JPH06281027A - Opening/closing valve for high temperature fluid passage - Google Patents

Abstract

PURPOSE:To enhance heat resistance and corrosion resistance of a pressure operating member by using a metallic diaphragm as the pressure operating member in a high pressure fluid passage opening/closing valve suitable for a secondary air introducing valve for introducing secondary air into an exhaust gas passage for an automobile engine. CONSTITUTION:In a secondary air introducing valve, a diaphragm 10 is deviated upward against a spring 5 and a valve body 7 is deviated upward accordingly so as to release a passage 9 when an intake negative pressure of an engine is introduced into a pressure chamber 15 from a surge tank disposed outside through a negative pressure passage 26 and a pressure port 14. Consequently, an intermediate chamber 24 communicated to an exhaust gas passage 25 is communicated with an intake chamber 13. When a pressure of exhaust gas of the engine becomes negative, air from an air cleaner is supplied to the exhaust gas passage 25 via the secondary air introducing valve 16. The diaphragm 10 is made of metal excellent in heat resistance and corrosion resistance, to be thus protected from deterioration in its performance even in the case of contact with high temperature fluid. As a result, the structure of a valve as a whole is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-off valve for high temperature fluid passages, and is effective as a secondary air introduction valve for introducing secondary air into an exhaust gas passage of an automobile engine, for example.

[0002]

2. Description of the Related Art Conventionally, in this type of high-temperature fluid passage opening / closing valve, a rubber diaphragm is used as a pressure responsive member so that a predetermined displacement amount can be secured according to a pressure change. As an example, in order to re-burn carbon monoxide (CO) and hydrocarbon (HC) contained in the exhaust gas of an automobile engine, in order to introduce secondary air into the exhaust gas passage,
A conventional example of the next air introduction valve is shown in FIG. In the conventional secondary air introduction valve, the rubber diaphragm 54 operates the valve body 55 in the vertical direction via the shaft 52 according to the pressure in the pressure chamber 60 to open and close the passage 61. While the passage 61 is open, the air discharged from the external air cleaner (not shown) is sucked into the main body of the secondary air introducing valve through the introduction port 58, passes through the passage 61, and is sent to the exhaust gas passage (not shown) through the discharge port 62. Be done.

[0003]

However, since the rubber diaphragm 54, which is weak against high temperature, is used as the diaphragm forming the pressure responsive member, the shaft 52, 52 is used for the purpose of protecting the rubber diaphragm 54 from high temperature exhaust gas. An upper plate 53, a lower plate 63, a carbon bushing 59 for positioning, and an oil seal 6 for preventing exhaust gas from entering the pressure chamber 60.
4. A cup 65 made of stainless steel for mounting the oil seal 64, a support 66 slidably supporting the bushing 59 made of carbon, the pressure chamber 60 is insulated from exhaust gas, and leakage of exhaust gas is sealed. Since a large number of components such as the gasket 67 are mounted in combination and the rubber diaphragm 54 is structured so as not to come into contact with the high temperature fluid, the structure is complicated and the cost is high.

In view of the above problems, it is an object of the present invention to provide an on-off valve for a high temperature fluid passage which is inexpensive and can be simply constructed.

[0005]

In order to achieve the above object, the present invention provides a casing forming an outer frame, a suction port provided in the casing for introducing a high temperature fluid from the outside, and a casing inside the casing. A passage through which the high-temperature fluid introduced through the suction port passes, a valve body that opens and closes the passage, and a discharge port through which the high-temperature fluid that passes through the passage is discharged to the outside, A pressure chamber provided in the casing, into which an operating pressure is introduced from the outside, and a metal pressure responsive member capable of displacing the valve body by a predetermined amount according to the pressure of the pressure chamber. Adopt the technical means of being equipped.

[0006]

The on-off valve for the high temperature fluid passage of the present invention uses a metal diaphragm having high heat resistance and corrosion resistance as a pressure responsive member, and the metal diaphragm contacts the high temperature fluid. However, since its performance does not deteriorate, it is not necessary to protect it from a high temperature fluid. Therefore, compared to a conventional high-temperature fluid passage on-off valve that uses a rubber diaphragm, the structure can be simplified and the number of parts can be reduced, resulting in a significant cost reduction and reduction in the number of manufacturing steps. Can be obtained.

[0007]

EXAMPLE An on-off valve for a high temperature fluid passage according to the present invention will be described below.
An example when applied to a secondary air introduction valve to an exhaust gas passage of an automobile engine will be shown.

As shown in FIG. 1, a pressure port 14 is provided in the first casing 1 made of stainless steel, and from this pressure port 14, the negative intake pressure of the automobile engine from a surge tank (not shown) outside is negative. It is introduced into the pressure chamber 15 via the pressure passage 26. The pressure chamber 15 is formed by the first casing 1 and the metal diaphragm 10.

A spring 5 is arranged in the pressure chamber 15, and a plate 6 is attached to the lower end of the spring 5. At the bottom of the plate 6, a disc-shaped valve body 7 is attached across a central flat portion 10a of a metal diaphragm 10 made of SUS304 having high heat resistance and corrosion resistance, and these are riveted. Fixed by 8,
It is urged downward by the spring 5. Also,
The outer peripheral portion of the metal diaphragm is sealed by a ring-shaped metal seal material having a convex shape (not shown), and is fixed so as to be sandwiched between the first casing 1 and the second casing 2. . In the natural state, the metal diaphragm 10 has a flat portion 10a at the center as shown in FIG. 2A, and a portion 10c from the outer periphery of the flat portion 10a to the inner periphery of the outer peripheral portion 10b has
Concave and wavy concavo-convex portions 10d as shown in (c) are formed. This corrugated uneven portion 10d provides flexibility like a conventional rubber diaphragm.
The outer diameter d is about 65 mm, and the pressure chamber 15 has 650 mmHg.
It is possible to have a displacement amount 1 of 4 mm at the maximum according to the pressure change. Here, for example, the state of FIG. 2A is when the displacement amount is 0 mm in the natural state, that is, when the passage 9 is closed. Further, in the state of FIG. 2B, when the pressure chamber 15 has a negative pressure, the displacement amount 1 is 4 mm, that is, when the passage 9 is open. Since the metal diaphragm 10 is made of a metal having a high pressure resistance, the negative pressure of the pressure chamber 15 is maximum.
Even if it becomes 86.7 KPa (gauge), it will not be torn and damaged. The corrugated irregularities are not limited to concentric circles, but may be spirals. A passage 9 which is opened and closed by the valve body 7 is formed by a second casing 2, and the second casing 2 and the first casing 1 are not shown with a peripheral portion 10b of the diaphragm 10 interposed therebetween. It is fixed by screws. In the second casing 2, an intermediate chamber 24 and an exhaust passage 11 for guiding the air passing through the passage 9 to the exhaust port 12 are formed. The outlet 12 is connected to the exhaust gas passage 25.

The suction chamber 13 is formed by the second casing 2 and the diaphragm 10. Further, in the third casing 3, an intake port 17 for introducing air from an air cleaner (not shown) into the intake chamber 13 via the secondary air introduction valve 16 and an intake passage 18 are formed. The casing 3 is fixed to the second casing 2 by screws (not shown). Valve seat 1 of the secondary air introduction valve 16
Above the valve 9, there is a thin metal valve body 20 that opens and closes according to the pressure change in the suction chamber 13, and a stopper 21 that restricts the movement of the valve body 20 toward the suction chamber 13 side.
It is fixed by 3. Also, the valve seat 19 and the second
A rubber seal member 22 is provided between the casing 2 and the casing 2 to keep the suction chamber 13 airtight.

Next, the operation of this embodiment having the above-mentioned structure will be described with reference to FIG. The intake negative pressure of the automobile engine from the external surge tank passes through the negative pressure passage 26,
When introduced into the pressure chamber 15 through the pressure port 14, this intake negative pressure acts on the diaphragm 10 as an operating pressure, and the metal diaphragm 10 is displaced upward as shown in FIG. 2 (a) to FIG. 2 (b). In conjunction with this, the valve body 7 also moves upward and the passage 9 is opened. At this time, the side end portion 6a of the plate 6 hits the portion 1a on the pressure chamber side of the casing 1 to prevent the valve body 7 from moving too much upward, thereby preventing the diaphragm 10 from being reversed.

When the passage 9 is opened and the intermediate chamber 24 and the suction chamber 13 are communicated with each other, the exhaust gas of the engine is exhausted.
It is introduced into the suction chamber 13 via the discharge port 5, the discharge port 12, the discharge passage 11, and the intermediate chamber 24. The exhaust gas of this engine has a pulsating pressure, its frequency is about 200 Hz, and it oscillates between a positive pressure and a negative pressure across an atmospheric pressure (P = 0). The thin stainless valve body 20 of the secondary air introduction valve 16 is responsive to the pulsating frequency of the exhaust gas in the suction chamber 13 and is closed when the exhaust gas has a positive pressure and closed when the exhaust gas has a negative pressure. Then, the air from the air cleaner is taken into the suction chamber 13 through the suction port 17 and the suction passage 18 by opening the stopper 21 to the position.

The air from the air cleaner taken into the suction chamber 13 passes through the passage 9 and is sent out to the exhaust pipe 25 through the intermediate chamber 24, the discharge passage 11 and the discharge port 12 so that the exhaust gas is discharged. Used for reburning.

In the above embodiment, the on-off valve for the high temperature fluid passage of the present invention is applied to the secondary air introduction valve to the exhaust gas passage of the automobile engine. However, the intake valve (EGR) in the exhaust gas recirculation device of the automobile engine is used. It is also possible to apply to (valve). Further, the working pressure introduced into the pressure chamber is not limited to the negative pressure, and the positive pressure may be the working pressure to actuate the diaphragm and open / close the valve element.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an on-off valve for a high temperature fluid passage according to an embodiment of the present invention.

FIG. 2 is a diagram of a metal diaphragm according to an embodiment of the present invention.

FIG. 3 is a diagram showing an outline of a conventional secondary air introduction valve.

[Explanation of symbols]

 1 1st casing 2 2nd casing 3 3rd casing 9 Passage 10 Metal diaphragm 12 Discharge port 14 Pressure port 15 Pressure chamber 17 Suction port

Claims (1)

[Claims] 1. A casing forming an outer frame, a suction port provided in the casing for introducing a high temperature fluid from the outside, and a high temperature fluid provided in the casing for passing the high temperature fluid introduced through the suction port. Passage, a valve body that opens and closes the passage, a discharge port that is provided in the casing to discharge the high-temperature fluid that has passed through the passage to the outside, and a discharge port that is provided in the casing and receives an operating pressure from the outside. And a pressure response member made of metal capable of displacing the valve body by a predetermined amount according to the pressure of the pressure chamber. .