JP2020051318A - Vehicle muffler discharge hole opening-closing device - Google Patents

Abstract

To open and close a discharge hole of a muffler with a simple configuration.SOLUTION: A muffler 10 has a discharge hole 16 to discharge condensate water therethrough on a rear wall 12 thereof. An opening-closing lid 30 which rotates around a support shaft 32 to open and close the discharge hole 16 is installed in the muffler 10. The opening-closing lid 30 is rotated in a direction to open the discharge hole 16 by the force of gravity on a weight 36 and in the direction to close the same by the exhaust flow in the muffler 10. Thus, the discharge hole 16 can be opened or closed depending on a state of exhaust.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle muffler discharge hole opening / closing device that opens and closes a condensed water discharge hole of a vehicle muffler.

  Moisture generated by combustion condenses and accumulates in the muffler of the vehicle (sometimes referred to as “vehicle muffler”).

  Patent Document 1 below discloses a structure in which a drain hole is provided on a bottom surface of a muffler, and the drain hole is closed by an on-off valve. A spring is attached to the on-off valve, and when there is no flow of exhaust gas, the on-off valve opens by the force of the spring. On the other hand, when there is an exhaust gas flow, the spring is compressed by the exhaust gas pressure, and the on-off valve closes.

Japanese Utility Model Publication No. 61-175529

  In the technique of Patent Document 1, a spring is installed in a high-temperature environment in a muffler. In order to ensure the durability of the spring, the cost of parts increases.

  An object of the present invention is to open and close a discharge hole with a simple configuration.

  An opening and closing device for a discharge hole of a vehicle muffler according to one embodiment of the present invention includes a discharge hole provided on a wall surface of the vehicle muffler and a discharge hole provided inside the vehicle muffler and rotated around a support shaft. An opening / closing lid that opens and closes, wherein the opening / closing lid rotates in a direction to open the exhaust hole by its own weight, and rotates in a direction to close the exhaust hole by exhaust gas flowing into the vehicle muffler. Features.

  A discharge hole opening and closing device for a vehicle muffler according to one aspect of the present invention includes a discharge hole for condensed water provided on a wall surface of the vehicle muffler, and provided in the vehicle muffler so as to face the discharge hole. An opening / closing lid for opening and closing the discharge hole, wherein the opening / closing lid is deformed in a direction to close the discharge hole by thermal expansion or elastic deformation due to heat of exhaust gas flowing through the vehicle muffler. Features.

  ADVANTAGE OF THE INVENTION According to the discharge hole opening / closing apparatus of the vehicle muffler concerning this invention, opening / closing of the discharge hole of the condensed water provided in the vehicle muffler is realized by a simple structure.

It is a perspective view of the vehicle muffler concerning an embodiment. It is a figure showing the discharge hole opening and closing device concerning a 1st embodiment. FIG. 5 is a diagram illustrating a rotation state of the exhaust hole opening / closing device when the engine is started. It is a figure showing the discharge hole opening and closing device concerning a modification. It is a figure showing the discharge hole opening and closing device concerning a 2nd embodiment. It is a figure which shows the deformation | transformation state of the opening / closing lid in a discharge hole opening / closing apparatus. It is a figure showing the discharge hole concerning a reference form.

  Hereinafter, embodiments will be described with reference to the drawings. In the description, specific modes are shown for easy understanding, but these are merely examples of the embodiments, and various other embodiments can be adopted.

  FIG. 1 is a perspective view of a muffler 10 according to the present embodiment. In the coordinate system in the figure, the F axis indicates the forward direction of the vehicle, the U axis indicates the upward direction, and the R axis indicates the right direction of the occupant (the same applies to the following figures). The muffler 10 is a substantially elliptical cylindrical component formed of a metal such as stainless steel. The muffler 10 is installed near the lower surface of the rear part of the vehicle with the cylinder axis oriented in the front-rear direction and the short axis of the ellipse oriented in the vertical direction. FIG. 1 shows an elliptical rear wall 12 and a side wall 14 surrounding an axis. The lower part of the rear wall 12 is provided with a discharge hole 16 communicating with the inside.

  An exhaust pipe 20 is connected to the muffler 10. Among the exhaust pipes 20, an upstream exhaust pipe 20a connected to the front surface of the muffler 10 is a pipe that flows exhaust gas from an engine provided in front of the vehicle to the muffler 10. In the exhaust pipe 20, a downstream exhaust pipe 20b connected to the rear surface of the muffler 10 is a pipe that discharges exhaust gas from the muffler 10 to the outside air. Inside the muffler 10, an inner pipe connected to the upstream exhaust pipe 20a is provided. Usually, this inner pipe is also connected to the downstream side exhaust pipe 20b. However, in some cases, the inner pipe to which the upstream exhaust pipe 20a is connected and the inner pipe to which the downstream exhaust pipe 20b is connected are not directly connected in the muffler 10. The rear wall 12 and the side wall 14 are provided outside the inner pipe, and have a role as an outer pipe whose diameter is larger than that of the inner pipe.

  During the operation of the engine, high-temperature and high-pressure exhaust gas flows into the muffler 10 through the upstream exhaust pipe 20a. In the muffler 10, the temperature and pressure of the exhaust gas are reduced by using the internal space whose diameter is larger than that of the upstream exhaust pipe 20a, thereby suppressing noise. In this process, water vapor contained in the exhaust gas condenses inside the muffler 10 to generate condensed water, which accumulates in the lower part of the muffler 10. The discharge hole 16 in the rear wall 12 of the muffler 10 functions as a drain hole for discharging condensed water. The discharge hole 16 has a diameter of, for example, about 3 mm to 5 mm.

  In the discharge hole 16, exhaust leakage or heat leakage also occurs. This is because the exhaust gas inside the muffler 10 is in a high-temperature and high-pressure state as compared with the outside air. If the high-temperature and high-pressure exhaust gas leaks out of the discharge hole 16, an explosion sound is generated due to rapid expansion. Further, when discharging the condensed water from the discharge hole 16, an unusual noise “bumpy” may be generated. This is because the water film formed in the discharge hole 16 is broken intermittently and drainage is performed. In the present embodiment, a discharge hole opening / closing device is provided in order to suppress or prevent these.

(1) First Embodiment A discharge hole opening and closing device according to a first embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a view of the vicinity of the rear wall 12 from the inside of the muffler 10 according to the first embodiment. An inner pipe 22 connected to the exhaust pipe 20 passes through the rear wall 12 slightly above the center in the vehicle width direction. The inner pipe 22 is provided with a branch flow path 24 near the rear wall 12 that allows a part of the exhaust to flow in the lower left direction in the figure. In the lower part of the rear wall 12 at the center in the vehicle width direction, a discharge hole 16 as a drain hole is provided.

  An opening / closing lid 30 for opening and closing the discharge hole 16 is mounted slightly above the discharge hole 16. The opening / closing lid 30 is a component made of metal such as stainless steel, and is rotatably attached around a support shaft 32. The rotation refers to a motion of reciprocating around the support shaft 32 at an appropriate angle around the support shaft 32 as a rotation axis. The support shaft 32 is a metal member, and is provided slightly above the discharge hole 16 at the center of the rear wall 12 in the vehicle width direction.

  The opening / closing lid 30 is formed in a shape extending from the support shaft 32 mainly in three directions. One is a weight holding portion 34 extending in the right direction (the direction opposite to the R axis) in FIG. A weight 36 is attached to the weight holding portion 34. The weight 36 is made of a thick metal plate or the like, and applies a downward load (a direction opposite to the U axis) to the weight holding portion 34. The other is a lid 38 extending from the support shaft 32 to the lower left direction in FIG. 2 (slightly leftward of the discharge hole 16). The lid 38 functions as a lid for opening and closing the discharge hole 16. The remaining one is an exhaust receiving portion 40 extending from the support shaft 32 to the left in the drawing. An exhaust receiving plate 42 is attached to the exhaust receiving portion 40. The exhaust receiving plate 42 is a metal plate-like member that extends in the forward direction of the vehicle. The exhaust receiving plate 42 is provided so as to be substantially orthogonal to the flow of the exhaust gas from the branch channel 24, and applies a downward load to the exhaust receiving portion 40 by receiving the pressure of the exhaust gas.

  A stopper 50 is provided directly below the weight holding portion 34 in the opening / closing lid 30. The stopper 50 is a metal fixedly attached to the rear wall 12, and prevents the weight holding portion 34 from lowering (turning clockwise) below the state of FIG.

  FIG. 2 shows a state where no exhaust gas flows, that is, a state where the engine is stopped. In this state, no exhaust pressure acts on the exhaust receiving plate 42. For this reason, only a slight gravity corresponding to its own weight acts on the exhaust receiving portion 40. On the other hand, the weight holding portion 34 receives a large gravity due to the weight 36. Therefore, the opening / closing lid 30 acts on the right as a whole due to gravity. However, the weight holding portion 34 of the opening / closing lid 30 is restricted from moving clockwise by the stopper 50, and receives a drag from the stopper 50. As a result, it comes to rest in the state shown in FIG.

  In the state shown in FIG. 2, the lid 38 does not cover the discharge hole 16, and the discharge hole 16 communicates with the outside. For this reason, the condensed water accumulated in the muffler 10 flows out from the discharge hole 16. Therefore, for example, in a cold region in winter, clogging of the exhaust system due to freezing of condensed water in the muffler 10 during the night when the engine is stopped is also prevented.

  FIG. 3 is a diagram corresponding to FIG. 2 and shows a state in which the engine is running at a high speed. For this reason, the exhaust 52 flows out of the branch channel 24 to apply pressure to the exhaust receiving plate 42. When the moment acting on the exhaust receiving portion 40 by this pressure becomes larger than the moment acting on the weight holding portion 34 through the weight 36, the opening / closing lid 30 rotates counterclockwise around the support shaft 32. However, when the displacement of the left rotation increases, the exhaust receiving plate 42 moves away from the exhaust 52 and the angle between the exhaust receiving plate 42 and the exhaust 52 also decreases (goes away from the vertical), so that the exhaust receiving plate 42 The pressure received from is weakened. As a result, in the state shown in FIG. 3, the opening / closing lid 30 is in a substantially stationary state in which the moment acting on the exhaust receiving portion 40 and the moment acting on the weight holding portion 34 are balanced.

  In the state shown in FIG. 3, the lid 38 is located at a position overlapping the discharge hole 16, and the discharge hole 16 is in a closed state. Therefore, the condensed water does not flow out of the discharge hole 16. However, in general, when the engine rotates at a high speed and the exhaust gas flows through the inner pipe 22 at a high speed, the condensed water hardly accumulates in the muffler 10. This is because the muffler 10 is in a high temperature state and condensed water is easily vaporized, and the condensed water is blown off by the force of the exhaust gas flowing in the muffler 10.

  The lid 38 closes the discharge hole 16, thereby preventing leakage of exhaust gas and heat through the discharge hole 16 during high-speed traveling. Thereby, the generation of the explosion sound from the discharge hole 16 can be reduced.

  In this manner, a discharge hole opening / closing device that opens and closes the discharge hole 16 can be formed by using the branch channel 24 and the opening / closing lid 30. It is possible to variously set whether or not to start closing the exhaust hole 16 or completely close the exhaust hole 16 at the stage of the rotation speed of the engine. For example, only when the engine is not started, the exhaust hole 16 is completely opened, and when the engine is idling, the exhaust hole 16 may be started to be closed or may be completely closed. Alternatively, the exhaust hole 16 may be completely opened when the engine is in the idling state. The specific adjustment is performed in consideration of, for example, the amount of condensed water accumulated in the muffler 10, the sound of explosion from the muffler 10, and the like.

  In the above description, the rotation width of the opening / closing lid 30 is limited by using the stopper 50. However, for example, by adjusting the positional relationship between the shape of the opening / closing lid 30 and the support shaft 32, it is also possible to realize a configuration that does not use the stopper 50. As an example, a mode in which the exhaust hole 16 is opened in a state where the engine is stopped and the weight 36 is located directly below the support shaft 32 by the action of gravity.

  The flow of the exhaust 52 from the branch channel 24 shown in FIG. 3 can be created in various modes. For example, an embodiment in which the inner pipe 22 is separated into an inner pipe 22a connected to the upstream exhaust pipe 20a and an inner pipe 22b connected to the downstream exhaust pipe 20b, and the branch pipe 24 is provided in the inner pipe 22a. Is mentioned. In this embodiment, the high-temperature high-pressure exhaust 52 can easily flow out of the inner pipe 22a through the branch channel 24 into the muffler 10, and then flow into the inner pipe 22b.

  Further, as another aspect, there is an example in which the flow area has a directivity by increasing the opening area of the flow path returning to the inner pipe 22 as compared with the opening area of the branch flow path 24 provided in the inner pipe 22. Can be In this embodiment, the flow of the exhaust 52 from the branch channel 24 is created by utilizing the change in the airflow resistance. The specific configuration of the flow path can be variously set based on the hydrodynamic knowledge.

  Here, a modified embodiment of the discharge hole opening / closing device shown in FIGS. 2 and 3 will be described with reference to FIG. FIG. 4 is a view of the rear wall 12 viewed from the inside of the muffler 10. In this embodiment, the inner pipe 22 is not provided with the branch channel 24. The opening / closing lid 60 for opening / closing the discharge hole 16 is supported by the support shaft 62, but has a simple shape, and is merely provided with the lid 64.

  In this embodiment, a motor is provided outside the muffler 10 not shown. When the support shaft 62 is rotated by the motor, the opening / closing lid 60 is rotated. Since the motor is provided outside the muffler 10, the temperature does not rise so much and the motor operates stably. When a motor is used, manufacturing costs increase, but fine control can be performed according to, for example, the amount of exhaust gas, the amount of condensed water, and the like.

(2) Second Embodiment A discharge hole opening and closing device according to a second embodiment will be described with reference to FIGS. FIG. 7 is a perspective view of the vicinity of the discharge hole 16 from the inside of the muffler 10 according to the second embodiment. As shown in FIG. 7, an opening / closing lid 70 formed by processing a metal plate is provided on the front surface of the discharge hole 16 provided in the rear wall 12. The opening / closing lid 70 is a component having a hat-shaped cross section. Specifically, the opening / closing lid 70 includes a mounting portion 72 which is a brim portion of a hat, a side portion 74 forming a side surface, and a lid portion 76 corresponding to a hat top. The attachment portion 72 is a portion attached to the rear wall 12 by bolting or welding. The side portion 74 is a portion that rises from the rear wall 12 toward the front of the vehicle. The lid 76 is a part that covers the front surface of the discharge hole 16.

  FIG. 6 is an end view cut along the AA plane shown in FIG. 6, the open / close lid 70 corresponding to FIG. 5 is indicated by a solid line on the front surface of the rear wall 12 and the discharge hole 16. This opening / closing lid 70 shows a state where the engine has been stopped for a long time and the inside of the muffler 10 has become equal to the temperature of the outside air. When the temperature is relatively low, the opening / closing lid 70 is set to have such a size that the lid 76 is separated from the discharge hole 16. Therefore, the discharge hole 16 is in an open state, and the condensed water accumulated inside the muffler 10 flows out from the discharge hole 16.

  FIG. 6 also shows the open / close lid 70a when deformed by a two-dot chain line. The opening / closing lid 70a shows a state where the engine is started and the inside of the muffler 10 is filled with high-temperature and high-pressure exhaust. When the temperature rises, the rear wall 12 of the muffler 10 and the opening / closing lid 70 both undergo thermal expansion. At this time, on the rear wall 12, for example, a portion having a length L1 in the drawing has a length of L1 (1 + α1ΔT) when the linear expansion coefficient α1 and the temperature rise ΔT. On the other hand, in the opening / closing lid 70 connected to the rear wall 12 at both ends, a portion having a length L2 including the lid 76 and the two side parts 74 thermally expands.

  When the linear expansion coefficients α1 and α2 of the rear wall 12 and the opening / closing lid 70 are equal, the ratio of the lengths after thermal expansion is the same as that before thermal expansion, and thus the shape after thermal expansion is similar to that before thermal expansion. become. However, when the linear expansion coefficient α2 of the opening / closing lid 70 is larger than the linear expansion coefficient α1 of the rear wall 12 (α2> α1), the opening / closing lid 70 is larger than the rear wall 12 after thermal expansion. Relatively long. Therefore, it can be expected that the lid portion 76a will be deformed so as to close the discharge hole 16 like the open / close lid 70a shown by the two-dot chain line in FIG. In particular, the lid 76 is formed in a shape that is gently convex toward the discharge hole 16. Therefore, it can be expected that the protrusion is emphasized by the thermal expansion and approach the discharge hole 16 side. For example, when the rear wall 12 is formed of SUS436 stainless steel and the opening / closing lid 70 is formed of SUS304 stainless steel, the linear expansion coefficient α2 of the opening / closing lid 70 may be larger than the linear expansion coefficient α1 of the rear wall 12. it can.

  When the linear expansion coefficient α2 of the opening / closing lid 70 is smaller than the linear expansion coefficient α1 of the rear wall 12, the opening / closing lid 70 becomes relatively shorter than the rear wall 12 due to thermal expansion. Therefore, using this mechanism, a deformation may be caused in which the opening / closing lid 70 approaches the discharge hole 16 at a high temperature.

  The opening / closing lid 70 is deformed by the pressure of exhaust gas regardless of the effect of thermal expansion. The inside of the muffler 10 is filled with exhaust gas having a higher temperature and a higher pressure than the outside air when the engine is started. For this reason, when the discharge hole 16 is open, the exhaust gas flows toward the outside at a relatively low pressure. Due to this flow or the pressure difference, the opening / closing lid 70 is deformed toward the discharge hole 16. Then, as shown in FIG. 6, the discharge hole 16 is closed by the deformed lid portion 76a. The opening / closing lid 70 has a bent portion between the mounting portion 72 and the side portion 74, and also has a bent portion between the side portion 74 and the lid portion 76, and the deformation thereof is controlled by these. Can close the discharge hole 16 steadily. In the closed state, the lid 76a is pressed against the rear wall 12 by receiving a force due to the difference between the pressure in the muffler 10 and the pressure of the outside air, so that the discharge hole 16 is stably closed.

  The discharge hole opening / closing device according to the second embodiment is formed using the opening / closing lid 70 and the discharge hole 16 in this manner. As in the first embodiment, also in the exhaust hole opening / closing device of the second embodiment, it is possible to prevent exhaust leakage and heat leakage when the engine is started, and reduce explosion sound. As with the first embodiment, various settings can be made as to whether the discharge hole 16 starts to be closed or completely closed when the rotation speed of the engine is reached.

(3) Reference Embodiment A reference embodiment regarding the shape of the discharge hole 16 will be described with reference to FIG. FIG. 7 is an end view of the rear wall 12 cut along a plane including the discharge hole 16. Here, one of the rear walls 12 is bent around the discharge hole 16 to the outside of the muffler 10 to form a partial burring flange 12a. When the partial burring flange 12a is provided, the line length around the discharge hole 16 becomes longer and the shape becomes irregular as compared with the case where the partial burring flange 12a is not provided. As a result, the water film of the condensed water is less likely to be formed on the discharge hole 16, and it is possible to suppress the generation of abnormal noise when the condensed water is discharged.

  The partial burring flange 12a may be provided at only one place, but by providing a plurality of unequally, it is possible to enhance the effect of preventing a water film.

  The partial burring flange 12a according to this reference embodiment can be implemented together with the discharge hole opening / closing device according to the first embodiment or the second embodiment.

  10 muffler, 12 rear wall, 12a partial burring flange, 14 side wall, 16 exhaust hole, 20 exhaust pipe, 20a upstream exhaust pipe, 20b downstream exhaust pipe, 22, 22a, 22b inner pipe, 24 minute flow path, 30 opening and closing Lid, 32 support shaft, 34 weight holding portion, 36 weight, 38 lid portion, 40 exhaust receiving portion, 42 exhaust receiving plate, 50 stopper, 52 exhaust, 60 opening / closing lid, 62 supporting shaft, 64 lid portion, 70, 70a opening / closing Lid, 72 mounting part, 74 side part, 76, 76a lid part.

Claims (2)

A discharge hole for condensed water provided on the wall of the vehicle muffler,
An opening / closing lid that is provided inside the vehicle muffler and opens and closes the discharge hole by rotation about a support shaft;
With
The opening / closing device for a vehicle muffler, wherein the opening / closing lid rotates in a direction to open the discharge hole by its own weight, and rotates in a direction to close the discharge hole by exhaust gas flowing into the vehicle muffler. . A discharge hole for condensed water provided on the wall of the vehicle muffler,
An opening / closing lid that is provided in the vehicle muffler so as to face the discharge hole and opens and closes the discharge hole by shape deformation;
With
The opening / closing device for a vehicle muffler, wherein the opening / closing lid is deformed in a direction in which the exhaust hole is closed by thermal expansion due to heat of exhaust gas flowing into the vehicle muffler or elastic deformation due to pressure.