JP2007205183A - Exhaust flow control valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the increase of back pressure and the consequent degradation of engine output by reducing turbulent flow coming around to the back face of a butterfly valve in an exhaust flow control valve provided with the butterfly valve switched to the closing side of reducing the passage area of an exhaust pipe and to the opening side of enlarging the area. <P>SOLUTION: A weight 40 is welded to the back face of the butterfly valve 22 and constituted such that the outer peripheral outline of the weight 40 matches that of the butterfly valve 22 at the swing tip part of the butterfly valve 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust flow control valve provided in an exhaust pipe through which exhaust gas of an engine passes.

2. Description of the Related Art Conventionally, a butterfly valve that is urged to the closing side by an elastic member is provided in an exhaust passage through which engine exhaust gas passes. By switching, the exhaust passage is shut off / communication or the cross-sectional area of the flow passage is increased / decreased to improve the noise reduction effect when the engine is under a low load while preventing the output from being reduced when the engine is under a high load. What has been made is known (see Patent Document 1 below), and this type of butterfly valve may vibrate due to the pulsation of the exhaust gas pressure, generating abnormal noise. A valve with a weight added to the valve is also known (see Patent Document 2 below).
US Pat. No. 5,355,673 official specification JP 2002-235536 A

  By the way, in order to increase or decrease the flow cross-sectional area of the exhaust gas formed between the inner peripheral surface of the exhaust passage and the outer periphery of the butterfly valve by opening and closing the butterfly valve, the butterfly valve is installed in the middle of the exhaust passage. Unlike the case where a butterfly valve is installed at the downstream end of the exhaust passage (for example, the butterfly valve disclosed in Patent Document 2), when the butterfly valve is opened, as shown in FIG. It is easy to generate turbulent flow in which the exhaust gas circulates in a loop shape (surface on the downstream side of the exhaust gas flow direction), and this turbulent flow decreases the exhaust gas flow rate and increases the back pressure. There is a problem of inviting.

  The present invention has been made in view of the above circumstances, and is a novel type in which generation of the turbulent flow is reduced as much as possible by using a weight attached to a butterfly valve to prevent a decrease in engine output. An object is to provide an exhaust flow control valve.

In order to achieve the above object, an invention according to claim 1 is provided in an exhaust system of an engine, is swingably supported in an exhaust passage through which exhaust gas passes, and is formed between an inner peripheral surface of the exhaust passage. A butterfly valve that switches between a closed side that reduces the cross-sectional area of the exhaust gas and an open side that increases the cross-sectional area of the exhaust gas, and an elastic member that biases the butterfly valve toward the closed side. In the exhaust flow control valve that switches the butterfly valve from the closed side to the open side against the biasing force of the elastic member by increasing the exhaust gas pressure acting on the
A weight is attached to the butterfly valve, and the outer peripheral contour of the weight is adapted to match the outer peripheral contour of the butterfly valve at least at the swinging tip of the butterfly valve.

  Here, the swinging tip portion of the butterfly valve is a portion that greatly changes the cross-sectional area of the flow path formed between the butterfly valve and the inner peripheral surface of the exhaust passage.

  In order to achieve the above object, the invention described in claim 2 is characterized in that, in the invention described in claim 1, the weight is attached to the back surface of the butterfly valve.

  Here, the back surface of the butterfly valve is a surface on the downstream side in the flow direction of the exhaust gas flowing through the exhaust passage.

  According to the first and second aspects of the present invention, the weight is attached to the butterfly valve, and at least the swinging tip of the butterfly valve is configured such that the outer contour of the weight matches the outer contour of the butterfly valve. The thickness of the swing tip of the butterfly valve that forms the exhaust gas flow path with the inner peripheral surface of the exhaust passage is substantially increased, and the exhaust gas flowing through the swing tip is rectified. Thereby, the turbulent flow which goes around to the back surface of a butterfly valve is reduced, and an increase in back pressure due to a decrease in the exhaust gas flow rate and a decrease in engine output resulting therefrom are prevented.

  In particular, according to the invention described in claim 2, since the weight is attached to the back surface of the butterfly valve, the exhaust gas flowing through the exhaust passage is not directly injected to the attachment portion of the weight. Therefore, it is possible to prevent weld peeling that easily occurs when the weight is attached by welding.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on examples of the present invention shown in the accompanying drawings.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 7. This embodiment is a case where the exhaust flow control valve of the present invention is implemented in an exhaust system of an automobile engine. FIG. 2 is an overall side view of an exhaust system of an engine provided with a flow control valve, FIG. 2 is a fragmentary enlarged view of a portion surrounded by an imaginary line shown in FIG. 1, and FIG. 3 is a portion shown in FIG. 4 is a perspective view of the exhaust flow control valve, FIG. 5 is an enlarged sectional view taken along line 5-5 in FIG. 2, and FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. FIG. 7 is a view showing a flow state of exhaust gas flowing through the butterfly valve.

  In FIG. 1, an exhaust system Ex connected to an exhaust port of an engine E extends in the front-rear direction of the automobile. A direct exhaust catalyst C extends from the upstream side to the downstream side of the exhaust system. The valve V, the primary silencer (prechamber) M1, and the secondary silencer M2 are sequentially connected. The exhaust gas discharged from the operation of the engine E is purified by the direct exhaust catalyst C after the harmful components such as HC, CO, NOx contained in the exhaust gas are purified. Then, the exhaust noise is silenced by the primary and secondary silencers M1 and M2, and is discharged to the outside.

  Next, the configuration of the exhaust flow control valve V according to the present invention will be specifically described with reference to FIGS.

  This exhaust flow control valve V is located between the downstream end of the upstream exhaust pipe 1 connected to the outlet of the direct type catalyst C and the upstream end of the downstream exhaust pipe 2 connected to the inlet of the primary silencer M1. The exhaust pipe 3 is provided with an inner pipe 4 and an outer pipe 5 surrounding the inner pipe 4 with an annular space 6 therebetween. The upstream side of the outer tube 5 is formed in a cone shape and is joined to the upstream side of the inner tube 4. A connection pipe 8 coupled to the upstream side connection flange 9 is inserted into this joint, and the joint is joined. The part and the connection pipe 8 are welded 10 in an airtight manner. As shown in FIGS. 2 and 3, the downstream side of the outer tube 5 is subjected to spatula drawing (spinning), and its downstream end is welded 14 to a connection pipe 12 coupled to a downstream connection flange 13. ing. The downstream side of the inner pipe 4 is floatingly supported on the downstream side of the outer pipe 5 via a stainless steel mesh ring 15 so that the thermal extension of the inner pipe 4 can be absorbed.

  The upstream connection flange 9 is integrally coupled to the downstream connection flange 1 f of the upstream exhaust pipe 1 by a plurality of bolts and nuts, and the downstream connection flange 13 is an upstream connection flange of the downstream exhaust pipe 2. It is integrally connected to 2f by a plurality of bolts and nuts.

  As shown most clearly in FIG. 5, the inner tube 4 is formed by welding 17 left and right divided halves 4L and 4R which are divided into two in the longitudinal direction. In the intermediate part, a recess 18 is formed on one side of the upper half part thereof, so that the cross-sectional area of the upper half part of the inner tube 4 is made smaller than the cross-sectional area of the lower half part thereof. ing. Left and right bearing holes 19L and 19R bulging outward are formed on the left and right opposing surfaces of the upper half of the inner tube 4 where the recesses 18 are formed, and stainless steel mesh is formed in these bearing holes 19L and 19R. The left and right bushes 20L and 20R are accommodated on the same axis, and the valve shaft 23 to which the butterfly valve 22 is welded is rotatably passed through the bushes 20L and 20R. The swing support portion 22S of the butterfly valve 22 is formed with a notch 22C that narrows the valve width. The swing support portion 22S of the butterfly valve 22 has an upper half of the inner pipe 4 having a reduced cross-sectional area. The valve shaft 23 which is accommodated in the portion and is welded to the swing support portion 22S of the butterfly valve 22 is swingably supported by the upper half of the inner tube 4 via the left and right bushes 20L and 20R. Flanges 23F and 23F are integrally formed on the left and right sides of the valve shaft 23. The flanges 23F and 23F are opposed to the left and right bushes 20L and 20R, and the axial direction of the valve shaft 23 and the butterfly valve 22 welded to the valve shaft 23 Is positioned. Further, the left and right bushes 20L, 20R made of stainless mesh prevent the butterfly valve 22 and the valve shaft 23 from directly contacting the inner pipe 4, so that it is possible to avoid the generation of noise during the opening / closing operation of the butterfly valve 22. Is done.

  As shown in FIGS. 5 and 6, the butterfly valve 22 includes a swing support portion 22 </ b> S formed to be narrow and a swing main body portion 22 </ b> M that is formed wide and constitutes a main part of the butterfly valve 22. As described above, the valve shaft 23 is welded to the swing support portion 22S and supported by the inner tube 4 so as to be swingable. The swing main portion 22M is connected to the flow of the inner tube 4. In the lower half of the inner pipe 4 having a large passage cross-sectional area, the rocking tip is formed between the inner peripheral surface of the exhaust passage in the inner pipe 4 when the butterfly valve 22 is opened and closed. This is the part that greatly changes the area.

  As shown in FIGS. 2, 5, and 6, a weight 40 is welded to the back surface of the swinging main portion 22 </ b> M of the butterfly valve 22, that is, the downstream surface in the exhaust gas flow direction. The outer peripheral contour is formed so as to match the outer peripheral contour of the swing main body 22M. Further, the upper edge of the weight 40 is formed flat and is located at the boundary portion of the butterfly valve 22 between the swing support portion 22S and the swing main body portion 22M, and between the back surface of the butterfly valve 22. Have a step. Thus, the weight 40 has a function of suppressing the turbulent flow of the exhaust gas generated on the back side of the butterfly valve 22 in cooperation with the butterfly valve 22 in addition to the vibration preventing action of the butterfly valve as described later. Yes.

  As shown in FIGS. 2 to 5, the recess 18 formed in the upper portion of the inner tube 4 is elastic to urge the butterfly valve 22 toward the closed side, that is, the side of reducing the passage area of the exhaust gas in the inner tube 4. A member 26 is provided. In this embodiment, the elastic member 26 is constituted by a torsion coil spring, and this torsion coil spring 26 is supported in a cantilevered manner from the wall surface of the inner tube 4 toward the recess 18. The member 27 is fitted and supported. The torsion coil spring 26 has a fixed arm 26a extending from one end in the axial direction, and a movable arm 26b extending from the other end. A fixing member 28 is welded to the inner tube 4, and the fixing member 28 is formed in a comb-like shape by arranging a plurality (three) of locking portions 28A, 28B, 28C. One end of the movable arm 26a of the coil spring 26 is selectively locked to one of the locking portions 28A, 28B, 28C. Thereby, the spring characteristic of the torsion coil spring 26 can be changed. The other end of the torsion coil spring 26 is connected to the butterfly valve 22 via a link mechanism 30. The link mechanism 30 includes a stay 31 accommodated in the recess 18. The stay 31 has a boss portion 31a at the base end and a hook portion 31b at the tip end, and the boss portion. 31a is fitted and welded to the valve shaft 23, and its hook portion 31b is detachably engaged with a connector 33 provided on the movable arm 26b of the torsion coil spring 26. As shown in FIG. 5, the connector 33 is formed of a cylindrical carbon bush.

  As indicated by a solid line in FIG. 2, the elastic force of the torsion coil spring 26 causes the connector 33 to elastically engage the hook portion 31b at the tip of the stay 31, and the stay 31 is rotated in the clockwise direction (the direction of arrow a in FIG. 2). The butterfly valve 22 to which the weight 40 is attached is urged to the closing side, and the butterfly valve 22 is switched to the closing side. When the butterfly valve 22 is switched to the closed side, a narrow exhaust gas passage cross-sectional area is formed in the inner pipe 4 according to low speed operation such as idling operation or start operation of the engine E. Further, as the exhaust pressure of the exhaust gas flowing through the inner pipe 4 becomes larger than the elastic force of the torsion coil spring 26, the butterfly valve 22 is switched counterclockwise (arrow b in FIG. 2), that is, opened. At this time, the connector 33 slides from the hook portion 31b side to the boss portion 31a side as shown in FIG. When the elastic force of the torsion coil spring 26 and the exhaust pressure of the exhaust gas are balanced, the butterfly valve 22 is stably maintained at a predetermined opening, and the butterfly valve 22 fluctuates due to fluctuations in the exhaust pressure. There is no.

  Next, the operation of this embodiment will be described.

  Now, when the engine E is operated, the exhaust gas discharged from the engine E flows into the exhaust system Ex. The exhaust gas flowing through the exhaust system Ex flows to the direct type exhaust catalyst C, and after harmful components such as HC, CO, NOx contained in the exhaust gas are purified, the exhaust gas passes through the exhaust flow control valve V according to the present invention. After the flow rate of the exhaust gas is controlled, the exhaust gas flows to the primary and secondary silencers M1 and M2, and the exhaust sound is silenced sequentially and discharged to the outside.

  By the way, in the low speed operation region including the idling operation and the start operation of the engine E, the combustion pressure of the engine E is low and the exhaust gas pressure of the exhaust gas discharged from the engine E is low, so the exhaust gas dynamic pressure flowing into the exhaust pipe 3 is low. The butterfly valve 22 is held on the closed side as shown by a solid line in FIG. 2, and the exhaust gas passage area in the inner pipe 4 is most narrowed. The exhaust noise is preliminarily silenced before the container M1, and the charging efficiency of the engine E is increased.

  On the other hand, when the combustion of the engine E reaches a complete explosion state and the rotational speed reaches the high speed operation range, the combustion pressure also increases, and the pressure of the exhaust gas exhausted therefrom also increases. The exhaust gas dynamic pressure that has flowed into the exhaust gas switches the butterfly valve 22 to the open side against the elastic force of the elastic member, that is, the torsion coil spring 26, as indicated by the chain line in FIG. The passage cross-sectional area of the exhaust passage in the pipe 3 can be increased, and the exhaust pressure loss in the high-speed rotation region of the engine E can be reduced.

  Thus, when the butterfly valve 22 is opened in the low-speed operation region of the engine E (particularly when the butterfly valve 22 starts to open), the conventional butterfly valve has a rear surface of the butterfly valve 22 as shown in FIG. It is easy to generate a turbulent flow in which the exhaust gas circulates in a loop shape on the downstream side of the exhaust gas flow direction), thereby reducing the exhaust gas flow rate to increase the back pressure and lowering the engine output. In this embodiment, as shown in FIG. 7, a weight 40 is attached to the back surface of the swing main body 22M of the butterfly valve 22, and the outer contour of the weight 40 is defined as the swing of the butterfly valve 22. By matching the outer peripheral contour of the main body portion 22M, the thickness of the rocking tip portion of the rocking main body portion 22M of the butterfly valve 22 is substantially increased while reducing the vibration of the butterfly valve 22 by the weight 40. Rectifying action is generated in the exhaust gas flowing between the outer peripheral edge of the butterfly valve 22 and the inner peripheral surface of the exhaust passage, thereby reducing the turbulent flow that flows around the back surface of the butterfly valve 22 and the exhaust gas flow rate. The increase in the back pressure due to the decrease in the engine pressure and the decrease in the output of the engine due to this are prevented. Further, since the weight 40 is welded to the back surface of the swinging main portion 22M of the butterfly valve 22, the exhaust gas is not directly injected to the welded portion of the weight 40, and the welding peeling is prevented.

  Further, in this embodiment, a notch 22C is formed in the butterfly valve 22 and a recess 18 corresponding to the notch 22C is formed in the upper portion of the inner tube 4, and between the recess 18 and the outer tube 5 is formed. Since the elastic member 26 that urges the butterfly valve 22 in the closing direction is disposed in the formed space, the space for disposing the elastic member 26 and the link mechanism 30 that connects the elastic member 26 and the butterfly valve 22. And the elastic member 26 and the link mechanism 30 are not restricted by being formed thin in the radial direction. Accordingly, the degree of freedom in setting the operating characteristics of the butterfly valve 22 is increased, and the performance of the exhaust flow control valve V can be greatly improved. Further, the exhaust pipe 3 does not need to have a larger diameter of the outer pipe 5. Therefore, the exhaust structure at the portion where the exhaust flow rate control valve V of the exhaust system Ex is provided does not increase in size, and as a whole, the exhaust system Ex can be reduced in weight and size.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention.

  For example, in the above embodiment, the exhaust flow rate control valve V according to the present invention is provided between the direct type catalyst C and the primary silencer M1, but this may be provided at other locations of the exhaust system Ex. Moreover, in the said Example, although the weight 40 is attached to the butterfly valve 22 by welding, you may attach by another attachment means.

Overall side view of an exhaust system of an engine equipped with an exhaust flow control valve of the present invention FIG. 1 is a fragmentary enlarged view of the imaginary line encircled portion indicated by the arrow 2 in FIG. FIG. Perspective view of exhaust flow control valve Enlarged sectional view taken along line 5-5 in FIG. 2 is an enlarged sectional view taken along line 6-6 in FIG. 2 (front view of the butterfly valve). The figure which shows the flow state of the exhaust gas which flows through a butterfly valve The figure which shows the flow state of the exhaust gas which flows through the conventional butterfly valve

Explanation of symbols

22 ·············· Butterfly valve 26 ······· Elastic member (torsion coil spring)
40 ・ ・ ・ ・ ・ ・ ・ ・ ・ Weight 40
E ... Engine Ex ... Exhaust system

Claims (2)

Provided in the exhaust system (Ex) of the engine (E),
A closed side that reduces the cross-sectional area of the exhaust gas that is swingably supported by the exhaust passage through which the exhaust gas passes and that is formed between the inner peripheral surface of the exhaust passage and an open side that increases the cross-sectional area of the exhaust gas A butterfly valve (22) that switches to
An elastic member (26) for biasing the butterfly valve (22) toward the closing side,
In the exhaust flow control valve for switching the butterfly valve (22) from the closed side to the open side against the biasing force of the elastic member (26) due to an increase in the exhaust gas pressure acting on the butterfly valve (22),
A weight (40) is attached to the butterfly valve (22) so that the outer contour of the weight (40) matches the outer contour of the butterfly valve (22) at least at the swinging tip of the butterfly valve (22). An exhaust flow control valve, characterized in that The exhaust flow control valve according to claim 1, wherein the weight (40) is attached to a back surface of the butterfly valve (22).

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