Exhaust valve and muffler for automobile

Abstract

To provide an exhaust valve capable of simply and reliably adjusting and setting biasing force of a valve body in a closing direction within a moderate range, and capable of ensuring high durability.SOLUTION: An exhaust valve 1 opens and closes an exhaust path with a valve body 3 according to an exhaust pressure, where the valve body 3 is supported via a support shaft 4 so as to be able to swing relative to a valve seat 2 having an opening 22, the valve body 3 is biased in a closing direction by a coil spring 5 externally fitted onto the support shaft 4, and an elastic cylindrical part 73 having an outer diameter larger than an inner diameter of the coil spring 5 in an open state of the valve body 3, which contracts when the valve body is opened, is externally fitted near both ends of the support shaft 4, and internally fitted into both end parts of the coil spring 5.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an exhaust valve that is installed in an exhaust passage through which exhaust from an automobile or the like flows, and a valve body that opens and closes in response to exhaust pressure to adjust the amount of exhaust gas flowing through the exhaust valve, and a muffler equipped with the exhaust valve. [Background technology]

[0002] Conventionally, there is an exhaust valve that is installed in the exhaust passage of an automobile, as disclosed in Patent Document 1. In the exhaust valve of Patent Document 1, a valve body is supported via a support shaft so as to be able to swing with respect to a valve seat having an opening, the valve body is biased in a closing direction by a coil spring fitted onto the support shaft, valve seat hooks are provided to hold both ends of the support shaft in the circumferential direction, and valve body wrapping parts are provided to hold the coil spring in the circumferential direction from the opposite direction to the valve seat hooks and to hold the coil spring in the circumferential direction over the entire length of the coil spring.

[0003] Furthermore, in this exhaust valve, the tubular cushioning material, which is composed of a tubular portion and a flange portion, is made of a metal mesh material, and with the spindle and coil spring inserted into the valve disc winding portion, the tubular portions are fitted into both ends of the valve disc winding portion to fix the tubular cushioning material. Both ends of the spindle are inserted into the tubular cushioning material fitted into the valve disc winding portion, and the pair of tubular cushioning materials act as bearings for the spindle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-188516 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in an exhaust valve in which a coil spring biases the valve disc in the closing direction and the valve disc is opened and closed by exhaust pressure as in Patent Document 1, if the biasing force in the closing direction of the valve disc is too strong, the valve disc will not open, and if the biasing force in the closing direction of the valve disc is too weak, the valve disc will flutter excessively and large surging will occur. Therefore, it is necessary to adjust the biasing force in the closing direction of the valve disc within an appropriate range so that the valve disc opens and closes appropriately due to the exhaust pressure.

[0006] The biasing force of the valve disc in the closing direction can be adjusted by adjusting the wire diameter and number of turns of the coil spring, but adjusting the biasing force to an appropriate range by only adjusting the wire diameter and number of turns of the coil spring requires a great deal of effort through trial and error. In addition, a weight can be attached to the valve disc to appropriately adjust the biasing force of the valve disc in the closing direction to suppress surging, but the weight of the valve disc that opens and closes with the weight attached increases, causing another problem of reduced durability of the components of the exhaust valve, such as the coil spring. Therefore, there is a demand for an exhaust valve that can easily and reliably adjust and set the biasing force of the valve disc in the closing direction to an appropriate range and ensure high durability.

[0007] The present invention has been proposed in consideration of the above-mentioned problems, and has an object to provide an exhaust valve in which a valve body is biased in a closing direction by a coil spring and the valve body opens and closes in response to exhaust pressure, in which the biasing force in the closing direction of the valve body can be easily and reliably adjusted and set within an appropriate range while ensuring a high level of durability, and an automobile muffler equipped with this exhaust valve. [Means for solving the problem]

[0008] The exhaust valve of the present invention is an exhaust valve that opens and closes an exhaust passage with a valve body in response to exhaust pressure, characterized in that the valve body is supported via a support shaft so that it can swing against a valve seat having an opening, the valve body is urged in a closing direction by a coil spring externally fitted onto the support shaft, and elastic tubular portions having an outer diameter larger than the inner diameter of the coil spring in the open state of the valve body which contracts as the valve body opens are externally fitted near both ends of the support shaft and internally fitted into both ends of the coil spring. According to this, when the inner diameter of the coil spring is reduced by the opening action of the valve body, the opening action of the valve body is suppressed by the resistance of the elastic cylindrical portion, so that it is not necessary to adjust the biasing force of the valve body in the closing direction by trial and error, which requires a lot of effort, by only adjusting the wire diameter and number of turns of the coil spring. For example, if the wire diameter and number of turns of the coil spring are adjusted to increase the spring rate and increase the frictional resistance between the windings of the coil spring in order to suppress surging, in which the valve body flutters significantly, the opening degree of the valve body may be insufficient. However, in the exhaust valve of the present invention, even if the spring rate of the coil spring is lowered to make the valve body easier to open, surging can be suppressed by suppressing the opening action of the valve body due to the resistance of the elastic cylindrical portion. Therefore, the biasing force of the valve body in the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve body opens and closes appropriately according to the expected exhaust pressure. In addition, since it is not necessary to attach a weight to the valve body to suppress surging, and the weight of the valve body that opens and closes is not increased, a high durability of the exhaust valve components such as the coil spring or the exhaust valve can be ensured. Furthermore, since there is no need to use an expensive coil spring with an excessively high spring rate or a weight attached to the valve body, the manufacturing costs and parts costs of the exhaust valve can be reduced.

[0009] The exhaust valve of the present invention is characterized in that the elastic cylindrical portion is press-fitted into the coil spring, which has an inner diameter larger in the closed state of the valve body than in the open state of the valve body. According to this, from the start of the opening operation of the valve body, the surging energy that causes the valve body to flutter and is transmitted to the coil spring can be dissipated in the elastic cylindrical portion, and surging can be suppressed throughout the entire opening and closing operation of the valve body.

[0010] The exhaust valve of the present invention is characterized in that the valve body is provided with a valve body wrapping portion that is arranged to circumferentially embrace the coil spring over the entire length of the coil spring, the base tube portion of a tubular cushioning material consisting of a base tube portion and a flange portion is fitted into both ends of the valve body wrapping portion, the elastic tubular portion is integrally formed with the tubular cushioning material, and the pair of tubular cushioning materials serve as bearings for the support shaft. According to this, by integrally providing the elastic cylindrical portion with the cylindrical cushioning material that serves as a bearing for the spindle, the number of parts can be reduced, and the manufacturing cost of the exhaust valve can be further reduced. Also, by using a pair of cylindrical cushioning materials with integral elastic cylindrical portions as a bearing for the spindle, the strength and impact resistance of the bearing for the spindle can be increased. Also, since the elastic cylindrical portion can be inserted externally onto the spindle and internally into the coil spring in accordance with the internal fitting of the cylindrical cushioning material with the valve body winding portion, the manufacturing process of the exhaust valve can be made more efficient.

[0011] The exhaust valve of the present invention is characterized in that a valve seat hook portion is provided on the valve seat so as to circumferentially embrace both ends of the support shaft and is fixed to the support shaft, and the valve body winding portion is provided so as to circumferentially embrace the coil spring from the opposite direction to the valve seat hook portion. According to this, by providing the valve seat hook of the valve seat so as to circumferentially embrace both ends of the support shaft and fixing it to the support shaft, and providing the valve body wrapping portion so as to circumferentially embrace the coil spring from the opposite direction to the valve seat hook and to embrace the coil spring in the circumferential direction over the entire length of the coil spring, it is possible to prevent or minimize as much as possible misalignment of the coil spring that is inserted coaxially with the support shaft for opening and closing the valve body.By eliminating or minimizing as much as possible the misalignment of the coil spring and the support shaft, the biasing force of the coil spring with the elastic cylindrical portion inserted therein in the valve body closing direction can be more accurately adjusted and set to an optimal range.

[0012] The automotive muffler of the present invention is characterized in that the valve seat base plate of the valve seat in the exhaust valve of the present invention is fixed to the peripheral edge of an opening of a separator that divides the inside of the muffler installed in the exhaust passage. According to this, by installing the exhaust valve of the present invention in the separator of an automobile muffler, the exhaust valve can be closed when the engine speed is low to prevent the passage of pressure waves that are a source of noise, and the exhaust valve can be opened when the engine speed is high to allow the exhaust to pass, thereby ensuring engine output. In other words, by installing an exhaust valve in an automobile muffler with the biasing force of the valve body in the closing direction adjusted and set within an appropriate range, it is possible to reliably achieve both quietness during regular city driving and ensuring engine output during high-speed driving. Effect of the Invention

[0013] According to the present invention, in an exhaust valve in which a coil spring urges a valve body in the closing direction and the valve body opens and closes in response to exhaust pressure, the urging force of the valve body in the closing direction can be easily and reliably adjusted and set within an appropriate range, and a high degree of durability can be ensured. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing an exhaust valve in a closed state according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing an open state of an exhaust valve according to the embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of an exhaust valve according to the embodiment. [Figure 4] FIG. 4 is a perspective view illustrating a coil spring and a cylindrical cushioning material in the exhaust valve according to the embodiment. [Diagram 5] FIG. 4 is an explanatory diagram showing a coil spring, a cylindrical cushioning material, and a support shaft in the exhaust valve of the embodiment. [Figure 6] 1 is an explanatory diagram of an automobile muffler in which an exhaust valve according to an embodiment is attached to a separator. [Figure 7] FIG. 2 is a front view of the exhaust valve according to the embodiment attached to a separator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [Exhaust valve of embodiment] An exhaust valve 1 according to an embodiment of the present invention is installed in, for example, a muffler in an exhaust passage of an automobile, and opens and closes the exhaust passage in response to the exhaust pressure of the engine, and is preferably attached to a separator that divides the inside of the muffler. As shown in Figures 1 to 3, the exhaust valve 1 comprises a valve seat 2, a valve element 3 that opens and closes, a support shaft 4, a coil spring 5, a ring cushion 6, and a cylindrical cushion 7. The valve element 3 is supported via the support shaft 4 so as to be able to swing relative to the valve seat 2, and is biased in a closing direction by the coil spring 5 fitted around the support shaft 4.

[0016] The valve seat 2 has a valve seat substrate 21 formed in a generally flat ring shape arranged, for example, along a separator, and an opening 22 constituting an exhaust path that is opened and closed is provided in the center of the valve seat substrate 21. The valve seat 2 is provided with a pair of valve seat hooks 23, 23 spaced apart on both sides of the width of the valve seat substrate 21. The valve seat hook 23 rises obliquely upward from the upper end portion of the valve seat substrate 21 in the figure, is curved in an arc on the back side of the valve seat substrate 21, and is formed integrally with the valve seat substrate 21.

[0017] A pair of valve seat hooks 23, 23 are provided near both ends of the support shaft 4. The valve seat hook 23 in the illustrated example is engaged with the support shaft 4 so as to embrace both ends of the support shaft 4 in the circumferential direction from the valve body 3 side, and is fixed to the support shaft 4 by welded parts 41 formed on both ends of the support shaft 4. The shape and size of the inner circumferential surface of the tip of the valve seat hook 23 are formed to approximately follow the shape and size of the outer circumferential surface of the support shaft 4 with which it engages.

[0018] The valve seat base plate 21 of the valve seat 2 is provided with a welding area 241 on the spindle 4 side that protrudes outward from the outer periphery of the valve body base plate 31 of the valve body 3 in a closed state, which will be described later, and a tongue-shaped welding area 242 located on the opposite side to the spindle 4. The welding areas 241, 242 are used, for example, as locations for welding when attaching the exhaust valve 1 to a separator of a muffler by welding.

[0019] A ring cushioning material 6 having a substantially flat ring shape is fixed by welding or the like to the valve body 3 side of the valve seat substrate 21, and the ring cushioning material 6 is provided at a position substantially corresponding to a flat edge 32 of the valve body 3 described below, so as to cushion the impact of the closing operation of the valve body 3. For the ring cushioning material 6, any suitable cushioning material that has a cushioning function due to elasticity or the like and is heat resistant can be used, and a metal mesh material is preferable, for example.

[0020] The valve body 3 has a valve body substrate 31, which is formed in a flat dish shape with a flat edge 32. A recess 33 that is approximately circular in plan view and recessed so as to protrude toward the valve seat 2 is provided on the front surface of the valve body substrate 31, and the flat edge 32 is formed in a ring shape around the periphery of the recess 33 or around the protruding portion of the recess 33.

[0021] The valve 3 is formed with a valve body winding portion 34 that protrudes from the support shaft 4 side of the valve body substrate 31 and curves back in a hook shape from the valve body substrate 31, and the valve body winding portion 34 is formed integrally with the valve body substrate 31 so as to protrude from the valve body substrate 31 in the opposite direction to the valve seat 2 in the closed state. The shape and size of the inner circumferential surface of the valve body winding portion 34 are formed so as to roughly follow the shape and size of the outer circumferential surface of the coil body 51 of the coil spring 5, and the size of the inner circumferential surface of the valve body winding portion 34 is slightly larger than the size of the outer circumferential surface of the coil body 51.

[0022] The valve body winding portion 34 is formed in an arc shape that exceeds a semicircle in cross section, preferably an arc shape that exceeds 3 / 4 of a circle or is approximately 3 / 4 of a circle, and is arranged to circumferentially embrace the coil spring 5 inserted onto the spindle 4 from the opposite direction to the direction in which the valve seat hook portion 23 circumferentially embraces the spindle 4. In this embodiment, the valve body winding portion 34 is arranged to circumferentially embrace the coil spring 5 from the valve seat side over the entire length of the coil spring 5.

[0023] The valve disc winding portion 34 is formed to extend in the width direction at approximately the center of the valve disc base plate 31 in the width direction, and is formed as a continuous, elongated portion with a length that fits between the pair of valve seat hooks 23 of the valve seat 2. The continuous, elongated valve disc winding portion 34 is provided so as to embrace the coil spring 5 inserted around the support shaft 4 in the circumferential direction over the entire length of the coil spring 5.

[0024] Cylindrical cushioning materials 7·7 are provided on both ends of the valve body wrapping portion 34. The cylindrical cushioning material 7 is composed of a base cylindrical portion 71, a flange portion 72 that protrudes outward at one axial end of the base cylindrical portion 71, and an elastic cylindrical portion 73 that protrudes toward the outer end side in the axial direction of the base cylindrical portion 71, and the base cylindrical portion 71, the flange portion 72, and the elastic cylindrical portion 73 are integrally formed.

[0025] With the support shaft 4 and coil spring 5 inserted into the valve disc rolling-up portion 34, the tubular cushioning materials 7·7 are fixed by internally fitting the tubular base portions 71·71 onto both ends of the valve disc rolling-up portion 34, and the flange portions 72 abut against the widthwise end faces of the valve disc rolling-up portion 34 by being internally fitted into the tubular base portion 71. The flange portions 72 are each located between the widthwise end faces of the valve disc rolling-up portion 34 and the inner end faces of the valve seat hook portions 23 of the valve seat 2, and are located close to the inner end faces of the valve seat hook portions 23.

[0026] The valve disc winding portion 34 is engaged with the spindle 4 inserted through the tubular cushioning materials 7·7 via the tubular cushioning materials 7·7, in other words, the pair of tubular cushioning materials 7·7 fitted into the valve disc winding portion 34 serve as bearings for the spindle 4 of the valve disc 3. For the tubular cushioning material 7, any suitable cushioning material that has a cushioning function due to elasticity or the like and is heat resistant can be used, and a metal mesh material is preferable, for example.

[0027] The elastic cylindrical portion 73, such as a metal mesh material, which is provided integrally with the cylindrical cushioning material 7, is formed with an outer diameter larger than the inner diameter of the coil spring 5 in the open state of the valve body 3, which contracts when the valve body is opened, in other words, the inner diameter of the coil body 51 of the coil spring 5. The elastic cylindrical portion 73 is fitted externally near both ends of the support shaft 4, and is also fitted internally into both ends of the coil spring 5, in other words, both ends of the coil body 51 of the coil spring 5. In this embodiment, the elastic cylindrical portion 73 is press-fitted into the coil spring 5 or the coil body 51 of the valve body 3 in the closed state, which has an inner diameter larger than the inner diameter when the valve body 3 is in the open state (see Figs. 4 and 5).

[0028] The wound coil body 51 of the coil spring 5 is disposed within the valve body winding portion 34 over its entire length and is fitted onto the support shaft 4. One arm 52 of the coil spring 5 is disposed extending out to the front side of the valve body base plate 31 of the valve body 3 near the base of the valve body winding portion 34, in the illustrated example, the front side of the flat edge 32, and the other arm 53 of the coil spring 5 is disposed extending out to the rear side of the rising portion of the valve seat hook portion 23 near the base of the valve seat hook portion 23, and the valve body 3 is biased and pressed in the closing direction by the one arm 52 of the coil spring 5.

[0029] A notch 35 is formed on one side in the width direction of the valve body base plate 31 near the rising portion of the valve body wrap-around portion 34 of the valve body 3, and the other arm 53 of the coil spring 5 is led out from the notch 35 to the back side of the valve body base plate 31. The other arm 53 of the coil spring 5 is led out to the back side near the base of the valve seat hook 23 through the space between the notch 35 and the valve seat hook portions 23, 23, and presses and urges the rising portion of the valve seat hook portion 23 from the back side.

[0030] Between the valve seat hooks 23 of the valve seat 2, there is formed an upright portion 25 which rises at the same angle as the upright portion of the valve seat hook 23 and at a lower height than the upright portion of the valve seat hook 23. The other arm 53 of the coil spring 5 passes through the notch 35 and the tip face side of the upright portion 25 and is led out to the back side near the base of the valve seat hook 23.

[0031] The exhaust valve 1 of this embodiment is preferably used by attaching it to, for example, a separator 102 of a muffler 100 shown in Figures 6 and 7. In the muffler 100, the inside of a housing 101 is divided by a first separator 102 and a second separator 103, each of which is in the shape of a flat plate, and an expansion chamber 104, a resonance chamber 105, and an expansion chamber 106 are provided. The second separator 103, which divides the expansion chamber 104 and the resonance chamber 105, has a large number of small holes (not shown) formed over the entire surface.

[0032] The muffler 100 includes an exhaust inlet pipe 107 that communicates with the exhaust pipe of the engine and introduces exhaust into the housing 101, and an exhaust outlet pipe 108 that outlets exhaust from the housing 101. The exhaust inlet pipe 107 is provided so as to penetrate the first separator 102 from the outer wall on the expansion chamber 106 side, crossing the expansion chamber 106, with the expansion chamber 104 serving as the exhaust port of the exhaust inlet pipe 107. The exhaust outlet pipe 108 has the outer wall on the resonance chamber 105 side as the outlet, and is provided so as to penetrate the second separator 103 and the first separator 102, crossing the resonance chamber 105 and the expansion chamber 104, with the expansion chamber 106 serving as the intake port of the exhaust outlet pipe 108.

[0033] An exhaust circulation pipe 109 bent in a substantially σ-shape is provided inside the housing 101, and the exhaust circulation pipe 109 is formed with a smaller diameter than the exhaust introduction pipe 107 and the exhaust discharge pipe 108. The exhaust circulation pipe 109 has an intake opening in the expansion chamber 104, penetrates the second separator 103 at two points, the introduction side and the discharge side, and is disposed so as to cross the resonance chamber 105 in a substantially arc shape, and is further disposed so as to cross the expansion chamber 104 and penetrate the first separator 102, and is curved so as to turn back inside the expansion chamber 106, with an exhaust port disposed near the inlet of the exhaust discharge pipe 108.

[0034] The exhaust valve 1 is provided on the expansion chamber 106 side of the first separator 102, and is disposed at a position corresponding to an opening serving as an exhaust path of the first separator 102 so as to close the opening. The exhaust valve 1 has a valve seat substrate 21 having a generally flat ring shape disposed corresponding to the periphery of the opening of the first separator 102, and is welded at welding regions 241, 242 of the valve seat substrate 21 at welds 110 such as spot welding, so that the valve seat substrate 21 is fixed to the periphery of the opening of the first separator 102.

[0035] In the muffler 100, when the engine exhaust pressure is below a predetermined pressure, the exhaust flows as shown by the thick solid arrow in Figure 6, from the exhaust inlet pipe 107 to the expansion chamber 104, the exhaust circulation pipe 109 in the expansion chamber 104, the exhaust circulation pipe 109 in the resonance chamber 105, the exhaust circulation pipe 109 in the expansion chamber 104, the exhaust circulation pipe 109 in the expansion chamber 106, and finally the exhaust lead-out pipe 108. At this time, the valve element 3 of the exhaust valve 1 is continuously biased in the closing direction by the coil spring 5, and the valve element 3 is maintained in a closed state, providing a high noise reduction effect.

[0036] When the engine exhaust pressure in the muffler 100 exceeds a predetermined pressure, the valve element 3 of the exhaust valve 1 is opened by the exhaust pressure against the force of the coil spring 5 in the closing direction, and an exhaust flow indicated by a thick two-dot chain line arrow is generated in addition to the exhaust flow indicated by the thick solid line arrow in Fig. 6. That is, an exhaust flow is added from the exhaust introduction pipe 107 to the expansion chamber 104, the exhaust path of the exhaust valve 1 in the open state, the expansion chamber 106, the gap between the exhaust circulation pipe 109 and the exhaust discharge pipe 108, and the exhaust discharge pipe 108 in that order, and the back pressure of the exhaust of the engine is reduced. After that, when the engine exhaust pressure drops below the predetermined pressure, the valve element 3 closes while being cushioned by the ring cushion 6, and abuts against the ring cushion 6 or the valve seat substrate 21.

[0037] According to the exhaust valve 1 of this embodiment, when the inner diameter of the coil spring 5 is reduced by the opening operation of the valve body 3, the opening operation of the valve body 3 is suppressed by the resistance of the elastic cylindrical portion 73, so there is no need to adjust the biasing force of the valve body 3 in the closing direction by trial and error, which requires a lot of effort, by only adjusting the wire diameter and number of turns of the coil spring 5. For example, if the wire diameter and number of turns of the coil spring 5 are adjusted to increase the spring rate and increase the frictional resistance between the turns of the coil spring 5 in order to suppress surging, in which the valve body 3 flutters significantly, the opening degree of the valve body 3 may be insufficient. However, in the exhaust valve 1 of this embodiment, even if the spring rate of the coil spring 5 is lowered to make the valve body 3 easier to open, surging can be suppressed by suppressing the opening operation of the valve body due to the resistance of the elastic cylindrical portion 73. Therefore, the biasing force of the valve body 3 in the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve body 3 opens and closes appropriately according to the expected exhaust pressure.

[0038] Furthermore, since there is no need to attach a weight to the valve body 3 to suppress surging, and there is no increase in the weight of the valve body 3 that opens and closes, it is possible to ensure high durability of the components of the exhaust valve 1, such as the coil spring 5, or of the exhaust valve 1. Furthermore, since there is no need to use an expensive coil spring with an excessively high spring rate or a weight to be attached to the valve body 3, the manufacturing costs and parts costs of the exhaust valve 1 can be reduced.

[0039] In addition, by pressing the elastic tubular portion 73 into the coil spring 5 in the closed state of the valve body 3, which has a larger inner diameter than the valve body 3 in the open state, the surging energy that causes the valve body 3 to flutter and is transmitted to the coil spring 5 can be consumed by the elastic tubular portion 73 from the start of the opening operation of the valve body 3, and surging can be suppressed throughout the entire opening and closing operation of the valve body 3.

[0040] Furthermore, by providing the elastic tubular portion 73 integrally with the tubular cushioning material 7 that serves as a bearing for the spindle 4, the number of parts can be reduced, and the manufacturing costs of the exhaust valve 1 can be further reduced. Furthermore, by using a pair of tubular cushioning materials 7·7 with the elastic tubular portion 73 integrally provided as a bearing for the spindle, the strength and impact resistance of the bearing for the spindle can be increased. Furthermore, since the elastic tubular portion 73 can be inserted externally onto the spindle 4 and internally into the coil spring 5 in conjunction with the internal fitting of the tubular cushioning material 7 into the valve body winding portion 34, the manufacturing process for the exhaust valve 1 can be made more efficient.

[0041] Furthermore, by providing the valve seat hook 23 of the valve seat 2 so as to circumferentially embrace both ends of the support shaft 4 and fixing it to the support shaft 4, and providing the valve body wrapping portion 34 so as to circumferentially embrace the coil spring 5 from the opposite direction to the valve seat hook 23 and to embrace the coil spring 5 circumferentially over its entire length, it becomes possible to prevent or minimize axial misalignment of the coil spring 5 that is inserted coaxially with the support shaft 4 onto the support shaft 4 for opening and closing the valve body. By eliminating or minimizing axial misalignment between the coil spring 5 and the support shaft 4, the biasing force of the coil spring 5 with the elastic cylindrical portion 73 inserted therein in the valve body closing direction can be more accurately adjusted and set within an optimal range.

[0042] Furthermore, by installing the exhaust valve 1 in the first separator 102 of the muffler 100 for an automobile, the exhaust valve 1 can be closed when the engine speed is low to prevent the passage of pressure waves that are a source of noise, and the exhaust valve 1 can be opened when the engine speed is high to allow the exhaust to pass, thereby ensuring engine output. In other words, by installing the exhaust valve 1 in the muffler 100 for an automobile, with the biasing force of the valve body 3 in the closing direction adjusted and set within an appropriate range, it is possible to reliably achieve both quietness during regular city driving and ensuring engine output during high-speed driving.

[0043] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the inventions and embodiments listed as inventions, those specified by changing partial contents of these to other contents disclosed in this specification, those specified by adding other contents disclosed in this specification to these contents, or those specified by deleting partial contents of these to the extent that partial effects can be obtained, and specifying them as a higher-level concept. The inventions disclosed in this specification also include the following modified examples and added contents.

[0044] For example, the exhaust valve of the present invention also includes a configuration in which the elastic tubular portion is loosely inserted into the coil spring without being pressed into it when the valve disc is in a closed state, the inside diameter of which is larger than that of the valve disc in the open state. The elastic tubular portion in the exhaust valve of the present invention may be any appropriate portion within the scope of the spirit of the present invention, and is not limited to the elastic tubular portion 73 provided integrally with the tubular cushioning material 7 in the above embodiment. The valve disc wrapping portion in the exhaust valve of the present invention may be any appropriate valve disc wrapping portion provided on the valve disc so as to embrace the coil spring in the circumferential direction over the entire length of the coil spring, and is not limited to the valve disc wrapping portion 34 in the above embodiment.

[0045] For example, in the exhaust valve 1 of the above embodiment, the ring cushioning material 6 having a substantially flat ring shape is fixed to the valve seat substrate 21, but the ring cushioning material 6 having a substantially flat ring shape may be fixed to the valve seat 2 side of the flat edge 32 of the valve body substrate 31. Furthermore, the fixing structure for fixing the valve seat substrate 21 of the exhaust valve 1 to the periphery of the opening of the separator of the muffler 100 can be any suitable fixing structure within the spirit of the present invention other than welding at the welded parts 110 of the welding regions 241, 242.

[0046] Furthermore, the exhaust valve of the present invention is preferably an exhaust valve that is attached to a separator that divides the inside of an automobile muffler, but it can also be attached, for example, to the end of an exhaust pipe installed in an automobile muffler, and can be installed at an appropriate location in the exhaust duct of an automobile within an applicable range, and further, can be installed at an appropriate location in the exhaust duct of an automobile or other object within an applicable range. [Industrial Applicability]

[0047] The present invention can be used, for example, as an exhaust valve attached to a separator that divides the inside of a muffler in an exhaust passage of an automobile. [Explanation of symbols]

[0048] 1... exhaust valve 2... valve seat 21... valve seat base plate 22... opening 23... valve seat hook portion 241, 242... welding area 25... rising portion 3... valve body 31... valve body base plate 32... flat edge 33... recess 34... valve body roll-up portion 35... notch 4... support shaft 41... welding portion 5... coil spring 51... coil body 52... one arm 53... other arm 6... ring cushioning material 7... tube cushioning material 71... base tube portion 72... flange portion 73... elastic tube portion 100... muffler 101... housing 102... first separator 103... second separator 104... expansion chamber 105... resonance chamber 106... expansion chamber 107... exhaust inlet pipe 108... exhaust outlet pipe 109... exhaust flow pipe 110…Welded section

Claims

1. An exhaust valve that opens and closes an exhaust passage with a valve body according to exhaust pressure, The valve body is supported via a support shaft so as to be able to swing relative to a valve seat having an opening, The valve body is biased in a closing direction by a coil spring fitted around the support shaft, an elastic tubular portion having an outer diameter larger than an inner diameter of the coil spring when the valve body is in an open state, the elastic tubular portion being fitted externally near both ends of the support shaft and being fitted internally to both ends of the coil spring.

2. 2. The exhaust valve according to claim 1, wherein the elastic cylindrical portion is press-fitted into the coil spring, the coil spring having an inner diameter larger in the closed state of the valve body than in the open state of the valve body.

3. The valve body is provided with a valve body wrapping portion that is provided so as to embrace the coil spring in a circumferential direction over the entire length of the coil spring, The base tube portion of the cylindrical cushioning material, which is composed of a base tube portion and a flange portion, is fitted inside both ends of the valve body winding portion, The elastic cylindrical portion is integrally provided with the cylindrical cushioning material, 3. The exhaust valve according to claim 1, wherein the pair of cylindrical cushioning members serve as bearings for the support shaft.

4. The valve seat hook is provided on the valve seat so as to hold both ends of the support shaft in the circumferential direction and is fixed to the support shaft, 4. The exhaust valve according to claim 3, wherein the valve body wrapping portion is provided so as to circumferentially embrace the coil spring from a direction opposite to the valve seat hook portion.

5. 3. An automotive muffler, comprising: an exhaust valve according to claim 1, wherein the valve seat base plate of the valve seat is fixed to a peripheral edge of an opening of a separator which divides the inside of the muffler disposed in an exhaust passage.

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