JPH0598930A - Valve structure for exhaust system of internal combustion engine - Google Patents

Abstract

PURPOSE:To manufacturing a means, which shows the muffling property priority function by sealing an exhaust pipe at the time of idling condition or low speed and low load condition of an engine and which shows the back pressure reduction priority function by increasing the opening quantity of the exhaust pipe at the time of high speed and high lord condition of the engine, with the simple structure at a low cost, and prevent the generation of noise by eliminating sliding of parts and mutual interference or the like, and improve the reliability of the operation. CONSTITUTION:A switching valve 17 is provided in the end of an exhaust pipe 13 to be opened/closed freely to be oscillated in the core direction of the exhaust pipe 13 around of a part of the switching valve 17 as a support point. This support point part is made of bimetal 19 so that the switching valve 17 is opened/closed by elevation of the temperature. An extension part 13a for covering the periphery of the switching valve 17 over the range from the vertical position of the switching valve 17 against the core of the exhaust pipe 13 to the inclined position inclined outward of the exhaust pipe 13 at a predetermined angle is projected at the end of the exhaust pipe 13.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a valve structure in an exhaust system of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in an exhaust system of an internal combustion engine, as a means for opening and closing one of branch exhaust pipes and for opening and closing a predetermined inner pipe in a muffler, an opening and closing valve is controlled by a bimetal (actual opening 57-53013),
An on-off valve that is opened and closed by transformation of a shape memory alloy (Japanese Utility Model Laid-Open No. 61-62225), and an on-off valve that is controlled by an actuator provided outside the silencer (No. 60-110615). Gazette).

[0003]

By the way, in a silencer for an internal combustion engine, an opening / closing valve is provided in a predetermined exhaust pipe in the silencer, and the opening / closing valve is opened to open the exhaust resistance when the engine is running at high rotation and high load. It has been known that the back pressure reduction priority type is achieved by reducing the above, and the engine is closed and changed to the noise reduction priority type when the engine is idling or at low rotation and low load.

If, for example, the above-mentioned conventional bimetal type is applied as the opening / closing control means of the opening / closing valve in the exhaust pipe in such a silencer, there are the following problems.

That is, as shown in FIG. 9, the exhaust pipe 1
When the opening / closing valve 2 is installed in the vertical terminal opening 1a of the above so as to block the terminal opening 1a at the time of assembling through the bimetal 3, it is shown in FIG. As shown in FIG. 11, although the opening / closing valve 2 is wide open and its purpose is achieved, the end opening 1a should be closed when the engine is in the idle state or the low rotation / low load state. The valve 2 is in a slightly opened state, and the sound deadening priority type is not obtained.

This is because the on-off valve 2 is assembled at room temperature, and the inside of the muffler is not at room temperature when the engine is rotating, but it is always above room temperature. Further, it is conceivable to apply a conventional type in which a shape memory alloy is used instead of the above bimetal, but in the present situation where the transformation temperature of the memory alloy is 100 ° C. or less, 1
In a muffler that must be controlled to open and close within the range of 00 ° C. or higher, it cannot be used in reality.

Further, when the means for opening and closing by the actuator is applied as shown in FIG. 12, in order to operate the opening / closing valve 5 from outside the silencer, a controller for controlling the drive source such as electricity and air pressure and the actuator 4. The operating shaft 6 and means for protecting the operating shaft from high temperatures, and means for protecting external parts such as actuators from flying stones, etc. are required, and their control becomes complicated and expensive.

The present invention solves the above problems,
It is an object of the present invention to propose a silencer that prioritizes silence when the engine is idling or at low rotation and low load, and prioritizes back pressure reduction when the engine is at high rotation and high load.

[0009]

In order to solve the above-mentioned problems, the present invention provides an exhaust pipe (13) with an opening / closing valve (17) at the end of an exhaust pipe (13) to be opened and closed, with a part of the valve as a fulcrum. Of the exhaust pipe (13) so that the opening / closing valve (17) is opened and closed by raising and lowering the temperature. , The opening / closing valve (17) is vertically positioned with respect to the axis of the exhaust pipe (13), and the exhaust pipe (1
It is characterized in that an extension portion (13a) that covers the outer periphery of the on-off valve (17) is formed so as to project over a range inclined by a predetermined angle to the outside of 3).

[0010]

At normal temperature when the engine is stopped, the open / close valve (17) is in the vertical position shown by A in FIG. 2 and closes the exhaust pipe (13).

In the idling state of the engine or the low rotation and low load state at a temperature higher than room temperature and lower than a predetermined temperature, the bimetal (19) is deformed to open and close the open / close valve (1).
7) swings in the extension (13a). Therefore, in this range, the closed state of the end of the exhaust pipe (13) is maintained, and the function of the silencer with priority to silence is exhibited.

When the engine temperature becomes higher than a predetermined temperature due to high rotation and high load, the bimetal (19) is further deformed and the opening / closing valve (17) moves to the outside of the extension portion (13a) and the exhaust pipe (13) moves. A large opening is made at the end to increase the distribution area. Therefore, in this range, the exhaust gas flow amount in the exhaust pipe (13) is increased, and the function as the silencer of the back pressure reduction priority type is exhibited.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention shown in FIGS. 1 to 3 will be described. 10, a silencer body for an internal combustion engine, 11 an inlet pipe, 12 an outlet pipe, 13,
Reference numeral 14 is an exhaust pipe connecting the plurality of chambers 15a, 15b, 15c, and 16a, 16b are partition walls.

An opening / closing valve 17 is attached to the end of a specific exhaust pipe 13 of the exhaust pipes 13 and 14. The end shape, the shape of the opening / closing valve 17 and the assembly structure are shown in FIGS. 2 and 3. Will be described in detail.

The exhaust pipe 13 is formed in a cylindrical shape, and a disc-shaped opening / closing valve 17 is connected to the downstream end of the exhaust pipe 13 and is made of a flexible metal material fixed between the bottom of the exhaust pipe 13 and the bottom of the exhaust pipe 13. It is provided with a plate 18, and the opening / closing valve 17 is tilted up and down with the connecting plate 18 as a fulcrum. Further, a bimetal 19 is formed on the outer surface of the connecting plate 18.
The temperature of the bimetal 19 is set so that the opening / closing valve 17 is perpendicular to the axis of the exhaust pipe 13 when the opening / closing valve 17 is assembled at room temperature.

The outer peripheral shape of the opening / closing valve 17 is such that there is a small gap between the opening / closing valve 17 and the exhaust pipe 13 so that the opening / closing valve 17 can swing back and forth around the bimetal 19 part. Has been formed.

At the end of the exhaust pipe 13, the on-off valve 1
An extension portion 13a having a wall surface along the outer peripheral surface movement locus of the on-off valve 17 in a range in which the bimetal 19 is a fulcrum and is inclined from the vertical state to the outside of the exhaust pipe 13 by a predetermined angle is formed. That is, the extension 1
The end surface 13b of 3a projects forward from the vertical line by a predetermined angle θ with the bimetal 19 part as the center, and extends 13
The upper part of "a" bends slightly downward as it goes forward.

The operation of this embodiment will be described. At room temperature when the engine is stopped, the opening / closing valve 17 is in a vertical form as shown in A of FIG.

When the engine is idling or the engine is running at a low speed and a low load, at a temperature higher than room temperature and lower than a predetermined temperature, the bimetal 19 is deformed by a predetermined amount in proportion to the temperature, and the opening / closing valve 17 is opened by the valve A in FIG. It swings in the range from B to B, that is, in the extension portion 13a. Therefore, the end of the exhaust pipe 13 is kept closed by the opening / closing valve 17. Therefore, the function of the silencer of the priority type of silence, which increases the silencing effect, is exerted.

Next, when the inside of the silencer reaches a temperature higher than a predetermined temperature due to the high rotation and high load condition of the engine, the bimetal 19 is further deformed in proportion to the temperature, and the opening / closing valve 17 is opened as shown in FIG.
In the range of B to C of (3), it swings in proportion to the temperature.
Therefore, in the high rotation and high load state, the exhaust pipe 13
It has a large opening at the end to reduce exhaust resistance and functions as a silencer of the back pressure reduction priority type.

FIG. 4 shows a second embodiment of the present invention.
The outer peripheral shape of the opening / closing valve 17 is made considerably smaller than the inner diameter of the extension portion 13a so that a predetermined amount of exhaust flow area 20 is generated between the opening / closing valve 17 and the extension portion 13a.

In this embodiment, when it is desired to discharge a predetermined amount of exhaust gas through the exhaust pipe 13 even when the engine is idling or at low rotation and low load, and to fully open the open / close valve 17 at high rotation and high load. Applicable to

FIG. 5 shows a third embodiment of the present invention.
In the second embodiment (FIG. 4), the extension 13a
The shape is reduced to a smaller diameter toward the front, and the inner diameter of the end face 13b is set to a diameter close to the outer circumference of the opening / closing valve 15.

According to this embodiment, the exhaust flow area 20 is gradually reduced as the temperature rises in the idling state of the engine or in the low rotation and low load state, and the opening / closing valve 17 is increased in the high rotation and high load state. It can be applied when you want to fully open.

FIG. 6 shows a fourth embodiment of the present invention.
Exhaust pipe 13 and its extension 1 in the first embodiment
3a, the open / close valve 17 is a semi-cylindrical type having a straight line on the side serving as the movement fulcrum of the open / close valve 17.
It should be noted that the shape other than the semi-cylindrical shape may be square or the like.

FIG. 7 shows a fifth embodiment of the present invention.
The extension 13a in the above embodiment is formed as a separate component 13c from the exhaust pipe 13 and is connected and fixed to the end of the exhaust pipe 13.

FIG. 8 shows a sixth embodiment of the present invention, in which the extension 13a is separated from the exhaust pipe 13 by a part 13d.
The extension part 13d is fixed to the partition wall 16a for mounting the exhaust pipe 13. Further, the other end of the connecting plate 18 holding the open / close valve 17 is also fixed to the partition wall 16a.

In each of the above embodiments, the present invention is applied to the exhaust pipe in the muffler, but in addition, the muffler is provided with two main and sub outlet pipes, and the sub outlet pipe of the present invention is provided. You may apply the valve structure of.

[0029]

As described above, according to the present invention, when the engine is in the idling state or in the low rotation and low load state, the end of the exhaust pipe is closed or a certain amount of flow area is surely controlled to give priority to noise reduction. In addition, when the engine is running at high speed and high load, the end of the exhaust pipe can be opened wide to exert the function of prioritizing back pressure reduction.

Since the opening / closing control structure of the opening / closing valve having such a function is a structure in which only a bimetal is connected and an extension is provided at the end of the exhaust pipe, it is different from the conventional control by the actuator. The structure is extremely simple and can be manufactured at low cost, and since no control parts are provided outside the muffler, there is no risk of damage to the control parts of the on-off valve due to the external environment such as stepping stones, and its protective means is unnecessary. It is possible to secure the maximum silencer capacity for the vehicle space.

Further, since the contact interference between the control operating shaft of the on-off valve, the sliding portion, and the parts can be eliminated, the reliability of the on-off valve can be improved and interference noise due to vibration can be prevented.

Further, since the bimetal is used for the opening / closing control, it can be actually used at a high temperature as compared with the conventional shape memory alloy.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a side sectional view showing the end of the exhaust pipe and an opening / closing valve.

FIG. 3 is a perspective view of the same.

FIG. 4 is a side sectional view of an essential part showing a second embodiment of the present invention.

FIG. 5 is a side sectional view of an essential part showing a third embodiment of the present invention.

FIG. 6 is a side sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 7 is a side sectional view of a main part showing a fifth embodiment of the present invention.

FIG. 8 is a side sectional view of a main part showing a sixth embodiment of the present invention.

FIG. 9 is a side sectional view showing a conventional structure at room temperature.

FIG. 10 is a side sectional view at the same high temperature.

FIG. 11 is a side sectional view of the same idling state.

FIG. 12 is a side sectional view showing another conventional structure.

[Explanation of symbols]

 13 Exhaust pipe 13a Extension 17 Open / close valve 19 Bimetal

Claims (1)

[Claims] 1. An opening / closing valve (17) is provided at the end of an exhaust pipe (13) to be opened and closed so as to be swingable in the axial direction of the exhaust pipe (13) with a part of the valve as a fulcrum, and the fulcrum portion is provided. The open / close valve (17) is made of a bimetal (19) so that the open / close valve (17) is opened / closed by increasing / decreasing the temperature, and the open / close valve (17) is provided at the end of the exhaust pipe (13) with respect to the axis of the exhaust pipe (13). Exhaust pipe (1
3) A valve structure in an internal combustion engine, characterized in that an extension (13a) covering the outer periphery of the on-off valve (17) is formed so as to project over a range inclined outward by a predetermined angle.