JPH10259764A - Exhaust gas reflux control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate insertion and fixing of a valve stem in an annular member fixed at a diaphragm and prevent the increase of the number of manufacturing processes. SOLUTION: A valve 8 is provided to be coupled to a diaphragm 17 through a valve stem 9 and control opening and closing of an exhaust gas reflux flow passage 2 responding to the diaphragm 17. An annular member 25 is fixed at the diaphragm 17 and the annular member 25 is attached to a valve stem 9. The annular member 25 comprises a shaft part 27 having a through-hole 26 in which the valve stem 9 is securely inserted; and a flange part 28 formed in a manner to protrude from the outer periphery of the shaft part 27. The shaft part 27 is protruded through the diaphragm 17, the protruding end 32 is folded in an expanding manner, and a diaphragm 17 is nipped between the flange part 28 and the protrusion end. The through-hole 26 of the shaft part 27 is formed in a stepped manner, and the inside diameter of the through-hole 26 formed in the folded part of the flange part 27 is increased to a value higher than the inside diameter of a part in which a valve stem 9 is securely inserted.

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 device which is provided in an exhaust gas recirculation passage provided between an intake passage and an exhaust gas passage of an internal combustion engine and controls the amount of exhaust gas recirculation.

[0002]

2. Description of the Related Art An exhaust gas recirculation control apparatus is used to recirculate a part of exhaust gas of an internal combustion engine into intake air to suppress combustion temperature and reduce NOx level generated during combustion to purify exhaust gas. This exhaust gas recirculation control device is used to control the amount of exhaust gas recirculation according to the operating state of the internal combustion engine.

[0003] This type of exhaust gas recirculation control device includes a diaphragm that partitions the inside of a diaphragm case into two pressure chambers;
A valve that is connected to the diaphragm via a valve stem, and that controls opening and closing of an exhaust gas recirculation passage in response to the diaphragm, according to a control pressure guided into a pressure chamber in a diaphragm case according to an operation state of the internal combustion engine. A valve is actuated via a diaphragm to control the amount of exhaust gas recirculation.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 2-271062, the diaphragm is connected to the valve stem via an annular member fixed to the valve stem by welding.

[0005] The annular member has a shaft portion formed with a through hole into which the valve stem is inserted and fixed, and a flange portion protruding from the outer periphery of the shaft portion. The diaphragm and the plate arranged on both sides of the diaphragm protrude through the plate, and the protruding end is bent so as to expand in diameter, and the diaphragm and the plate arranged on both sides of the diaphragm are sandwiched between the flange and the flange. I have.

The annular member fixed to the diaphragm has a valve stem inserted into a through hole thereof and is fixed to the valve stem by welding.

Thus, the annular member is airtightly fixed to the diaphragm, and the annular member is airtightly attached to the valve stem.

[0008]

However, in the conventional example, in order to fix the annular member to the diaphragm, the shaft of the annular member is bent so that the protruding end is enlarged, and the flange is formed. When the diaphragm is pressed between the shaft portion and the portion, the shaft portion may be deformed in a direction in which the inner diameter of the through hole is reduced in the bent portion. If the inner diameter of the through-hole is deformed in a direction to reduce the diameter, it becomes difficult to insert the valve stem into the through-hole. As a result, it is necessary to expand the through-hole after fixing the annular member. The man-hour will be increased.

The present invention has been devised in view of the above-mentioned conventional circumstances, and it is possible to easily insert and fix a valve stem into an annular member fixed to a diaphragm, thereby advantageously avoiding an increase in the number of manufacturing steps. It is an object of the present invention to provide an exhaust gas recirculation control device capable of performing the following.

[0010]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a diaphragm for partitioning a diaphragm case into two chambers, the diaphragm being connected to the diaphragm via a valve stem, and an exhaust gas recirculation passage in response to the diaphragm. A valve for controlling the opening and closing of the valve, wherein an annular member is fixed to the diaphragm, and the annular member is attached to a valve stem, and the annular member has a shaft portion formed with a through hole through which the valve stem is inserted and fixed. And a flange formed to protrude on the outer periphery of the shaft, the shaft of the annular member protrudes through the diaphragm, and the protruding end is bent so as to expand in diameter,
In the exhaust gas recirculation control device in which the diaphragm is sandwiched between the flange and the flange, the through hole of the shaft of the annular member is formed in a stepped shape, and the inner diameter of the through hole in the bent portion of the shaft is The valve stem is formed to be larger than the inner diameter of the portion where the valve stem is inserted and fixed.

The invention according to claim 2 is configured such that the annular member is attached to the valve stem by welding.

Here, the inside diameter of the through hole in the bent portion of the shaft portion is formed to be larger than the inside diameter of the portion where the valve stem is inserted and fixed.
A predetermined gap is formed between the inner diameter of the through hole and the outer diameter of the valve stem. In addition, the thickness of the shaft portion is reduced.

For this reason, when the shaft of the annular member is bent so that the protruding end expands in diameter, and the diaphragm is clamped between the flange and the flange, the shaft is bent at the bent portion at the inner diameter of the through hole. Is deformed in the direction of reducing the diameter, this deformation is absorbed by the gap between the inner diameter of the through hole and the outer diameter of the valve stem, and the insertion of the valve stem is prevented from being hindered.

Further, since the thickness of the bent portion of the shaft portion is reduced, bending deformation becomes easy, and a large bending stress does not remain in the bent portion.

Accordingly, an exhaust gas recirculation control device is provided which can easily insert and fix the valve stem into the annular member fixed to the diaphragm, and can advantageously avoid an increase in the number of manufacturing steps.

Further, since the residual stress can be kept small,
In the invention according to claim 2, even if the bending stress is relaxed by the heat of welding the annular member to the valve stem, the fixing of the annular member to the diaphragm due to the bending of the shaft portion is not loosened. Airtight fixation can be obtained stably.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an exhaust gas recirculation control device showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a main part of FIG. 1, and FIG. 3 is a sectional view of an annular member.

In FIG. 1, reference numeral 1 denotes a housing, and 2 denotes an exhaust gas recirculation passage formed in the housing 1. The exhaust gas recirculation passage 2 extends between an intake passage 3 and an exhaust passage 4 of an internal combustion engine (not shown). It is.

Reference numeral 5 denotes an orifice sheet provided in the middle of the exhaust gas recirculation passage 2. The orifice sheet 5 has a communication hole 6 which substantially reduces the opening area of the exhaust gas recirculation passage 2. The opening and closing of the communication hole 6 is controlled by a valve 8 seated on a valve seat 7 of the communication hole 6. Therefore, the exhaust gas recirculation passage 2 is closed when the valve 8 closes the communication hole 6, and is opened when the valve 8 opens the communication passage 6.

Reference numeral 9 denotes a valve stem integrally connected to the valve 8. The valve stem 9 is fixed to the housing 1 and guides the insertion / removal operation of the valve stem 9. The sealing plate 11 has a peripheral portion fixed therebetween and seals the outer periphery of the valve stem 9 in an airtight manner, and extends upward in FIG.

Reference numeral 12 denotes a diaphragm case attached to the housing 1. The diaphragm case 12
Is composed of an upper case 13 and a lower case 14. When the lower case 14 is attached to the housing 1 via the heat insulating material 15, it is attached to the housing 1 as a whole. Reference numeral 16 denotes a mounting bolt that passes through the lower case 14 and the heat insulating material 15 and is screwed to the housing 1.

Reference numeral 17 denotes the inside of the diaphragm case 12
It is a diaphragm that is divided into rooms. That is, the diaphragm 17 has an outer peripheral side peripheral edge 17a sandwiched between joints of the upper case 13 and the lower case 14 to partition the inside of the diaphragm case 12, and forms a negative pressure chamber 18 on the upper case 13 side. An atmosphere chamber 19 is formed on the lower case 14 side. The diaphragm 17 is made of a rubber material and a base cloth, and has a flexible portion 20 which is convexly curved toward the negative pressure chamber 18.

In the negative pressure chamber 18 in the diaphragm case 12 partitioned by the diaphragm 17, a pipe 2 is provided.
A control negative pressure is introduced via 1. Also,
The inside of the atmosphere chamber 19 is open to the atmosphere via an opening 22.

Reference numerals 23 and 24 denote an upper plate and a lower plate which hold the diaphragm 17 from both sides.

An annular member 25 is fixed to a substantially central portion of the diaphragm 17.
The diaphragm 17 is fixed between the lower plate 3 and the lower plate 24. The annular member 25 includes a shaft portion 27 having a through hole 26 into which the valve stem 9 is inserted and fixed, and a flange portion 28 formed at a substantially central portion of the shaft portion 27 in the axial direction so as to protrude outward in the radial direction. Have. The through hole 26 of the annular member 25 is formed in a stepped shape, and the remaining portion 26 is larger than the inner diameter of the portion 26a into which the valve stem 9 is inserted and fixed.
The inner diameter of b is large (see FIGS. 2 and 3).

The attachment of the annular member 25 to the diaphragm 17 is as follows. That is, the shaft portion 27 of the annular member 25 is connected to the through hole 29 formed in the diaphragm 17, the upper plate 23, and the lower plate 24 by the through hole 2.
9 is inserted into through holes 30 and 31 formed concentrically and concentrically therewith, and protrudes toward the atmosphere chamber 19, and is bent and crushed so as to expand the protruding end 32 of the shaft portion 27 on the lower plate 24 side. By pressing the upper plate 23, the diaphragm 17, and the lower plate 24 between the flange 28 and
Installed airtight.

The annular member 25 hermetically attached to the diaphragm 17 is hermetically attached by inserting one end of the valve stem 9 into the through hole 26 and fixing it to the valve stem 9 by welding. Arc welding or laser beam welding can be employed for welding the annular member 25 to the valve stem 9.

After welding the annular member 25 to the valve stem 9, the upper case 13 is attached to the peripheral edge 17 a of the diaphragm 17.
Are overlapped, the upper edge 14a of the lower case 14 is folded back, and the upper edge 14a is used to surround the peripheral edge 17a of the diaphragm 17 and the lower edge 13a of the upper case 13.
Pinch. As a result, the peripheral edge 17a of the diaphragm 17 is pinched at the joint between the upper case 13 and the lower case 14, and the inside of the diaphragm case 12 is
8 and the atmosphere chamber 19.

The negative pressure chamber 18 accommodates a control spring 33 for antagonizing a control negative pressure introduced into the negative pressure chamber 18. The control spring 33 constantly urges the diaphragm 17 toward the atmosphere chamber 19 via the upper plate 23, and thereby urges the valve stem 9 connected to the diaphragm 17 via the annular member 25 downward. Then, the valve 8 integral with the valve stem 9 is seated on the valve seat 7 of the orifice seat 5. Therefore, the valve 8 is in a normal state, and the communication hole 6 is closed by the spring force of the control spring 33.

In such a configuration, when the control negative pressure is introduced into the negative pressure chamber 18 via the pipe 21, the diaphragm 17 moves toward the negative pressure chamber 18 against the spring force of the control spring 33. , The valve 8 separates from the valve seat 7 and opens the communication hole 6. As a result, the exhaust gas recirculation passage 2 is opened, and a part of the exhaust gas in the exhaust passage 4 is recirculated into the intake passage 3 under the control of the opening degree of the communication hole 6.

Since a part of the exhaust gas in the exhaust passage 4 is recirculated into the intake air, the combustion temperature is suppressed, the NOx level generated during combustion is reduced, and the exhaust gas is purified.

Here, when the shaft portion 27 of the annular member 25 is bent so that the protruding end 32 expands in diameter, and when the diaphragm 17 is pressed against the flange portion 28, the shaft portion 27 is bent. Even in the case where the through hole 26 (26b) is deformed in the direction in which the diameter is reduced in this portion, this deformation is absorbed by the gap c between the inner diameter of the through hole 26b and the outer diameter of the valve stem 9,
The insertion of the valve stem 9 is prevented from being hindered.

Further, since the thickness of the bent portion of the shaft portion 27 is reduced, bending deformation becomes easy,
No large bending stress remains in this bent portion.

Therefore, an exhaust gas recirculation control device can be obtained in which the valve stem 9 can be easily inserted into and fixed to the annular member 25 fixed to the diaphragm 17, and an increase in the number of manufacturing steps can be advantageously avoided.

Also, since the residual stress can be kept small,
Even if the bending stress is relaxed by the heat of welding the annular member 25 to the valve stem 9, the fixing of the annular member 25 to the diaphragm 17 due to the bending of the shaft portion 27 is not loosened.
The hermetic fixing of the annular member 25 can be stably obtained.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment, and can be changed without departing from the spirit of the invention.

[0038]

As described above in detail, according to the present invention, it is possible to easily insert and fix the valve stem into the annular member fixed to the diaphragm, and to advantageously avoid an increase in the number of manufacturing steps. The exhaust gas recirculation control device which can perform the above is obtained.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is a sectional view of an annular member.

[Explanation of symbols]

 2 Exhaust recirculation passage 8 Valve 9 Valve stem 12 Diaphragm case 17 Diaphragm 18 Negative pressure chamber 19 Atmospheric chamber 25 Annular member 26 Through hole 27 Shaft 28 Flange 32 Projecting end

Claims (2)

[Claims] A diaphragm which partitions the inside of the diaphragm case into two chambers, and a valve which is connected to the diaphragm via a valve stem and controls opening and closing of an exhaust gas recirculation passage in response to the diaphragm; Is fixed, and this annular member is attached to the valve stem,
The annular member has a shaft portion formed with a through hole through which the valve stem is inserted and fixed, and a flange portion formed on the outer periphery of the shaft portion, and the shaft portion of the annular member penetrates the diaphragm. In the exhaust gas recirculation control device in which the protruding end is bent so as to expand in diameter and the diaphragm is sandwiched between the flange and the flange, the through hole in the shaft of the annular member has a stepped shape. An exhaust gas recirculation control device, wherein an inner diameter of a through hole in a bent portion of the shaft portion is formed larger than an inner diameter of a portion where the valve stem is inserted and fixed. 2. The exhaust gas recirculation control device according to claim 1, wherein the annular member is attached to the valve stem by welding.