JP4046263B2 - 2 passage exhaust pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust pipe constituting an exhaust system of a vehicle engine, and more specifically, two passages developed so as to be able to both ensure engine output in a high speed rotation region of the engine and reduce exhaust noise in a low speed rotation region. It relates to the exhaust pipe.
[0002]
[Prior art]
In general, in a vehicle, it is required to sufficiently secure an output in a high-speed rotation region of an engine in order to improve performance during acceleration traveling or high-speed traveling. In addition, it is required to reduce exhaust noise in order to ensure quietness during idling or low speed running. That is, it is required to reduce exhaust noise at least in the low-speed rotation region of the engine while ensuring a sufficient output in the high-speed rotation region of the engine.
[0003]
Here, it is known that the engine output and the exhaust noise are greatly influenced by the passage sectional area of the exhaust pipe constituting the exhaust system of the vehicle engine. That is, if the exhaust pipe passage cross-sectional area is increased, the engine output can be sufficiently secured by reducing the exhaust resistance, but the exhaust noise is increased by reducing the exhaust resistance, and conversely the exhaust pipe passage cross-sectional area is increased. It is known that if it decreases, the exhaust noise can be reduced by increasing the exhaust resistance, while the engine output decreases by increasing the exhaust resistance.
[0004]
[Problems to be solved by the invention]
However, conventional exhaust pipes generally do not have a variable passage cross-sectional area, so it is difficult to ensure both output in the high-speed rotation range of the engine and reduction of exhaust noise in the low-speed rotation range of the engine. is there. That is, if the exhaust pipe passage cross-sectional area is set large enough to ensure sufficient output in the high-speed rotation range of the engine, exhaust noise will increase due to a decrease in exhaust resistance, and the vehicle will be quiet when idling or at low speeds. There is a problem that quietness is impaired by exhaust noise when traveling. However, if the passage cross-sectional area of the exhaust pipe is set to be small, the exhaust noise is reduced by increasing the exhaust resistance, so that the quietness of the vehicle can be ensured. Cannot be secured sufficiently, and there is a problem that the performance of the vehicle during acceleration traveling or high-speed traveling deteriorates.
[0005]
Therefore, an object of the present invention is to provide a two-passage exhaust pipe for a vehicle that can sufficiently reduce exhaust noise in a low-speed rotation region of an engine and can sufficiently secure engine output in a high-speed rotation region of the engine.
[0006]
[Means for Solving the Problems]
As a means for solving the above-mentioned problem, a two-passage exhaust pipe according to the present invention is an exhaust pipe constituting an exhaust system of a vehicle engine, and the inside is divided into two paths, In the two-passage exhaust pipe provided with an on-off valve that opens the passage in response to an increase in exhaust pressure, the on-off valve is formed in a plate shape and is inclined in the exhaust passage in the one passage. An installed valve seat, a plate-like valve body attached to the valve seat on the upstream side in the flow direction of the exhaust gas so as to be swingable, and a valve in a state of crossing the valve body And a leaf spring member that biases the tip of the body in the valve closing direction.
[0007]
According to the two-passage exhaust pipe of the present invention configured as described above, in the low-speed rotation region of the engine where the exhaust pressure is low, the on-off valve closes one passage of the exhaust pipe and sets the effective passage cross-sectional area of the exhaust pipe to the other passage. Therefore, exhaust resistance is increased and exhaust noise is reduced. Further, in the high-speed rotation range of the engine where the exhaust pressure is high, the on-off valve opens the one passage and increases the effective passage cross-sectional area of the exhaust pipe, so that the exhaust resistance is reduced and the engine output is sufficiently secured.
Further, when the on-off valve is configured in this way, the valve body can be smoothly opened and closed along the flow direction of the exhaust gas, so that the exhaust resistance when the valve body is opened can be reduced. Further, the leaf spring member can instantaneously open and close the valve body in accordance with the exhaust pressure, and the responsiveness is good. In addition, since the on-off valve having such a configuration has a simple structure that operates autonomously without requiring a control device or the like, it can be installed without difficulty in the exhaust pipe and does not hinder the layout of the exhaust pipe. . Further, since the on-off valve is not exposed to the outside of the exhaust pipe at all, it is not damaged by splashing rainwater or jumping stones.
[0010]
In the two-passage exhaust pipe of the present invention, the on-off valve is preferably made of a material having high resistance to the exhaust pressure and exhaust temperature in the exhaust pipe, such as stainless steel. Further, the valve body constituting the on-off valve can be made of a leaf spring having a habit of self-returning in the valve closing direction and closing the opening of the valve seat. In this case, the leaf spring member that urges the other end of the valve body is not necessary, and the structure of the on-off valve can be further simplified.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a two-passage exhaust pipe according to the present invention will be described with reference to the drawings. In the drawings to be referred to, FIG. 1 is a perspective view of an engine exhaust system to which a two-passage exhaust pipe according to an embodiment is applied, and FIG. 2 is a cross-sectional view showing the internal structure and operation of the two-passage exhaust pipe shown in FIG. is there.
[0012]
The two-passage exhaust pipe according to one embodiment is applied to the engine exhaust system shown in FIG. The engine exhaust system includes a catalytic converter 1, a sub silencer 2, and a main silencer 3. The catalytic converter 1 includes an exhaust pipe 4 connected to an exhaust manifold (not shown) and an exhaust pipe on the downstream side thereof. 5 is interposed. The sub silencer 2 is interposed between an exhaust pipe 6 connected to the exhaust pipe 5 and an exhaust pipe 7 on the downstream side thereof. The main silencer 3 is connected to the exhaust pipe 7 via an inlet pipe 3A. That is, in this engine exhaust system, CO in the exhaust gas discharged to an exhaust manifold of an engine (not shown) flows into the catalytic converter 1 through the exhaust pipe 4, HC, NO _X is processed. Further, the exhaust gas flows into the auxiliary silencer 2 through the exhaust pipe 5 and the exhaust pipe 6, and further flows into the main silencer 3 through the exhaust pipe 7 and the inlet pipe 3A, whereby the exhaust noise is silenced. The Then, the exhaust gas treated with CO, HC, NO _x is discharged from the outlet pipe 3B of the main silencer 3.
[0013]
Here, the two-passage exhaust pipe according to an embodiment is applied as an exhaust pipe 6 connected to the exhaust pipe 5 of the engine exhaust system. As shown in FIG. 2, the exhaust pipe 6 composed of the two-passage exhaust pipe includes a large-diameter outer pipe 6A connected to the rear end portion of the exhaust pipe 5, and a small-diameter arranged in the outer pipe 6A. The inside of the exhaust pipe 6 is divided into two exhaust passages, a main passage 6C inside the inner pipe 6B and a sub-passage 6D outside the inner pipe 6B. An on-off valve 8 that opens the sub-passage 6D in response to an increase in exhaust pressure is provided in the sub-passage 6D between the inner pipe 6B and the outer pipe 6A that is one of the passages.
[0014]
As shown in an enlarged view of FIG. 3, the front end portion of the outer tube 6A has a square cross section having a circular upper cross section with the lower half portion being flat, and an upper wall portion 6A1 and a left and right side wall portions 6A2 being flat only in the upper half portion. It is plastic processed. The front end portion of the outer pipe 6A is fitted inside the rear end portion of the exhaust pipe 5 which has been plastically processed into a cross-sectional shape similar to this, and is airtightly welded (see FIG. 2). Further, the front end portion of the inner tube 6B is plastic processed into a semicircular cross section that is joined to the circular cross section of the lower half of the outer tube 6A. The front end of the inner tube 6B is set at a position retracted by a predetermined dimension from the front end of the outer tube 6A. The inner tube 6B is fixed to the outer tube 6A by laser welding at the portion that is in line contact with the bottom of the outer tube 6A along the axial direction. In this fixed state, the flat upper wall portion 6B1 at the upper front end of the inner tube 6B and the upper wall portion 6A1 of the outer tube 6A are parallel to each other (see FIG. 3).
[0015]
Here, as shown in FIGS. 2 and 4, the on-off valve 8 includes a valve body 8C that opens the opening 8B of the valve seat 8A against a spring biasing force in response to an increase in exhaust pressure. The valve seat 8A is formed in a substantially rectangular plate shape having a rectangular opening 8B, for example, by punching a stainless steel plate. The valve seat 8A has one end in the longitudinal direction welded to the front end inner surface of the upper wall 6A1 of the outer tube 6A, and the other end welded to the front end inner surface of the upper wall 6B1 of the inner tube 6B. Both side edges are in contact with the inner surfaces of the left and right side wall portions 6A2 of the outer tube 6A, so that the one sub-passage 6D is partitioned in an inclined state along the exhaust gas flow direction. The shape of the opening 8B is not limited to a rectangle, and may be a circle or an ellipse.
[0016]
The valve body 8C is made of, for example, a flexible thin stainless steel rod, and is formed in a substantially rectangular shape having a size capable of closing the opening 8B of the valve seat 8A. The valve body 8C is inclined toward the sub-passage 6D side of the valve seat 8A so that the opening 8B can be opened along the flow of exhaust gas flowing out from the left side to the right side in FIG. It is attached to the upper surface side. That is, the valve body 8C is fastened and fixed to one end portion side of the valve seat 8A in a state where the base end portion facing the upstream side in the exhaust gas flow direction is sandwiched between the base end portion and the base end portion of the stopper member 8D. The front end side is configured to be swingable upward along the flow of exhaust gas.
[0017]
The stopper member 8D is a member that restricts the swinging of the valve body 8C, and the distal end portion extends from the intermediate portion excluding the base end portion so that the valve body 8C can swing a predetermined amount to sufficiently open the opening 8B. The valve seat 8A is warped upward away from the valve seat 8A. And the base end part of the leaf | plate spring member 8E is being fixed to the front-end | tip part of this stopper member 8D.
[0018]
The leaf spring member 8E is a member that elastically biases the valve body 8C toward the valve seat 8A against the pressure of the exhaust gas, and is formed in a substantially rectangular shape having substantially the same width as the valve body 8C. . The leaf spring member 8E protrudes from the stopper member 8D toward the valve body 8C in an inclined state opposite to the valve body 8C, and its tip end is in contact with the tip end portion of the valve body 8C obliquely. Yes. The distal end portion of the leaf spring member 8E is bent in an arc shape and slidably contacts the valve body 8C so that the valve body 8C can be smoothly opened and closed. The leaf spring member 8E is configured to be bent upward instantly by being pushed by the valve body 8C when the exhaust pressure exceeds a predetermined pressure corresponding to a high rotation range of the engine (not shown).
[0019]
In the engine exhaust system including the exhaust pipe 6 that is the two-pass exhaust pipe of the embodiment configured as described above, exhaust gas discharged to the exhaust manifold when the engine (not shown) is started includes the exhaust pipe 4, the catalyst It is discharged through the path of the converter 1, the exhaust pipe 5, the exhaust pipe 6, the auxiliary silencer 2, the exhaust pipe 7, the inlet pipe 3A, the main silencer 3, and the outlet pipe 3B. The exhaust gas is treated with CO, HC, and NO _x by the catalytic converter 1 and is silenced by the auxiliary silencer 2 and the main silencer 3.
[0020]
Here, in the low-speed rotation region of the engine where the pressure of the exhaust gas flowing into the exhaust pipe 6 is low, such as when the vehicle is idling or running at a low speed, as shown in FIG. The valve body 8C abuts against the valve seat 8A by the urging force of 8E and closes the opening 8B. That is, the on-off valve 8 closes the sub passage 6 </ b> D that is one passage in the exhaust pipe 6. For this reason, the exhaust gas flows only through the main passage 6 </ b> C which is the other passage in the exhaust pipe 6. Thus, since the passage through which the exhaust gas flows is limited to the main passage 6C and the effective passage sectional area of the exhaust pipe 6 is reduced, the exhaust resistance is increased and the exhaust noise is reduced. As a result, the quietness of the vehicle is sufficiently ensured when the vehicle is idling or traveling at a low speed.
[0021]
On the other hand, in the high-speed rotation range of the engine where the pressure of the exhaust gas flowing into the exhaust pipe 6 exceeds a predetermined pressure, such as when the vehicle is accelerating or traveling at high speed, as shown in FIG. The valve body 8C instantly opens the opening 8B of the valve seat 8A against the urging force of the leaf spring member 8E. That is, the on-off valve 8 opens the sub passage 6D in the exhaust pipe 6. For this reason, the exhaust gas flows through both the main passage 6C and the sub-passage 6D in the exhaust pipe 6. In this way, the passage through which the exhaust gas flows becomes both the main passage 6C and the sub passage 6D, and the effective passage sectional area of the exhaust pipe 6 increases, so that the exhaust resistance is reduced and the engine output is sufficiently secured. . As a result, the performance of the vehicle during acceleration traveling or high speed traveling is improved.
[0022]
In the exhaust pipe 6 to which the two-passage exhaust pipe of one embodiment is applied, the on-off valve 8 is installed in the sub-passage 6D in a state where the valve seat 8A and the valve body 8C are inclined along the flow direction of the exhaust gas. The body 8C can smoothly open the valve along the flow direction of the exhaust gas, and the exhaust resistance when the valve is opened can be reduced. Further, since the leaf spring member 8E is in contact with the tip end portion of the valve body 8C in an oblique state, the valve body 8C can be opened and closed instantaneously, and the responsiveness is good. Since the on-off valve 8 has a simple structure that operates autonomously without requiring a control device or the like, it can be installed in the exhaust pipe 6 without difficulty, and the layout of the exhaust pipe 6 is not hindered. Further, since the on-off valve 8 is not exposed to the outside of the exhaust pipe 6, it is not damaged by rainwater splashes or stone jumps.
[0023]
The valve body 8C constituting the on-off valve 8 can be made of a leaf spring having a habit of self-returning in the valve closing direction and closing the opening 8B of the valve seat 8A. In this case, the leaf spring member 8E that urges the other end of the valve body 8C is not necessary, and the structure of the on-off valve 8 can be further simplified.
[0024]
In the embodiment, the two-passage exhaust pipe of the present invention is applied to the exhaust pipe 6 shown in FIG. 1. However, the two-passage exhaust pipe may be applied to the exhaust pipe 7 and the exhaust pipe 5. 6 and the exhaust pipe 7 may be applied.
[0025]
【The invention's effect】
As described above, according to the two-passage exhaust pipe according to the present invention, in the low-speed rotation region of the engine where the exhaust pressure is low, the on-off valve closes one passage of the exhaust pipe and the effective passage sectional area of the exhaust pipe is the other. Therefore, the exhaust noise can be reduced because the exhaust resistance is increased only by the number of passages. As a result, it is possible to sufficiently ensure the quietness of the vehicle when the vehicle is idling or traveling at a low speed. Also, in the high-speed rotation range of the engine with high exhaust pressure, the open / close valve also opens one passage of the exhaust pipe to increase the effective passage cross-sectional area of the exhaust pipe and reduce the exhaust resistance, thus ensuring sufficient engine output. be able to. As a result, it is possible to improve the performance of the vehicle during acceleration traveling or high-speed traveling.
[Brief description of the drawings]
FIG. 1 is a perspective view of an engine exhaust system to which a two-passage exhaust pipe according to an embodiment of the present invention is applied.
FIG. 2 is a cross-sectional view showing the internal structure and operation of the two-passage exhaust pipe shown in FIG.
3 is an arrow view in the direction indicated by a white arrow III in FIG.
4 is a perspective view showing the structure of the on-off valve shown in FIG. 3. FIG.
[Explanation of symbols]
6: Exhaust pipe (2-passage exhaust pipe)
6A: Outer pipe 6B: Inner pipe 6C: Main passage 6D: Sub passage 8: Open / close valve 8A: Valve seat 8B: Opening 8C: Valve body 8D: Stopper member 8E: Leaf spring member

Claims (1)

An exhaust pipe constituting an exhaust system of a vehicle engine, the inside of which is divided into two passages, and an opening / closing valve that opens the passage in response to an increase in exhaust pressure is provided in one of the passages 2 in the passage the exhaust pipe,
The on-off valve is formed in a plate shape and is installed in an inclined state along the exhaust gas flow direction in the one passage, and an end on the upstream side in the exhaust gas flow direction is fixed to the valve seat. And a plate-like valve body attached so as to be swingable, and a leaf spring member that biases the tip of the valve body in a valve closing direction in a state of being obliquely intersected with the valve body. A two-passage exhaust pipe characterized by

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