JP2008255879A - Method for controlling exhaust sound for vehicle and device for controlling exhaust sound for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide powerful exhaust sound at an engine start while securing silence in a vehicle in an engine low rotation speed zone. <P>SOLUTION: A device for controlling exhaust sound for a vehicle shuts off flow of exhaust gas in an exhaust channel by a baffle plate 1 and is provided with an opening part 1a on the baffle plate 1, and a communication part establishing communication between a face side and a back side of the baffle plate 1, namely a contact surface 8b and a clearance forming surface 8a facing another end surface 2d of a control valve 2 under a condition where the control valve 2 rotate to separate from the baffle plate 1 and the opening part 10. The communication part is opened and closed by the control valve 2. The control valve opens in engine start zone, and closes in an idling zone and an engine low rotation speed zone. The valve opens in an engine high speed zone and opening increases as engine rotation speed rises. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle exhaust sound control method and a vehicle exhaust sound control apparatus for controlling exhaust sound generated from an exhaust system of an automobile or the like.

2. Description of the Related Art Conventionally, as a vehicle exhaust sound control device, there has been proposed an apparatus that reduces exhaust noise in the low engine speed range and also reduces exhaust noise while reducing exhaust loss in the high engine speed range.
For example, Patent Document 1 discloses an open / close valve that switches an exhaust flow path in response to an exhaust pressure, a biasing means such as a spring that biases the open / close valve in a valve closing direction against the exhaust pressure, There is disclosed a vehicle exhaust sound control device including spring constant changing means for reducing an increase in reaction force of a biasing means when a rotation angle exceeds a predetermined value.
JP-A-8-109815

  By the way, recently, it is required for the structure of the exhaust system to change the level of the exhaust sound according to the traveling scene as well as to reduce the back pressure. In other words, when the engine is started, the exhaust sound is increased and the passenger is given a powerful sound. Further, when the vehicle is idling from a slow acceleration (low engine speed range), the exhaust sound is reduced to ensure quietness in the vehicle. At the time of sudden acceleration (high engine speed range), there is a desire to increase the exhaust noise again and let the passengers hear a comfortable acceleration sound in the vehicle.

However, the device disclosed in the cited document 1 is urged by a spring or the like until the pressure in the muffler reaches a certain pressure in the low engine speed range so as to ensure quietness in the vehicle. Is maintained. That is, the exhaust system is configured so as to emphasize reduction of exhaust noise by keeping the on-off valve closed even when the engine is started. Therefore, the exhaust sound is not powerful when the engine is started.
An object of the present invention is to make a powerful exhaust sound when starting an engine while ensuring quietness in a vehicle in a low engine rotation range.

In order to solve the above-mentioned problem, the vehicle exhaust sound control method according to claim 1 according to the present invention is configured to first control the flow rate of the exhaust gas passing through the exhaust passage of the engine in accordance with the increase in the engine speed. In the engine speed range higher than the engine speed range targeted by the first control step, the flow rate is increased in the second control step as the engine speed increases.
According to a fifth aspect of the present invention, there is provided the vehicle exhaust sound control apparatus according to the fifth aspect, wherein the exhaust gas flow is blocked by the baffle plate in the exhaust flow path, and the baffle plate is opened to connect the front side of the baffle plate. A communication part communicating with the back side is provided, and the communication part is opened and closed by an open / close valve. The valve is opened in the engine start range, and is closed in the idling range and the engine low speed range. In the high speed range, the valve is opened and the opening degree is increased as the engine speed increases.
That is, in the vehicle exhaust sound control apparatus according to claim 5 according to the present invention, in the engine start region, the exhaust gas flows in the exhaust passage by opening the communication portion that becomes the exhaust gas passage. In the idling range and the low engine speed range, the exhaust gas flow is blocked by the baffle plate by closing the valve.

  According to the present invention, when the engine is started, the exhaust gas flows in the exhaust passage, so that a powerful exhaust sound can be generated and the flow of the exhaust gas in the exhaust passage is interrupted in the low engine rotation range. By doing so, quietness in the vehicle can be secured.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
(Constitution)
This embodiment is a vehicle exhaust sound control apparatus to which the present invention is applied.
1 and 2 show a configuration of a valve structure in a vehicle exhaust sound control device. FIG. 1 is a front view, and FIG. 2 is a cross-sectional view taken along line AA shown in FIG.
As shown in FIGS. 1 and 2, the valve structure of the vehicle exhaust sound control device is formed on a baffle plate 1 that divides a muffler into a plurality of expansion chambers and blocks the flow of exhaust gas in an exhaust passage. Yes.

A substantially rectangular opening 1a is formed in the baffle plate 1, and a control valve 2 is attached so that the opening 1a can be opened and closed. That is, the pair of support portions 3a and 3b are fixed to the baffle plate 1 by welding or the like, and both ends are supported by the pair of support portions 3a and 3b, and the valve shaft 4 is attached. A control valve 2 is attached to the valve shaft 4 so as to be rotatable.
The control valve 2 is a substantially rectangular plate member. One end portion 2a rises to form a curved curved portion, and the valve shaft 4 is inserted into a pair of support portions 2b provided on both sides of the curved portion 2a. ing. As a result, the control valve 2 rotates about the valve shaft 4 as a rotation axis, and the closing plate portion (main body portion) 2c which is a flat plate portion can come into contact with and separate from the baffle plate 1.

Here, the curved portion 2a has a shape having a predetermined radius with the valve shaft 4 as the center. That is, while the control valve 2 is rotating, the curved portion 2a is placed on the baffle plate 1. Opposing outer peripheral surfaces come to substantially contact (slide) the baffle plate 1.
A torsion spring 5 is attached to the valve shaft 4, and the control valve 2 (blocking plate portion 2 c) that is rotatable by the valve shaft 4 is urged toward the baffle plate 1 by the torsion spring 5. . The control valve 2 biased by the torsion spring 5 is in a state where the flat plate surface of the closing plate portion 2c is in contact with the side surface of the baffle plate 1, that is, the flat plate surface position of the closing plate portion 2c matches the side surface position of the baffle plate 1. A state is reached (the state shown in FIG. 2).

  An opening 1 a formed in the baffle plate 1 corresponding to the control valve 2 is formed in a shape that can be substantially closed by the control valve 2. Specifically, the opening 1a is equal to or slightly narrower than the width of the control valve 2 in the axial direction of the valve shaft 4, and in the direction orthogonal to the axial direction of the valve shaft 4, the control valve 2 (by the torsion spring 5). In the urged state), the other end surface (the other end surface) 2d (the lower end surface in FIGS. 1 and 2) not provided with the support portion 2b is formed to reach the outside. That is, even when the control valve 2 is urged by the torsion spring 5 and the closing plate portion 2c is in contact with the side surface of the baffle plate 1, the opening 10 that cannot always be closed by the control valve 2 is controlled. An opening 1a is formed so as to be formed outside the other end surface 2d of the bulb 2. In other words, even when the control valve 2 is in a position to close the opening 1a, the opening 1a has the opening 10 that cannot always be closed by the control valve 2.

  Valve guides 6, 7, and 8 are provided for the baffle plate 1 so as to surround the outer periphery of the control valve 2. The valve guides 6, 7, 8 are disposed outside the side surface valve guides 6, 7 disposed on both sides of the control valve 2 and the other end surface 2 d of the control valve 2 (disposed facing the other end surface 2 d). And an end valve guide 8. The side surface valve guides 6 and 7 are plate-like, and are erected with respect to the baffle plate 1 so as to be along both side surfaces of the control valve 2 when rotating with the valve shaft 4 as a rotation axis.

  An end valve guide 8 is provided on the other end side of the control valve 2 so as to be sandwiched between the extended portions of the side surface valve guides 6 and 7. The end valve guide 8 is erected with a predetermined height from the baffle plate 1 along the edge of the opening 1a. The end valve guide 8 has a side surface facing the control valve 2 or the valve shaft 4 (a side surface facing upward in FIGS. 1 and 2), a surface portion 8a rising substantially perpendicular to the baffle plate 1 at the edge of the opening 1a, and a valve shaft. 4 has a curved surface portion 8b formed along the other end surface 2d of the control valve 2 when rotating around the rotation axis 4. That is, the side surface of the end valve guide 8 facing the control valve 2 or the valve shaft 4 is first controlled when the control valve 2 in contact with the baffle plate 1 rotates about the valve shaft 4 as a rotation axis. A surface (hereinafter referred to as a “gap forming surface”) 8a that forms a gap with the other end surface 2d, and a surface (hereinafter referred to as a contact surface) 8b that the other end surface 2d of the control valve 2 approaches or contacts. have. As described above, the other end surface 2 d which is a part of the outer peripheral end of the control valve 2 is close to or in contact with the end valve guide 8.

(Operation and action)
Operation and action are as follows.
The operation and action will be described with reference to FIG.
As shown in FIG. 3, the control valve 2 is normally in a position to close the opening 1 a of the baffle plate 1 by the urging force of the torsion spring 5. At this time, the opening 10 which is a part of the opening 1 a provided in the baffle plate 1 outside the other end surface 2 d of the control valve 2 is not blocked by the control valve 2, and the front side of the baffle plate 1 It communicates with the back side. That is, in a state where the control valve 2 is in contact with the baffle plate 1, the baffle plate 1 is in an open state (hereinafter referred to as a first open state) that allows the front side and the back side to communicate with each other. The valve is opened by the so-called control valve 2.

  When a certain amount of external force is applied to the control valve 2 in the direction of rotating away from the baffle plate 1, the control valve 2 acts on the urging force of the torsion spring 5 with the valve shaft 4 as the center of rotation. It will turn against. At this time, when the amount of rotation is small in the rotation operation (the initial rotation from position A to position B shown in the figure), that is, when the degree of separation between the closing plate portion 2c and the baffle plate 1 is small. A gap is formed between the other end surface 2 d of the control valve 2 and the gap forming surface 8 a of the end valve guide 8. Therefore, the communication state between the front side and the back side of the baffle plate 1 is maintained, and the first opening state is maintained. Thereafter, when the amount of rotation reaches a certain amount, that is, when the degree of separation becomes medium, the control valve 2 has the other end surface 2d substantially in contact with the contact surface 8b of the end valve guide 8 (while substantially sliding). ) To rotate (rotation of the section between position B and position C shown in the figure). That is, the communication state between the front side and the back side of the baffle plate 1 is blocked, and the first opening state is blocked. The valve is closed by the so-called control valve 2.

  Further, when the amount of rotation increases, that is, when the degree of separation becomes large, the contact surface 8b of the end valve guide 8 does not exist outside the other end surface 2d of the control valve 2, so that the control valve 2 The other end surface 2d and the end valve guide 8 are separated from each other, and the front side and the back side of the baffle plate 1 communicate with each other again (hereinafter referred to as a second opening state). That is, the control valve 2 is opened again. At this time, the degree of opening in the second opening state is a degree corresponding to the amount of rotation (opening amount) of the control valve 2, that is, as the amount of rotation increases or the degree of separation increases, The degree of opening increases.

  Here, when the control valve 2 is in a position to close the opening 1 a of the baffle plate 1, the opening 10 existing outside the other end surface 2 d of the control valve 2, and the control valve 2 is connected to the baffle plate 1. The gap forming surface 8a and the contact surface 8b that face the other end surface 2d in a state of rotating away from the other side constitute a communication portion (communication path) that communicates the front side and the back side of the baffle plate 1.

FIG. 4 shows the structure of the muffler 20 provided with the valve structure.
As shown in FIG. 4, the muffler 20 has, for example, a substantially oval cross section, and a baffle plate 21 is disposed inside the muffler 20 in the transverse direction of the muffler 20. Thus, the first and second expansion chambers 22 and 23 are sequentially defined at positions adjacent to each other from the left side in FIG.
The muffler 20 is provided with an inlet tube 24 having one end connected to an exhaust pipe from an engine (not shown) and having the other end opened in the second expansion chamber 23 after passing through the first expansion chamber 22. Thereby, the inlet tube 24 guides the exhaust gas from the engine to the second expansion chamber 23.
Further, the muffler 20 is provided with a pass tube 25 that allows the first expansion chamber 22 and the second expansion chamber 23 to communicate with each other through the baffle plate 21. Further, the muffler 20 is provided with a tail tube 26 having one end opened in the first expansion chamber 22 and the other end opened outside (atmosphere) after passing through the second expansion chamber 23 from the first expansion chamber 22. Yes.

  The baffle plate 21 is formed with an opening 21a communicating with the first expansion chamber 22 and the second expansion chamber 23 so as to be adjacent to the pass tube 25. The baffle can be opened and closed. The valve structure described with reference to FIGS. 1 to 3 is provided on the surface of the plate 21 on the first expansion chamber 22 side. That is, the exhaust flow path includes an inlet tube 24 that is a first continuous pipe that communicates with the engine, a tail tube 26 that is a second communication pipe that communicates with outside air, and one end of the inlet tube 24 opposite to the engine. The first and second expansion chambers 22, the other end communicates with the end of the tail tube 26 opposite to the communicating portion with the outside air, and the cross-sectional area is larger than that of the inlet tube 24 and the tail tube 26. The inlet tube 24 and the tail tube 26 communicate with each other in the first and second expansion chambers 22 and 23.

  In the muffler structure as described above, when the engine is started, the exhaust sound discharged from the engine sequentially passes through the inlet tube 24, the second expansion chamber 23, the pass tube 25, the first expansion chamber 22, and the tail tube 26 ( 4 is discharged from the tail tube 26 to the atmosphere by a path indicated by a solid arrow A in FIG. 4 (hereinafter referred to as a first path).

  At this time, in the valve structure, when the exhaust gas flow is zero and when the exhaust gas starts flowing at the engine start, the outside of the other end surface 2d of the control valve 2 is opened, and the first open state is established. That is, that is, the opening 10 exists outside the other end surface 2 d of the control valve 2, or there is a gap between the other end surface 2 d of the control valve 2 and the gap forming surface 8 a of the end valve guide 8. It is formed. As a result, when the engine is started, the exhaust sound from the engine that sequentially passes through the inlet tube 24 and the second expansion chamber 23 passes through the opening 10 or the gap, that is, a path different from the path tube 25. The control valve 2 passes through a valve structure part (a path indicated by a dotted arrow B in FIG. 4, hereinafter referred to as a second path) and is discharged from the tail tube 26 to the atmosphere. Thereby, in addition to the first path, the exhaust sound from the second path is discharged to the atmosphere, so that the exhaust sound at the time of starting the engine is increased compared to the conventional example.

Further, when the engine speed increases and reaches a certain engine speed (idling range), the control valve 2 has a pressure immediately before it (the pressure in the second expansion chamber 23, hereinafter referred to as a pre-valve pressure). Is raised to the position B (see FIG. 3). At this time, the other end surface 2d of the control valve 2 comes into substantially contact with the contact surface 8b of the end valve guide 8, and the first opening state is blocked. This is equivalent to the fact that the opening area of the opening 10 existing outside the other end surface 2d of the control valve 2 at the start of the engine or the passage area of the communication portion (communication passage) becomes substantially zero.
As a result, the exhaust sound discharged from the engine is discharged from the tail tube 26 mainly via the first path, and the discharge of the exhaust sound from the tail tube 26 is limited. .

In addition, even if the engine speed increases, if the engine speed is maintained at a low engine speed range (such as during slow acceleration) and does not reach a high engine speed range (such as during rapid acceleration), the engine As the number of revolutions increases, the pressure before the valve also increases, thereby increasing the amount of rotation of the control valve 2, but the other end surface 2d of the control valve 2 is in contact with the end valve guide 8 until the position C (see FIG. 3). The state in contact with the surface 8b is maintained.
Therefore, at this time, the exhaust sound discharged from the engine is mainly discharged from the tail tube 26 via the first path, and the restriction on the discharge of the exhaust sound from the tail tube 26 is maintained. Is done.

  Then, when the engine is in a high engine speed range (during rapid acceleration, etc.), the control valve 2 is rotated beyond the position C (see FIG. 3) due to the increase in the pressure before the valve due to the increase in the exhaust gas flow rate. A second opening state is achieved in which the outside of the other end surface 2d of the control valve 2 is opened again. Thereby, since the exhaust gas discharged from the engine also passes through the second path, an increase in pressure loss is suppressed even when the flow rate is increased. Thereby, an engine output comes to improve in an engine high rotation area.

FIG. 5 shows the relationship between the engine speed described above and the opening area (opening degree) controlled by the control valve 2.
As shown in FIG. 5, when the engine speed is that at the start of the engine, the valve is opened by the control valve 2 and is in the open state (first open state), and then the engine speed is in the idling range. To the slow acceleration region (low rotation region), the valve is closed by the control valve 2. When the engine speed reaches the high speed range, the control valve 2 is opened again to enter the open state (second open state).

  That is, it is assumed that the structure of the vehicle exhaust sound control device is designed so that the control valve 2 operates in accordance with the engine speed as described above. For example, the elastic force (spring constant, etc.) of the torsion spring 5, the area of the control valve 2 and the opening 1a, etc. are appropriately set so that the control valve 2 operates in accordance with the engine speed as described above. Yes. Alternatively, as described above, the pre-valve pressure (for example, the second expansion chamber 23) is appropriately set so that the control valve 2 operates in accordance with the engine speed.

For example, as shown in FIG. 6, the pre-valve pressure changes corresponding to the flow rate of the exhaust gas. As shown in FIG. 6, the flow rate of the exhaust gas increases as the engine speed increases, that is, in the order of the engine start range, the idling range, the low rotation range, and the high rotation range.
The structure of the vehicle exhaust sound control device is appropriately designed based on such characteristics. That is, for example, with respect to the spring constant (biasing force) of the torsion spring 5, in the engine start range, the rotation range of the control valve 2 is positioned from the position A against the force that the control valve 2 receives due to the pre-valve pressure at that time. In the idling range and the low rotation range, the rotation range of the control valve 2 is resisted against the force received by the control valve 2 due to the pre-valve pressure at that time. Is in the section from position B to position C (see FIG. 3), and in the high speed range, the control valve 2 is positioned against the force received by the control valve 2 due to the pre-valve pressure at that time. The spring constant (biasing force) of the torsion spring 5 is set so as to rotate more than C (see FIG. 3).

  By doing so, for example, even when the flow of exhaust gas pulsates in the idling region and the low rotation region, and the rotation state of the control valve 2 also pulsates accordingly, the rotation of the control valve 2 is prevented. Since it is maintained between the position B and the position C, the control valve 2 can be prevented from coming into contact with the baffle plate 1. As a result, it is possible to prevent the control valve 2 from coming into contact with the baffle plate 1 in the idling region and the low rotation region, thereby preventing the hitting sound and maintaining the quietness in the vehicle.

(effect)
The effect is as follows.
As described above, the flow of the exhaust gas is blocked by the baffle plate 1 in the exhaust flow path, and the baffle plate 1 is opened to communicate the front side and the back side of the baffle plate 1, that is, the opening 10. In addition, when the control valve 2 is rotated away from the baffle plate 1, by providing the clearance forming surface 8 a and the contact surface 8 b facing the other end surface 2 d of the control valve 2, the communication portion is controlled by the control valve 2. The valve is open and closed.Opens in the engine start range, closes in the idling range and low engine rotation range, opens in the high engine rotation range, and opens as the engine speed increases. Is increasing. That is, by opening the valve in the engine starting region, the exhaust gas flows in the exhaust passage, and in the idling region and the low engine rotation region, closing the valve, the exhaust gas flow is blocked by the baffle plate. ing.

As a result, when the engine is started, exhaust gas flows in the exhaust passage, so that a powerful exhaust sound can be produced, and the flow of the exhaust gas in the exhaust passage can be cut off in the low engine speed range. , Quietness in the car can be secured. Further, in the high engine speed range, the opening degree is increased as the engine speed increases, so that an increase in pressure loss can be suppressed even when the exhaust gas flow rate is increased.
Further, such exhaust noise can be controlled by the simple valve structure as described above. Furthermore, as described above, such exhaust noise can be controlled only by setting the spring constant (biasing force) of the torsion spring 5 to a predetermined setting.

Further, as described above, while the control valve 2 is rotating, the outer peripheral surface facing the baffle plate 1 in the curved portion 2a is substantially in contact (sliding) with the baffle plate 1. . Thereby, it is possible to prevent the exhaust gas (exhaust sound) from leaking downstream from the support portion of the control valve 2 while the control valve 2 is operating.
In addition, the said embodiment can also be implement | achieved by the following structures.

7 and 8 show the configuration of another valve structure in the vehicle exhaust sound control apparatus. 7 is a front view, and FIG. 8 is a BB cross-sectional view shown in FIG.
As shown in FIGS. 7 and 8, the valve structure is configured to prevent the exhaust gas (exhaust sound) from leaking from the support portion of the control valve 2. That is, unlike the above-described embodiment, the control valve 2 is a substantially rectangular plate member in which the one end portion 2e does not rise, and the valve shaft 4 is inserted into the support portions 2b provided on both sides of the one end portion 2e. ing. Here, one end 2e of the control valve 2 is attached to a portion extending from the insertion hole of the valve shaft 4 in the support portion 2b.

  A gas leakage prevention member 11 is attached to the baffle plate 1 on the one end 2 e side of the control valve 2. The gas leakage prevention member 11 is a rod-shaped member having a substantially L-shaped cross section disposed in parallel with one end (the upper end in FIGS. 7 and 8) of the control valve 2 or the valve shaft 4, and one side 11 a on the baffle plate 1. It is attached to. The other side 11b is erected with respect to the baffle plate 1, but more specifically, it is inclined toward the opening 1a.

In such a structure, when the control valve 2 rotates, the movement trajectory of one end of the control valve 2 becomes a trajectory that draws an arc around the valve shaft 4. At this time, one end of the control valve 2 moves along the other side (surface) 11 b of the gas leakage preventing member 11. Thereby, it is possible to prevent the exhaust gas (exhaust sound) from leaking downstream from the support portion of the control valve 2 as in the above-described embodiment. For this reason, the other side (surface) 11b of the gas leakage preventing member 11 is formed in a shape (curved shape) along one end of the control valve 2 at the time of rotation as much as possible. Is preferred.
The muffler structure to which the valve structure is applied is not limited to the structure shown in FIG.

FIG. 10 shows another muffler structure.
As shown in FIG. 10, first and second baffle plates 41, 42 are disposed inside the muffler 40 in the transverse direction of the muffler 40, and the first to second baffle plates 41, 42 are arranged from the left side in FIG. Three expansion chambers 43, 44, and 45 are sequentially defined at adjacent positions.
The muffler 40 is provided with an inlet tube 46 having one end connected to an exhaust pipe from an engine (not shown) and having the other end opened in the second expansion chamber 44 after passing through the first expansion chamber 43. Thereby, the inlet tube 46 guides exhaust gas from the engine to the second expansion chamber 44.

  The muffler 40 has a first pass tube 47 whose axial center is coaxial with the inlet tube 46 and allows the second expansion chamber 44 and the third expansion chamber 45 to communicate with each other through the second baffle plate 42. Is provided. Further, a second pass tube 48 is provided so as to pass through the second baffle plate 42 and communicate with the second expansion chamber 44 and the third expansion chamber 45 so as to be adjacent to the first pass tube 47. Specifically, the first baffle plate 41 has an opening 41a communicating with the second expansion chamber 44 and the third expansion chamber 45, and the first baffle plate is communicated with the opening 41a. An end portion of the second pass tube 48 is attached to the surface of the 41 on the second expansion chamber 44 side. The valve structure described with reference to FIG. 1 to FIG. 3 or FIG. 7 to FIG. 9 is provided on the surface of the first baffle plate 41 on the first expansion chamber 43 side so that the opening 41a can be opened and closed.

  The muffler 40 has a first tail tube 49 that opens at one end in the first expansion chamber 43, sequentially passes through the first to third expansion chambers 43, 44, and 45 and opens at the other end outside (atmosphere). Is provided. Further, one end of the muffler 40 is opened in the second expansion chamber 44 so as to be adjacent to the first tail tube 49, and the other end passes through the third expansion chamber 45 from the second expansion chamber 44. ) Is provided with a second tail tube 50.

In the muffler structure as described above, when the engine is started, the exhaust sound discharged from the engine sequentially passes through the inlet tube 46, the second expansion chamber 44, and the second tail tube 50 (indicated by the solid arrow A in FIG. 10). The second tail tube 50 is discharged into the atmosphere by the route shown in FIG.
At this time, in the valve structure, the outside of the other end surface 2d of the control valve 2 is opened and the first opening state is maintained, that is, the opening 10 is formed outward of the other end surface 2d of the control valve 2. Or a gap is formed between the other end surface 2d of the control valve 2 and the gap forming surface 8a of the end valve guide 8, so that the inlet tube 46, the second expansion chamber 44, and the first pass tube 47 are connected to each other. The exhaust sound from the engine that has passed sequentially passes through the opening 10 or the gap, that is, the second expansion chamber through the valve structure portion by the control valve 2 which is a path different from the first path. 43 and the first tail tube 49 are sequentially discharged from the first tail tube 49 to the atmosphere through a route (a route indicated by a dotted arrow B in FIG. 10, a second route). Thereby, in addition to the first path, the exhaust sound from the second path is discharged to the atmosphere, so that the exhaust sound at the time of starting the engine is increased compared to the conventional example.

Further, when the engine speed increases and reaches a certain engine speed (idling range), the control valve 2 rotates to the position B (see FIG. 3) due to the increase of the pre-valve pressure. At this time, the other end surface 2d of the control valve 2 comes into substantially contact with the contact surface 8b of the end valve guide 8, and the first opening state is blocked.
As a result, the exhaust sound discharged from the engine is mainly discharged from the second tail tube 50 via the first path, and the discharge of the exhaust sound from the first tail tube 49 is restricted. Become a shape.

In addition, even if the engine speed increases, if the engine speed is maintained at a low engine speed range (such as during slow acceleration) and does not reach a high engine speed range (such as during rapid acceleration), the engine As the number of revolutions increases, the pressure before the valve also increases, thereby increasing the amount of rotation of the control valve 2, but the other end surface 2d of the control valve 2 is in contact with the end valve guide 8 until the position C (see FIG. 3). The state in contact with the surface 8b is maintained.
Accordingly, the exhaust sound discharged from the engine is mainly discharged from the second tail tube 50 via the first path, and the discharge of the exhaust sound from the first tail tube 49 is restricted. Maintained.

  When the engine is in a high engine speed range (during rapid acceleration, etc.), the control valve 2 is rotated beyond the position C (see FIG. 3) by increasing the pre-valve pressure due to the increase in the exhaust gas flow rate. A second opened state is obtained in which the outside of the end 2c of the valve 2 is opened again. Accordingly, since the exhaust gas discharged from the engine passes through the second path, an increase in pressure loss is suppressed even when the flow rate is increased. Thereby, an engine output comes to improve in an engine high rotation area.

  In the description of the embodiment, the baffle plate 1 realizes a baffle plate that blocks the flow of exhaust gas in the exhaust passage, and the opening 1a realizes an opening provided in the baffle plate. The control valve 2 realizes a plate-like opening / closing valve disposed so as to be able to come in contact with and separate from the baffle plate in a direction away from the flow direction of the exhaust gas so as to cover the opening. Realizes an urging means for urging the open / close valve in the baffle plate direction (direction in contact with the baffle plate). The valve guides 6, 7 and 8, particularly the end valve guide 8, The surrounding member is provided so as to surround the outer peripheral edge of the baffle plate, and the opening is provided when the exhaust gas flow is zero. At the position of the on-off valve, or in a state where the on-off valve is in contact with the baffle plate, the outer opening of the on-off valve is opened to the outside of the on-off valve. The surfaces (the gap forming surface 8a and the contact surface 8b) that face each other have a shape corresponding to the degree of separation of the opening / closing valve from the baffle plate, and the state in which the opening / closing valve is in contact with the baffle plate and the degree of separation are When the degree of separation is intermediate, the outer end of the opening / closing valve is close or slid, and when the degree of separation is large, the opening / closing valve is separated from the outer peripheral end of the opening / closing valve. As the distance from the outer peripheral end increases, the degree of separation from the outer peripheral end of the on-off valve increases as the degree of separation increases.

  In the embodiment, the first control step for reducing the flow rate of the exhaust gas passing through the exhaust passage of the engine in accordance with the increase in the engine speed, and the engine speed range targeted by the first control step. In a high engine speed range, a vehicle exhaust sound control method comprising a second control step of increasing the flow rate in accordance with an increase in engine speed is realized. Further, in the first engine control step, the flow rate of the exhaust gas is set in the first engine control step in the engine speed region targeted by the first control step and the engine speed region targeted by the second control step. And it has implement | achieved having the 3rd control process made into the flow volume smaller than the flow volume of the said exhaust gas in a 2nd control process. Here, the engine speed targeted by the first control process includes the engine speed at the start of the engine, and the engine speed targeted by the third control process includes the idling range and the engine low speed range. The engine speed including the engine speed, and the engine speed targeted by the second control step includes the engine speed in the high engine speed range.

It is a front view which shows the structure of the valve structure in the vehicle exhaust sound control apparatus to which this invention is applied. FIG. 2 is a cross-sectional view taken along line AA shown in FIG. 1, showing a configuration of a valve structure in a vehicle exhaust sound control device to which the present invention is applied. It is the figure used for description of operation | movement and an effect | action of a valve structure. It is a figure which shows the structure of the muffler which provided the valve structure. It is a characteristic view which shows the relationship between an engine speed and the valve opening area of a control valve. It is a characteristic view which shows the relationship between the flow volume of exhaust gas, and the valve | bulb front pressure. It is a front view which shows the structure of another valve structure. FIG. 8 is a cross-sectional view taken along line BB shown in FIG. 7, showing another valve structure configuration. It is the figure used for description of operation | movement and an effect | action of another valve structure. It is a figure which shows the structure of another muffler.

Explanation of symbols

  1 baffle plate, 1a opening, 2 control valve, 5 torsion spring, 8 end valve guide, 8a clearance forming surface, 8b contact surface, 10 opening

Claims (8)

A first control step of reducing the flow rate of exhaust gas passing through the exhaust passage of the engine in accordance with an increase in the engine speed;
A second control step of increasing the flow rate in accordance with an increase in engine speed in an engine speed range higher than the engine speed range targeted by the first control step;
A vehicle exhaust noise control method comprising: In the engine speed range targeted by the first control step and the engine speed range targeted by the second control step, the flow rate of the exhaust gas is set in the first control step and the first control step. The vehicle exhaust sound control method according to claim 1, further comprising a third control step in which the flow rate is lower than the flow rate of the exhaust gas in the second control step. 3. The vehicle exhaust sound control method according to claim 1, wherein the engine speed targeted by the first control step includes an engine speed at the time of starting the engine. 4. 4. The vehicle exhaust sound control method according to claim 1, wherein the engine speed targeted by the third control step includes an engine speed during idling. 5.   The flow of exhaust gas is blocked by a baffle plate in the exhaust flow path, and the baffle plate is opened to provide a communication portion that communicates the front side and the back side of the baffle plate, and the communication portion is opened by an open / close valve. And closed in the engine start range, closed in the idling range and the low engine speed range, and opened in the high engine speed range, and increased in opening as the engine speed increases. An exhaust sound control device for a vehicle, characterized in that: A baffle plate that blocks the flow of exhaust gas in the exhaust flow path;
An opening provided in the baffle plate;
A plate-like on-off valve disposed so as to be able to come in contact with and separate from the baffle plate as a direction away from the flow direction of the exhaust gas so as to cover the opening;
An urging means for urging the open / close valve toward the baffle plate;
An enclosing member erected with respect to the baffle plate so as to surround the outer peripheral end of the on-off valve;
The opening is sized to open outside the outer peripheral end of the open / close valve at the position of the open / close valve when the flow of exhaust gas is zero, and the outer peripheral end of the open / close valve in the surrounding member When the degree of separation of the opening / closing valve from the baffle plate is small, the surface facing the surface is separated from the outer edge of the opening / closing valve, and when the degree of separation is moderate, at least one of the outer edges of the opening / closing valve. When the part is close or slid and the degree of separation is large, the part is separated from the outer peripheral end of the opening / closing valve, and the degree of separation from the outer peripheral end of the opening / closing valve increases as the degree of separation increases. A vehicle exhaust sound control device.   The biasing means has a small degree of separation when the on-off valve is separated from the baffle plate due to the gas pressure of exhaust gas flowing in the exhaust passage in the engine starting region, and in the idling region and the engine low rotation region. The degree of separation when the opening / closing valve is separated from the baffle plate due to the gas pressure of the exhaust gas flowing through the exhaust passage is medium, and the gas pressure of the exhaust gas flowing through the exhaust passage is at a high engine speed range. The vehicle exhaust sound control device according to claim 6, further comprising an urging force that increases a degree of separation when the open / close valve is separated from the baffle plate. The exhaust passage has a first communication pipe communicating with the engine, a second communication pipe communicating with the outside air, one end communicating with an end of the first communication pipe opposite to the engine, and the other end An expansion chamber that communicates with an end of the second communication pipe opposite to the communication section with the outside air and has a cross-sectional area larger than that of the communication pipe, and the vehicle exhaust sound control device includes the expansion chamber. An exhaust sound control device for a vehicle, wherein the first communication pipe and the second communication pipe are communicated with each other.

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