JPH04143450A - Exhaust gas recirculation system - Google Patents

Abstract

PURPOSE:To make a shaft element possible for smooth operation by supporting this shaft element, equipped with a control valve, through a bearing part and a guide member of a holder, setting up two shielding plates in a closed space partitioned off by the bearing part and the holder in the axial direction, and forming them into a labyrinth structure. CONSTITUTION:A control valve 12 opens or closes a valve seat 11 by means of vertical motion of a shaft element 13, but this shaft element 13 is supported by two spots of a bearing part 21 and a guide member 23 attached tight to the inner circumferential part of a shaft inserting hole of a holder 22, and thereby its inclination comes to minuteness and smooth motion is imparted. In this connection, from requisite to reduce sliding resistance as the support of the shaft 13 comes to two spots, a shaft sliding hole 21 of the bearing part 21 is made smaller than ever before. On the other hand, carbon or the like of exhaust gas is penetrated into a space 24 from a clearance between an inner circumferential part of the guide member 23 and the shaft 13, but any possible penetration into the shaft sliding hole 21a of the bearing part 21 is almost completely preventable owing to a zigzag form, namely, a labyrinth structure formed by shielding plates 25, 26 in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust gas recirculation control device, and more particularly to a shaft support structure for a control device in an exhaust gas recirculation system of an internal combustion engine of an automobile, vehicle, etc. Regarding.

(Prior Art) Conventionally, this type of exhaust gas recirculation control device has been configured as disclosed in, for example, Japanese Utility Model Application Laid-Open No. 63-162964. This conventional exhaust gas recirculation control device is shown in FIGS. 5 and 6, and its configuration will be briefly described with reference to these figures.

In Fig. 5, 1 is an engine having a combustion chamber 2, 3 is an exhaust pipe connected to the combustion chamber 2 for passing through an exhaust guide, and 4 is connected to the exhaust pipe 3 to cool the exhaust gas from the combustion chamber 2. A cooler device 5 is connected to the cooler device 4, and is an exhaust gas recirculation control device that introduces the cooled exhaust gas here to adjust the amount of exhaust gas recirculation to the intake pipe (not shown) of the engine 1. , 6 is a control valve that is provided in the exhaust gas recirculation control device 5 and adjusts the opening degree of the exhaust gas passage in response to a negative pressure signal from the intake pipe; 7 forms a negative pressure chamber 8; A rubber diaphragm for actuating the control valve 6 is shown in each case.

The exhaust gas recirculation system is constituted by each device schematically shown in FIG. will be introduced in This exhaust gas recirculation control device 5 was constructed as shown in FIG. In FIG. 6, reference numeral 9 denotes a housing 10 formed by aluminum die-casting and having an exhaust gas passage 10 inside.
a is a passage inlet into which exhaust gas is introduced from the exhaust pipe 3 of the engine 1; 10b is a passage outlet through which the exhaust gas is led to the intake pipe of the engine I; and 11 is a passage which divides the exhaust gas passage 10 into an inlet side passage and an outlet side passage. An annular valve seat 12 installed using the inner wall of the housing 9 so as to divide the valve seat 12 is integrally formed at the lower end of the axially movable shaft part 13, and opens and closes the opening of the valve seat 11 to open and close the opening. A control valve 14 is a bearing member fixed to the housing 9 and slidably supports the shaft portion 13. A control valve 15 is provided at the lower part of the bearing member 14 to adjust the amount of exhaust gas flowing through the exhaust gas passage IO. The holder 16, which has a zero-shaped cross section to prevent carbon, etc. in the gas from entering the shaft sliding hole of the bearing member 14, has two discs 16a and 16b fixed to each other so as to sandwich the diaphragm 7. A case 17 is fixed to the upper part of the housing 10 by crimping to surround the diaphragm 7 to form a negative pressure chamber 8 therein; A compression spring 18 is arranged between the case 17 and the holding plate 16 and presses the holding plate 16 downward.
Reference numeral 9 indicates a negative pressure introduction pipe that is attached to the case 17 and introduces negative pressure from the intake pipe of the engine 1 into the negative pressure chamber 8.

Conventional exhaust gas recirculation control device 5 configured as described above
In this case, exhaust gas led from the exhaust pipe 3 of the engine 1 enters the introduction side passage of the exhaust gas passage from the passage passage 10a. On the other hand, the control valve 12 operates according to the thickness of the negative pressure introduced into the negative pressure chamber 8 through the negative pressure introduction pipe 19.
The flow rate of exhaust gas to the outlet side passage is controlled by the opening degree of the valve seat 11, and the exhaust gas is led out from the passage outlet 10b to the intake pipe. A portion of the exhaust gas thus recirculated is supplied to the air-fuel mixture, introduced into the second combustion chamber, and combusted. This eliminates nitrogen oxides (N), a harmful component in exhaust gas.
0x) is reduced.

(Problem to be Solved by the Invention) However, in the conventional exhaust gas recirculation control device described above, the shaft portion 13 may tilt due to insufficient support for the shaft portion 13, and as a result, the tan valve 12 and the valve seat 1
The contact with engine 1 became unstable, causing exhaust gas to leak and causing engine 1 to malfunction. Further, although the holder 15 prevents carbon, etc. from entering the shaft sliding hole of the bearing member 14, it cannot completely prevent the intrusion, and as a result, the shaft 13 does not slide smoothly. There was a problem that it could not be done.

The purpose of the present invention was to solve such conventional problems, and it is possible to prevent the shaft from tilting, prevent carbon, etc. from entering the shaft sliding hole of the bearing, and ensure smooth sliding of the shaft. An object of the present invention is to provide an exhaust gas recirculation control device that achieves the following.

Means for Solving Problem 1) The exhaust gas recirculation control device of the present invention provides a guide member for supporting the shaft on the inner circumferential surface of the shaft insertion hole of the holder, and also provides a closure partitioned by the bearing and the holder. The space is characterized in that at least two shielding plates are provided at a slight distance from each other on the circumferential surface of the shaft portion and on the inner circumferential surface of the closed space.

(Function) According to the exhaust gas recirculation control device of the present invention, the shaft portion is supported at two points by the bearing portion and the guide member of the holder, thereby eliminating the occurrence of wobbling or tilting of the shaft portion. Since a plurality of shielding plates are arranged along the axial direction in the closed space defined by the bearing and the holder, the path to reach the shaft sliding hole of the bearing has a zigzag shape, or in other words, a labyrinth structure, and the carbon etc. will be prevented from flowing in.

(Embodiments) Hereinafter, the exhaust gas recirculation control device of the present invention will be described in more detail with reference to embodiments shown in the accompanying drawings.

FIG. 1 shows an exhaust gas recirculation control system 20 according to one embodiment of the present invention. In FIG. 1 showing the control device 20, the same or corresponding portions as those constituting the conventional control device W5 shown in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted.

In the exhaust gas recirculation control device 20 of this embodiment, a bearing portion 21 is fixed to the housing 9 and disposed above the valve seat 11 in the outlet side passage, and as shown in FIG. The shaft sliding hole 21a formed in the center of the shaft 1
3 is inserted.

A funnel-shaped holder 22, which is attached with a peripheral flange portion 22b sandwiched between the peripheral lower end surface of the bearing portion 21 and a step formed on the inner wall of the housing 9, has a central shaft portion insertion hole 22a.
It is provided with an annular guide member 23 attached to. The shaft portion 13 passes through the guide member 23 and is supported by the guide member 23.

On the other hand, two shielding plates 25 and 26 are arranged in a closed space 24 defined by the bearing part 21 and the holder 22. One shielding plate 25 has its outer peripheral edge connected to the bearing part 21.
and the flange portion 22b of the holder 22, and the shaft portion 13 passes through the central opening. The central opening of the shielding plate 25 is sized to form a minute gap between the inner peripheral portion 25a and the peripheral surface of the shaft portion 13, so as not to hinder the sliding movement of the shaft portion 13. . Another shielding plate 26 is arranged above this shielding plate 25, and unlike the previous shielding plate 25, this shielding plate 26 is different from the previous shielding plate 25.
3, and its outer peripheral end 26a forms a small gap with the inner surface 21b of the bearing part 21. This shielding plate 26
It is very easy to obtain as it is possible to use commercially available bush nuts as shown in Fig. 3(a) and Fig. 3(b).
As shown in the figure, this bushing nut 26 is attached to the shaft portion 13.
Since it can be attached by simply fitting it into the shaft, machining of the shaft portion 13 is also unnecessary. Note that a simple washer can be used as the shielding plate 25.

In the exhaust gas recirculation control device 20 configured as described above, the control valve 12 is moved upwardly and downwardly from the valve seat 11 by the vertical movement of the shaft portion 13.
When opening and closing, the shaft 13 is supported by two places: the bearing 21 and the guide member 23 fixed to the inner circumference of the shaft insertion hole of the holder 22, so the inclination is slight and smooth operation is possible. .

Therefore, the control valve 12 and the annular valve seat 11 can be brought into contact reliably and stably without any gaps. Note that since the shaft portion 13 is supported at two places, it is necessary to reduce the sliding resistance, and therefore the shaft portion sliding hole 21a of the bearing portion 21 is made shorter than before.

On the other hand, carbon in the exhaust gas enters the space 24 through the gap between the inner peripheral part of the guide member 23 and the shaft part 13, but the zigzag or labyrinth structure in the axial direction formed by the shielding plates 25 and 26 is Accordingly, intrusion of the bearing portion 21 into the shaft portion sliding hole 21a can be almost completely prevented. Therefore, smooth operation will not be hindered due to the intrusion of carbon or the like.

(Effects of the Invention) As explained above, according to the exhaust gas recirculation control device of the present invention, the shaft portion provided with the control valve at the lower end is supported at two places: the bearing portion and the guide member of the holder. This prevents the shaft from wobbling or tilting, improves the accuracy of the contact position of the control valve against the valve seat, and at the same time stabilizes the engine so that it does not cause malfunction. By arranging at least two shielding plates in the axial direction to form a labyrinth structure, smooth movement of the shaft is ensured without carbon entering the shaft sliding hole of the bearing. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an exhaust gas recirculation control device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the shaft support structure in the exhaust gas recirculation control device shown in FIG. A fragmentary cross-sectional view, Fig. 3 (Chrysanthemum is a plan view showing a bushnut that can be used as a shielding plate, Fig. 3) is a side view of the bushnut shown in Fig. 3(a), and Fig. 4 is a side view of the bushnut shown in Fig. 3(a). Diagram (a)
A plan view showing the bush nut attached to the shaft,
FIG. 5 is a configuration explanatory diagram showing a conventional exhaust gas recirculation system, and FIG. 6 is a sectional view showing a conventional exhaust gas recirculation control device. 7... Diaphragm, 8... Negative pressure chamber, 9... Housing, 10... Exhaust gas passage, 11... Valve seat, 1
DESCRIPTION OF SYMBOLS 2... Control valve, 13... Shaft part, 20... Exhaust gas recirculation control device, 21... Bearing part, 22... Holder, 23... Guide member, 24... Space Part, 25...
- Shielding plate, 26... Shielding plate. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masu Oiwa Figure R Figure 25゜Figure (b) Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] The inside of the housing has an inlet passage and an outlet passage communicating through an opening of an annular valve seat, and a control valve provided at an end of a shaft movable by differential pressure generating means is connected to the opening of the valve seat. In an exhaust gas recirculation control device that adjusts the amount of exhaust gas passing through by opening and closing a bearing part, the bearing part is located in one of the passages and is attached to the housing to slidably support the shaft part. (21) and the bearing part (21)
a holder (22) provided on the passage side, supported by a guide member (23) with respect to the shaft part, and cooperating with the bearing part to form a closed space below the holder; an exhaust gas recirculation control comprising: at least two shielding plates disposed in the axial direction and provided with a slight spacing between the circumferential surface of the shaft portion and the inner circumferential surface of the closed space, respectively; Device.