JP4401860B2 - Exhaust control valve - Google Patents

Description

  The present invention provides an exhaust pressure sensitive exhaust that is provided at an end of an exhaust pipe disposed in a silencer, a communicating hole formed in a partition plate (baffle plate), and the like, and opens and closes according to the exhaust pressure. It relates to a control valve.

This type of conventional exhaust control valve opens and closes a part of the exhaust passage that is arranged so that the small chambers in the silencer main body communicate with each other in an arbitrary combination corresponding to the pressure fluctuation of the exhaust flowing in from the engine side. As a result, it is incorporated in the silencer in order to prevent a decrease in engine output due to exhaust pressure loss while improving the silencing effect.
As such an exhaust control valve, for example, as shown in FIG. 6, it opens and closes via a support shaft 104 with respect to an annular seat surface 103 of a valve seat 102 provided at an end of an exhaust pipe 101 in a silencer body. A valve body 105 that is provided, and a coil that a coil portion 106a is locked to the support shaft 104, and the valve body 105 is brought into contact with the seat surface 103 of the valve seat 102 to urge the exhaust control valve in a closing direction. For example, when the engine rotates at a low speed, the exhaust pipe 101 is closed by the urging force of the coil spring 106 to narrow the exhaust gas flow path inside the silencer body. When the exhaust pressure exceeds the urging force of the coil spring 106 during high-speed rotation of the engine, the valve is operated so as to enhance the silencing effect due to the increase in exhaust resistance. The exhaust pipe 101 is opened by pushing 105 open, and thereby the exhaust gas flow passage in the silencer body is widened to give priority to the prevention of engine output reduction due to low back pressure at high speed. (For example, refer to Patent Document 1).

  This type of conventional exhaust control valve opens and closes the exhaust passage in response to fluctuations in exhaust pressure flowing in from the engine side, thereby improving the silencing effect and preventing the engine output from decreasing. In the conventional exhaust control valve (Patent Document 1), as described above, the coil portion 106a of the coil spring 106 is mounted on the support shaft 104 that pivotally supports the valve body 105 (see FIG. Therefore, the urging force of the coil spring 106 acts so as to increase as the opening degree becomes larger than when the valve body 105 is initially opened. There is a problem that the back pressure cannot be lowered sufficiently at times.

  In this case, by setting the urging force of the coil spring 106 to be weak, it is possible to sufficiently reduce the back pressure at the time of high-speed rotation of the engine and reduce exhaust pressure loss. Since the valve body 105 starts to open from the time of rotation, there is a problem that a request for noise reduction at the time of low-speed rotation of the engine is not satisfied.

  Thus, in the conventional structure, the noise reduction measures at the time of engine low speed rotation and the low back pressure measures at the time of engine high speed rotation have a trade-off relationship, and there is a problem that both requirements cannot be satisfied at the same time. .

  Therefore, as a solution to the above problems, as shown in FIG. 7, one end of the valve body 105 is pivotally supported on the support shaft 104 at the end of the exhaust pipe 101, and the coil portion 106 a of the coil spring 106 is attached. The valve body 105 is mounted on a support shaft 107 that is different from the shaft center of the support shaft 104, and one end of the coil spring 106 is slid on the base plate portion 105 a outside the seat surface 103 of the valve body 105. By slidably abutting and pressing against the moving surface, the urging force of the coil spring 106 is maximized at the valve closing position, and the urging force of the coil spring 106 is decreased as the valve is opened. There are some (see, for example, Patent Document 2).

JP 2002-235536 A (page (3) of the specification, FIG. 1) JP 2001-090529 A (Specification (page 3), FIG. 1)

  However, in the conventional example (Patent Document 2), the support shaft 104 that supports the valve body 105 is disposed on the downstream side of the seat surface 103 with which the valve body 105 abuts, but the support shaft 107 that supports the coil spring 106. Is disposed upstream of the seat surface 103 with which the valve body 105 abuts (on the outer surface side of the exhaust pipe 101), and one end of the coil spring 106 is connected to the base plate portion 105a outside the seat surface 103 of the valve body 105. Since the exhaust control valve is maintained in a closed state by slidably abutting and pressing against the sliding surface provided on the exhaust surface, the position of the support shaft 107 that supports the coil spring 106 is the exhaust pipe. As a result, the configuration of the valve seat increases in the radial direction of the exhaust pipe 101. There is.

  That is, in the silencer in which this exhaust control valve is arranged, a plurality of exhaust pipes are arranged in parallel in the width direction, so the width direction depends on the positional relationship with the plurality of exhaust pipes and the space. There are many restrictions on the dimensions, and therefore, even in the exhaust control valve, it is not desirable to increase the size of the valve seat in the radial direction.

  The problem to be solved by the present invention is to increase the opening angle of the valve body with respect to the engine speed by setting the urging force of the urging means weakly without enlarging the valve seat portion in the radial direction. An object of the present invention is to provide an exhaust control valve that can satisfy the requirement for lowering the noise required when the engine rotates at a low speed while satisfying the requirement for lowering the back pressure during high-speed driving.

  In order to solve the above-mentioned problem, in the invention according to claim 1, a valve body that can be opened and closed via a support shaft with respect to a valve seat provided in the middle of the exhaust flow passage in the silencer body, and the valve body And an urging means for urging the exhaust control valve in a direction to close the exhaust control valve in contact with the seat surface of the valve seat, wherein the support shaft that pivotally supports the valve body is located from the position of the seat surface. It is provided at a position separated by a predetermined distance on the downstream side, and the shaft support portion of the urging means is upstream of the shaft center of the support shaft that supports the valve body and downstream of the position of the seat surface. The biasing force applied to the valve body by the biasing means is applied to a position within the circumferential surface of the seat surface, so that the point of application of the biasing force to the valve body is opened from the time of valve closing. Configured to move in the direction of the spindle as the degree increases, The contact surface of the valve body, which is the point of application of the urging force by the urging means, is urged against the valve body in the direction of increasing the apparent pre-torque of the urging means against the valve body at the initial stage of opening the valve body. An upward inclined surface for guiding and moving the point of application of the biasing force of the means is formed.

  According to a second aspect of the present invention, in the first aspect of the present invention, the contact surface of the valve body that is the point of application of the urging force by the urging means is against the valve body at the initial stage of opening the valve body. An upward inclined surface that guides and moves the point of application of the urging force of the urging means to the valve body in the direction of increasing the apparent pre-torque of the urging means, and an appearance of the urging means against the valve body when the upward inclined surface is overcome The means is characterized in that a projection having an approximately chevron-shaped cross section having a downwardly inclined surface for guiding and moving the point of application of the urging force of the urging means to the valve body in the direction of decreasing the upper pre-torque is provided.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the shaft support portion of the urging means is the same as the point of application of the urging force to the valve body downstream from the position of the seat surface. It is a means characterized by being provided on the upstream side.

  According to the first aspect of the present invention, since it is configured as described above, first, by setting the biasing force of the biasing means to such an extent that the engine speed does not open in a predetermined low speed range. Therefore, it is possible to satisfy the demand for noise reduction required when the engine rotates at a low speed.

  Next, at the time of valve opening when the engine speed exceeds a predetermined low speed rotation range and the exhaust pressure overcomes the urging force of the urging means and the valve body is pushed open from the seat surface, than the shaft support portion of the urging means. Since the valve body rotates around the support shaft located on the downstream side, the shaft center position of the valve body moves greatly in the direction away from the support shaft in proportion to the valve opening relative to the axial position of the seat surface. On the other hand, since the shaft support portion of the urging means is disposed at a position closer to the seat surface on the upstream side than the support shaft supporting the valve body, the urging force acts on the valve body in the urging means. Since the amount of movement of the point from the valve closing position when the valve is opened is relatively small compared to the movement amount of the axial center position of the valve body, as the valve is opened, the biasing force by the biasing means for the valve body is increased. The action point moves in the direction of the support shaft from the action point when the valve is closed.

  The contact surface of the valve body, which is the point of application of the urging force by the urging means, is applied to the valve body in the direction of increasing the apparent pre-torque of the urging means for the valve body in the initial stage of opening the valve body. Since the upward inclined surface that guides and moves the application point of the urging force of the urging means is formed, the valve opening timing with respect to the engine speed in the initial stage of valve opening can be delayed.

  Further, when the valve body exceeds the initial stage of opening the valve body, the upward inclined surface is finished, so that the opening degree of the valve body with respect to the engine speed is increased as the valve body is opened.

  Therefore, by setting the biasing force of the biasing means to be weak and increasing the opening angle of the valve body with respect to the engine speed, it is necessary for low-speed rotation of the engine while satisfying the demand for low back pressure during medium and high-speed driving. The effect that it becomes possible to simultaneously satisfy the demanded reduction in noise is obtained.

Further, the shaft support portion of the biasing means is provided on the upstream side of the shaft center of the support shaft that supports the valve body and on the downstream side of the position of the seat surface, and the biasing force on the valve body in the biasing means is the seat. By being configured to act on a position within the peripheral surface of the surface, the shaft support portion of the urging means can be attached to the shaft of the exhaust pipe without being restricted by the outer diameter of the exhaust pipe and the position of the point of application of the urging force. It is possible to place the sensor as close as possible to the inner side in the heart direction.
Therefore, the valve seat portion can be made compact in the radial direction.

  In the second aspect of the present invention, as described above, the contact surface of the valve body that is the point of application of the urging force by the urging means is provided on the urging means for the valve body at the initial stage of opening the valve body. Since an upwardly inclined surface that guides and moves the point of application of the urging force of the urging means to the valve body in the direction of increasing the apparent pre-torque is formed, the valve opening timing with respect to the engine speed in the initial stage of valve opening can be delayed. become able to.

  In addition, a descending inclined surface is formed that guides and moves the point of application of the urging force of the urging means against the valve body in a direction to lower the apparent pre-torque of the urging means against the valve body when the climbing surface is overcome. Therefore, as the valve body is opened, the valve body opening degree changes with respect to the engine speed.

  Therefore, by setting the urging force of the urging means to be weak and increasing the opening angle of the valve body with respect to the engine speed, the low back pressure requirement during medium / high speed running is further satisfied, while the engine is running at low speed. There is an effect that the required noise reduction requirement can be satisfied at the same time.

  In the invention according to claim 3, as described above, the shaft support portion of the urging means is provided downstream of the seat surface at the same point as the point of application of the urging force to the valve body or upstream thereof. Thus, as described above, the axial position of the valve body largely moves in the direction away from the support shaft in proportion to the valve opening degree with respect to the axial position of the seat surface. Since the point moves in the direction approaching the shaft support part of the urging means, as the valve opening increases, the point of action of the urging force by the urging means on the valve body changes from the action point when the valve is closed to the direction of the support shaft. The amount of movement will be further increased.

  Therefore, as the valve opening degree of the valve body increases, the degree of reduction of the shaft torque acting on the support shaft of the valve body increases further, and thereby, the valve opening force due to the exhaust pressure becomes relatively stronger. It is possible to further satisfy the demand for lower back pressure during high-speed engine rotation.

  Further, since the amount of movement from the action point in the initial stage of valve opening in the direction of the support shaft is further increased, the effect of delaying the valve opening timing due to the upward slope can be further enhanced.

  An embodiment of the present invention will be described with reference to the drawings.

The exhaust control valve of the first embodiment corresponds to the invention described in claim 1.
First, the configuration of the exhaust control valve of the first embodiment will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a silencer in which the exhaust control valve of the first embodiment is incorporated, and FIG. 2 is a vertical cross-sectional view showing details of the exhaust control valve of the first embodiment ((A) is in a closed state. (B) is the initial stage of valve opening, and (c) is the valve open state).
As shown in FIG. 2, the exhaust control valve A of the first embodiment includes a valve seat 1, a valve body 2, a support shaft 3 that pivotally supports the valve body 2, and a coil spring (biasing means) 4. , And a support shaft 5 that supports the coil spring 4 as a main component.

  The valve seat 1 includes a pipe portion 11 connected and fixed to an upstream opening end portion of an inner pipe (exhaust flow passage) 9b in a silencer body 7 to be described later, and an outward direction from the end portion of the pipe portion 11 And an annular seat surface 12 extending substantially horizontally, a substrate portion 13 extending horizontally from one outer peripheral edge of the seat surface 12 toward the outside, and both side surfaces thereof are bent upward. And a pair of shaft support portions 14 and 14 raised vertically.

The valve body 2 includes a main body portion 21 having a wide range in contact with the seat surface 12, and an arm portion 22 extending obliquely outward and upward from one outer peripheral edge side of the main body portion 21. The upper end of the arm portion 22 is pivotally supported with respect to the support shaft 3 laid horizontally between the shaft support portions 14, 14, so that the valve seat 1 is centered on the support shaft 3. On the other hand, the valve body 2 is assembled so as to be freely opened and closed.
That is, the support shaft 3 is provided at a position away from the position of the seat surface 12 by a predetermined distance L on the downstream side.

  The coil spring 4 has a coil portion 41 attached to a support shaft 5 that is horizontally mounted between the shaft support portions 14 and 14 at a position closer to the seat surface 12 than the support shaft 3. The main body 21 of the valve body 2 is brought into contact with the seat surface 12 of the valve seat 1 by abutting and locking the shaft center Q2 of the main body 21 of the valve body 2 and the one end locking portion 15 of the valve seat 1, respectively. Thus, an urging force is applied in a direction to close the exhaust control valve. When the exhaust control valve is closed, the shaft center Q2 portion of the main body portion 21 and the shaft center Q1 portion of the inner pipe 9b and the seat surface 12 are in alignment.

  That is, the support shaft 5 constituting the shaft support portion of the coil spring 4 is provided at a position separated from the seat surface 12 by a predetermined distance H on the downstream side, and the coil for the valve body 2 is closed when the valve is closed. The biasing force of the spring 4 is configured to act on the axial center Q2 portion of the main body portion 21 in the peripheral surface of the seat surface 12.

  Then, the contact surface of the main body 21 in the valve body 2 that is the point of action of the urging force by the coil spring 4 is formed on the coil spring 4 with respect to the main body 21 of the valve body 2 in the initial stage of opening the exhaust control valve A. A stepped portion 10 is formed through an upward inclined surface 10a that guides and moves the point of application of the urging force of the coil spring 4 with respect to the main body portion 21 in the direction of increasing the apparent pre-torque.

  The silencer incorporating the exhaust control valve A according to the first embodiment includes a silencer body 7, an inner plate 8, an inlet pipe 9a, an inner pipe 9b, and an outlet pipe 9c as main components. .

  The silencer main body 7 includes a substantially cylindrical outer shell 71 and outer plates 72 and 73 that close both front and rear openings of the outer shell 71. The interior of the silencer body 7 is partitioned by the inner plate 8 into a first silencer chamber (expansion chamber) 7a and a second silencer chamber (expansion chamber) 7b.

  The inlet pipe 9a penetrates the upstream outer plate 72 and the inner plate 8, and the downstream opening thereof communicates with the second silencing chamber 7b. The outlet pipe 9c is connected to the inner plate 8 and the downstream side. The upstream opening is communicated with the first silencing chamber 7a in a state of passing through the outer plate 73.

The inner pipe 9b is provided in a state of penetrating the inner plate 8, so that the first silencing chamber 7a and the second silencing chamber 7b are in communication with each other. And the said exhaust control valve A is assembled | attached to the opening part by the side of the 1st silencer chamber 7a in this inner pipe 9b.
The inner plate 8 is formed with a communication hole 8a (or an inner pipe) that always communicates between the first silencing chamber 7a and the second silencing chamber 7b.

Next, functions and effects of the first embodiment will be described.
[When engine is running at low speed]
Since the exhaust control valve according to the first embodiment is configured as described above, first, the coil is set so that the engine speed is not opened in a predetermined low speed range, such as when idling or running at low speed. By setting the urging force of the spring 4, the exhaust pressure of the exhaust gas flowing through the silencer is small when the engine is running at a low speed. Therefore, as shown in FIGS. 1 (a) and 2 (a). The urging force of the coil spring 4 is increased and the exhaust control valve A is kept closed.

  As described above, when the engine is rotating at a low speed, the exhaust gas from the engine first flows into the second silencer chamber (expansion chamber) 7b via the inlet pipe 9a, thereby causing a predetermined pressure loss based on a predetermined pressure loss. The silencing effect can be obtained.

  Next, the exhaust gas flowing into the second silencing chamber (expansion chamber) 7b flows into the first silencing chamber (expansion chamber) 7a from the communication hole 8a formed in the inner plate 8, thereby causing a predetermined pressure loss. A predetermined silencing effect based on the above can be obtained.

Then, the exhaust gas flowing into the first silencer chamber (expansion chamber) 7a is discharged to the outside of the silencer body 7 via the outlet pipe 9c.
Accordingly, it is possible to satisfy the demand for noise reduction required when the engine rotates at a low speed.

[When engine is rotating at medium and high speed]
Next, in the middle and high speed rotation of the engine where the engine speed exceeds a predetermined low speed rotation range and the exhaust pressure exceeds the urging force of the coil spring 4, it is shown in FIGS. 1 (b) and 2 (c). Thus, the exhaust control valve A is opened.

  As described above, during the middle / high speed rotation of the engine, the exhaust gas from the engine first flows into the second silencing chamber (expansion chamber) 7b via the inlet pipe 9a, thereby reducing the pressure loss to a predetermined level. A predetermined silencing effect is obtained.

  Next, a part of the exhaust gas flowing into the second silencing chamber (expansion chamber) 7 b flows into the first silencing chamber (expansion chamber) 7 a from the communication hole 8 a formed in the inner plate 8, thereby In addition to obtaining a predetermined silencing effect based on the pressure loss, most of the exhaust gas flowing into the second silencing chamber (expansion chamber) 7b passes through the inner pipe 9b and the opened exhaust control valve A. A predetermined silencing effect based on a predetermined pressure loss can be obtained by flowing into one silencing chamber (expansion chamber) 7a.

Then, the exhaust gas flowing into the first silencer chamber (expansion chamber) 7a is discharged to the outside of the silencer body 7 via the outlet pipe 9c.
Accordingly, when the exhaust control valve A is opened, the exhaust resistance when the exhaust gas flows from the second silencing chamber (expansion chamber) 7b into the first silencing chamber (expansion chamber) 7a is reduced. The low back pressure requirement required during medium and high speed rotation can be satisfied.

  Further, in the valve open state in which the engine speed exceeds a predetermined low speed rotation range, the exhaust pressure exceeds the urging force of the coil spring 4 and the valve body 2 is pushed open from the seat surface 12, FIG. As shown, since the valve body 2 rotates around the support shaft 3 positioned downstream of the support shaft 5 on which the coil portion 41 of the coil spring 4 is supported, the valve body 2 rotates at the position of the axis Q1 of the seat surface 12. On the other hand, the position of the axis Q2 of the main body 21 in the valve body 2 greatly moves in the direction away from the support shaft 3 (and the support shaft 5) in proportion to the valve opening angle θ (valve opening degree). The support shaft 5 on which the coil portion 41 of the coil spring 4 is pivotally supported is disposed at a position closer to the seat surface 12 on the upstream side than the support shaft 3 that pivotally supports the valve body 2. Action point F when the biasing force of the coil spring 4 against the portion 21 is opened The amount of movement from the position when the valve is closed (the position of the axis Q2 of the seat surface 12) is relatively smaller than the amount of movement of the valve body 2 from the axis Q1 to the axis Q2 of the main body 21. Therefore, as the valve opening angle θ increases, the action point F2 of the urging force of the coil spring 4 against the main body 21 of the valve body 2 moves in the direction of the support shaft 3 (and the support shaft 5) from the action point F1 when the valve is closed. The amount to do will increase.

  Therefore, as the valve opening angle θ of the valve body 2 increases, the apparent pre-torque of the coil spring 4 with respect to the valve body 2 decreases, and thereby, the valve opening force due to the exhaust pressure becomes relatively strong. It can fully satisfy the demand for low back pressure during medium and high speed rotation of the engine.

  An apparent pre-torque of the coil spring 4 with respect to the valve body 2 in the initial stage of valve opening of the valve body 2 is applied to the contact surface of the main body portion 21 in the valve body 2 that is the point of action of the urging force of the coil spring 4. As shown in FIG. 2 (b), the engine speed at the initial stage of valve opening is formed because the upward inclined surface 10a is formed to guide and move the point of application of the urging force of the coil spring 4 against the main body 21 in the direction of increasing The valve opening timing with respect to can be delayed.

  Further, when the valve body 2 exceeds the initial stage of opening the valve body 2, the upward inclined surface 10 a ends, so that the opening degree of the valve body with respect to the engine speed changes as the valve body opens.

Incidentally, FIG. 3 is an exhaust pressure (kg / cm ² ) characteristic diagram with respect to the engine speed (rpm). In the exhaust control valve of the first embodiment, as shown by the solid line, compared to the conventional example shown by the dotted line, FIG. The valve opening timing with respect to the engine speed in the initial stage of the valve can be delayed, and the exhaust pressure (exhaust resistance) at the time of valve opening can be reduced.

  Therefore, by setting the biasing force of the coil spring 4 to be weak and increasing the opening angle θ of the valve body 2 with respect to the engine speed, it is possible to satisfy the demand for low back pressure during medium and high speed driving while sufficiently satisfying the upward inclination. By delaying the valve opening timing on the surface 10a, it is possible to obtain an effect that it is possible to sufficiently satisfy the noise reduction requirement required at the time of low-speed rotation of the engine at the same time.

  Further, the support shaft 5 that supports the coil portion 41 of the coil spring 4 is provided on the upstream side of the shaft center of the support shaft 3 that supports the valve body 2 and on the downstream side of the position of the seat surface 12. The urging force of the coil spring 4 against the valve body 2 is configured to act on the main body portion 21 (the center Q2 portion thereof) which is the position inside the seat surface 12, whereby the outer diameter and the urging force of the inner pipe 9b. Without being restricted by the positions of the operating points F1 and F2, the support shaft 5 that supports the coil portion 41 of the coil spring 4 can be arranged as close as possible to the inside of the inner pipe 9b in the direction of the axis Q1. Therefore, the valve seat 1 can be made compact in the radial direction.

  When the distance M in the seat surface 12 direction from the axis Q2 of the main body 21 to the support shaft 3 in the valve body 2 is constant, the distance in the direction perpendicular to the seat surface 12 from the seat surface 12 to the support shaft 5 The longer the difference W (or the distance L from the seat surface 12 to the support shaft 3) between the H and the distance L in the direction perpendicular to the seat surface 12 from the seat surface 12 to the support shaft 3, the longer the support shaft 3 and the shaft. As a result of an increase in the span between the center Q1 (Q2), the amount of movement of the main body 21 from the axis Q1 when the valve is closed to the axis Q2 when the valve is opened increases. The longer the distance L is, the stronger the valve opening force due to the exhaust pressure becomes as the valve opening angle θ of the valve body 2 increases. It will be possible to further satisfy the demands for conversion.

Further, when the distance L in the direction perpendicular to the seat surface 12 from the seat surface 12 to the support shaft 3 is constant, the distance in the seat surface 12 direction from the axis Q2 of the main body 21 to the support shaft 3 in the valve body 2. As M becomes longer, the rotation angle with respect to the valve opening angle θ becomes relatively smaller. As a result, the amount of movement from the axis Q1 of the main body 21 when the valve is closed to the axis Q2 when the valve is opened becomes smaller. As the support shaft 3 moves away from the axis Q2 in the seat surface 12 direction, the valve opening force due to the exhaust pressure becomes relatively weaker as the valve opening angle θ of the valve body 2 increases.
Therefore, in order to further satisfy the demand for lower back pressure during high-speed rotation of the engine, it is better to bring the support shaft 3 as close as possible to the axis Q2 in the seat surface 12 direction.

  Next, another embodiment of the present invention will be described. In the description of the other embodiments, the same components as those in the previous embodiment are denoted by the same reference numerals and the description thereof is omitted, and only the differences will be described.

The exhaust control valve of the second embodiment corresponds to the invention described in claim 2.
First, the configuration of the exhaust control valve of the second embodiment will be described with reference to the drawings.
FIG. 5 is a longitudinal sectional view showing the exhaust control valve of the second embodiment ((a) in the figure is a closed state, (b) is an initial stage of valve opening, and (c) is a valve opened state).

  That is, the exhaust control valve according to the second embodiment has a valve body at the initial stage of opening of the exhaust control valve A on the contact surface of the main body portion 21 of the valve body 2 that is the point of action of the urging force of the coil spring 4. An upward inclined surface 6a that guides and moves the point of action of the urging force of the coil spring 4 against the main body 21 in the direction of increasing the apparent pre-torque of the coil spring 4 with respect to the main body portion 21; And a downward inclined surface 6b for guiding and moving the point of action of the biasing force of the coil spring 4 against the main body 21 in a direction to lower the apparent pre-torque of the coil spring 4 with respect to the main body 21 is formed. This is different from the first and second embodiments.

  In the second embodiment, as described above, the contact surface of the valve body 2 that is the point of action of the urging force of the coil spring 4 is provided on the contact surface of the coil spring 4 with respect to the valve body in the initial stage of opening the valve body 2. Since the upward inclined surface 6a for guiding and moving the point of application of the urging force of the coil spring 4 to the valve body 2 in the direction of increasing the apparent pre-torque is formed, the engine in the initial stage of valve opening is formed as in the first embodiment. The valve opening timing with respect to the rotation speed can be delayed.

  On the other hand, when the climbing surface 6a is overcome, there is a descending tilting surface 6b that guides and moves the point of action of the urging force of the coil spring 4 against the valve body 2 in the direction of decreasing the apparent pre-torque of the coil spring 4 with respect to the valve body 2. Therefore, as the valve body 2 is opened, the valve body opening degree changes with respect to the engine speed.

  Therefore, by setting the biasing force of the coil spring 4 to be weak and increasing the opening angle of the valve body 2 with respect to the engine speed, the low-speed rotation of the engine can be achieved while further satisfying the demand for low back pressure during medium / high-speed driving. There is an effect that it is possible to satisfy the demand for noise reduction that is sometimes required.

The exhaust control valve of the third embodiment corresponds to the invention described in claims 1 and 3.
First, the configuration of the exhaust control valve of the third embodiment will be described with reference to the drawings.
FIG. 5 is a longitudinal sectional view showing an exhaust control valve according to the third embodiment (FIG. 5A is a closed state, FIG. 5B is an initial stage of valve opening, and FIG. 5C is an opened state).

  That is, the exhaust control valve according to the third embodiment is provided with the urging force acting portion 23 projecting toward the downstream side at the central portion of the main body portion 21 in the valve body 2, so that the coil portion 41 of the coil spring 4 is provided. The support shaft 5 is mounted on the downstream side of the seat surface 12 and at the same position as the point Q1 of the urging force of the coil spring 4 against the valve body 2. This is different from 1.

  Since the third embodiment is configured as described above, the action point F2 when the urging force of the coil spring 4 with respect to the urging force action portion 23 of the valve body 2 is opened is the position of the action point F1 when the valve is closed ( As the valve opening angle θ increases, the coil with respect to the biasing force acting portion 23 of the valve body 2 is moved from the position of the axis Q2 of the seat surface 12 toward the support shaft 3 (support shaft 5). The amount by which the action point F2 of the urging force of the spring 4 moves from the action point F1 when the valve is closed in the direction of the support shaft 3 (and the support shaft 5) is further increased.

Therefore, as the valve opening angle θ of the valve body 2 increases, the degree of reduction in the shaft torque acting on the support shaft 3 of the valve body 2 increases further, thereby further increasing the valve opening force due to the exhaust pressure. Since it becomes stronger, it becomes possible to further satisfy the demand for lower back pressure when the engine rotates at high speed.
In the third embodiment, the urging force action portion 23 is formed with a protrusion 6.

Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and design changes and the like within a scope not departing from the gist of the present invention are included in the present invention.
For example, in the embodiment, the seat surface 12 of the valve seat 1 and the main body 21 of the valve body 2 are formed in a flat shape, but the present invention is also applied to those formed in a tapered shape. be able to.

In the embodiment, the coil spring 4 is used as the biasing means, but other known biasing means such as a plate spring can be used.
In the embodiment, the point of application of the urging force of the coil spring 4 is the position of the axis Q1, but the position is arbitrary as long as it is within the peripheral surface of the seat surface 12.

  In the embodiment, the valve seat 1 is provided at the upstream opening end of the inner pipe 9b in the silencer body 7. However, the valve seat 1 is provided on the inner plate in the silencer body 7 according to the internal structure of the silencer. In this case, the same effect can be obtained.

It is a schematic sectional drawing which shows the silencer in which the exhaust control valve of Example 1 was integrated. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an exhaust control valve of Embodiment 1 ((A) is a valve closing state, (B) is an initial stage of valve opening, and (C) is a valve opening state). FIG. 4 is a characteristic diagram of exhaust pressure (kg / cm) with respect to engine speed (rpm) in the exhaust control valve of the first embodiment. FIG. 3 is a longitudinal sectional view showing an exhaust control valve of Example 2 ((A) is a valve closing state, (B) is an initial valve opening stage, and (C) is a valve opening state). FIG. 6 is a longitudinal sectional view showing an exhaust control valve of Example 3 ((A) is a valve closing state, (B) is an initial valve opening stage, and (C) is a valve opening state). It is a longitudinal cross-sectional view which shows the exhaust control valve of a prior art example (patent document 1). It is a longitudinal cross-sectional view ((A) is a valve closing state and (B) is a valve opening state) which shows the exhaust control valve of a prior art example (patent document 2).

Explanation of symbols

A Exhaust control valve 1 Valve seat 10 Stepped portion 10a Ascending inclined surface 11 Pipe portion 12 Seat surface 13 Substrate portion 14 Shaft support portion 2 Valve body 21 Body portion 22 Arm portion 23 Energizing force acting portion 3 Support shaft 4 Coil spring (biasing) means)
41 Coil part 5 Support shaft 6 Projection part 6a Up slope surface 6b Down slope surface 7 Silencer body 7a First silence room (expansion room)
7b Second noise reduction room (expansion room)
71 Outer shell 72 Outer plate 73 Outer plate 8 Inner plate 8a Communication hole 9a Inlet pipe 9b Inner pipe 9c Outlet pipe

Claims (3)

A valve body that can be opened / closed via a support shaft with respect to a valve seat provided in the middle of the exhaust flow passage in the silencer body, and an exhaust control valve by contacting the valve body with a seat surface of the valve seat An exhaust control valve provided with an urging means for urging in a closing direction,
A support shaft that pivotally supports the valve body is provided at a position separated from the position of the seat surface by a predetermined distance downstream,
The shaft support portion of the urging means is provided on the upstream side of the shaft center of the support shaft that supports the valve body and on the downstream side of the position of the seat surface,
Since the urging force for the valve body in the urging means is applied to a position in the circumferential surface of the seat surface, the point of action of the urging force for the valve body is larger than the valve closing time. The urging force applied to the valve body at the initial stage of opening of the valve body is formed on the contact surface of the valve body, which is configured to move in the direction of the support shaft as it becomes. An exhaust control valve characterized in that an upward inclined surface is formed for guiding and moving the point of application of the urging force of the urging means to the valve body in a direction to increase the apparent pre-torque of the means.   The apparent pre-torque of the urging means with respect to the valve body in the valve opening initial stage of the valve body is formed on the contact surface of the valve body, which is the point of action of the urging force by the urging means. An upward inclined surface that guides and moves the point of application of the urging force of the urging means to the valve body in the direction of raising the valve, and the valve in a direction to lower the apparent pre-torque of the urging means against the valve body when the upward inclined surface is overcome. An exhaust control valve, characterized in that a projecting portion having a substantially mountain-shaped cross section having a descending inclined surface for guiding and moving the point of application of the urging force of the urging means to the body is formed.   In the invention according to claim 1 or 2, the shaft support portion of the urging means is provided on the downstream side of the position of the seat surface and at the same point as the urging force acting point on the valve body or on the upstream side. An exhaust control valve characterized by having

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