JPH08200165A - Exhaust gas mixing valve for engine - Google Patents

Abstract

PURPOSE: To maintain opening closing operation of a valve body in an excellent state through prevention of lodging of soot on the slide surface of a valve stem by providing an air feed means for removing soot having a guard sleeve, formed integrally with a valve body and slidably fitted in the outer periphery of a guide sleeve fronting on a gas passage, and feeding air to a spring chamber. CONSTITUTION: In an exhaust gas passage 8 through which exhaust gas flows, a guard sleeve 13 formed integrally with a valve body 11 is slidably fitted in the outer periphery of a guide sleeve 12 fronting on the interior of an exhaust gas passage 8. Thereby, adhesion of soot to a valve stem 10 is prevented from occurring. Further, air in a spring chamber 6 is pressed, and flows through a gap 15 between the slide surfaces of the guide sleeve 12 and the valve stem 10 and further is discharged in an exhaust gas passage 8 after the flow of it through a gap 16 between the slide surfaces of the guide sleeve 12 and the guard sleeve 13. This way removes soot and prevents lodging of soot in the gap 16 between the slide surfaces of the guide sleeve 12 and the guard sleeve 13 and the gap 15 between the slide surfaces of the guide sleeve 12 and the valve stem 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas mixing valve used in an exhaust gas recirculation system for an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine of an automobile, a part of the exhaust gas discharged from the exhaust passage is returned to the intake passage and NO
Exhaust gas recirculation (EGR) is being performed to reduce x. An exhaust gas mixing valve for controlling the mixing of the exhaust gas with the intake air in the intake passage is arranged in the exhaust gas mixing line of the exhaust gas recirculation device as needed.

As shown in FIG. 7, the exhaust gas mixing valve has a structure in which a valve body 11 seated on a valve seat 9 of an exhaust gas passage 8 is opened and closed via a valve shaft 10 by an air cylinder. Has been.

[0004]

In the exhaust gas mixing valve, when the soot contained in the exhaust gas adheres to the valve shaft 10 and the valve shaft 10 moves back and forth in the axial direction, the valve shaft 10
Soot is caught in the sliding surface between the guide sleeve 12 and the valve shaft 10 that guides the valve shaft 10, which impedes the smooth forward and backward movement of the valve shaft 10 and causes the valve element 11 to malfunction. In order to prevent this inconvenience, as shown in FIG. 7, a guard sleeve 20 is provided on the valve body 11 by caulking, and the guide sleeve 1
2 surrounds the valve shaft 10 in the exhaust gas passage 8,
The tubular member 1 so as to wrap with the guide sleeve 12.
9 is fixed, and the guide sleeve 12 and the tubular member 19 prevent soot from adhering to the valve shaft 10.

However, the guard sleeve 20 that is caulked to the valve body 11 may be damaged from the caulked portion due to vibration stress, and soot cannot be completely prevented from adhering.

An object of the present invention is to provide an exhaust gas mixing valve which reliably prevents soot from being caught in the sliding surface of the valve shaft and is resistant to vibration stress.

[0007]

SUMMARY OF THE INVENTION An object of the present invention to achieve the above object is to provide an exhaust gas having a cylinder at one end and a spring chamber communicating with the cylinder and a valve seat at the other end. A valve housing having a gas passage, which is provided so as to penetrate between the spring chamber and the exhaust gas passage and has one end facing the exhaust gas passage, and an air pressure in the cylinder. A valve shaft having one end coupled to a piston that is moved forward and backward by a spring installed in the spring chamber, and the other end having a valve body seated on the valve seat, and being slidably guided by the guide sleeve, A guard sleeve which is formed integrally with the valve body and is slidably fitted to the outer periphery of a guide sleeve facing the exhaust gas passage; and a soot-eliminating air supply means for supplying air to the spring chamber. Those were example.

Further, a guard sleeve is integrally provided on the valve body which opens and closes the exhaust gas passage by an air cylinder, and surrounds the valve shaft of the valve body in the exhaust gas passage, and the guard sleeve is opened when the valve body is opened. Is a fixed cylindrical member.

[0009]

According to the present invention, a soot-proofing strong soot-preventing action is obtained by the structure in which the guard sleeve is formed integrally with the valve body, and the soot-eliminating air supply means is provided, so that the soot is constantly supplied to the valve shaft. Adhesion is eliminated to reliably prevent soot from being caught and to maintain a good valve opening / closing operation.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention, and 1 is an exhaust gas mixing valve. Reference numeral 2 denotes a valve housing constituting the exhaust gas mixing valve 1, which has a cylinder 3 at one end and a spring chamber 6 communicating with the cylinder 3 and an exhaust gas passage 8 having a valve seat 9 formed at the other end. A guide sleeve 12 whose one end faces the inside of the exhaust gas passage 8 is provided so as to penetrate between the spring chamber 6 and the exhaust gas passage 8.

A piston 4 is moved forward in the cylinder 3 by an air pressure introduced from an air supply / discharge port 5, and is moved backward by a spring 7 installed in the spring chamber 6.
Is provided, and the cylinder 3 is provided by this piston 4.
Is partitioned into a front chamber 3a on the side of the spring chamber 6 and a rear chamber 3b on the side of the air supply / discharge port 5. A two-stroke cylinder having a two-stage piston in the cylinder 3 and two air supply / discharge ports for operating the two pistons may be used.

A valve shaft 10 is slidably guided by the guide sleeve 12, and one end thereof is connected to the piston 4. Further, the other end of the valve shaft 10 has a valve body 11 which is seated on the valve seat 9. The valve body 11 is integrally formed with a guard sleeve 13 slidably fitted to the outer periphery of a guide sleeve 12 facing the exhaust gas passage 8.

Further, the spring chamber 6 is provided with soot-eliminating air supply means for supplying air into the spring chamber 6.

The soot-eliminating air supply means is a one-way valve 14 which sucks atmospheric air into the spring chamber 6 only when the piston 4 is retracted. Although not shown, the one-way valve 14 may be replaced by an electromagnetic valve that is connected to an air source and opens / closes according to a control signal.

In the first practical example of the above construction, when the air pressure is not introduced from the air supply / discharge port 5 to the rear chamber 3b of the cylinder 3, the piston 4 is retracted by the spring 7 as shown in FIG. Pushed to the end, the valve element 11 is seated on the valve seat 9 to block the exhaust gas passage 8.

When the piston 4 is pushed to the backward end by the spring 7, in the case of the one-way valve 14 as shown in the drawing, the backward end of the piston 4 causes the spring chamber 6 to move.
Becomes a negative pressure, and the negative pressure in the spring chamber 6 sucks the atmosphere into the spring chamber 6 from the one-way valve 14. Therefore, at the retracted end of the piston 4 shown in FIG.
Air is enclosed inside.

Part of the exhaust gas is returned to the intake passage, and NOx
When exhaust gas recirculation (EGR) for reducing the exhaust gas is performed, air pressure is introduced from the air supply / exhaust port 5 to the rear chamber 3b of the cylinder 3, the piston 4 is moved forward, and the valve element 11 is separated from the valve seat 9. The exhaust gas passage 8 is opened as shown in FIG.

When the piston 4 moves forward, the air enclosed in the spring chamber 6 is pressed. Since the air in the spring chamber 6 that is pressed is not discharged to the atmosphere from the one-way valve 14, it passes through the gap 15 on the sliding surface between the guide sleeve 12 and the valve shaft 10, and further, the guide sleeve 12 and the guard. It is discharged into the exhaust gas passage 8 through the gap 16 on the sliding surface of the sleeve 13. When the one-way valve 14 is replaced with a solenoid valve, the solenoid valve is opened at the retracted end of the piston 4, and air is enclosed in the spring chamber 6 from an air source.

Therefore, in the exhaust gas passage 8 through which the exhaust gas flows, the guard sleeve 13 formed integrally with the valve body 11 is slidable on the outer periphery of the guide sleeve 12 facing the exhaust gas passage 8. Since they are fitted together, soot is prevented from adhering to the valve shaft 10. However, the gap 1 between the sliding surfaces of the guide sleeve 12 and the guard sleeve 13
Although some soot cannot be prevented from entering the gap 15 of the sliding surface between the guide sleeve 12, the guide sleeve 12 and the valve shaft 10, the air in the spring chamber 6 is pressed, and the guide sleeve 12 and the valve shaft 10 are pressed. 10 through the gap 15 on the sliding surface with the guide sleeve 12 and the guard sleeve 13
The soot is removed by being discharged into the exhaust gas passage 8 through the gap 16 on the sliding surface of the guide sleeve 12 and the guard sleeve 13 and the sliding between the guide sleeve 12 and the valve shaft 10. The soot is prevented from being caught in the gap 15 of the moving surface.

3 to 6 show a second embodiment of the present invention. The second embodiment is the same as the first embodiment in that the guard sleeve 13 is integrally provided on the valve body 11 that opens and closes the exhaust gas passage 8, and the valve body 11 is provided inside the exhaust gas passage 8. The valve body 11 is surrounded by the valve shaft 10.
The tubular member 17 into which the guard sleeve 13 is fitted at the time of opening is fixedly provided. The tubular member 17 may be a tubular member 18 such as a bellows that can expand and contract in the axial direction as shown in FIG.

In the second practical example having the above structure, the valve body 1
As shown in FIG. 3, the guard sleeve 13 is separated from the tubular member 17 in the state where 1 is closed, but when the valve body 11 is opened, as shown in FIG.
Fits into the tubular member 17, prevents soot from entering the sliding surface of the valve shaft 10, and prevents soot from being caught.

The expandable and contractible tubular member 18 such as the bellows shown in FIGS. 5 and 6 is suitable for opening and closing the valve body by a two-stroke piston two-stroke cylinder. That is, when the valve body 11 is closed, the guard sleeve 13 is separated from the tubular member 18 as shown in FIG. 5, but FIG.
In the first stroke shown by, the tubular member 18 in the expanded state is
Then, the guard sleeve 13 is fitted to the first sleeve, and in the second stroke, the tubular member 18 is compressed as shown in FIG.
The fitting state with the guard sleeve 13 in the second stroke larger than the stroke is maintained. In this case as well, the soot is prevented from entering the sliding surface of the valve shaft 10 and the soot is prevented from being caught as in the above case.

In both the first embodiment and the second embodiment, the guard sleeve 13 is formed integrally with the valve body 11, so that it provides a soot-proof action that is strong against vibration stress.

[0024]

As described above, according to the present invention, since the guard sleeve is formed integrally with the valve body, the guard sleeve is resistant to vibration stress, and the soot-preventing action can be obtained for a long period without damage. The soot-removing air supply means removes soot from adhering to the sliding surface of the valve shaft and reliably prevents soot from getting caught, so that it has the effect of maintaining good opening / closing operation of the valve body. .

[Brief description of drawings]

FIG. 1 is a sectional view of a valve body closed state according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the valve body according to the first embodiment of the present invention in an open state.

FIG. 3 is a sectional view of a valve body closed state according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a valve body opening state according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a valve body closed state in a design modification example of the second embodiment of the present invention.

FIG. 6 is a sectional view of a two-stroke valve body opening state in a design modification example of the second embodiment of the present invention.

FIG. 7 is a sectional view of a conventional structure.

[Explanation of symbols]

 1 Exhaust Gas Mixing Valve 2 Valve Housing 3 Cylinder 4 Piston 5 Air Supply / Exhaust Port 6 Spring Chamber 7 Spring 8 Exhaust Gas Passage 9 Valve Seat 10 Valve Shaft 11 Valve Body 12 Guide Sleeve 13 Guard Sleeve 14 One-way Valve 15 Gap 16 Gap 17 Cylindrical member 18 Stretchable tubular member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Honda 3-1-1 Hinodai, Hino-shi, Tokyo Hino Motors Ltd.

Claims (4)

[Claims] 1. An exhaust gas passage having a cylinder at one end and a spring chamber communicating with the cylinder and a valve seat formed at the other end, and penetrating between the spring chamber and the exhaust gas passage. A valve housing provided with a guide sleeve having one end facing the exhaust gas passage, and one end coupled to a piston that moves forward and backward by air pressure in the cylinder and a spring installed in the spring chamber, The other end has a valve body seated on the valve seat, a valve shaft slidably guided by the guide sleeve, and a guide formed integrally with the valve body and facing the exhaust gas passage. An exhaust gas mixing valve for an engine, comprising: a guard sleeve slidably fitted to the outer circumference of the sleeve; and a soot-eliminating air supply means for supplying air to the spring chamber. 2. The exhaust gas mixing valve for an engine according to claim 1, wherein the soot-eliminating air supply means for supplying air to the spring chamber is a one-way valve that sucks the atmosphere into the spring chamber only when the piston is retracted. 3. The exhaust gas mixing valve for an engine according to claim 1, wherein the soot-eliminating air supply means for supplying air to the spring chamber is an electromagnetic valve connected to an air source and opened / closed by a control signal. 4. A guard sleeve is integrally provided on a valve body that opens and closes an exhaust gas passage by an air cylinder, and surrounds the valve shaft of the valve body in the exhaust gas passage, and the guard sleeve is opened when the valve body is opened. An exhaust gas mixing valve for an engine, characterized in that a tubular member into which is fitted is fixedly provided.