JP2019210905A - Exhaust gas recirculation valve - Google Patents

Abstract

To obtain an EGR valve that can prevent an exhaust gas from entering an actuator without using a stretchable member.SOLUTION: A housing 2 has a multi-wall 2b exposed to a space 11. A spring holder 12 has a lateral wall 12b protruding along an axial direction X. The housing 2 and the spring holder 12 form a labyrinth structure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas recirculation (EGR) valve that recirculates exhaust gas.

  In the EGR valve, the exhaust gas that has entered the space in which the spring is placed from the gap existing between the bearing portion and the valve shaft further enters the actuator. Exhaust gas that has entered the actuator causes a reduction in the operating performance of the actuator. Therefore, for example, the EGR valve of Patent Document 1 includes a shielding member that can be expanded and contracted with the operation of the valve shaft. The shielding member is provided between the space where the spring is placed and the actuator, and prevents the exhaust gas from entering the actuator.

JP2013-124580A

  The shielding member of Patent Document 1 is required to be able to expand and contract with the operation of the valve shaft. Therefore, the shielding member needs to be made using a stretchable material such as a resin. However, stretchable materials such as resins have low heat resistance. Since the exhaust gas flowing through the EGR valve is at a high temperature, a shielding member made of a material having low heat resistance is difficult to use in the EGR valve.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an EGR valve that can prevent exhaust gas from entering the actuator without using an extendable member.

  The EGR valve according to the present invention has an exhaust gas passage at one end by a housing having an exhaust gas passage through which exhaust gas flows, an actuator attached to the housing, and a bearing provided between the exhaust gas passage and the actuator. A valve shaft that is supported in a protruding state and that is driven along the axial direction by receiving the driving force of the actuator, a spring holder that is mounted in the space between the bearing portion and the actuator, and one end of which is a spring A spring supported by the holder and biasing the valve shaft in a direction opposite to the driving force, the housing has a multiple wall exposed to the space, and the spring holder projects along the axial direction of the valve shaft It has a side wall, and a side wall is accommodated in multiple walls, and forms a labyrinth structure.

  According to the present invention, since the labyrinth structure is formed by the side wall of the spring holder and the multiple walls of the housing, the labyrinth structure can prevent the exhaust gas from entering the actuator without using an extendable member. it can.

2 is a partial cross-sectional view of an EGR valve according to Embodiment 1. FIG. It is a partial cross section figure which shows the reference example for helping the understanding of the EGR valve which concerns on Embodiment 1. FIG. It is an enlarged view of the periphery of the through-hole in FIG. 6 is a partial cross-sectional view showing a modification of the EGR valve according to Embodiment 1. FIG.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view of an EGR valve 1 according to the first embodiment. The EGR valve 1 is provided in an exhaust gas recirculation passage that connects the intake passage and the exhaust passage of the internal combustion engine, and recirculates the exhaust gas of the internal combustion engine to the intake system.
The EGR valve 1 has a housing 2 in which a through hole 2a is formed at the center. A substantially cylindrical bearing portion 3 is provided in the through hole 2a. The bearing portion 3 is provided between an exhaust gas passage 8 (described later) and an actuator 9, and supports the valve shaft 4 penetrating the through hole 2a. At that time, the valve shaft 4 is supported in a state where one end protrudes into an exhaust gas passage 8 described later. The valve shaft 4 inserted into the bearing portion 3 is movable along its own axial direction X by a gap 5 existing between the inner peripheral surface of the bearing portion 3 and the outer peripheral surface of the valve shaft 4. .

  A valve seat 6 is provided inside the housing 2. A valve body 7 provided at one end of the valve shaft 4 contacts and separates from the valve seat 6 to open and close an exhaust gas passage 8 through which exhaust gas from the internal combustion engine flows. The exhaust gas passage 8 provided in the housing 2 is connected to the intake passage of the internal combustion engine through the opening 8a and connected to the exhaust passage of the internal combustion engine through the opening 8b. FIG. 1 shows a closed state in which the valve body 7 is seated on the valve seat 6.

  An actuator 9 that drives the valve shaft 4 along the axial direction X in a direction in which the valve body 7 moves away from the valve seat 6 is attached to the housing 2. The direction in which the valve body 7 moves away from the valve seat 6 is the valve opening direction, which is the downward direction in FIG. The actuator 9 has a motor such as a stepping motor or a DC motor, and the actuator shaft 9a is driven along the axial direction X when the motor operates. The valve shaft 4 is pushed and driven in the valve opening direction by the driving force of the actuator shaft 9a.

  On the other hand, a spring 10 that urges the valve shaft 4 in a direction in which the valve body 7 contacts the valve seat 6 is provided in a space 11 between the bearing portion 3 and the actuator 9. The direction in which the valve body 7 contacts the valve seat 6 is the valve closing direction, which is the upward direction in FIG. The space 11 is provided with a spring holder 12 and a plate 13, and the spring holder 12 and the plate 13 are attached to the valve shaft 4. One end of the spring 10 is supported by the spring holder 12, and the other end of the spring 10 is supported by the housing 2. The urging force of the spring 10 is transmitted to the valve shaft 4 via the spring holder 12. The plate 13 has a substantially annular shape and is on the bearing 3 side when viewed from the spring holder 12. The plate 13 functions as a receiving surface for the spring holder 12 when the spring holder 12 is attached to the valve shaft 4.

The spring holder 12 has a substantially cylindrical shape with a bottom, and opens toward the bearing portion 3. The spring holder 12 supports the spring 10 with a bottom wall 12a having a substantially circular shape in plan view. From the bottom wall 12 a, the side wall 12 b protrudes along the axial direction X toward the bearing portion 3.
The housing 2 has a multiple wall 2b exposed to the space 11, and a substantially annular recess 2c in plan view is formed between the walls constituting the multiple wall 2b.

In the valve closed state shown in FIG. 1, the side wall 12b has the lower end in FIG. 1 inserted into the recess 2c. Further, in the valve open state, the spring holder 12 moves together with the valve shaft 4 downward in FIG. 1, and the side wall 12b is inserted deeper into the recess 2c.
Thus, in the state where the side wall 12b is inserted into the recess 2c and accommodated in the multiple wall 2b, a labyrinth structure is formed by the side wall 12b and the multiple wall 2b. Hereinafter, with respect to the space 11, the part where the spring 10 is placed is defined as the space 11 a and the part where the actuator shaft 9 a is exposed is defined as the space 11 b with the spring holder 12 as a boundary.

  Exhaust gas enters the space 11 a from the exhaust gas passage 8 through the gap 5. The exhaust gas that has entered the space 11a attempts to further enter the space 11b. However, the labyrinth structure formed by the side walls 12b and the multiple walls 2b prevents entry into the space 11b. The exhaust gas that has entered the space 11a is discharged to the outside through the through hole 2d of the housing 2.

  Thus, the EGR valve 1 is not a stretchable shielding member as in the above-mentioned Patent Document 1, but prevents the exhaust gas from entering the space 11b and thus the actuator 9 by a labyrinth structure. Stretchability is not essential for the side wall 12b forming the labyrinth structure. The material of the stretchable shielding member as in Patent Document 1 has a low heat resistance such as a resin from the viewpoint of stretchability, but the material of the spring holder 12 is a heat resistant viewpoint regardless of the stretchability. You can choose at. The spring holder 12 can be made of various metals, for example, steel. Steels including carbon steel and stainless steel have high heat resistance and are particularly suitable for use in a high temperature environment. The spring holder 12 may be made of stainless steel made of stainless steel. Stainless steel has high corrosion resistance in addition to heat resistance.

  Here, FIG. 2 shows a reference example for helping understanding of the EGR valve 1 according to the first embodiment. The reference example shown in FIG. 2 differs in the shape of the EGR valve 1 and the spring holder shown in FIG. 1 and the shape of the housing. Specifically, the spring holder 120 and the housing 200 in the reference example shown in FIG. 2 do not form a labyrinth structure. Therefore, in the reference example shown in FIG. 2, the exhaust gas that has entered the space 110 in which the spring 10 is placed from the gap 5 easily reaches the actuator 9 through the side of the spring holder 120 like the path R1. . The actuator 9 has a hole (not shown) through which the actuator shaft 9a is inserted. If the exhaust gas enters the inside of the actuator 9 through a gap existing between the hole and the actuator shaft 9a, the actuator 9 may become inoperable.

As described above with reference to FIG. 1, the EGR valve 1 has the through hole 2d in the housing 2 for releasing the exhaust gas that has entered the space 11a to the outside. The through hole 2d is located on the bearing portion 3 side when viewed from the spring holder 12. The through hole 2d connects the space 11a and the atmosphere.
FIG. 3 is an enlarged view of the periphery of the through hole 2d. A gap is formed between the multiple wall 2b and the side wall 12b so as not to hinder the movement of the valve shaft 4 and the spring holder 12 along the axial direction X. The gap has a substantially annular shape in plan view. The cross-sectional area S1 of the gap is preferably smaller than the cross-sectional area S2 of the through hole 2d. Since the cross-sectional area S1 is smaller than the cross-sectional area S2, the airflow resistance between the multiple wall 2b and the side wall 12b becomes larger than the airflow resistance of the through hole 2d. Therefore, the exhaust gas that has entered the space 11a easily flows into the through-hole 2d, and is released into the atmosphere.

  In the above description, the multiple wall 2b is a double wall. However, the multiple wall 2b may be a triple or more wall. For example, when the multiple wall 2b is a triple wall, the spring holder 12 is provided with double side walls 12b. In this way, a more complicated labyrinth structure may be formed.

  Although the side wall 12b is illustrated as being integrally formed with the bottom wall 12a, the bottom wall 12a and the side wall 12b are formed as separate bodies, and the side wall 12b is attached to the bottom wall 12a, whereby the spring holder 12 is formed. May be formed. The same applies to the multiple wall 2b. In the housing 2, the multiple wall 2b and a portion other than the multiple wall 2b may be created separately.

  FIG. 4 is a partial cross-sectional view showing a modified example of the EGR valve 1 according to the first embodiment. The modified example shown in FIG. 4 includes a plate 13A having a shape different from that of the plate 13. The plate 13 </ b> A has a bowl shape that opens toward the bearing portion 3. The plate 13 </ b> A has a bottom wall 13 a that is substantially the same shape as the plate 13, and a side wall 13 b that projects from the bottom wall 13 a toward the bearing portion 3. The side wall 13b is inclined so as to be away from the valve shaft 4 as it approaches the bearing portion 3.

The exhaust gas that has passed through the gap 5 from the exhaust gas passage 8 forms a flow toward the actuator 9 as in the course R2. Further, since the exhaust gas is hotter than the atmosphere in which the space 11a communicates through the through-hole 2d, the EGR valve 1 is installed particularly so that the actuator 9 is located above the housing 2 in the vertical direction. The flow of exhaust gas toward the actuator 9 is accelerated.
However, when the exhaust gas that has entered the space 11a from the gap 5 reaches the plate 13A, it is guided to the side wall 13b and changes the course from the course R2 to the course R3 so as to return to the bearing 3 side. In this way, the exhaust gas path becomes the path R3 returning from the path R2 toward the actuator 9 to the bearing portion 3 side, so that the exhaust gas enters the space 11b more than the EGR valve 1 shown in FIG. Can be prevented. There is a through hole 2d on the bearing 3 side, and the exhaust gas flowing along the course R3 is guided to the through hole 2d and released to the atmosphere.

Similar to the spring holder 12, the plate 13 and the plate 13A can be made of various metals, for example, steel from the viewpoint of heat resistance. Further, the plate 13 and the plate 13A may be made of stainless steel from the viewpoint of corrosion resistance in addition to heat resistance.
Moreover, the bottom wall 13a and the side wall 13b are not integrally formed, but the plate 13A may be formed by attaching a separate side wall 13b to the bottom wall 13a.

As described above, according to the first embodiment, the labyrinth structure is formed by the housing 2 and the spring holder 12, thereby preventing the exhaust gas from entering the actuator 9 without using an extendable member. Can do. Therefore, it is possible to prevent the exhaust gas from entering the actuator 9 even in a high temperature environment.
Further, the housing 2 having the multiple walls 2b, the spring holder 12 having the side walls 12b, and the plate 13A having the side walls 13b can be realized only by changing the shapes of the housing, the spring holder, and the plate in the existing EGR valve. In this case, the EGR valve 1 of Embodiment 1 can be realized without increasing the number of parts.

  The EGR valve 1 is on the bearing 3 side when viewed from the spring holder 12 in the space 11, and includes a plate 13 </ b> A attached to the valve shaft 4. The plate 13 </ b> A is a bowl-shaped opening that opens toward the bearing 3. The side wall 13b is inclined so as to move away from the valve shaft 4 as it approaches the bearing portion 3. Therefore, it is possible to further prevent the exhaust gas from entering the actuator 9.

  The housing 2 has a through-hole 2d that connects the space 11 and the atmosphere on the bearing 3 side as viewed from the spring holder 12, and a gap formed between the side wall 12b of the spring holder 12 and the multiple wall 2b. Is smaller than the cross-sectional area S2 of the through hole 2d. Therefore, it is possible to further prevent the exhaust gas from entering the actuator 9.

  The spring holder 12 is made of steel. Therefore, the heat resistance of the spring holder 12 can be increased.

  The spring holder 12 is made of stainless steel. Therefore, the heat resistance and corrosion resistance of the spring holder 12 can be increased.

  The plates 13 and 13A are made of steel. Therefore, the heat resistance of the plates 13 and 13A can be increased.

  The plates 13 and 13A are made of stainless steel. Therefore, the heat resistance and corrosion resistance of the plates 13 and 13A can be increased.

  Furthermore, within the scope of the invention, the invention of the present application can be modified with any component of the embodiment or omitted with any component of the embodiment.

  1 EGR valve, 2 housing, 2a through hole, 2b multiple wall, 2c recess, 2d through hole, 3 bearing part, 4 valve shaft, 5 clearance, 6 valve seat, 7 valve body, 8 exhaust gas passage, 8a opening, 8b opening, 9 actuator, 9a actuator shaft, 10 spring, 11, 11a, 11b space, 12 spring holder, 12a bottom wall, 12b side wall, 13, 13A plate, 13a bottom wall, 13b side wall, 110 space, 120 spring holder 200 housing.

Claims (7)

A housing having an exhaust gas passage through which exhaust gas flows;
An actuator attached to the housing;
A valve shaft that is supported by a bearing provided between the exhaust gas passage and the actuator in a state in which one end protrudes into the exhaust gas passage, and that is driven along the axial direction by receiving the driving force of the actuator; ,
A spring holder that is in a space between the bearing portion and the actuator and is attached to the valve shaft;
One end is supported by the spring holder, and includes a spring that biases the valve shaft in a direction opposite to the driving force,
The housing has multiple walls exposed to the space,
The spring holder has a side wall protruding along the axial direction of the valve shaft,
The exhaust gas recirculation valve according to claim 1, wherein the side wall is housed in the multiple wall to form a labyrinth structure. The plate is on the bearing portion side as viewed from the spring holder in the space, and includes a plate attached to the valve shaft,
2. The exhaust gas recirculation according to claim 1, wherein the plate is a bowl-shaped opening that opens toward the bearing portion, and the side wall is inclined so as to move away from the valve shaft as it approaches the bearing portion. valve. The housing has a through hole that connects the space and the atmosphere on the bearing portion side when viewed from the spring holder;
The exhaust gas recirculation according to claim 1 or 2, wherein a cross-sectional area of a gap formed between the side wall and the multiple wall of the spring holder is smaller than a cross-sectional area of the through hole. valve.   The exhaust gas recirculation valve according to any one of claims 1 to 3, wherein the spring holder is made of steel.   The exhaust gas recirculation valve according to claim 4, wherein the spring holder is made of stainless steel.   The exhaust gas recirculation valve according to claim 2, wherein the plate is made of steel.   The exhaust gas recirculation valve according to claim 6, wherein the plate is made of stainless steel.

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