JPH06280686A - Exhaust gas recirculation control valve - Google Patents

Abstract

(57) [Abstract] [Purpose] In the exhaust gas recirculation control valve 5, the shaft portion 17 supporting the adjusting valve 6 always slides smoothly in the hole of the guide member 18. [Structure] To prevent carbon contained in exhaust gas flowing into the passage inlet 12 from entering the hole of the guide member 18, a metal fiber filler 30 is provided in the holder 19.
Was placed. [Effect] The metal fiber filler 30 is inexpensive, and the filler 30 prevents the exhaust gas from entering the holder 19 and wipes off the carbon adhering to the shaft portion 17, so that the control valve 6 always slides smoothly. .

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 used in an exhaust gas recirculation system for internal combustion engines such as automobiles.

[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
Is a recirculation exhaust gas cooler which is connected to the exhaust gas and through which the exhaust gas passes and which is connected to the exhaust pipe 3 and cools the exhaust gas from the combustion chamber 2. Reference numeral 5 is an exhaust gas recirculation control valve. The valve 5 is connected to the recirculation exhaust gas cooler 4 to introduce the exhaust gas cooled by the recirculation exhaust gas cooler 4 and adjust the recirculation amount of the exhaust gas to the intake pipe (not shown) of the engine 1. Reference numeral 6 denotes a control valve which is provided in the exhaust gas recirculation control valve 5 and which responds to a negative pressure signal from the intake pipe to adjust the opening degree of the exhaust gas passage. Reference numeral 7 is a rubber diaphragm which forms a negative pressure chamber 8 in the upper portion and operates the control valve 6 by a differential pressure.

Generally, the exhaust gas recirculation system is constructed as described above, and the exhaust gas from the exhaust pipe 3 is cooled by the recirculation exhaust gas cooler 4 and then 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 re-combusted in the engine 1 and harmful nitrogen oxides in the exhaust gas are reduced. Although the exhaust gas introduced from the exhaust pipe 3 has a high temperature, when it is introduced into the exhaust gas recirculation control valve 5 by being cooled by the recirculation exhaust gas cooler 4, the temperature of the exhaust gas is reduced, so that it is generated by heat. The deterioration of the diaphragm 7 is reduced. The exhaust gas recirculation control valve 5 is shown in more detail in a sectional view in FIG. 4, showing a conventional example disclosed in Japanese Patent Laid-Open No. 52-89721. 10 in the figure
Is a housing having an exhaust gas passage 11 therein, 12
Is a passage inlet for introducing exhaust gas from the exhaust pipe 3 of the engine 1, and 13 is a passage outlet for introducing exhaust gas to an intake pipe (not shown) of the engine. Reference numeral 14 is an annular valve seat formed inside the housing 10 in the middle of the exhaust gas passage 11 and against which the control valve 6 abuts. Reference numeral 17 is a shaft portion that is connected to the control valve 6 and slides vertically inside a guide member 18 mounted on the housing 10. Reference numeral 19 is a holder which is laid under the guide member 18 and is located above the exhaust gas passage 11, and which has a U-shaped cross section for preventing carbon and the like contained in the exhaust gas from entering. Reference numerals 20 and 21 are holding plates, and the diaphragm 7 is held between them. These pressing plates are disc-shaped, and the central portion thereof is attached to the upper end portion 22 of the shaft portion 17 of the control valve 6. 24 is a bolt 23
Is a first case fixed to the housing 10 at three locations (not shown). Reference numeral 25 is a second case that holds the peripheral edge of the diaphragm 7 in cooperation with the first case 24.
A 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 pressing plate 20 and presses the pressing plate 20 downward. Reference numeral 28 is a negative pressure introducing pipe that is connected to the second case 25 and introduces a negative pressure from the intake pipe of the engine 1 into the negative pressure chamber 8. Reference numeral 29 is a heat insulating material that is 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, the exhaust gas introduced from the exhaust pipe 3 of the engine 1 first enters the exhaust gas passage 11 from the passage inlet 12. The exhaust gas is guided to the intake pipe from the passage outlet 13 according to the opening degree of the control valve 6. The exhaust gas is mixed with a mixture of fuel and air in the intake pipe, is introduced into the combustion chamber 2, and is burned. This reduces the amount of harmful nitrogen oxides in the exhaust gas. The control valve 6 changes the opening of the valve 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 as described above, the shaft portion 17 is caused by variations in component dimensions and component assembly variations.
Considering the eccentricity and the like, an appropriate gap is provided between the hole of the holder 19 and the shaft portion 17 and between the hole of the guide member 18 and the shaft portion 17.

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 or the like contained in the exhaust gas from entering the hole of the guide member 18. It is not possible to prevent the carbon from entering the hole of the guide member 18, the carbon enters the hole of the guide member 18, and the sliding operation of the shaft portion 17 is not smoothly performed by the carbon or the like, so that the control valve 6 is It may not operate accurately 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 leak to the first case 24 through a gap in the hole of the guide member 18 due to the influence of the pressure in the passage, and are further discharged to the outside (atmosphere) from there. The inside is polluted with exhaust gas and the like.

Therefore, as in Japanese Utility Model Laid-Open No. 63-174562, a blocking plate 32 fixed to the shaft portion 17 (see FIG. 3),
A labyrinth packing 31 (see FIG. 2) fixed to the 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 is inserted, and the assembly accuracy is required to be high, which is expensive. In addition, the sealing performance of the blocking plate 32 also largely depends on the accuracy of its outer diameter and the inner diameter of the holder 19. The present invention has been made to solve the above problems, and is an exhaust gas recirculation control valve having a structure that is effective and inexpensive to prevent carbon from entering the holes of the guide member. Aim to get.

[0008]

An exhaust gas recirculation control valve according to the present invention is a housing having an exhaust gas passage therein, and the amount of exhaust gas flowing in the exhaust gas passage provided in the housing. Adjusting valve, a shaft portion carrying the adjusting valve at one end, a guide member fixed to the housing with a hole through which the shaft portion slidably passes, and the other end of the shaft portion. An exhaust gas recirculation control valve having a diaphragm attached to the control valve for adjusting the opening of the control valve in response to a negative pressure in the intake pipe, the shaft being provided on a surface of the guide member on the control valve side. A holder having a hole through which a portion is slidably formed and forming a predetermined space with the surface of the guide member, and a resilience provided in the space of the holder so as not to hinder the movement of the shaft portion. Contact with the shaft Characterized by comprising a pad of that metal fibers.

[0009]

According to the present invention, carbon or the like in the exhaust gas passing through the exhaust gas passage enters into the hole of the guide member, while the holder and the metal fiber filling block the carbon and adhere to the shaft. After it has been wiped with a pad of metal fiber, the shank enters the hole in the guide member so that it operates smoothly.

[0010]

【Example】

Example 1. An embodiment of the exhaust gas recirculation control valve according to the present invention will be described below with reference to FIG. The reference numerals in FIG. 1 are the same as or equivalent to those of the members shown in FIG. Reference numeral 30 denotes a metal fiber filling filled in the space formed by the holder 19. The filling is in contact with the outer peripheral surface of the shaft portion 17 with appropriate elasticity. The exhaust gas recirculation control valve of the present invention uses the padding 30 in the holder 19
The exhaust gas recirculation control valve is different from the conventional exhaust gas recirculation control valve in that it is provided inside, and other configurations are the same as the conventional example. Therefore, the operation of the exhaust gas recirculation control valve of the present invention is the same as that of the conventional one, so that the description thereof will be omitted and only the operation and effect of the padding 30 which is the feature of the present invention will be described. Since the padding 30 is in the holder 19, the exhaust gas is
Even when it is difficult to pass through the inside 9 and the pressure in the passage 11 rises, the ventilation resistance is large, and the amount of exhaust gas leaking from the exhaust gas recirculation control valve 5 into the engine room is greatly reduced. Further, since the padding 30 is in contact with the shaft portion 17 with an appropriate elasticity, the carbon particles and the like attached to the shaft portion 17 are wiped off, and the shaft portion 17 is cleaned and the guide member 1 is removed.
Since it enters the hole of No. 8, the shaft portion 17 can always move smoothly up and down 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 stuffing 30 is made of metal, it is not deteriorated by a little heat and retains the above function for a long time.

Embodiment 2. The metal fiber filling 30 is, for example, a fine metal wire having a wire diameter of 0.15 mm (for example, SUS310).
(Steel S) is knitted like a knitting and wound into a roll to obtain a filling 30 having a bulk density of about 1 g per cm ³ . The inner diameter of the padding is substantially the same as or slightly larger than the diameter of the shaft portion 17, the outer diameter is substantially the same as or slightly smaller than the inner diameter of the holder 19, and the height is equal to or smaller than that of the holder 19.
It is set larger than the distance between the guide member 18 and the guide member 18. When the padding 30 is assembled in the state shown in FIG.
As a result of being compressed in the axial direction, the swells uniformly around the shaft portion 17 and comes into contact with the shaft portion 17 with an appropriate elastic force. Such a pad 30 is inexpensive and does not require strict assembly accuracy.

[0012]

As described above, since the exhaust gas recirculation control valve of the present invention is provided with the metal fiber filling 30 in the holder 19, the ventilation resistance of the exhaust gas passing through the holder 19 is greatly reduced by the inexpensive structure. The amount of exhaust gas that leaks into the engine room can be reduced by increasing the amount. Also, the stuffing 30
Is in contact with the shaft portion 17 with an elastic force that does not hinder the movement of the shaft portion 17, so that carbon or the like adhering to the shaft portion 17 can be wiped off, and the control valve 6 can always operate accurately.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an exhaust gas recirculation control valve 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 sectional view showing another example of a conventional exhaust gas recirculation control valve.

FIG. 4 is a sectional view showing still another example of a 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 30 Packing

Claims (2)

[Claims] 1. A housing having an exhaust gas passage therein, a control valve provided in the housing for adjusting the amount of exhaust gas flowing through the exhaust gas passage, and a shaft carrying the control valve at one end thereof. And a guide member fixed to the housing with a hole through which the shaft slidably passes,
An exhaust gas recirculation control valve having a diaphragm attached to the other end of the shaft portion for adjusting the opening of the control valve in response to a negative pressure in an intake pipe, wherein a surface of the guide member on the control valve side. A holder having a hole for slidably passing through the shaft portion and forming a predetermined space with the surface of the guide member, and a movement of the shaft portion arranged in the space of the holder. An exhaust gas recirculation control valve, which is provided with a metal fiber filling material that contacts with a slight elastic force that does not hinder it. 2. The exhaust gas recirculation control valve according to claim 1, wherein the metal fiber filler is a filler having a structure in which a metal wire is reticulated and wound around the shaft portion.