Exhaust valves and automotive mufflers

Abstract

To provide an exhaust valve that allows the biasing force in the valve body closing direction to be easily and reliably adjusted and set within an appropriate range, while also ensuring high durability.SOLUTION: Provided is an exhaust valve 1 that opens and closes an exhaust passage by a valve body 3 in accordance with exhaust pressure. The valve body 3 is swingably supported, through a support shaft 4, on a valve seat 2 having an opening 22. The valve body 3 is biased in the closing direction by a coil spring 5 fitted around the support shaft 4. An arc-shaped inner spring 8 with an arc-shaped cross-section is inserted into the coil spring 5 whose inner diameter is reduced by a valve body opening operation. The arc-shaped inner spring 8 applies a load to the coil spring 5 to resist the reduction of the inner diameter of the coil spring 5 due to the valve body opening operation.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 whose valve body opens and closes in response to exhaust pressure to adjust the amount of exhaust gas flowing through, and a muffler equipped with the exhaust valve. [Background technology]

[0002] Conventionally, an exhaust valve installed in the exhaust passage of an automobile is disclosed in Patent Document 1. In the exhaust valve of Patent Document 1, a valve element is supported via a support shaft so as to be able to swing relative to a valve seat having an opening, a coil spring fitted onto the support shaft biases the valve element in the closing direction, valve seat hooks are provided to circumferentially hold both ends of the support shaft, and a valve element wrapping portion is provided to circumferentially hold the coil spring from the opposite direction to the valve seat hook and to circumferentially hold the coil spring over the entire length of the coil spring.

[0003] Furthermore, in this exhaust valve, the cylindrical cushioning material, which is composed of a cylindrical portion and a flange portion, is made of a metal mesh material, and the cylindrical cushioning material is fixed by fitting the cylindrical portions into both ends of the valve disc winding portion with the support shaft and coil spring inserted into the valve disc winding portion. Both ends of the support shaft are inserted into the cylindrical cushioning material fitted into the valve disc winding portion, and the pair of cylindrical cushioning materials serve as bearings for the support shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-188516 Summary of the Invention [Problem to be solved by the invention]

[0005] In an exhaust valve such as that disclosed in Patent Document 1, in which a coil spring biases the valve disc in the closing direction and the valve disc opens and closes in response to exhaust pressure, 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, resulting in significant surging. 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 in response to 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 solely adjusting the wire diameter and number of turns of the coil spring requires a great deal of trial and error effort. Also, while attaching a weight to the valve disc is one way to adjust the biasing force of the valve disc in the closing direction to suppress surging, the increased weight of the valve disc that opens and closes with the weight attached creates another problem: reduced durability of exhaust valve components such as the coil spring. Therefore, there is a need 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 while also ensuring high durability.

[0007] The present invention has been proposed in light of the above-mentioned problems, and aims to provide an exhaust valve in which the valve body is biased in the closing direction by a coil spring and 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, and which can ensure high durability, and an automotive 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 element in accordance with exhaust pressure, wherein the valve element is supported via a support shaft so that it can swing against a valve seat having an opening, the valve element is urged in the closing direction by a coil spring fitted around the support shaft, an arc-shaped inner spring that is arc-shaped in cross section is fitted into the coil spring, whose inner diameter reduces when the valve element is opened, and the arc-shaped inner spring applies a load to the coil spring so as to resist the reduction in the inner diameter of the coil spring when the valve element is opened. Furthermore, the exhaust valve of the present invention is an exhaust valve that opens and closes an exhaust passage with a valve element in accordance with exhaust pressure, wherein the valve element is supported via a support shaft so that it can swing against a valve seat having an opening, a coil spring inserted around the support shaft urges the valve element in the closing direction, an arc-shaped inner spring that is arc-shaped in cross section is disposed between the support shaft and the coil element and inserted into a wound coil body of the coil spring, whose inner diameter reduces when the valve element is opened, the arc-shaped inner spring is loosely inserted into the coil body so as not to press against the coil body when the valve element is closed, and the coil body comes into contact with and presses against the arc-shaped inner spring when the inner diameter of the coil body is reduced by a predetermined amount when the valve element is opened, thereby causing the arc-shaped inner spring to apply a load to the coil spring so as to resist the reduction in the inner diameter of the coil body. According to this, when the inner diameter of the coil spring contracts during the opening movement of the valve disc, the resistance of the arc-shaped inner spring suppresses the opening movement of the valve disc. This eliminates the need for laborious trial-and-error adjustment of the biasing force of the valve disc toward the closing direction by adjusting only the wire diameter or number of coils of the coil spring. For example, adjusting the wire diameter or number of coils of the coil spring to increase the spring rate and increase the frictional resistance between the coil spring windings in order to suppress surging, which causes the valve disc to flutter significantly, can result in insufficient valve opening. However, with the exhaust valve of the present invention, even if the spring rate of the coil spring is reduced to make the valve disc easier to open, surging can be suppressed by suppressing the opening movement of the valve disc due to the resistance of the arc-shaped inner spring. Therefore, the biasing force of the valve disc toward the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve disc opens and closes appropriately in response to the expected exhaust pressure. Furthermore, since there is no need to attach a weight to the valve disc to suppress surging and there is no increase in the weight of the valve disc that opens and closes, high durability of the exhaust valve components such as the coil spring and the exhaust valve itself 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 circumferential length of the arc-shaped inner spring is equal to or greater than a semicircular arc and is set to a length that prevents the tips of the coil springs from coming into contact with each other when the coil springs are in a compressed state that 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 come 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 abut against each other when the valve body is open, it is possible to ensure that the arc-shaped inner spring applies elastic resistance to the coil spring when the valve body is open, and to reliably suppress surging when the valve body is open.

[0010] The exhaust valve of the present invention is an exhaust valve that opens and closes an exhaust passage with a valve element in accordance with exhaust pressure, wherein the valve element is supported via a support shaft so that it can swing against a valve seat having an opening, the valve element is urged in the closing direction by a coil spring fitted onto the support shaft, the coil spring expands in outer diameter when the valve element is opened, and an arc-shaped outer spring that is arc-shaped in cross section is fitted on the exterior of the coil spring, 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 when the valve element is opened. According to this configuration, when the outer diameter of the coil spring expands during the opening movement of the valve disc, the resistance of the arc-shaped outer spring suppresses the opening movement of the valve disc. This eliminates the need for laborious trial-and-error adjustment of the biasing force of the valve disc toward the closing direction by adjusting only the wire diameter and number of coils of the coil spring. For example, adjusting the wire diameter and number of coils of the coil spring to increase the spring rate and increase the frictional resistance between the coil spring windings in order to suppress surging, which causes the valve disc to flutter significantly, can result in insufficient valve opening. However, with the exhaust valve of the present invention, even if the spring rate of the coil spring is reduced to make the valve disc easier to open, surging can be suppressed by suppressing the opening movement of the valve disc through the resistance of the arc-shaped outer spring. Therefore, the biasing force of the valve disc toward the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve disc opens and closes appropriately in response to the expected exhaust pressure. Furthermore, since there is no need to attach a weight to the valve disc to suppress surging and there is no increase in the weight of the valve disc that opens and closes, high durability of the exhaust valve components such as the coil spring and the exhaust valve itself 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.

[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 externally 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, there is no need to use a separate arc-shaped outer spring, reducing the number of parts and lowering 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 periphery of the 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 cause noise, and 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 normal city driving and sufficient engine output during high-speed driving. In addition, it is possible to prevent and suppress the occurrence of surging caused by exhaust pulsation, thereby preventing and suppressing unstable driving conditions of the automobile. [Effects of the Invention]

[0014] According to the present invention, in an exhaust valve in which a coil spring biases a valve body in the closing direction and the valve body opens and closes in response to exhaust pressure, the biasing 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 explanation 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. [Figure 2] FIG. 2 is a perspective view showing an open state of an exhaust valve according to the first embodiment. [Figure 3] FIG. 2 is an exploded perspective view of the exhaust valve of 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. [Figure 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 the 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. 10 is an exploded perspective view of an exhaust valve according to a second embodiment. [Figure 10] FIG. 10 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. 10 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 INVENTION

[0016] [Exhaust valve of the first embodiment] An exhaust valve 1 according to a first embodiment of the present invention is installed in a muffler in the exhaust passage of an automobile, for example, 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 interior of the muffler. As shown in Figures 1 to 5, 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 buffer 6, a cylindrical buffer 7, and an arc-shaped inner spring 8 in the form of an arc-shaped leaf spring. 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 the closing direction by the coil spring 5 that is fitted around the support shaft 4.

[0017] The valve seat 2 has a valve seat substrate 21 formed in a generally flat ring shape that is placed along the separator, for example, and an opening 22 that forms an exhaust path that opens and closes 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 hooks 23 rise obliquely upward from the upper end portion of the valve seat substrate 21 in the figure, and are curved in an arc on the back side of the valve seat substrate 21, and are 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 hooks 23 in the illustrated example are engaged with the support shaft 4 by circumferentially embracing both ends of the support shaft 4 from the valve body 3 side, and are fixed to the support shaft 4 by welds 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 roughly follow the shape and size of the outer circumferential surface of the support shaft 4 with which it engages.

[0019] The valve seat substrate 21 of the valve seat 2 is provided with a welding area 241 on the spindle 4 side that protrudes outward from the outer peripheral edge of the valve body substrate 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 from the spindle 4. The welding areas 241 and 242 are used as welding locations when, for example, 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 seat substrate 21 on the valve disc 3 side, and is provided at a position substantially corresponding to a flat edge 32 of the valve disc 3, which will be described later, so as to cushion the impact of the closing operation of the valve disc 3. The ring cushioning material 6 can be any suitable cushioning material that has a cushioning function due to elasticity or the like and is heat resistant, and a metal mesh material is preferable, for example.

[0021] The valve body 3 has a valve body substrate 31, which is formed in the shape of a flat dish with a flat edge 32. The front surface of the valve body substrate 31 is provided with a recess 33 that is generally circular in plan view and recessed so as to protrude toward the valve seat 2, 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 has a valve body winding portion 34 that protrudes from the support shaft 4 side of the valve body base plate 31 and curves in a hook shape so as to fold back from the valve body base plate 31. The valve body winding portion 34 is formed integrally with the valve body base plate 31 so as to protrude from the valve body base plate 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] In cross section, the valve body winding portion 34 is formed in an arc shape that exceeds a semicircle, 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 that is extrapolated onto the support shaft 4 from the opposite direction to the direction in which the valve seat hook portion 23 circumferentially embraces the support shaft 4, and 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 to extend in the width direction at approximately the center of the valve disc base plate 31, and is formed as a continuous, elongated portion having 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, which is 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 winding portion 34, there is provided a tubular cushioning material 7, which is composed of a tubular portion 71 and a flange portion 72 that protrudes outward from one axial end of the tubular portion 71. With the support shaft 4 and coil spring 5 inserted into the valve disc winding portion 34, the tubular cushioning materials 7·7 are fixed by internally fitting the tubular portions 71·71 onto both ends of the valve disc winding portion 34, and the flange portion 72 abuts against the widthwise end face of the valve disc winding portion 34 by being internally fitted into the tubular portion 71. The flange portions 72 are each located between the widthwise end face of the valve disc winding portion 34 and the inner end face of the valve seat hook portion 23 of the valve seat 2, and are located close to the inner end face of the valve seat hook portion 23.

[0026] The valve body winding portion 34 is engaged with the support shaft 4, which is 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 body winding portion 34 serve as bearings for the support shaft 4 of the valve body 3. For the tubular cushioning material 7, any appropriate 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 disc 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 to extend out from the front side of the valve disc base plate 31 of the valve disc 3 near the base of the valve disc 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 to extend out from the rear side of the rising portion of the valve seat hook 23 near the base of the valve seat hook 23, and the valve disc 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 so that the inner diameter of the coil body 51 decreases as the valve disc opens (see the thick arrow in FIG. 5 ).

[0028] A notch 35 is formed on one side in the width direction of the valve disc base plate 31 near the rising portion of the valve disc wrapping portion 34 of the valve disc 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 disc 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 23 from the back side.

[0029] Between the valve seat hooks 23 of the valve seat 2, there is formed a rising portion 25 that rises at the same angle as the rising portion of the valve seat hook 23 at a lower height than the rising 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 rising 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, which extends in an arc-shaped 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 decrease 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 disc 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 or 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 in the early stages, ensuring a smooth opening operation of the valve disc 3. Then, when the inner diameter of the coil body 51 is reduced by a predetermined amount due to the valve disc opening operation, the coil body 51 comes into contact with and begins to press the arc-shaped inner spring 8, and 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 closed is smaller than the necessary amount of force with which the coil spring 5 closes the valve body 3, it is 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 closed.

[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 compressed, which corresponds 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, more reliably transmitting the resistance of the arc-shaped inner springs 8 to the coil springs 5, and further ensures 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 the separator 102 of the muffler 100 shown in Figures 6 and 7. The muffler 100 has a housing 101 whose interior is divided by a flat first separator 102 and a flat second separator 103, which are provided with an expansion chamber 104, a resonance chamber 105, and an expansion chamber 106. The second separator 103, which separates the expansion chamber 104 and the resonance chamber 105, has a large number of small holes (not shown) formed over its entire surface.

[0035] Muffler 100 includes exhaust inlet pipe 107 that communicates with the engine's exhaust pipe and introduces exhaust into housing 101, and exhaust outlet pipe 108 that discharges exhaust from housing 101. Exhaust inlet pipe 107 is provided so as to pass through first separator 102 from the outer wall on the expansion chamber 106 side, crossing expansion chamber 106, with expansion chamber 104 serving as the outlet for exhaust inlet pipe 107. Exhaust outlet pipe 108 is provided so as to pass through second separator 103 and first separator 102, crossing resonance chamber 105 and expansion chamber 104, with expansion chamber 106 serving as the intake for exhaust outlet pipe 108.

[0036] An exhaust circulation pipe 109 that is bent in a roughly σ shape is provided inside the housing 101, and 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, on the introduction side and the discharge side, and is arranged to cross the resonance chamber 105 in a roughly arc shape, and is further arranged 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 outlet located 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 arranged at a position corresponding to an opening that serves as an exhaust path in the first separator 102 so as to close the opening. The exhaust valve 1 has a valve seat substrate 21 that is substantially in the shape of a flat ring arranged to correspond 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 with 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 muffler 100, when the engine exhaust pressure is below a predetermined pressure, exhaust flows as shown by the thick solid arrows in Figure 6, from exhaust inlet pipe 107 to expansion chamber 104, exhaust circulation pipe 109 in expansion chamber 104, exhaust circulation pipe 109 in resonance chamber 105, exhaust circulation pipe 109 in expansion chamber 104, exhaust circulation pipe 109 in expansion chamber 106, and finally exhaust lead-out pipe 108. At this time, valve element 3 of exhaust valve 1 is continuously biased in the closing direction by coil spring 5, so that 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 exhaust pressure opens the valve element 3 of the exhaust valve 1 against the closing bias of the coil spring 5, and an exhaust flow indicated by a thick, two-dot chain arrow is generated in addition to the exhaust flow indicated by the thick, solid arrow in Figure 6. That is, the exhaust flow is added in this order from the exhaust inlet pipe 107 to the expansion chamber 104, through the exhaust path of the open exhaust valve 1, through the expansion chamber 106, through the gap between the exhaust circulation pipe 109 and the exhaust outlet pipe 108, and back through the exhaust outlet pipe 108, reducing the engine exhaust back pressure. Thereafter, 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 decreases during the opening movement of the valve disc 3, the opening movement of the valve disc 3 is suppressed by the resistance of the arc-shaped inner spring 8, eliminating the need to laboriously adjust the biasing force of the valve disc 3 in the closing direction by trial and error, relying solely on 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 windings of the coil spring 5 in order to suppress surging, in which the valve disc 3 flutters significantly, this may result in insufficient opening of the valve disc 3. However, with the exhaust valve 1 of the first embodiment, even if the spring rate of the coil spring 5 is reduced to make the valve disc easier to open, surging can be suppressed by suppressing the opening movement of the valve disc 3 due to the resistance of the arc-shaped inner spring 8. Therefore, the biasing force of the valve disc 3 in the closing direction can be easily and reliably adjusted and set within an appropriate range so that the valve disc 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 element 3 to suppress surging and there is no increase in the weight of the valve element 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, and 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 attached to the valve element 3, the manufacturing costs and parts costs of the exhaust valve 1 can be reduced.

[0042] [Exhaust valve of second embodiment] An exhaust valve 1a according to a second embodiment of the present invention is also installed in a muffler in an automobile exhaust passage, for example, and opens and closes the exhaust passage in response to engine exhaust pressure. It is preferably attached to a separator that divides the interior of the muffler. As shown in Figures 8 to 11, the exhaust valve 1a includes a valve seat 2a, an opening / closing valve element 3a, a support shaft 4 similar to that of the first embodiment, a coil spring 5a, a ring-shaped buffer material 6 made of a metal mesh material or the like similar to that of the first embodiment, a cylindrical buffer material 7 also made of a metal mesh material or the like similar to that of the first embodiment, and an arc-shaped outer spring 9a, which is an arc-shaped leaf spring extending from an independent member and has an arc-shaped cross section. The valve element 3a is supported via the support shaft 4 so as to be able to swing relative to the valve seat 2a, and is biased in the closing direction by the coil spring 5a fitted around the support shaft 4.

[0043] The valve seat 2a has the same configuration as in the first embodiment, that is, a valve seat base plate 21 on which a welding area 241 and a welding area 242 are formed, an opening 22, and a pair of valve seat hooks 23, 23, 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 that rises at the same angle as the rising portion of the valve seat hook 23 but at a height lower than the rising portion of the valve seat hook 23. 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 that rises at the same angle as the rising portion 25 but at a height lower than the rising portion of the valve seat hook 23 but higher than the rising portion 25. The restricting wall portion 26a abuts against the back surface of the valve seat hook 23 so as to push back the other arm 53a of the coil spring 5a (described later) so as to stably maintain the state in which the other arm 53a of the coil spring 5a (described later) is positioned behind the rising portion of the valve seat hook 23 near the base of the valve seat hook 23.

[0045] The valve 3a has the same configuration as in the first embodiment, namely, a valve base plate 31, a flat edge 32, a recess 33, and a valve coiling portion 34, but the shape and size of the inner peripheral surface of the valve coiling portion 34 are formed to roughly 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 coiling portion 34 is slightly larger than the size of the outer peripheral surface of the arc-shaped outer spring 9a. The valve coiling portion 34, which extends in a continuous, elongated manner, is provided so as to circumferentially embrace the coil spring 5a, which is fitted onto the support shaft 4, over the entire length of the coil spring 5a.

[0046] The cylindrical cushioning materials 7·7 on both sides are fixed by fitting cylindrical portions 71·71 onto both ends of the valve disc winding portion 34, with the support shaft 4, coil spring 5a, and arc-shaped outer spring 9a inserted into the valve disc winding portion 34, and the flange portion 72 abuts against the end face in the width direction of the valve disc winding portion 34 by fitting into the cylindrical portion 71. The valve disc winding portion 34 is engaged with the support shaft 4, which is inserted through the cylindrical cushioning materials 7·7, via the cylindrical cushioning materials 7·7; in other words, the cylindrical cushioning materials 7·7 fitted into the valve disc winding portion 34 serve as bearings for the support shaft 4 of the valve disc 3.

[0047] The wound coil body 51a of the coil spring 5a is disposed within 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 to extend 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 to extend to the rear side of the rising portion of the valve seat hook 23 near its base and the rear side of the restriction wall portion 26a, and the one arm 52a of the coil spring 5a biases and presses the valve body 3 in the closing direction. 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 Figure 11).

[0048] A notch 35a is formed on one side of the valve body base plate 31 in the width direction near the rising portion of the valve body wrapping 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 on the coil spring 5a, or on 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 so as to resist 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 disc 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 disc winding portion 34, so that the elastic force of the arc-shaped inner spring 9a does not inhibit the expansion of the outer diameter of the coil spring 5a in the early stages, ensuring a smooth opening operation of the valve disc 3a. Then, when the coil body 51a contacts and begins to press the arc-shaped outer spring 9a after a predetermined amount of expansion of the outer diameter of the coil body 51a due to the valve disc 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 perspective of ensuring that the arc-shaped outer spring 9a applies a load to the coil spring 5a reliably, 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 closed is smaller than the force with which the coil spring 5a closes the valve body 3a by more than the necessary amount, it is also possible to install 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 closed.

[0052] The circumferential length of the arc-shaped outer spring 9a is preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is expanded, which corresponds to the open state of the valve disc 3a. More preferably, the length is set to a length equal to or greater than a semicircular arc when the coil spring 5a is expanded, which corresponds to the open state of the valve disc 3a, and is long enough not to come into 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, more reliably transmitting the resistance of the arc-shaped outer spring 9a to the coil spring 5a and preventing interference with the opening operation of the valve disc due to contact with one arm 52a of the coil spring 5a. The exhaust valve 1a of the second embodiment is also preferably attached to a separator 102 of a muffler 100 shown in FIGS. 6 and 7.

[0053] According to the exhaust valve 1a of the second embodiment, when the outer diameter of the coil spring 5a expands during the opening movement of the valve disc 3a, the resistance of the arc-shaped outer spring 9a suppresses the opening movement of the valve disc 3a. This eliminates the need for laborious trial-and-error adjustment of the closing biasing force of the valve disc 3a by adjusting only 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 coil windings of the coil spring 5a in order to suppress surging, which is the fluttering of the valve disc 3a, the valve disc 3a may not open sufficiently. However, in the exhaust valve 1a of the second embodiment, even if the spring rate of the coil spring 5a is reduced to make the valve disc 3a easier to open, surging can be suppressed by suppressing the opening movement of the valve disc 3a due to the resistance of the arc-shaped outer spring 9a. Therefore, the closing biasing force of the valve disc 3a can be easily and reliably adjusted and set within an appropriate range so that the valve disc 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 same configuration.

[0054] [Scope of the invention disclosed herein] The inventions disclosed in this specification include, in addition to the individual inventions and embodiments listed as inventions, those specified by modifying partial contents of these with 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 are obtained and creating a generic concept. The inventions disclosed in this specification also include the following modifications and additions.

[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 also 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 and scope 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 to the end of an exhaust pipe that is installed in an automobile muffler, for example, and can be installed at an appropriate location in an automobile exhaust duct within the applicable range, and further, can be installed at an appropriate location in an exhaust duct other than an automobile within the 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 and has an arc-shaped cross section, it is also possible to provide a valve element winding portion 341a that is provided so as to embrace the coil spring 5a in the circumferential direction over the entire length as an arc-shaped outer spring that applies a load to the coil spring 5a so as to resist the expansion of the outer diameter of the coil spring 5a due to the valve element opening operation, as shown in Fig. 12. By making the valve element winding portion 341a an arc-shaped outer spring, there is no need to use an arc-shaped outer spring that is a separate, independent member, and it is possible to reduce the number of parts and lower manufacturing costs.

[0058] The shape and size of the inner peripheral surface of the valve element winding portion 341a are formed to roughly 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 element 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 allows the valve element winding portion 341a to abut when the outer diameter of the coil body 51a expands as the valve element opens, and the resistance of the valve element winding portion 341a, which corresponds to an arc-shaped outer spring, suppresses the opening operation of the valve element 3a, making it possible to suppress surging.

[0059] The valve element winding portion 341a, which extends in a long and slender series, is provided so as to circumferentially embrace the coil spring 5a, which is fitted onto 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 element 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 provided over the entire length of the coil body 51a, and eliminates any 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, enabling reliable and stable suppression of surging.

[0060] The circumferential length of the valve disc winding portion 341a is preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in the expanded state corresponding to the open state of the valve disc 3a, and more preferably set to a length equal to or greater than a semicircular arc when the coil spring 5a is in the expanded state corresponding to the open state of the valve disc 3a and not to come into contact with one arm 52a of the coil spring 5a. This allows the valve disc winding portion 341a to come into contact with the coil spring 5a over a wide area, more reliably transmitting the resistance of the valve disc winding portion 341a to the coil spring 5a and preventing the valve disc 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... Upstanding portion 26a... Restricting wall portion 3, 3a... Valve body 31... Valve body base plate 32... Flat edge 33... Recessed portion 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... Cylinder cushioning material 71... Cylinder 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 portion

Claims

1. An exhaust valve that opens and closes an exhaust passage with a valve body according to exhaust pressure, the valve element is supported via a support shaft so as to be swingable relative to a valve seat having an opening; A coil spring fitted around the support shaft biases the valve body in the closing direction, An arc-shaped inner spring having an arc-shaped cross section is disposed between the support shaft and the coil body and inserted into the wound coil body of the coil spring, the inner diameter of which is reduced by the valve body opening operation, the arc-shaped inner spring is loosely inserted into the coil body so as not to press and urge the coil body when the valve body is in a closed state; An exhaust valve characterized in that the coil body contacts and presses against the arc-shaped inner spring as the inner diameter of the coil body is reduced by a predetermined amount due to the valve body opening operation, and the arc-shaped inner spring applies a load to the coil spring so as to resist the reduction in the inner diameter of the coil body.

2. 2. The exhaust valve according to claim 1, wherein the circumferential length of the arc-shaped inner spring is equal to or greater than a semicircular arc and is set to a length such that the tips of the coil springs do not come into contact with each other when the coil springs are in a compressed state corresponding to the open state of the valve body.

3. 3. An automotive muffler according to claim 1, wherein the valve seat base plate of the valve seat in the exhaust valve is fixed to the periphery of an opening of a separator that separates the interior of the muffler installed in an exhaust passage.

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