Exhaust valves and mufflers for automobiles

Abstract

Provided is an exhaust valve in which the biasing force of a valve body in the closing direction can be easily and reliably adjusted and set within an appropriate range, and high durability can be ensured. [Solution] An exhaust valve 1 which opens and closes an exhaust passage with a valve element 3 in response to exhaust pressure, the valve element 3 being supported via a support shaft 4 so as to be able to swing against a valve seat 2 having an opening 22, the valve element 3 being urged in the closing direction by a coil spring 5 fitted onto the support shaft 4, and an arc-shaped inner spring 8 which is arc-shaped in cross section is fitted into the coil spring 5 whose inner diameter reduces when the valve element is opened, and the arc-shaped inner spring 8 applies a load to the coil spring 5 so as to resist the reduction in the inner diameter of the coil spring 5 caused by the valve element opening operation.

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 fitted onto the support shaft, an arc-shaped inner spring which is arc-shaped in cross section is fitted into the coil spring, the inner diameter of which decreases when the valve body is opened, and the arc-shaped inner spring applies a load to the coil spring so as to resist the decrease in the inner diameter of the coil spring caused by the valve body opening operation. 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 arc-shaped inner spring, so there is no need 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 arc-shaped inner spring. 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 there is no need to attach a weight to the valve body to suppress surging, and there is no need to increase the weight of the valve body that opens and closes, a high degree of durability can be ensured for the exhaust valve or for the exhaust valve itself. 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 circumferential length of the arc-shaped inner spring is equal to or longer than a semicircular arc, and is set to a length such that the tips of the coil spring do not come into contact with each other in a compressed state of the coil spring, which corresponds to the open state of the valve body. According to this, by setting the circumferential length of the arc-shaped inner spring to a length equal to or greater than a semicircular arc, the arc-shaped inner spring can be brought into contact with the coil spring over a wide area, and the resistance of the arc-shaped inner spring can be more reliably transmitted to the coil spring. Also, by setting the circumferential length of the arc-shaped inner spring to a length that does not allow the tips of the arc-shaped inner spring to come into contact with each other when the valve is open, it is possible to ensure that the arc-shaped inner spring applies elastic resistance to the coil spring when the valve is open, and it is possible to reliably suppress surging when the valve is open.

[0010] 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 spindle 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 to the spindle, the coil spring whose outer diameter expands when the valve body is opened is exteriorly fitted with an arc-shaped outer spring that is arc-shaped in cross section, and the arc-shaped outer spring applies a load to the coil spring so as to resist the expansion of the outer diameter of the coil spring due to the valve body opening operation. According to this, when the outer diameter of the coil spring expands due to the opening action of the valve body, the opening action of the valve body is suppressed by the resistance of the arc-shaped outer spring, so there is no need 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 arc-shaped outer spring. 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 there is no need to attach a weight to the valve body to suppress surging, and there is no need to increase the weight of the valve body that opens and closes, a high level of durability can be ensured for the exhaust valve components such as the coil spring or the exhaust valve. 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.

[0011] The exhaust valve of the present invention is characterized in that the circumferential length of the arc-shaped outer spring is set to a length equal to or greater than a semicircular arc when the coil spring is in an expanded state corresponding to the open state of the valve body. According to this, by setting the circumferential length of the arc-shaped outer spring to a length equal to or greater than a semicircular arc when the valve body is in the open state, the arc-shaped outer spring can be brought into contact with the coil spring over a wide area, and the resistance of the arc-shaped outer spring can be more reliably transmitted to the coil spring.

[0012] The exhaust valve of the present invention is characterized in that the arc-shaped outer spring is a valve body wrapping portion that is provided so as to embrace the coil spring in the circumferential direction over the entire length of the coil spring. According to this, by exteriorly mounting the valve body winding portion as an arc-shaped outer spring on a coil spring whose outer diameter expands when the valve body is opened, it is possible to eliminate the need to use a separate arc-shaped outer spring, reduce the number of parts, and lower manufacturing costs.

[0013] 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 the muffler of an automobile, 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 engine output during high-speed driving. In addition, it is possible to prevent and suppress the occurrence of surging caused by exhaust pulsation, and to prevent and suppress the destabilization of the automobile's operating state. Effect of the Invention

[0014] 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]

[0015] [Figure 1] 1 is a perspective view showing an exhaust valve of a first embodiment according to the present invention in a closed state. [Diagram 2] FIG. 2 is a perspective view showing an open state of an exhaust valve according to the first embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of the exhaust valve according to the first embodiment. [Figure 4] FIG. 2 is a perspective explanatory view showing a coil spring and an arc-shaped inner spring in the exhaust valve of the first embodiment. [Diagram 5] FIG. 4 is an explanatory diagram illustrating the relationship between a coil spring and an arc-shaped inner spring in the exhaust valve of the first embodiment. [Figure 6] 1 is an explanatory diagram of an automobile muffler in which an exhaust valve according to a first embodiment is attached to a separator. [Figure 7] FIG. 2 is a front view of the exhaust valve of the first embodiment attached to a separator. [Figure 8] FIG. 6 is a perspective view showing an exhaust valve in a closed state according to a second embodiment of the present invention. [Figure 9] FIG. 7 is an exploded perspective view of an exhaust valve according to a second embodiment. [Figure 10] FIG. 11 is a perspective explanatory view showing a coil spring and an arc-shaped outer spring in an exhaust valve according to a second embodiment. [Figure 11] FIG. 11 is an explanatory diagram illustrating the relationship between a coil spring and an arc-shaped outer spring in an exhaust valve according to a second embodiment. [Figure 12] FIG. 10 is an explanatory diagram illustrating the relationship between a coil spring and a valve body winding portion corresponding to an arc-shaped outer spring in an exhaust valve according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Exhaust valve of the first embodiment] An exhaust valve 1 according to a first 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 5, the exhaust valve 1 includes a valve seat 2, a valve body 3 that opens and closes, a support shaft 4, a coil spring 5, a ring cushioning material 6, a cylindrical cushioning material 7, and an arc-shaped inner spring 8 in the form of an arc-shaped leaf spring. The valve body 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The valve disc winding portion 34 is formed extending 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.

[0025] At both ends of the valve disc rolling-in portion 34, there is provided a tubular cushioning material 7 composed of a tubular portion 71 and a flange portion 72 protruding outward at one axial end of the tubular portion 71. With the support shaft 4 and the coil spring 5 inserted into the valve disc rolling-in portion 34, the tubular cushioning materials 7·7 are fixed by internally fitting the tubular portions 71·71 to both ends of the valve disc rolling-in portion 34, and the flange portion 72 abuts against the widthwise end face of the valve disc rolling-in portion 34 by the internal fitting of the tubular portion 71. The flange portions 72 are respectively disposed between the widthwise end faces of the valve disc rolling-in portion 34 and the inner end faces of the valve seat hook portions 23 of the valve seat 2, and disposed 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 tubular cushioning materials 7·7 fitted into the valve disc winding portion 34 serve as a bearing 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 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 leading 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 leading 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. The one arm 52 and the other arm 53 of the coil spring 5 are configured and disposed such that the inner diameter of the coil body 51 is reduced as the valve body opens (see the thick arrow in FIG. 5).

[0028] 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.

[0029] 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.

[0030] An arc-shaped inner spring 8 extending in an arc shape in cross section is inserted into the coil spring 5, or into the coil body 51 of the coil spring 5, whose inner diameter decreases when the valve body is opened, and the arc-shaped inner spring 8 applies a load to the coil spring 5 so as to resist the reduction in the inner diameter of the coil spring 5 or the coil body 51 caused by the valve body opening operation (see Figures 4 and 5).

[0031] In the exhaust valve 1 of the first embodiment, when the valve body 3 is in a closed state, the arc-shaped inner spring 8, which is arc-shaped in cross section, is disposed between the support shaft 4 and the coil body 51 and is loosely inserted into the coil body 51 so as not to press and urge the coil body 51, so that the elastic force of the arc-shaped inner spring 8 does not inhibit the reduction in the inner diameter of the coil spring 5 at an early stage, thereby ensuring a smooth opening operation of the valve body 3. Then, when the coil body 51 comes into contact with and begins to press the arc-shaped inner spring 8 due to a predetermined reduction in the inner diameter of the coil body 51 caused by the valve body opening operation, the arc-shaped inner spring 8 applies a load to the coil spring 5 against the reduction in the inner diameter of the coil body 51.

[0032] Furthermore, if the force with which the arc-shaped inner spring 8 presses against the inner surface of the coil body 51 when the valve body 3 is in the closed state is smaller than the necessary amount of force with which the coil spring 5 closes the valve body 3, it is also possible to insert the arc-shaped inner spring 8, which is arc-shaped in cross section, into the coil body 51 of the coil spring 5, whose inner diameter decreases when the valve body is opened, and to configure the arc-shaped inner spring 8 to be in pressing contact with the inner surface of the coil body 51 of the coil spring 5 when the valve body is in the closed state.

[0033] The circumferential length of the arc-shaped inner springs 8 is preferably set to a length equal to or greater than a semicircular arc, and to a length that prevents the tips of the arc-shaped inner springs 8 from abutting against each other when the coil springs 5 ​​are in a contracted state corresponding to the open state of the valve body 3. This allows the arc-shaped inner springs 8 to come into contact with the coil springs 5 ​​over a wide area, making it possible to more reliably transmit the resistance of the arc-shaped inner springs 8 to the coil springs 5, and further ensuring that the arc-shaped inner springs 8 apply elastic resistance to the coil springs 5 ​​when the valve body 3 is in the open state.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] According to the exhaust valve 1 of the first 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 arc-shaped inner spring 8, so that it is not necessary 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 the first embodiment, even if the spring rate of the coil spring 5 is lowered to make the valve body easier to open, surging can be suppressed by suppressing the opening operation of the valve body 3 due to the resistance of the arc-shaped inner spring 8. 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.

[0041] 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.

[0042] [Exhaust valve of the second embodiment] The exhaust valve 1a according to the second embodiment of the present invention is also installed in the muffler of the exhaust passage of an automobile, for example, and opens and closes the exhaust passage according to the exhaust pressure of the engine, and is preferably attached to a separator that divides the inside of the muffler. As shown in Figs. 8 to 11, the exhaust valve 1a includes a valve seat 2a, an opening and closing valve body 3a, a support shaft 4 similar to that of the first embodiment, a coil spring 5a, a ring cushioning material 6 such as a metal mesh material similar to that of the first embodiment, a tubular cushioning material 7 formed of a metal mesh material similar to that of the first embodiment, and an arc-shaped outer spring 9a in the shape of an arc-shaped leaf spring that is extended in an arc-shaped cross section of an independent member. The valve body 3a is supported via the support shaft 4 so as to be swingable relative to the valve seat 2a, and is biased in the closing direction by the coil spring 5a that is fitted onto the support shaft 4.

[0043] The valve seat 2a has a valve seat base plate 21 in which a welding area 241 and a welding area 242 are formed, an opening 22, and a pair of valve seat hooks 23, 23, which are configured in the same manner as in the first embodiment, and the valve seat hooks 23 are 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 are fixed to the support shaft 4 by welds 41.

[0044] Between the valve seat hooks 23 of the valve seat 2, there is formed a rising portion 25 which rises at the same angle as the rising portion of the valve seat hook 23 at a lower height. Between the left end of the rising portion 25 and the left valve seat hook 23 in Fig. 8, there is formed a restricting wall portion 26a which rises at the same angle as the rising portion 25 at a height lower than the rising portion of the valve seat hook 23 and higher than the rising portion 25. The restricting wall portion 26a abuts against the rear surface of the valve seat hook 23 so as to push back the other arm 53a so as to stably maintain a state in which the other arm 53a of the coil spring 5a described later is led out to the rear surface side of the rising portion of the valve seat hook 23 near the base of the valve seat hook 23.

[0045] The valve body 3a has the same configuration as the first embodiment, that is, the valve body base plate 31, the flat edge 32, the recess 33, and the valve body winding portion 34, but the shape and size of the inner peripheral surface of the valve body winding portion 34 is formed to approximately imitate the shape and size of the outer peripheral surface of the arc-shaped outer spring 9a arranged on the outer periphery of the coil body 51a of the coil spring 5a, and the size of the inner peripheral surface of the valve body winding portion 34 is slightly larger than the size of the outer peripheral surface of the arc-shaped outer spring 9a. The valve body winding portion 34, which extends in a continuous, elongated manner, is provided so as to embrace the coil spring 5a, which is inserted on the support shaft 4, in the circumferential direction over the entire length of the coil spring 5a.

[0046] With the spindle 4, coil spring 5a, and arc-shaped outer spring 9a inserted into the valve disc rolling-up portion 34, the tubular cushioning materials 7·7 on both sides are fixed by fitting tubular portions 71·71 into both ends of the valve disc rolling-up portion 34, and the flange portion 72 abuts against the widthwise end face of the valve disc rolling-up portion 34 by fitting into the tubular portion 71. The valve disc rolling-up portion 34 is engaged with the spindle 4, which is inserted through the tubular cushioning material 7·7, via the tubular cushioning material 7·7. In other words, the tubular cushioning material 7·7 fitted into the valve disc rolling-up portion 34 serves as a bearing for the spindle 4 of the valve disc 3.

[0047] The coil body 51a of the coil spring 5a is disposed in the valve body winding portion 34 over its entire length and is fitted onto the support shaft 4. One arm 52a of the coil spring 5a is disposed leading out to the front side of the valve body base plate 31 of the valve body 3a, in the illustrated example, the front side of the flat edge 32, and the other arm 53a of the coil spring 5a is disposed leading out to the rear side of the rising portion of the valve seat hook 23 near the base of the valve seat hook 23 and the rear side of the regulating wall portion 26a, and the valve body 3 is biased and pressed in the closing direction by the one arm 52a of the coil spring 5a. The one arm 52a and the other arm 53a of the coil spring 5a are configured and disposed so that the outer diameter of the coil body 51a expands as the valve body opens (see the thick arrow in FIG. 11).

[0048] A notch 35a is formed on one side in the width direction of the valve body base plate 31 near the rising portion of the valve body winding portion 34 of the valve body 3, and the other arm 53a of the coil spring 5a is led out from the notch 35a to the back side of the valve body base plate 31. The other arm 53a of the coil spring 5a presses and urges the rising portion of the valve seat hook portion 23 and the restriction wall portion 26a from the back side.

[0049] An arc-shaped outer spring 9a, which is arc-shaped in cross section, is fitted to the coil spring 5a, or to the coil body 51a of the coil spring 5a, whose outer diameter expands as the valve body opens, and the arc-shaped outer spring 9a is provided between the coil body 51 and the valve body winding portion 34. The arc-shaped outer spring 9a applies a load to the coil spring 5a against the expansion of the outer diameter of the coil spring 5 or the coil body 51 caused by the valve body opening operation (see Figures 10 and 11).

[0050] In the exhaust valve 1a of the second embodiment, when the valve body 3a is in the closed state, the arc-shaped outer spring 9a, which is arc-shaped in cross section, is loosely inserted between the coil body 51a and the valve body winding portion 34, so that the elastic force of the arc-shaped inner spring 9a does not suppress the expansion of the outer diameter of the coil spring 5a at an early stage, and a smooth opening operation of the valve body 3a is ensured. Then, when the coil body 51a comes into contact with the arc-shaped outer spring 9a and starts to press it with a predetermined amount of expansion of the outer diameter of the coil body 51a due to the valve body opening operation, the arc-shaped outer spring 9a applies a load to the coil spring 5a against the expansion of the outer diameter of the coil body 51a. From the viewpoint of the arc-shaped outer spring 9a applying a load reliably to the coil spring 5a, it is preferable to set the radius of curvature of the inner circumference of the arc-shaped outer spring 9a to be smaller than the radius of the outer circumference of the coil body 51a.

[0051] Furthermore, if the force with which the arc-shaped outer spring 9a presses against the outer periphery of the coil body 51a when the valve body 3a is in the closed state is smaller than the force with which the coil spring 5a closes the valve body 3a by a required amount, it is also possible to mount the arc-shaped outer spring 9a, which is arc-shaped in cross section, between the coil body 51a of the coil spring 5a, whose outer diameter expands when the valve body is opened, and the valve body winding portion 34, and to configure the arc-shaped outer spring 9a to be in pressing contact with the outer periphery of the coil body 51a of the coil spring 5a when the valve body is in the closed state.

[0052] The length of the arc-shaped outer spring 9a in the circumferential direction is preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in an expanded state corresponding to the open state of the valve body 3a, and more preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in an expanded state corresponding to the open state of the valve body 3a and not in contact with one arm 52a of the coil spring 5a. This allows the arc-shaped outer spring 9a to come into contact with the coil spring 5a over a wide area, so that the resistance of the arc-shaped outer spring 9a can be more reliably transmitted to the coil spring 5a, and the valve body opening operation can be prevented from being hindered by contact with one arm 52a of the coil spring 5a. The exhaust valve 1a of the second embodiment is also preferably attached to the separator 102 of the muffler 100 shown in Figures 6 and 7.

[0053] According to the exhaust valve 1a of the second embodiment, when the outer diameter of the coil spring 5a expands due to the opening operation of the valve body 3a, the opening operation of the valve body 3a is suppressed by the resistance of the arc-shaped outer spring 9a, so there is no need to adjust the urging force of the valve body 3a 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 5a. For example, if the wire diameter and number of turns of the coil spring 5a are adjusted to increase the spring rate and increase the frictional resistance between the turns of the coil spring 5a in order to suppress surging, in which the valve body 3a flutters significantly, the opening degree of the valve body 3a may be insufficient. However, in the exhaust valve 1a of the second embodiment, even if the spring rate of the coil spring 5a is lowered to make the valve body 3a easier to open, surging can be suppressed by suppressing the opening operation of the valve body 3a due to the resistance of the arc-shaped outer spring 9a. Therefore, the urging force of the valve body 3a in the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve body 3a opens and closes appropriately according to the expected exhaust pressure. Also, in the second embodiment, the same effects as those in the first embodiment can be obtained from the configuration corresponding to that in the first embodiment.

[0054] [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.

[0055] For example, in the exhaust valves 1, 1a of the first and second embodiments, 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, 1a 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.

[0056] 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.

[0057] As a modified example of the exhaust valve 1a of the second embodiment, instead of providing an arc-shaped outer spring 9a that is an arc-shaped leaf spring extending from an independent member in an arc-shaped cross section, it is also possible to provide a valve body winding portion 341a that is provided so as to embrace the coil spring 5a in the circumferential direction over the entire length of the coil spring 5a as an arc-shaped outer spring that applies a load to the coil spring 5a against the expansion of the outer diameter of the coil spring 5a due to the valve body opening operation, as shown in Fig. 12. By making the valve body winding portion 341a an arc-shaped outer spring, it is possible to eliminate the need to use an arc-shaped outer spring that is a separate independent member, thereby reducing the number of parts and the manufacturing costs.

[0058] The shape and size of the inner peripheral surface of the valve body winding portion 341a are formed to approximately follow the shape and size of the outer peripheral surface of the coil body 51a of the coil spring 5a. The size of the inner peripheral surface of the valve body winding portion 341a is slightly larger than the size of the outer peripheral surface of the coil body 51a, and is formed to a size that the valve body winding portion 341a abuts when the outer diameter of the coil body 51a expands with the valve body opening operation, and the resistance of the valve body winding portion 341a, which corresponds to an arc-shaped outer spring, suppresses the opening operation of the valve body 3a, making it possible to suppress surging.

[0059] The valve body winding portion 341a, which extends in an elongated series, is provided so as to circumferentially embrace the coil spring 5a inserted on the support shaft 4 over the entire length of the coil spring 5a, and is preferably formed longer than the longitudinal length of the coil body 51a so as to reliably embrace the coil spring 5a in the circumferential direction over the entire length of the coil spring 5a. This ensures that the valve body winding portion 341a, which applies a load to the coil spring 5a against the expansion of the outer diameter of the coil body 51a, is reliably provided over the entire length of the coil body 51a, and there is no portion of the coil body 51a to which a load against the expansion of the outer diameter of the coil body 51a is not applied, thereby enabling reliable and stable suppression of surging.

[0060] The circumferential length of the valve body winding portion 341a is preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in an expanded state corresponding to the open state of the valve body 3a, and more preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in an expanded state corresponding to the open state of the valve body 3a and not in contact with one arm 52a of the coil spring 5a. This allows the valve body winding portion 341a to come into contact with the coil spring 5a over a wide area, more reliably transmitting the resistance of the valve body winding portion 341a to the coil spring 5a, and prevents the valve body opening operation from being hindered by contact with one arm 52a of the coil spring 5a. [Explanation of symbols]

[0061] 1, 1a... exhaust valve 2, 2a... valve seat 21... valve seat base plate 22... opening 23... valve seat hook portion 24... welding area 25... upright portion 26a... regulating wall portion 3, 3a... valve body 31... valve body base plate 32... flat edge 33... recess 34, 341a... valve body winding portion 35, 35a... notch 4... support shaft 41... welding portion 5, 5a... coil spring 51, 51a... coil body 52, 52a... one arm 53, 53a... other arm 6... ring cushioning material 7... tube cushioning material 71... tube portion 72... flange portion 8... arc-shaped inner spring 9a... arc-shaped outer spring 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 circulation pipe 110... welded part

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 arc-shaped outer spring having an arc-shaped cross section is fitted around the coil spring, the outer diameter of which expands as the valve body opens.

1. An exhaust valve comprising: a valve body having a first end and a second end, the first end being connected to a first end of the exhaust valve body;

2. 2. The exhaust valve according to claim 1, wherein a circumferential length of the arc-shaped outer spring is set to a length equal to or greater than a semicircular arc when the coil spring is in an expanded state corresponding to an open state of the valve body.

3. 2. The muffler valve according to claim 1, wherein the arc-shaped outer spring is a valve body wrap portion that is provided so as to embrace the coil spring in the circumferential direction over the entire length of the coil spring.

4. 4. An automotive muffler, comprising: an exhaust valve according to claim 1, wherein the valve seat base plate of the valve seat is fixed to the periphery of an opening of a separator that divides the inside of the muffler to be installed in an exhaust passage.

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