JPH06173784A - Exhaust gas recirculation control valve device - Google Patents

Abstract

PURPOSE:To restrain corrosion of a housing caused by acidic substance contained in exhaust gas in an exhaust gas recirculation control valve. CONSTITUTION:In an exhaust gas recirculation gas 5A incorporating a housing made of an iron group material, molten aluminum plating 31 of a composite composed of an allay layer and an aluminum layer is carried out on a mother material base 10a of the iron group material from which the hoising 10A is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation control valve device, and more particularly to an exhaust gas recirculation control valve device used in an exhaust gas recirculation system of an internal combustion engine such as an automobile.

[0002]

2. Description of the Related Art A conventional exhaust gas recirculation control device is constructed as shown in FIG. In FIG. 3, 1 is an engine having a combustion chamber 2, 3 is an exhaust pipe that is connected to the combustion chamber 2 and passes exhaust gas, and 4 is an EGR that is connected to the exhaust pipe 3 and cools the exhaust gas from the combustion chamber 2. Cooler 5 is EGR cooler 4
Is a BGR valve that controls the amount of exhaust gas recirculation to the intake pipe (not shown) of the engine 1 by introducing the exhaust gas cooled by the cooler 4 and the exhaust gas recirculation control valve device. Reference numeral 6 is a control valve provided in the EGR valve 5 for adjusting the opening of the exhaust gas passage in response to a negative pressure signal from the intake pipe, and 7 is a control valve for forming a negative pressure chamber 8 and a differential pressure. 6 is a rubber diaphragm that operates 6.

FIG. 4 is a sectional view of the EGR valve 5 shown in FIG. In FIG. 4, 9 is an exhaust gas, 10 is a housing formed of cast iron and having an exhaust gas passage 11 therein, 11 a is a passage inlet to which the exhaust gas 9 from the exhaust pipe 3 of the engine 1 is guided, and 12 is an engine 1 A passage outlet that guides the exhaust gas 9 to the intake pipe, and 13 is an annular valve seat that is fitted inside the housing 10 in the middle of the exhaust gas passage 11 and contacts the control valve 6.

Further, 14 is a shaft portion which is formed integrally with the control valve 6 and slides vertically inside a sliding member 15 fixed to the housing 10, and 16 is laid under the sliding member 15 and A holder having a U-shaped cross section, which is located above the exhaust gas passage 11 and prevents carbon and the like contained in the exhaust gas 9, holds the diaphragm 7 and has a central portion at a shaft portion 14. The first and second disc-shaped pressers are fixed to the upper end portion 19 of the.

Reference numeral 23 denotes a lower case fixed to the housing 10 with screws 24, and 20 denotes an upper case fixed to the circumference of the case 23 by caulking. The diaphragm 7 and the case 20 form a negative pressure chamber 8 Has been formed. Reference numeral 21 is a compression spring that is interposed between the case 20 and the pressing plate 17 to press the pressing plate 17 downward, and 22 is a penetrating attachment to the case 20 to introduce a negative pressure from the intake pipe of the engine 1. It is a tube.

According to such a conventional exhaust gas recirculation control device, the exhaust gas from the exhaust pipe 3 is guided to the EGR valve 5 after being cooled by the EGR cooler 4. Then, the exhaust gas whose recirculation amount is adjusted by the adjusting valve 6 is supplied to the intake pipe. As a result, the exhaust gas is re-combusted in the engine 1 and harmful nitrogen oxides (NO
x) is reduced. Although the exhaust gas led from the exhaust pipe 3 has a high temperature, it is cooled by the EGR cooler 4 so that E
When guided to the GR valve 5, the temperature of the exhaust gas is reduced, so that the deterioration of the diaphragm 7 due to heat is reduced.

On the other hand, in the conventional EGR valve 5,
Exhaust gas 9 introduced from the exhaust pipe 3 of the engine 1 passes through the passage inlet 1
The exhaust gas passage 11 enters from 1a. The exhaust gas 9 is guided from the passage outlet 12 to the intake pipe in accordance with the opening degree of the control valve 6 that operates according to the magnitude of the negative pressure introduced into the negative pressure chamber 8 through the negative pressure introduction pipe 22, The exhaust gas 9 is mixed with a mixture of air and air, and is introduced into the combustion chamber 2 and burned. As a result, the amount of harmful nitrogen oxides in the exhaust gas is reduced as described above.

[0008]

However, in the conventional exhaust gas recirculation control valve device configured as described above, when the exhaust gas recirculation control valve device is used in a diesel engine, an engine using alcohol-mixed fuel, or the like, it is exhausted by combustion. Since the exhaust gas generated contains an acidic substance, there is a problem that the housing 10 is corroded.

The present invention has been made to solve the above problems, and an object thereof is to obtain an exhaust gas recirculation control valve device which does not corrode the housing even if the exhaust gas contains an acidic substance. To

[0010]

In an exhaust gas recirculation control valve device according to the present invention, a molten aluminum plating composed of a composite metal body of an alloy layer and an aluminum layer is formed on a base metal base material of a ferrous material of a housing. It was done.

[0011]

According to the present invention, even if the acidic substance contained in the exhaust gas flows into the exhaust gas passage portion of the housing,
Corrosion of the housing can be prevented by hot dip aluminum plating.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing an exhaust gas recirculation control valve device, and FIG. 2 is an enlarged view of a portion A of FIG. 1. The same or corresponding parts as those of the conventional device are designated by the same reference numerals and the description thereof will be omitted. . In the figure, reference numeral 10A denotes a housing, which is formed on a base metal base material 10a made of a cast iron-based material, an alloy layer 31a adhered in a tongue-like structure, an aluminum layer 31b formed thereon, and further formed on this surface. The molten aluminum plating 31 is formed of a composite metal body including the aluminum oxide film 31c. The alloy layer 31a is, for example, iron 50% + A
150% of intermetallic compound is used. Further, the aluminum oxide film 31c formed when the hot dip aluminum plating 31 is applied is very thin (the number of film thicknesses), and has little influence on the corrosion resistance.

In the exhaust gas recirculation control valve device 5A constructed as described above, the exhaust gas flows from the exhaust pipe of the engine when the control valve 6 is opened as shown in FIG. When the valve is closed, the exhaust gas is shut off. Condensed water generated by such exhaust gas flow contains an acidic substance, and in the conventional exhaust gas recirculation control valve device 5 used in such a state, the exhaust gas passage portion of the housing 10 is directly acidic substance. Corrosion progresses due to exposure to the housing 1
However, in the exhaust gas recirculation control valve device 5A shown in FIGS.
Since the molten aluminum plating 31 made of the composite metal body of the aluminum oxide film 31c, the aluminum layer 31b, and the alloy layer 31a formed on the base material base material 10a of the cast iron-based material of 0A can suppress the progress of corrosion, respectively. The base material 10a is not corroded.

[0014]

As described above, according to the present invention, by forming the hot-dip aluminum plating consisting of the composite metal body of the alloy layer and the aluminum layer on the base material base material of the iron-based material of the housing, the acidic substance, corrosion The effect of being excellent in corrosion resistance, salt damage resistance, chemical resistance, and heat resistance of the housing without being affected by a corrosive substance, etc., and capable of withstanding long-term use.

[Brief description of drawings]

FIG. 1 is a sectional view of an exhaust gas recirculation control valve device showing an embodiment of the present invention.

FIG. 2 is an enlarged view of part A of FIG.

FIG. 3 is a configuration explanatory view showing an exhaust gas recirculation control device configured using a conventional exhaust gas recirculation control valve device.

FIG. 4 is a sectional view showing a conventional exhaust gas recirculation control valve device.

[Explanation of symbols]

 1 Engine 3 Exhaust Pipe 5A Exhaust Gas Recirculation Control Valve Device 6 Control Valve 7 Diaphragm 8 Negative Pressure Chamber 10A Housing 10a Base Material Base 11 Exhaust Gas Passage 11a Passage Inlet 12 Passage Outlet 31 Molten Aluminum Plating 31a Alloy Layer 31b Aluminum Layer 31c Aluminum oxide film

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[Procedure amendment]

[Submission date] April 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing an exhaust gas recirculation control valve device, and FIG. 2 is an enlarged view of a portion A of FIG. 1. The same or corresponding parts as those of the conventional device are designated by the same reference numerals and the description thereof will be omitted. . In the figure, reference numeral 10A denotes a housing, which is formed on a base metal base material 10a made of a cast iron-based material, an alloy layer 31a adhered in a tongue-like structure, an aluminum layer 31b formed thereon, and further formed on this surface. The molten aluminum plating 31 is formed of a composite metal body including the aluminum oxide film 31c. The alloy layer 31a is, for example, iron 50% + A
150% of intermetallic compound is used. Further, the aluminum oxide film 31c formed when the hot dip aluminum plating 31 is applied is extremely thin (film thickness number Å ) and has little influence on the corrosion resistance.

Claims (1)

[Claims] 1. An exhaust gas recirculation control valve having an inflow side passage communicating with an exhaust passage of an engine and an outflow side passage communicating with an intake passage of the engine and having a housing made of a ferrous material. In the device, an exhaust gas recirculation control valve device, characterized in that a molten aluminum plating made of a composite metal body of an alloy layer and an aluminum layer is formed on a base material base material of the iron-based material of the housing.