JPH11336616A - Valve structure for exhaust gas passage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively hinder carbon from entering a hole of a guide member by providing a holder provided on the control valve side of a guide member so as to form specified space of a shaft part, and metallic fiber packing brought into contact with the outer peripheral part of the shaft part arranged in the specified space of the holder. SOLUTION: Metallic fiber packing 30 coming in contact with the outer peripheral surface of a shaft part 17 with adequate resilience is provided in space formed by a holder 19. Since the packing 30 exits in the holder 19, exhaust gas is restrained from passing in the holder 19, and even in the case of pressure in a passage 11 being built up, ventilation resistance is large, and the quantity of exhaust gas leaking into an engine room from an exhaut recirculation control valve 5 is considerably reduced. Since the packing 30 comes in contact with the shaft part 17 with adequate resilience, attachment such as carbon adhering to the shaft part 17 is wiped off, and the shaft part 17 in a cleaned state enters a hole of a guide member 18. The shaft part 17 can therefore move always smoothly in a vertical direction inside the hole of the guide member 18, and a control valve 6 accurately acts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve structure for an exhaust gas passage used in an exhaust gas recirculation system of an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art FIG. 5 shows an example of an exhaust gas recirculation system. In the figure, 1 is an engine, 2 is a combustion chamber, 3 is a combustion chamber 2
A recirculation exhaust gas cooler 5 connected to the exhaust pipe 3 and cooling the exhaust gas from the combustion chamber 2 is connected to the exhaust pipe 3 and an exhaust gas recirculation control valve 5. The valve 5 is connected to the recirculated exhaust gas cooler 4 and introduces the exhaust gas cooled by the recirculated exhaust gas cooler 4 to regulate the amount of exhaust gas recirculated to an intake pipe (not shown) of the engine 1. Reference numeral 6 denotes a control valve provided in the exhaust gas recirculation control valve 5 and responsive to a negative pressure signal from the intake pipe to adjust the opening degree of the exhaust gas passage. Reference numeral 7 denotes a rubber diaphragm which forms a negative pressure chamber 8 at the upper part and operates the control valve 6 by a differential pressure.

In general, the exhaust gas recirculation system is configured as described above. After the exhaust gas from the exhaust pipe 3 is cooled by the recirculation exhaust gas cooler 4, it is guided to the exhaust gas recirculation control valve 5. Then, the recirculation amount is adjusted by the control valve 6. Such exhaust gas is again supplied to the intake pipe. As a result, the exhaust gas is reburned in the engine 1, and harmful nitrogen oxides in the exhaust gas are reduced. Although the exhaust gas led from the exhaust pipe 3 has a high temperature, it is cooled by the recirculating exhaust gas cooler 4 and is led to the exhaust gas recirculation control valve 5 so that the temperature of the exhaust gas is reduced. Deterioration of the diaphragm 7 is reduced. FIG. 4 is a sectional view showing the exhaust gas recirculation control valve 5 in more detail by taking a conventional example described in, for example, Japanese Patent Application Laid-Open No. 52-89721. In the figure, 10
Denotes a housing having an exhaust gas passage 11 therein;
Is a passage inlet through which exhaust gas from the exhaust pipe 3 of the engine 1 is led, and 13 is a passage outlet through which exhaust gas is led to an intake pipe (not shown) of the engine. Reference numeral 14 denotes an annular valve seat formed in the housing 10 in the middle of the exhaust gas passage 11 and in contact with the control valve 6. Reference numeral 17 denotes a shaft portion which is connected to the control valve 6 and slides vertically inside a guide member 18 mounted on the housing 10. Reference numeral 19 denotes a holder laid under the guide member 18 and positioned above the exhaust gas passage 11, and having a U-shaped cross section for preventing intrusion of carbon and the like contained in the exhaust gas. Reference numerals 20 and 21 denote holding plates, which hold the diaphragm 7 therebetween. These holding plates have a disk shape, and the center thereof is mounted on the upper end 22 of the shaft 17 of the control valve 6. 24 is a bolt 23
This is the first case fixed to the housing 10 at three places (not shown). Reference numeral 25 denotes a second case which clamps the periphery of the diaphragm 7 in cooperation with the first case 24.
The negative pressure chamber 8 is formed by the diaphragm 7 and the second case 25. Reference numeral 27 denotes a compression spring that is interposed between the second case 25 and the holding plate 20 and presses the holding plate 20 downward. Reference numeral 28 denotes a negative pressure introducing pipe which is connected to the second case 25 and introduces negative pressure from the intake pipe of the engine 1 into the negative pressure chamber 8. Reference numeral 29 denotes a heat insulating material interposed between the first case 24 and the housing 10 to block heat from the housing 10.

In the conventional exhaust gas recirculation control valve 5 configured as described above, first, the exhaust gas guided from the exhaust pipe 3 of the engine 1 enters the exhaust gas passage 11 from the passage inlet 12. The exhaust gas is guided from the passage outlet 13 to the intake pipe according to the opening of the control valve 6. This exhaust gas is mixed with a mixture of fuel and air in the intake pipe, guided to the combustion chamber 2 and burned. This reduces the amount of nitrogen oxides, which are harmful components, in the exhaust gas. The opening of the control valve 6 is changed according to the magnitude of the negative pressure introduced into the negative pressure chamber 8 through the negative pressure introducing pipe 28. By the way, in order to smoothly open and close the control valve 6, the shaft portion 17 due to variations in component dimensions and variations in assembly of components.
An appropriate gap is provided between the hole of the holder 19 and the shaft 17 and between the hole of the guide member 18 and the shaft 17 in consideration of the eccentricity and the like.

The holder 19 having a U-shaped cross section is attached to the lower portion of the guide member 18 in order to prevent carbon and the like contained in the exhaust gas from entering the holes of the guide member 18. It is impossible to prevent carbon from entering the hole of the guide member 18, and carbon enters the hole of the guide member 18, and the sliding operation of the shaft portion 17 is not smoothly performed due to the carbon or the like, so that the control valve 6 cannot operate. It may not operate correctly depending on the magnitude of the negative pressure in the negative pressure chamber 8. When used in an engine with a supercharger (turbocharger), exhaust gas and the like leaks from the gap in the hole of the guide member 18 to the first case 24 under the influence of the pressure in the passage, and is further discharged to the outside (atmosphere) from the engine room. The inside is polluted by exhaust gas and the like.

Accordingly, as shown in Japanese Utility Model Laid-Open Publication No. 63-174562, a blocking plate 32 (see FIG. 3) fixed to the shaft portion 17,
A labyrinth packing 31 (see FIG. 2) fixed to a holder 19 has been proposed as disclosed in Japanese Utility Model Laid-Open No. 57-38974.

[0007]

However, in the labyrinth packing 31, the sealing performance is greatly affected by the dimensional accuracy of the hole through which the shaft portion 17 passes, and a high assembling accuracy is required, so that the labyrinth packing is expensive. Also, the sealing performance of the blocking plate 32 is greatly affected by the accuracy of the outer diameter and the inner diameter of the holder 19. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has an effective and inexpensive structure for an exhaust gas passage valve for preventing carbon from entering a hole of a guide member. The purpose is to obtain the structure.

[0008]

An exhaust gas passage valve structure according to the present invention comprises a housing having an exhaust gas passage therein, and an amount of exhaust gas provided in the housing and flowing through the exhaust gas passage. Control valve for adjusting the pressure, a shaft portion carrying the control valve, a guide member provided in a housing having a hole through which the shaft portion slidably passes, and a guide member provided on the control valve side of the guide member. A holder for forming a predetermined space of the shaft portion, and a filling of metal fibers arranged in the predetermined space of the holder and in contact with the outer peripheral portion of the shaft portion are provided.

[0009]

The valve structure for an exhaust gas passage according to the present invention comprises a holder provided on the control valve side of the guide member to form a predetermined space for the shaft, and a holder for the shaft disposed in the predetermined space of the holder. A metal fiber filling that contacts the outer peripheral portion, and wipes off carbon and the like adhered by the metal fiber filling that contacts the outer peripheral portion when the shaft slides.

[0010]

[Embodiment 1] Hereinafter, an embodiment of the valve structure for an exhaust gas passage according to the present invention will be described with reference to FIG. The same reference numerals in FIG. 1 denote the same or corresponding members as those in FIG. 5, and a description thereof will not be repeated. Numeral 30 is a filling of metal fibers packed in the space formed by the holder 19, and the filling is in contact with the outer peripheral surface of the shaft portion 17 with an appropriate elasticity. As described above, since the filler 30 is provided in the holder 19, the exhaust gas hardly passes through the holder 19, and even if the pressure in the passage 11 increases, the ventilation resistance is large, and the exhaust gas is exhausted by the exhaust gas recirculation control valve 5. The amount that leaks from the engine into the engine compartment is greatly reduced. Further, since the padding 30 is in contact with the shaft portion 17 with an appropriate elasticity, the deposit such as carbon attached to the shaft portion 17 is wiped off, and the shaft portion 17 enters the hole of the guide member 18 in a cleaned state. The shaft 17 can always move up and down smoothly in the hole of the guide member 18, and the control valve 6 operates accurately according to the magnitude of the negative pressure in the negative pressure chamber 8. Of course, since the filling 30 is made of metal, it does not deteriorate even by a small amount of heat and retains the above function for a long time.

Embodiment 2 FIG. The metal fiber filling 30 may be, for example, a thin metal wire having a wire diameter of 0.15 mm (for example, SUS310).
(S steel) is knitted like a knitted knitted fabric and wound up into a roll to obtain a filling 30 having a bulk density of, for example, about 1 g per 1 cm ³ . The inner diameter of this padding is almost the same as or slightly larger than the diameter of the shaft portion 17, the outer diameter is almost the same as or slightly smaller than the inner diameter of the holder 19, and the height is
Larger than the distance between the guide member 18 and the guide member 18. When the stuffing 30 is assembled in the state shown in FIG.
Is compressed in the axial direction, and as a result, expands uniformly around the shaft 17 and contacts the shaft 17 with an appropriate elasticity. Such a padding 30 is inexpensive and does not require strict assembly precision.

[0012]

As described above, in the exhaust gas passage valve structure according to the present invention, since the holder is provided with the metal fiber filling, the ventilation resistance of the exhaust gas passing through the holder can be greatly reduced with an inexpensive structure. And the amount of exhaust gas leaking into the engine room can be reduced. In addition, since the padding comes into contact with the outer periphery of the shaft and wipes off carbon and the like adhering to the outer periphery of the shaft, the shaft can slide smoothly in the hole of the guide, and the control valve always operates accurately. There is an effect of doing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an exhaust gas passage valve structure of the present invention.

FIG. 2 is a sectional view showing an example of a conventional exhaust gas recirculation control valve.

FIG. 3 is a cross-sectional view showing another example of a conventional exhaust gas recirculation control valve.

FIG. 4 is a sectional view showing still another example of the conventional exhaust gas recirculation control valve.

FIG. 5 is a schematic diagram for explaining a general exhaust gas recirculation control system.

[Explanation of symbols]

5: exhaust gas recirculation control valve, 6: control valve, 7: diaphragm, 8: negative pressure chamber, 12: passage inlet, 13: passage outlet, 17: shaft, 18: guide member, 19: holder, 3
0: Stuffing

Claims (1)

[Claims] 1. A housing having an exhaust gas passage therein, a control valve provided in the housing for adjusting an amount of exhaust gas flowing through the exhaust gas passage, and a shaft carrying the control valve. A guide member provided in the housing having a hole through which the shaft portion slidably penetrates, and a holder formed on the control valve side of the guide member and forming a predetermined space of the shaft portion; A valve structure for an exhaust gas passage, comprising: a metal fiber filling member disposed in the predetermined space of the holder and in contact with an outer peripheral portion of the shaft portion.