JP2011252421A - Exhaust gas recirculation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation apparatus improving sealability between a valve and a seat during valve closing.SOLUTION: In an EGR valve 1 including: a housing 10 in which an introducing port 16 for introducing exhaust gas discharged from an engine, a discharge port 18 discharging some of the exhaust gas to an engine intake system for mixing it with intake air, and a communication passage 20 for communicating the introducing port 16 with the discharge port 18 are formed; a seat 22 provided at the communication passage 20; a valve 12 abutting against or separated from the seat 22; and a stepping motor 14 moving the valve 12, the seat 22 may be turned so as to be tilted relative to a direction X perpendicularly crossing a direction Y of moving the valve 12.

Description

  The present invention relates to an exhaust gas recirculation device for flowing a part of exhaust gas discharged from a combustion chamber of an engine to an intake passage and recirculating it to the combustion chamber.

  Conventionally, in an engine system, part of exhaust gas discharged from the engine is returned to the intake system. An exhaust gas recirculation device is used to control the recirculation amount of the exhaust gas to the intake system. In such an exhaust gas recirculation device, for example, as shown in FIG. 12, a valve 104 is provided at one end of a valve shaft 102 connected to the actuator 100, and the drive of the actuator 100 is controlled. The valve 104 provided in the cylinder is moved up and down so that the valve 104 is brought into contact with or separated from the seat 106 and the opening degree thereof is adjusted to control the recirculation amount of the exhaust gas returned to the intake system. .

  In Patent Document 1, a valve (valve element) is elastically connected to a valve shaft (valve rod), or a seat (valve seat) is elastically disposed in a housing (valve box). A technology is disclosed that can be sealed against thermal changes in the length of the shaft, absorbs an impact when the valve is closed, reduces noise generation, and increases assembly tolerances.

Japanese Patent Laid-Open No. 11-230002

  However, if the seat 106 is press-fitted and fixed in the housing as in the conventional exhaust gas recirculation device shown in FIG. 12, when a foreign object is caught between the valve 104 and the seat 106, the valve 104 and the seat 106 There is a possibility that a circumferential gap is formed between the valve 104 and the seat 106, and the airtightness between the valve 104 and the seat 106 cannot be ensured. FIG. 13 shows an example of the conventional exhaust gas recirculation device shown in FIG. 12, and when the foreign matter M is caught between the valve 104 and the seat 106, the airtightness between the valve 104 and the seat 106 is shown. It shows that sex cannot be secured.

  In addition, there is a possibility that a deviation between the central axis of the valve 104 and the central axis of the seat 106 may occur due to a dimensional deviation of the housing, the valve 104, the seat 106, and the like, and the airtightness between the valve 104 and the seat 106 may not be secured. . If the airtightness between the valve 104 and the seat 106 cannot be ensured in this way, the leakage flow rate increases when the valve is closed, which may lead to engine misfire.

  Also, in the technique disclosed in Patent Document 1, the valve seat only moves in the urging direction, so that when foreign matter is caught between the valve and the seat, the dimensions of the housing, the valve, the seat, etc. If a deviation between the central axis of the valve and the central axis of the seat occurs due to deviation or the like, there is a possibility that the airtightness between the valve and the seat cannot be ensured.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide an exhaust gas recirculation device that improves the airtightness between the valve and the seat when the valve is closed. .

  One aspect of the present invention made to solve the above problems is an exhaust port for introducing exhaust gas exhausted from an engine, and exhaust into an intake system of the engine for mixing a part of the exhaust gas into intake air. A housing formed with a communication port that communicates the introduction port and the discharge port, a seat provided in the communication channel, a valve that contacts or separates from the seat, and the valve In the exhaust gas recirculation apparatus having the movable actuator, the seat can be rotated so as to be inclined with respect to a direction perpendicular to a direction in which the valve is moved.

  According to the present invention, the seat can be rotated so as to be inclined with respect to a direction perpendicular to the direction in which the valve is moved, so that when a foreign object is caught between the valve and the seat, or the central axis of the seat When a deviation occurs between the valve and the central axis of the valve, the amount of the gap between the valve and the seat can be suppressed. Therefore, the airtightness between the seat and the valve is improved.

  As one aspect of the present invention, a stopper is provided to prevent the sheet from dropping into the inlet, and the outer peripheral surface of the sheet is formed in a convex spherical surface so as to be slidable on the inner surface of the communication path. It is characterized by this.

  According to this aspect, the airtightness between the seat and the valve is improved while ensuring the sealing performance between the seat and the housing.

  As an aspect of the present invention, an elastic body that biases the sheet in a direction in which the stopper is positioned is provided.

  According to this aspect, the sealing property between the sheet and the elastic body is realized by the force with which the elastic body urges the sheet. Therefore, the sealing performance between the seat and the elastic body is improved.

  As one aspect of the present invention, a surface of the sheet on which the elastic body is located is formed as a convex spherical surface.

  According to this aspect, the seat is easy to tilt, and the airtightness between the seat and the valve is further improved. Moreover, since the sealing performance between the sheet and the elastic body is reliably maintained even when the seat is rotated and inclined, the sealing performance between the sheet and the elastic body is further improved.

  As one aspect of the present invention, an edge on the outer peripheral side of the sheet is formed in a convex spherical surface on the surface of the sheet on the side where the stopper is located.

  According to this aspect, the seat is more easily inclined, and the airtightness between the seat and the valve is further improved.

  As one aspect of the present invention, the communication path includes a convex portion formed in a convex spherical surface on the inner surface, the outer peripheral surface of the sheet is formed in a concave spherical surface, and the outer peripheral surface of the sheet is fitted into the convex portion. It is characterized by that.

  According to this aspect, when a foreign object is caught between the valve and the seat or when a deviation occurs between the central axis of the seat and the central axis of the valve, the amount of the gap between the valve and the seat Can be suppressed. Therefore, the airtightness between the seat and the valve is improved.

  The exhaust gas recirculation device according to the present invention improves the airtightness between the valve and the seat when the valve is closed.

It is sectional drawing which shows schematic structure of the EGR valve which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the sheet | seat vicinity of the EGR valve which concerns on 1st Embodiment. It is a figure which shows a spring. It is a figure which shows a mode when a foreign material is caught between the valve | bulb and a sheet | seat. It is an enlarged view of the part which bitten the foreign material. It is a figure which shows the example of a change of a sheet | seat. It is a figure which shows the example of a change of a sheet | seat. It is a figure which shows a mode when a foreign material is caught between the valve | bulb and a sheet | seat. It is a figure which shows a mode when a foreign material is caught between the valve | bulb and a sheet | seat. It is sectional drawing which shows schematic structure of the sheet | seat vicinity of the EGR valve which concerns on 2nd Embodiment. It is a figure which shows a mode when a foreign material is caught between the valve | bulb and a sheet | seat. It is a figure which shows the conventional exhaust-gas recirculation apparatus. In the conventional exhaust-gas recirculation apparatus, it is a figure which shows a mode when a foreign material is caught between the valve | bulb and a sheet | seat.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<First Embodiment>
[Description of overall configuration and operation of exhaust gas recirculation system]
The exhaust gas recirculation device according to the first embodiment is an EGR valve for returning EGR gas to the intake system of the engine. FIG. 1 is a cross-sectional view showing a schematic configuration of the EGR valve according to the first embodiment.

As shown in FIG. 1, the EGR valve 1 according to the first embodiment includes a housing 10, a valve 12 slidably provided in the housing 10, and a stepping as an actuator that moves the valve 12 up and down. And a motor 14. The housing 10 is formed with an introduction port 16 through which EGR gas is introduced, a discharge port 18 through which EGR gas is discharged, and a communication path 20 that connects the introduction port 16 and the discharge port 18. The introduction port 16 opens downward on the upstream side of the valve 12, and the discharge port 18 is positioned on the downstream side of the valve 12 and above the valve 12 and opens in the lateral direction. A seat 22 with which the valve 12 abuts or separates is formed in the middle of the communication path 20.
A stopper 24 is provided below the seat 22, and a spring 26 is provided above the seat 22. Details of the seat 22, the stopper 24, and the spring 26 will be described later.

  The valve 12 has a valve shaft 28 extending to the stepping motor 14 side (upward). A holder member 30 is attached to the end of the valve shaft 28. A spring 32 is disposed between the holder member 30 and the housing 10, and the valve 12 is biased upward by the spring 32 via the holder member 30. Thereby, in a state where the stepping motor 14 is not energized, the valve 12 is in contact with the seat 22 and is in a fully closed state.

  As is well known, the stepping motor 14 includes a coil 34 and a rotor 36. A screw rod 38 is connected to the rotor 36. Thereby, the screw rod 38 rotates together with the rotor 36.

Subsequently, the operation of the EGR valve 1 having the above-described configuration will be described. First, part of the exhaust gas discharged from the engine is introduced into the EGR valve 1 from the inlet 16 as EGR gas.
When the EGR gas is returned to the intake system of the engine, when the stepping motor 14 is rotated forward, the screw rod 38 connected to the rotor 36 is rotated forward. Due to the forward rotation of the screw rod 38, the valve 12 is pushed downward against the urging force of the spring 32 and is separated from the seat 22. As a result, the communication passage 20 is opened and the introduction port 16 and the discharge port 18 communicate with each other, so that EGR gas is discharged from the EGR valve 1 and recirculated to the intake system of the engine.

  Thereafter, when the recirculation of the EGR gas to the intake system of the engine is stopped, the stepping motor 14 is rotated in the reverse direction. Then, the screw rod 38 connected to the rotor 36 rotates in the reverse direction. At this time, the holder member 30 also moves upward by the biasing force of the spring 32. As a result, the valve 12 moves upward and contacts the seat 22 (the state shown in FIG. 1). As a result, the communication passage 20 is blocked and the introduction port 16 and the discharge port 18 are not communicated with each other, so that EGR gas is not discharged from the EGR valve 1 and the return to the intake system of the engine is stopped.

[Description of the configuration near the seat]
FIG. 2 is a cross-sectional view showing a schematic configuration in the vicinity of the seat 22 of the EGR valve 1 according to the first embodiment. As shown in FIG. 2, in the EGR valve 1 according to the first embodiment, a stopper 24 is provided below the seat 22, and a spring 26 is provided above the seat 22. FIG. 2 shows the fully closed state.

The sheet 22 is formed in an annular shape, and includes an inner peripheral surface 40, an outer peripheral surface 42, and a first surface 44 and a second surface 46 provided on both end surfaces in the central axis direction. The first surface 44 is in contact with the first portion 56 (see FIG. 3) of the spring 26, and the second surface 46 is in contact with the second portion 52 that forms part of the stopper 24 on the outer peripheral side. In this embodiment, the outer peripheral surface 42 of the sheet 22 is formed into a convex spherical surface, and the outer peripheral surface 42 of the sheet 22 is in contact with the passage surface 47 of the communication passage 20 so as to be slidable.

  The stopper 24 is formed in an annular shape, and its cross section is formed in an L shape with corners having an R shape. A first portion 48 forming one side of the L shape in the cross-sectional shape of the stopper 24 is press-fitted into the inner wall surface 50 of the housing 10, whereby the stopper 24 is fixed to the housing 10. Further, the sheet 22 is placed on the second portion 52 that forms the other side of the L shape in the cross-sectional shape of the stopper 24. In this way, the stopper 24 supports the sheet 22 so that the sheet 22 does not fall to the introduction port 16 side.

  FIG. 3 is a view showing a spring 26 which is an example of the elastic body of the present invention. 3A is a cross-sectional view taken along line AA in FIG. 3B, and FIG. 3B is a top view. As shown in FIG. 3, the spring 26 is formed in an annular plate shape, and a hole as a flow path for exhaust gas is formed on the inner peripheral side. The cross section of the spring 26 is formed in an approximately S shape, and includes a first portion 56, a second portion 58, and a third portion 60 from the inner peripheral side to the outer peripheral side. Also, a curved first inflection portion 62 is formed between the first portion 56 and the second portion 58, and a curved second inflection portion 64 is formed between the second portion 58 and the third portion 60. Is formed. Then, the first portion 56 of the spring 26 and the first surface 44 of the seal 22 are in contact with each other, and the third portion 60 of the spring 26 and the protruding surface 65 (see FIG. 2) protruding inward from the inner wall surface 50 of the housing 10. Are in contact. Then, the spring 22 is urged in the direction in which the stopper 24 is positioned by the spring force of the spring 26, while sealing the gap between the outer peripheral surface 42 of the sheet 22 and the communication path 20 and the discharge port 18. is doing.

By configuring the vicinity of the seat 22 in this way, according to the EGR valve 1 according to the first embodiment, the following operational effects can be obtained.
FIG. 4 is a view showing the periphery of the valve 12 and the seat 22 when the foreign matter M is caught between the valve 12 and the seat 22 when fully closed. FIG. 5 is an enlarged view of a portion where the foreign matter M is bitten. When foreign matter M is caught between the valve 12 and the seat 22, as shown in FIG. 4, the seat 22 intersects the direction (Y direction in the figure) perpendicular to the direction in which the valve 12 is moved (Y direction in the figure). It rotates so as to be inclined with respect to (X direction). Specifically, as shown in FIG. 4, the outer peripheral surface 42 of the seat 22 slides on the passage surface 47 of the communication passage 20, and the side where the foreign matter M in the seat 22 bites is opposed to the spring force of the spring 26. While the sheet 22 is lifted up, the sheet 22 is inclined so that the opposite side of the sheet 22 from which the foreign matter M is bitten is not lifted up. For this reason, the gap between the valve 12 and the seat 22 is smaller than the gap between the portion 66 in which the foreign matter M is bitten and the portion 68 on the opposite side in the radial direction of the valve 12. Therefore, the airtightness between the valve 12 and the seat 22 when the valve is closed is improved.

At this time, a seal is made between the first portion 56 of the spring 26 and the first surface 44 of the seal 22 and between the third portion 60 of the spring 26 and the protruding surface 65 of the housing 10. . Therefore, EGR gas does not leak to the discharge port 18 from the gap between the outer peripheral surface 42 of the seal 22 and the inner wall surface 50 of the housing 10.
Thus, since the airtightness between the valve 12 and the seat 22 when the valve is closed is improved, the leakage flow rate when the valve is closed can be reduced. Therefore, engine misfire can be prevented.

  Even when the housing 10, the valve 12, the seat 22 and the like are displaced, any part of the seat 22 is lifted against the spring force of the spring 26, while The sheet 22 is inclined such that the portion on the opposite side in the radial direction is pressed against the stopper 24 by the spring force of the spring 26. Therefore, the gap between the valve 12 and the seat 22 can be reduced. Accordingly, it is possible to improve the deterioration of the adhesion between the valve 12 and the seat 22 due to the variation in the dimensions of each component, and to reduce the leakage flow rate when the valve is closed.

  6 and 7 are diagrams showing a modification example. As shown in FIG. 6, the first surface 44 that is the surface of the seat 70 on which the spring 26 is located may be a convex spherical surface. As shown in FIG. 7, the outer peripheral edge 73 of the second surface 46, which is the surface of the sheet 71 on which the stopper 24 is located, may be a convex spherical surface. In addition, the 2nd part 52 in the stopper 24 shown in FIG. 7 is formed in the inner peripheral side longer than the 2nd part 52 in the stopper 24 shown in FIG. As a result, when the sheet 71 is tilted, the second surface 46 of the sheet 71 and the second portion 52 of the stopper 24 are in reliable contact.

  As a result, the seats 70 and 71 are easily tilted. For example, as shown in FIGS. 8 and 9, even when the foreign matter M is caught between the valve 12 and the seats 70 and 71, The airtightness between the sheets 70 and 71 is further improved. Further, even when the seats 70 and 71 are inclined, the sealing performance between the seats 70 and 71 and the spring 26 is reliably maintained, so that the sealing performance between the seats 70 and 71 and the spring 26 is improved. To do.

<Second Embodiment>
Next, a second embodiment will be described. Unlike the first embodiment, the EGR valve according to the second embodiment is provided with a convex portion 76 in the communication path 20. Therefore, an EGR valve according to the second embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a cross-sectional view showing a schematic configuration in the vicinity of the seat of the EGR valve according to the second embodiment. FIG. 11 is a diagram illustrating a state when a foreign object is caught between the valve and the seat. In the second embodiment, the basic configuration is the same as that of the first embodiment. Therefore, the description of the same configuration will be omitted below, and differences will be mainly described.

  As shown in FIG. 10, the EGR valve 2 according to the second embodiment is provided with a convex portion 76 formed in a convex spherical shape on the passage surface 47 of the communication passage 20 of the housing 10. Further, the outer peripheral surface 80 of the sheet 78 is formed as a concave spherical surface. In addition, the curvature of the convex part 76 is made larger than the curvature of the outer peripheral surface 80 of the sheet 78. Further, the outer peripheral surface 80 of the sheet 78 is fitted to the convex portion 76.

  According to such an EGR valve 2 according to the second embodiment, as shown in FIG. 11, when the foreign matter M is caught between the valve 12 and the seat 78, the foreign matter M of the seat 78 is caught. The sheet 78 is inclined so that the opposite side is lifted. Therefore, the gap between the valve 12 and the seat 78 is smaller in the portion 84 on the opposite side in the radial direction of the valve 12 with respect to the gap in the portion 82 where the foreign matter M is bitten. Therefore, the airtightness between the valve 12 and the seat 78 when the valve is closed is improved.

  Even when the housing 10, the valve 12, the seat 78, etc. are displaced in size, the seat 78 is inclined so that any part of the seat 78 is lifted. Therefore, the gap between the valve 12 and the seat 78 can be reduced. Therefore, it is possible to improve the adhesion between the valve 12 and the seat 78 due to variations in the dimensions of the respective parts, and to reduce the leakage flow rate when the valve is closed.

At this time, a seal is provided between the convex portion 76 and the outer peripheral surface 80 of the seal 78. Therefore, EGR gas does not leak into the discharge port 18 from between the convex portion 76 and the outer peripheral surface 80 of the seal 78.
As described above, according to the EGR valve 2 according to the second embodiment, the valve 12 and the seat 78 when the valve is closed are maintained while maintaining the sealing performance between the convex portion 76 and the outer peripheral surface 80 of the seal 78. The airtightness between is improved. Therefore, the leakage flow rate when the valve is closed can be reduced. Therefore, engine misfire can be prevented.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 EGR valve 2 EGR valve 10 Housing 12 Valve 14 Stepping motor 16 Inlet port 18 Outlet port 20 Communication path 22 Seat 24 Stopper 26 Spring 28 Valve shaft 40 Inner peripheral surface 42 Outer peripheral surface 44 First surface 46 Second surface 47 Passage surface 56 First part 58 Second part 60 Third part 65 Protruding surface 76 Convex part 78 Sheet 80 Outer peripheral surface

Claims (6)

An introduction port for introducing exhaust gas discharged from the engine, an exhaust port for discharging a part of the exhaust gas to the intake system of the engine for mixing in the intake air, and the introduction port and the exhaust port communicate with each other. In an exhaust gas recirculation device having a housing formed with a communication path, a seat provided in the communication path, a valve that contacts or separates from the seat, and an actuator that moves the valve,
The seat can be rotated so as to be inclined with respect to a direction perpendicular to a direction in which the valve is moved;
An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 1,
Having a stopper to prevent the sheet from dropping into the inlet,
The outer peripheral surface of the sheet is formed into a convex spherical surface so as to be slidable on the inner surface of the communication path;
An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 2,
An elastic body that urges the sheet in a direction in which the stopper is positioned;
An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 3,
The surface of the sheet on which the elastic body is located is formed as a convex spherical surface;
An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 3 or 4,
The outer peripheral edge of the sheet is formed into a convex spherical surface on the surface of the sheet on which the stopper is located;
An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 1,
The communication path includes a convex portion formed into a convex spherical surface on the inner surface,
The outer peripheral surface of the sheet is formed into a concave spherical surface,
The outer peripheral surface of the sheet is fitted to the convex part,
An exhaust gas recirculation device characterized by the above.

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