Exhaust flow control valve

Abstract

The invention provides an exhaust flow control valve used in a muffler and the like. The present invention addresses the problem of providing an exhaust flow control valve capable of suppressing detachment of a connecting rod. The exhaust flow control valve comprises a valve seat provided with a valve hole; a valve body that is supported so as to be swingable and that opens and closes the valve hole; a valve spring that biases the valve body in the valve closing direction; and a connecting rod, one end of which is in contact with the valve seat and the other end of which is in contact with the valve spring, the connecting rod being capable of swinging about a second fulcrum portion on the valve seat in accordance with the position of the valve spring. The valve seat includes a buckling portion buckling toward the connecting rod. A bent portion abutting portion formed at one end of the connecting rod is formed in a shape that abuts only the front end of the bent portion when the valve body is in a fully closed state, and abuts both the front end and the tail end of the bent portion when the valve body is in a fully open state.

Description

Technical Field

[0001] The present invention relates to an exhaust gas flow control valve. Background Art

[0002] The exhaust gas generated by the engine is sent to the muffler to reduce the energy of heat and sound. However, the flow rate of the exhaust gas discharged from the engine is sometimes not constant and increases suddenly. In such a case, the exhaust flow control valve is opened to release part of the exhaust gas to the outside of the muffler. As a prior art related to the exhaust flow control valve used in this way, there is a technology disclosed in Japanese Patent No. 5689837.

[0003] The exhaust flow control valve shown in Japanese Patent Gazette No. 5689837 comprises: a valve seat, which is provided with a valve hole connecting the upstream chamber and the downstream chamber in the muffler; a valve core, which is arranged to be able to open and close the valve hole; a valve spring, one end of which abuts against the valve core to apply force to the valve core in the closing direction; and a connecting rod, which extends from the valve seat to the valve spring and swings in coordination with the swing of the valve core.

[0004] The other end of the valve spring is supported on the valve seat via a connecting rod. By providing the connecting rod, the valve spring can be swung together with the valve body.

[0005] The present inventors have studied the exhaust flow control valve disclosed in Japanese Patent No. 5689837 and found that the connecting rod may fall off when the valve core is opened. Summary of the invention

[0006] An object of the present invention is to provide an exhaust gas flow control valve capable of suppressing the rod from falling off.

[0007] The cam is an airtight container which is provided with a valve seat which is provided with a valve hole which connects an upstream chamber and a downstream chamber in an exhaust system of an engine; a valve core which is supported by a first fulcrum on the valve seat so as to be able to swing so as to open and close the valve hole, the valve core being subjected to the pressure on the upstream side in a valve opening direction; a valve spring which applies force to the valve core in a valve closing direction, the valve spring allowing the valve core to open the valve when the pressure on the upstream side rises to a predetermined value or above; and a connecting rod, one end of which is in contact with the valve seat. The other end of the connecting rod abuts against the valve spring, and the connecting rod can swing around the second fulcrum on the valve seat in coordination with the position of the valve spring. The valve seat includes a bent portion bent toward the connecting rod, and the front end of the bent portion becomes the second fulcrum. One end of the connecting rod becomes a bent portion abutting portion, and the bent portion abutting portion is formed to be able to abut against the bent portion. The bent portion abutting portion is formed in the following shape: when the valve core is fully closed, it only abuts against the front end of the bent portion, and when the valve core is fully open, it abuts against both the front end and the end of the bent portion.

[0008] According to the present invention, it is possible to provide an exhaust gas flow control valve capable of suppressing the link from falling off. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view of the main part of the exhaust muffler equipped with the exhaust gas flow control valve of the first embodiment.

[0010] Figure 2 yes Figure 1 A perspective view of the exhaust flow control valve is shown.

[0011] Figure 3 yes Figure 1 3 enlarged images of .

[0012] Figure 4 yes Figure 2 An exploded perspective view of the exhaust flow control valve is shown.

[0013] Figure 5 yes Figure 4 A three-dimensional view of the valve core is shown.

[0014] Figure 6 yes Figure 4 Front view of the connecting rod shown.

[0015] Figure 7 Yes Figure 1 A diagram illustrating the function of the exhaust muffler shown.

[0016] Figure 8 yes Figure 7 8 enlarged images of the .

[0017] Fig. 9 yes Figure 8 9 enlarged images of the .

[0018] Fig.10 It is a perspective view of the exhaust flow control valve of the second embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description, left and right refer to left and right based on the occupant of the vehicle equipped with the muffler, and front and back refer to front and back based on the traveling direction of the vehicle. In the drawings, Fr indicates front, Rr indicates rear, Le indicates left when viewed from the occupant, Ri indicates right when viewed from the occupant, Up indicates up, and Dn indicates down.

[0020] <Example 1>

[0021] Reference Figure 1 The exhaust muffler 10 constituting a part of the exhaust system of the engine E has an elliptical cylindrical muffler outer tube 11, an upstream cover portion 12 closing the upstream end of the muffler outer tube 11, a downstream cover portion 13 closing the downstream end of the muffler outer tube 11, and a first partition wall portion 30 and a second partition wall portion 15 as two partition walls fixed to the inside of the muffler outer tube 11.

[0022] The interior of the muffler outer tube 11 is divided into a first chamber R1 defined by the upstream cover 12 and the first partition wall 30 , a second chamber R2 defined by the first partition wall 30 and the second partition wall 15 , and a third chamber R3 defined by the second partition wall 15 and the downstream cover 13 .

[0023] The exhaust muffler 10 comprises: a first pipe member 17, which is a tubular member that guides the exhaust gas generated by the engine E from the upstream side cover portion 12 to the first chamber R1; a second pipe member 18, which passes through the first partition wall portion 30 and the second partition wall portion 15, and is a tubular member that guides the exhaust gas in the first chamber R1 to the third chamber R3; and a third pipe member 19, which passes through the second partition wall portion 15, and is a tubular member that discharges the exhaust gas in the second chamber R2 from the downstream side cover portion 13.

[0024] The first partition wall portion 30 is provided with a valve hole 31 that communicates the first chamber R1 with the second chamber R2, and the exhaust flow control valve 20 is provided in a manner that the valve hole 31 can be opened and closed. That is, the first partition wall portion 30 also serves as a valve seat of the exhaust flow control valve 20. Hereinafter, the first partition wall portion 30 is sometimes referred to as a valve seat 30. The valve seat 30 can also be said to be formed integrally with the first partition wall portion 30.

[0025] The second partition wall portion 15 is provided with a plurality of second partition wall holes 15 a that allow the exhaust gas to flow from the third chamber R3 to the second chamber R2 .

[0026] Normally, the exhaust gas generated by the engine E flows inside the first pipe member 17 and is guided to the first chamber R1, and is guided from the first chamber R1 to the third chamber R3 through the inside of the second pipe member 18. The exhaust gas reaching the third chamber R3 passes through the second partition wall hole 15a to reach the second chamber R2, and is discharged from the second chamber R2 to the outside of the exhaust muffler 10 through the third pipe member 19.

[0027] While the exhaust gas passes through the exhaust muffler 10 , its energy is attenuated, the temperature is lowered, and the sound when the exhaust gas is discharged to the atmosphere is reduced.

[0028] The shape of the muffler outer tube 11 can be any shape, and may be a cylindrical shape or an oval shape. The inside of the muffler outer tube 11 may be divided into two chambers, or may be divided into four or more chambers.

[0029] Reference Figure 2 to Figure 4 The exhaust flow control valve 20 includes: a valve seat 30 formed with a valve hole 31; a valve core 40 that opens and closes the valve hole 31; a support shaft 24 that is pressed toward the valve core 40 by a valve spring 25; a valve spring 25 that passes through the support shaft 24 and is supported by the support shaft 24; a connecting rod 50 that controls the reduction of the valve closing torque according to the increase in the opening of the valve core 40; a buffer material 27 that is fixed to the valve seat 30 to mitigate the impact when the valve seat 30 and the valve core 40 abut against each other; and a counterweight 28 that is installed on the valve core 40 to adjust the vibration characteristics.

[0030] Reference Figure 3 A fulcrum groove 32 is formed on the valve seat 30, protruding in a groove shape toward the first chamber R1 side. The groove bottom of the fulcrum groove 32 becomes the first fulcrum portion P1 serving as the swing axis of the valve core 40. In addition, on the valve seat 30, a bending portion 33 is formed between the first fulcrum portion P1 and the valve hole 31, which is bent toward the connecting rod 50. The front end of the bending portion 33 is the second fulcrum portion P2 serving as the swing axis of the connecting rod 50. In addition, on the valve seat 30, a bulging portion 34 bulging for accommodating the buffer material 27 is formed at a position opposite to the bending portion 33 across the valve hole 31.

[0031] Reference Figure 4 The valve core 40 is formed of a metal plate formed in a substantially square shape, and a protrusion 41 bent so that the tip thereof abuts against the first fulcrum portion P1 and a pair of stopper pieces 42 arranged to sandwich the protrusion 41 are formed at one end of the valve core 40. Figure 3 The stopper 42 is separated from the valve seat 30 before the valve body 40 is fully opened. The stopper 42 abuts against the valve seat 30 when the valve body 40 is fully opened.

[0032] The valve body 40 can swing about the first supporting point P1 from a fully closed position for closing the valve hole 31 to a fully open position for fully opening the valve hole 31 by making the stopper piece 42 contact with the valve seat 30 .

[0033] A convex portion 43 is formed at the center of the valve body 40 so as to protrude from the valve hole 31 in a closed state. The convex portion 43 has a trapezoidal cross section. The opposing surfaces of the convex portion 43 are tapered slopes 43a that expand toward the opening of the convex portion 43.

[0034] Reference Figure 4 The valve spring 25 is composed of a torsion coil spring, and has a coil portion 25a wound in a coil shape and through which the support shaft 24 passes, a rod-shaped first arm 25b extending linearly from one end of the coil portion 25a, and a second arm 25c extending from the other end of the coil portion 25a as a central portion. The valve spring 25 exerts a force in a direction in which the angle between the first arm 25b and the second arm 25c is opened.

[0035] The coil portion 25a is formed with two and is arranged adjacently on the same axis. One end of the coil portion 25a refers to the end portions at both ends of the two coil portions 25a arranged adjacently. On the other hand, the other end of the coil portion 25a refers to the end portions on one side adjacent to the two coil portions 25a arranged adjacently. The first arm 25b extends from one end of each coil portion 25a. In addition, the second arm portion 25c extends from the other end of each coil portion 25a and is connected to each other to form a roughly U-shaped shape.

[0036] Alternatively, the valve spring 25 may be composed of one coil portion 25a, one first arm 25b, and one second arm 25c. That is, the valve spring 25 is not limited to being composed of two coil portions 25a, two first arms 25b, and two second arms 25c.

[0037] Refer to Figure 3 The outer peripheral surface of the coil portion 25a is arranged close to the inclined surface portions 43a, 43a. In this way, a part of the coil portion 25a is accommodated in the above-mentioned protrusion 43. In addition, the front end portions of the pair of first arms 25b are locked to a pair of locking claws 45 provided at the free end of the valve core 40, and the front end portion of the U-shaped second arm 25c passes through the valve core hole portion 46. The front end of the second arm 25c is relatively swingably abutted against the second fulcrum portion P2 via the connecting rod 50.

[0038] Reference Figure 3 and Figure 5 The valve core 40 is provided with a valve core hole 46 through which the second arm 25c passes. The valve core hole 46 is substantially U-shaped. The valve core hole 46 includes a relief portion 46a for preventing the second arm 25c from contacting the second arm 25c when the second arm 25c is displaced relative to the valve core 40.

[0039] Reference only Figure 3The support shaft 24 is formed in a generally U-shape as a whole and penetrates the coil portion 25a. The support shaft 24 is fixed to the valve core 40 in a manner that vertically penetrates the opening of the convex portion 43 of the valve core 40, and a part of the inner peripheral surface of the coil portion 25a is supported by the arc surface of the support shaft 24, thereby making the outer peripheral surface of the coil portion 25a float from the inner peripheral surface of the convex portion 43.

[0040] By utilizing the support shaft 24 fixed to the valve core 40 to support a portion of the inner circumference of the coil portion 25a and making the outer circumference of the coil portion 25a float from the inner circumference of the protrusion 43, the friction portion of the coil portion 25a and the supporting portion become one. When the angle between the first arm 25b and the second arm 25c changes with the opening of the valve core 40, the friction generated between the coil portion 25a and the support shaft 24 can be suppressed to a smaller level, and the valve core 40 can be opened and closed more smoothly.

[0041] Reference Figure 3 and Figure 6 The connecting rod 50 is formed by bending a roughly rectangular metal plate into a roughly U-shape. The connecting rod 50 is roughly rectangular in shape when viewed from the front, and has U-shaped spring contact portions 51 and bent portion contact portions 52 formed at both ends. The spring contact portions 51 and the bent portion contact portions 52 are formed at respective opposing portions of the metal plate bent into a roughly U-shape. That is, when the connecting rod 50 is opened into a flat plate, the opened plate is line-symmetrical with the bent portion as the center.

[0042] Reference only Figure 3 . The U-shaped flexure of the second arm 25c abuts against the spring abutment portion 51 in a swingable manner. The flexure 33 abuts against the flexure abutment portion 52. One side of the flexure abutment portion 52 extends along the length direction of the approximately rectangular connecting rod 50 (extends perpendicularly to the width direction), and the other side opposite to the one side extends obliquely relative to the length direction, thereby forming a roughly U-shape that gradually opens toward the front end. The shape of the flexure abutment portion 52 is formed into a shape that can abut against two points, the front end and the end of the flexure 33 when the valve core 40 is fully opened. That is, the shape of the flexure abutment portion 52 is formed into a shape that abuts against two points when fully opened in accordance with the length, plate thickness, and extension angle of the flexure 33.

[0043] A groove 53 that is recessed toward the center is formed in a portion of the side surface between one end and the other end of the connecting rod 50. In addition, the connecting rod 50 is chamfered so that the corner 54 that faces the valve core 40 does not contact the valve core. These grooves 53 and corners 54 are also formed at respective opposing positions.

[0044] In addition, the connecting rod 50 is not limited to a bent shape that is roughly U-shaped when viewed from the side. The connecting rod 50 may also be composed of a single plate. In addition, the shapes of the spring abutment portion 51 and the bending portion abutment portion 52 are not limited to a roughly U-shaped shape. In addition to the C-shaped and J-shaped shapes, any shapes can be adopted. In particular, it is important that the bending portion abutment portion 52 abuts against the front end and the end of the bending portion 33 when the valve core 40 is fully opened, and any shape can be adopted as long as this condition is met.

[0045] A metal mesh can be used as the cushioning material 27. The cushioning material 27 is fixed to the bulging portion 34 by, for example, spot welding.

[0046] The weight 28 is fixed to the back surface of the valve element 40 at a location that contacts the buffer material 27. The weight 28 is made of metal, for example, and is fixed to the back surface of the valve element 40 by welding.

[0047] Next, the operation of the exhaust gas flow control valve 20 will be described.

[0048] When installing the valve spring 25, the two inclined surfaces 43a, 43a of the protrusion 43 of the valve core 40 on the side opposite to the valve hole 31 support the coil portion 25a, overcome the elastic repulsive force that attempts to expand the angle between the first arm 25b and the second arm 25c, and fix the first arm 25b to the locking claw 45 at the free end of the valve core 40, and support the second arm 25c to the second fulcrum portion P2 of the valve seat 30 via the connecting rod 50. Therefore, the elastic repulsive force that attempts to expand the angle between the first arm 25b and the second arm 25c applies force to the valve core 40 in the valve closing direction via the coil portion 25a.

[0049] Reference Figure 7 . When the engine E shifts to a high-speed, high-load operating state, the flow rate of exhaust gas increases and the pressure in the first chamber R1 rises. When the valve opening torque of the valve core 40 based on the pressure exceeds the valve closing torque of the valve core 40 based on the valve spring 25, the valve core 40 swings toward the fully open position, increasing the opening of the valve hole 31. Then, according to the opening of the valve hole 31, the exhaust gas flowing from the first pipe component 17 to the first chamber R1 short-circuits the valve hole 31, and is guided by the inclined valve core 40 while being released from the second chamber R2 through the third pipe component 19 to the atmosphere. As a result, the increase in engine output brought about by the reduction in back pressure can be achieved.

[0050] Here, the valve closing torque applied by the valve spring 25 to the valve element 40 will be considered.

[0051] exist Figure 3In the figure, the elastic repulsive force acting on the second fulcrum part P2 from the second arm 25c of the valve spring 25 via the connecting rod 50 is divided into a first component force perpendicular to the straight line connecting the first fulcrum part P1 and the second fulcrum part P2 and a second component force parallel to the above straight line. The product of the first component force and the distance between the first fulcrum part P1 and the second fulcrum part P2 becomes the valve closing torque applied to the valve core 40.

[0052] However, if Figure 3 and Figure 8 As shown in FIG. 1 , when the valve core 40 is opened from the fully closed position, the second fulcrum portion P2 supporting the connecting rod 50 is offset toward the valve hole 31 side relative to the first fulcrum portion P1 supporting the valve core 40, and thus the connecting rod 50 tilts toward the valve seat 30 side around the second fulcrum portion P2 as the valve core 40 opens, and the tilt angle is greater than the opening angle of the valve core 40. Accordingly, the angle formed by the elastic repulsive force acting on the second fulcrum portion P2 from the second arm 25c and the first component force increases as the valve core 40 opens, and thus the first component force decreases. As a result, as shown in FIG. 1 , the second arm 25c tilts toward the valve seat 30 side relative to the first fulcrum portion P2 as the valve core 40 opens. Figure 8 As shown, the valve closing torque of the valve core 40 based on the first force component decreases as the opening of the valve core 40 increases. In addition, the change in the angle between the first arm 25b and the second arm 25c accompanying the change in the opening of the valve core 40 is small, so the friction generated between the coil portion 25a and the inclined surface portions 43a, 43a of the protrusion 43 is also extremely small.

[0053] In this way, when the valve core 40 begins to open due to the pressure of the first chamber R1, it can automatically and smoothly swing to the fully open position, which can reliably reduce the back pressure and reduce the airflow noise. In addition, when the exhaust gas moves from the exhaust muffler 10 to the second chamber R2 via the valve hole 31, the inclined valve core 40 smoothly guides the flow of the exhaust gas, thereby further reducing the back pressure.

[0054] Reference Fig. 9 The bent portion contact portion 52 contacts two locations of the bent portion 33, namely, the front end and the rear end, when the valve body 40 is in the fully open state (see P2 and P3 ).

[0055] Reference Figure 1 and Figure 7 When the engine E returns to the low speed and low load operation state, the valve opening torque of the valve element 40 based on the pressure in the first chamber R1 becomes smaller than the valve closing torque based on the valve spring 25, and the valve element 40 returns to the fully closed position.

[0056] Reference Figure 3 In such an exhaust flow control valve 20 , by accommodating a portion of the coil portion 25 a of the valve spring 25 in the convex portion 43 of the valve element 40 , the protrusion amount of the coil portion 25 a from the valve element 40 can be reduced, thereby achieving compact exhaust flow control valve 20 .

[0057] In addition, the valve spring 25 is composed of a coil portion 25a, a pair of first arms 25b extending from both ends of the coil portion 25a, and a second arm 25c extending from the central portion of the coil portion 25a, so that the coil portion 25a is supported on the valve core 40, the front end portions of the pair of first arms 25b are clamped on a pair of clamping claws 45 of the valve core 40, and the front end of the second arm 25c is abutted against the spring abutment portion 51. In this way, a valve spring 25 is used to apply a valve closing torque to the valve core 40 as a whole, so that the opening and closing posture of the valve core 40 can be stabilized.

[0058] <Example 2>

[0059] Next, Embodiment 2 of the present invention will be described with reference to the accompanying drawings. Fig.10 2 shows an exhaust gas flow control valve 20A of the second embodiment. The same reference numerals are used for the parts as those of the first embodiment, and detailed descriptions are omitted.

[0060] The valve seat 30A of the exhaust gas flow control valve 20A is formed by contacting with the first partition wall portion 30 (see Figure 2 The exhaust gas flow control valve 20A is, for example, welded to the first partition wall portion 30. The exhaust gas flow control valve 20A is provided so as to close the hole formed in the first partition wall portion 30.

[0061] The exhaust gas flow control valve 20 , 20A described above will be summarized below.

[0062] Reference Figure 1 First, the exhaust gas flow control valve 20 includes a valve seat 30 in which a valve hole 31 is opened for connecting an upstream chamber (a first chamber R1 ) and a downstream chamber (a second chamber R2 ) in the exhaust system of the engine E.

[0063] Reference Figure 8 The exhaust flow control valve 20 also includes: a valve core 40, which is supported by the first fulcrum portion P1 on the valve seat 30 so as to be able to swing to open and close the valve hole 31, and the valve core 40 is subjected to the pressure on the upstream side in the valve opening direction; a valve spring 25, which applies force to the valve core 40 in the valve closing direction, allowing the valve core 40 to open the valve when the pressure on the upstream side rises to a predetermined value or more; and a connecting rod 50, one end of which abuts against the valve seat 30 and the other end abuts against the valve spring 25, and the connecting rod 50 can swing around the second fulcrum portion P2 on the valve seat 30 in coordination with the position of the valve spring 25.

[0064] The valve seat 30 includes a bent portion 33 bent toward the connecting rod 50. The front end of the bent portion 33 serves as the second fulcrum portion P2, and one end of the connecting rod 50 serves as a bent portion contact portion 52 formed to be able to contact the bent portion 33. The bent portion contact portion 52 contacts only the front end of the bent portion 33 when the valve core 40 is in the fully closed state (see Figure 3), when the valve core 40 is in the fully open state, it becomes a shape that abuts against the front end and the rear end of the bent portion 33.

[0065] Reference Fig. 9 The bent portion contact portion 52 contacts the front end and the end (particularly preferably the lower surface of the end) of the bent portion 33 at two locations when the valve core 40 is in the fully open state (see P2 and P3). Therefore, compared with the case where the bent portion 33 contacts at one location, the link 50 can be prevented from falling off. An exhaust flow control valve 20 that can prevent the link 50 from falling off can be provided. For the exhaust flow control valve 20A (see Fig.10 ) is the same.

[0066] Reference Figure 8 Second, in the first exhaust gas flow control valve 20, the corner 54 of the connecting rod 50 is chamfered so as not to contact the valve core 40. This can prevent the connecting rod 50 from contacting the valve core 40 and falling off. Fig.10 ) is the same.

[0067] Third, in the first or second exhaust gas flow control valve 20, the connecting rod 50 is substantially rectangular in shape, and a groove 53 is formed on a portion of the side surface between one end and the other end, which is recessed toward the center. This allows for orientation identification during assembly, thereby preventing misassembly. Fig.10 ) is the same.

[0068] Fourthly, in any one of the exhaust flow control valves 20 of the first to third embodiments, the valve spring 25 includes a coil portion 25a wound in a coil shape, a rod-shaped first arm 25b extending linearly from one end of the coil portion 25a, and a second arm 25c extending from the other end of the coil portion 25a. A force acts in a direction in which the angle formed by the first arm 25b and the second arm 25c is opened.

[0069] Refer to Figure 5 The valve core 40 is provided with a valve core hole 46 through which the second arm 25c passes. The valve core hole 46 includes a relief portion 46a for preventing the valve core 40 from contacting the second arm 25c when the second arm 25c is displaced relative to the valve core 40.

[0070] The contact between the second arm 25c and the valve element 40 can be suppressed, so that the valve element 40 and the connecting rod 50 can be operated smoothly. Fig.10 ) is the same.

[0071] Reference Figure 35. In any one of the exhaust flow control valves 20 of the first to fourth embodiments, a cushioning material 27 is provided at a portion of the valve seat 30 where the valve core 40 is seated. This can suppress the generation of noise and the leakage of exhaust gas when the valve is closed. Fig.10 ) is the same.

[0072] Sixth, in the fifth exhaust gas flow control valve 20, a weight 28 for adjusting the vibration characteristics is provided on the back side of the portion of the valve core 40 that contacts the buffer material 27. This improves the vibration characteristics and suppresses the generation of noise. Fig.10 ) is the same.

[0073] In addition, the present invention is not limited to the examples as long as the functions and effects of the present invention are achieved.

[0074] The exhaust flow control valve of the present invention is suitable for a muffler of a four-wheel vehicle.

Claims

1. An exhaust flow control valve, characterized in that: The exhaust flow control valve has: A valve seat having a valve hole for connecting an upstream chamber and a downstream chamber in an exhaust system of an engine; a valve core supported by a first fulcrum portion on the valve seat so as to be swingable so as to open and close the valve hole, the valve core receiving pressure on the upstream side in a valve opening direction; a valve spring that applies force to the valve core in a valve closing direction, the valve spring allowing the valve core to open when the pressure on the upstream side rises to or above a predetermined value; and a connecting rod, one end of which abuts against the valve seat and the other end of which abuts against the valve spring, and the connecting rod can swing around a second fulcrum on the valve seat in accordance with the position of the valve spring, The valve seat includes a curved portion curved toward the connecting rod, The front end of the bent portion becomes the second fulcrum portion. One end of the link becomes a bent portion contact portion, and the bent portion contact portion is formed to be able to contact the bent portion. The bent portion contact portion is formed in a shape that contacts only the front end of the bent portion when the valve body is in a fully closed state, and contacts both the front end and the rear end of the bent portion when the valve body is in a fully opened state.

2. The exhaust gas flow control valve according to claim 1, wherein: A corner portion of the connecting rod is chamfered so as not to contact the valve core.

3. The exhaust gas flow control valve according to claim 1, wherein: The link has a substantially rectangular shape, and a groove portion recessed toward the center is formed in a portion of a side surface between the one end and the other end.

4. The exhaust gas flow control valve according to claim 1, wherein: The valve spring includes a coil portion wound in a coil shape, a rod-shaped first arm extending linearly from one end of the coil portion, and a second arm extending from the other end of the coil portion. A force acts in the direction in which the angle formed by the first arm and the second arm opens. A valve core hole is provided on the valve core for the second arm to pass through. The valve body hole includes a relief portion that prevents the valve body from contacting the second arm when the second arm is displaced relative to the valve body.

5. The exhaust gas flow control valve according to claim 1, wherein: A cushioning material is provided at a portion of the valve seat where the valve core is seated.

6. The exhaust gas flow control valve according to claim 5, wherein: A weight for adjusting vibration characteristics is provided on the back surface of a portion of the valve element that contacts the buffer material.

Images