows in, the flow rate of the exhaust gas becomes relatively high, and as a result, water can be efficiently sucked up from the drain pipe 30 by a large negative pressure. Further, in the high-speed rotation region, the exhaust gas in the muffler chamber CM flows into both the first outlet pipe 18 and the second outlet pipe 19, so that a large flow path area can be secured for the high-pressure exhaust gas. Therefore, the passage resistance of the exhaust gas can be reduced, and water can be efficiently sucked up from the drain pipe 30 while reducing the output loss in the high speed rotation region of the engine. As described above, the efficiency of sucking up the water accumulated on the bottom surface of the silencer main body 10 can be improved in the entire rotation range of the low-speed rotation range and the high-speed rotation range of the engine.

It is a fracture perspective view of a silencer which carried out the present invention. It is plane explanatory drawing of the silencer which implemented this invention. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is CC sectional drawing in FIG. It is a plane explanatory view of the 1st outlet pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silencer 10 Silencer main body 11 Shell 16 Inlet pipe 17 Outlet pipe 18 1st outlet pipe 18b Curved part 18c Downstream straight part 18f Outer side surface 18g Outer peripheral surface 19 2nd outlet pipe 30 Drain pipe CM Silent room

Claims (2)

A silencer comprising an inlet pipe for introducing exhaust gas into the silencer chamber of the silencer body and an outlet pipe for exhausting exhaust gas inside the silencer chamber to the outside of the silencer body,
The outlet pipe has a curved portion formed bay songs, and the upstream-side straight portion formed at the upstream end of the curved portion, is formed on the downstream end side of the bending portion, parallel to the upstream-side straight portion And a downstream straight portion located obliquely below the upstream straight portion ,
Ri Tsurana the outer peripheral surface side of the curved portion, as viewed from the upstream-side straight portion and the axial direction of the downstream-side straight portion, the outermost portion of the downstream-side straight portion which intersects a virtual line connecting the axial line of the both persons, A silencer characterized by providing a drain pipe that faces the bottom of the silencer body. The outlet pipe includes a first outlet pipe that constantly discharges the exhaust gas in the muffler chamber to the outside of the muffler chamber, and only when the pressure of the exhaust gas in the muffler chamber reaches a predetermined value or more and the open / close valve in the muffler chamber is opened. It consists of a second outlet pipe that exhausts the exhaust gas inside the muffler chamber to the outside of the muffler chamber,
The silencer according to claim 1, wherein the drain pipe is provided on the first outlet pipe side.

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