JP2003227419A - Egr valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a flow rate of leakage at the time of full closing by avoiding the worst state where seating cannot be carried out at whole periphery of a valve head 14 even in the case that a foreign matter is bitten. <P>SOLUTION: The valve head 14 is inclinably supported by a valve shaft 13 with an elastic body (coil spring 15). A valve seat 12 is inclinably supported by a passage wall-constituting body 11 with an elastic body. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine EGR.
(Exhaust gas recirculation) valve.

[0002]

2. Description of the Related Art In an automobile engine, an EGR passage that connects an exhaust system and an intake system is provided so that a part of the exhaust gas is recirculated to the intake side as EGR gas.
In order to control this EGR gas amount, EG is
R valve is installed. For this EGR valve,
A so-called poppet type, that is, a valve umbrella supported by a valve shaft that is axially arranged on its center line and axially driven by a motor or the like with respect to an annular valve seat supported by the passage wall structure. What is made to use is used (refer to Japanese Patent Laid-Open No. 2000-314482).

[0003]

However, in the conventional EGR valve, when foreign matter such as chips is caught between the valve umbrella and the valve seat, the valve cannot be seated on the entire circumference of the valve umbrella. Even if the EGR valve is instructed to be fully closed, a large amount of EGR gas recirculates. For this reason, a large amount of EGR gas recirculates even when the EGR valve is originally supposed to be fully closed, such as when the engine is originally ignitable and when the engine is idle, and the engine cannot be started, and the idle speed is not stable. There was such a problem.

In view of the above conventional problems, the present invention avoids the worst situation in which the valve umbrella cannot be seated on the entire circumference even when foreign matter is caught, and the leakage flow rate when fully closed. An object of the present invention is to provide an EGR valve capable of reducing the above.

[0005]

Therefore, according to the invention of claim 1, the EG for recirculating a part of the exhaust gas of the engine to the intake side.
An annular valve seat provided in the R passage and supported by the passage wall structure, a valve shaft axially arranged on the center line of the valve seat and driven in the axial direction, and a valve supported by the valve shaft. In an EGR valve including a valve head facing a seat, the valve head is supported on the valve shaft so as to be tiltable.

According to a second aspect of the present invention, the valve umbrella is supported on the valve shaft by an elastic body so as to be tiltable. The invention of claim 3 is characterized in that a gap between the valve umbrella and the valve shaft is covered with a cover member in an airtight state. Further, in the invention of claim 4, the cover member has a convex curved surface shape on the upstream side in the EGR gas flow direction.

On the other hand, in the invention of claim 5, the valve umbrella is
The valve seat may be tiltably supported by the passage wall structure instead of being tiltably supported by the valve shaft. Further, in the invention of claim 6, the valve seat is supported by the passage wall constituting body so as to be tiltable by an elastic body.

[0008]

According to the invention of claim 1, since the valve umbrella is tiltably supported on the valve shaft, even if foreign matter is caught between the valve umbrella and the valve seat, the valve umbrella tilts. Can be seated in a flat shape. Therefore, compared with the case where the valve umbrella and the valve shaft are fixed, the entire circumference does not become open, and the flow path of approximately half the circumference is inclined so as to be blocked, so that the leakage gap at the time of fully closing is secured. The leakage flow rate of EGR gas can be reduced. Therefore, even if foreign matter is caught, the influence on engine startability and idle stability can be minimized.

According to the second aspect of the present invention, the tiltable structure can be easily realized by using the elastic body. According to the invention of claim 3, the cover member covers the gap between the valve umbrella and the valve shaft in an airtight state to prevent leakage from the gap due to the tiltable structure. , Reliability can be improved.

According to the invention of claim 4, the cover member is made of E
By forming a convex curved surface on the upstream side in the GR gas flow direction,
The resistance to the EGR gas flow can be minimized. According to the invention of claim 5, since the valve seat is tiltably supported by the passage wall structure, even if foreign matter is caught between the valve umbrella and the valve seat, the valve seat tilts and the valve umbrella is tilted. Can be seated. Therefore, compared with the valve seat and the passage wall structure fixed, the entire circumference does not become open, and the flow path of approximately half the circumference tilts so as to be blocked, so leakage at the time of full closure. The gap can be reduced, and the leakage flow rate of EGR gas can be reduced. Therefore, the same effect as the invention of claim 1 is obtained.

According to the sixth aspect of the invention, the tiltable structure can be easily realized by using the elastic body.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an engine including an EGR valve. An EGR passage 5 is provided between the exhaust passage 3 from the combustion chamber 2 of the engine 1 and the intake passage 4 to the combustion chamber 2, and an EGR passage 5 for returning a part of exhaust gas to the intake side is provided in the EGR passage 5. 6 is interposed.

The EGR valve 6 is driven by a motor 10, and the motor 10 operates according to a command signal from an engine control unit (ECU) 20. FIG. 2 shows the EGR as the first embodiment of the present invention.
A sectional view of the valve 6 is shown. An annular valve seat 12 is fixedly supported by a passage wall structure (valve body) 11 of the EGR passage.

A valve shaft 13 is provided with its axis located on the center line of the valve seat 12, and the valve shaft 13 is axially driven by a motor 10. A valve umbrella 14 is attached to the tip of the valve shaft 13, and the valve umbrella 14 faces the valve seat 12 from the upstream side in the EGR gas flow direction. Here, the valve umbrella 14 is tiltably supported by the valve shaft 13 by an elastic body (coil spring).

That is, a small-diameter portion 13a is formed at the tip of the valve shaft 13, and a hole 14a at the axial center of the valve umbrella 14 is fitted into the small-diameter portion 13a.
Fit relatively loosely with a. The small diameter portion 13a side may be spherical and the hole 14a may be straight. Then, after fitting the valve umbrella 14 to the small diameter portion 13a as described above,
The coil spring 15 as an elastic body is inserted, and the small diameter portion 1 is further inserted.
By fixing the retainer 16 to the tip of 3a, the valve umbrella 14
Is supported on the valve shaft 13 by a coil spring 15 so as to be tiltable.

Further, on the surface of the valve umbrella 14 on the upstream side in the EGR gas flow direction, the small diameter portion 1 of the valve shaft 13 projecting from this surface.
3a, the coil spring 15 and the retainer 16 are covered,
The bowl-shaped cover 17 is attached so that the EGR gas does not leak from the gap between the valve umbrella 14 and the valve shaft 13. The cover member 17 has a curved surface shape that is convex on the upstream side in the EGR gas flow direction.

Since the cover member 17 is exposed to the exhaust condensed water (acidic water such as sulfuric acid) in the gas at a high temperature equivalent to about 500 ° C., the cover member 17 is not attached by press fitting in consideration of thermal expansion. It is desirable that the attachment is made by welding, and that it has high heat resistance and high corrosion resistance such as stainless steel.
According to the present embodiment, as shown in FIG. 3, even if foreign matter such as cutting chips is caught in one place between the valve umbrella 14 and the valve seat 12, the valve spring is locally deformed due to the local deformation of the coil spring 15. 14 can be seated in a tilted form. Therefore, compared with the valve head 14 and the valve shaft 13 fixed to each other as shown in FIG. 4, the entire circumference is not opened, and the flow path of about half the circumference is blocked. The leakage gap when fully closed can be reduced, and the EGR gas flow rate can be reduced in an irregular situation such as biting.

Therefore, even if the EGR valve is in a fully closed state due to the entrapment of foreign matter in the EGR valve, a large amount of EGR gas is recirculated, and a misfire may occur especially when the combustion state is unstable, such as at a low temperature. It can be prevented and the influence on the engine startability and idle stability can be minimized.
Since the valve umbrella 14 is tiltably supported by the coil spring 15, after the valve umbrella 14 is seated, the valve shaft 13 can return more than the conventional mechanism by the stroke of the coil spring 15. This can be dealt with by recognizing on the side of the ECU 20, such as adding control that takes into account that amount in control, or performing position feedback using a potentiometer.

Further, by covering the gap between the valve umbrella 14 and the valve shaft 13 in an airtight state by the cover member 17, leakage from the gap due to the tiltable structure is eliminated as much as possible. The reliability of reducing the leakage flow rate when fully closed can be improved. Further, the cover member 17 is
By making the curved surface shape convex on the upstream side in the R gas flow direction, E
The resistance to the GR gas flow can be minimized to improve the gas flow around the valve umbrella 14, which can contribute to the reduction of pressure loss and the suppression of deposit accumulation in the EGR valve.

FIG. 5 shows an EGR as a second embodiment of the present invention.
A sectional view of the valve 6 is shown. In this embodiment, the valve umbrella 14
Are fixedly supported on the tip of the valve shaft 13. On the other hand,
The valve seat 12 is a passage wall constituent body (valve body) of the EGR passage.
An elastic body (coil spring) 11 is tiltably supported by 11. That is, the passage wall structure 11 is formed with a guide space 11a for guiding the valve seat 12 so that the valve seat 12 can move in the passage direction, and the valve seat 12 in the space 11a is formed.
By housing the coil spring 18 as an elastic body on the back side of the valve seat 12, the valve seat 12 is tiltably supported by the coil spring 18 on the passage wall constituting body 11.

According to this embodiment, since the valve seat 12 is tiltably supported by the passage wall forming body 11, even if foreign matter is caught between the valve umbrella 14 and the valve seat 12, the coil spring 18 is provided. Due to the local deformation of the valve seat 12,
4 can be seated. Therefore, as compared with a case where the valve seat 12 and the passage wall structure 11 are fixed, the entire circumference is not opened, and the flow path of approximately half the circumference is blocked, so that when fully closed. The leakage gap can be reduced, and the leakage flow rate of EGR gas can be reduced. Therefore, the same effect as that of the first embodiment can be obtained.

The EGR valve to which the present invention is applied is
Needless to say, it is not limited to the motor drive type.
It can also be applied to a diaphragm drive type.

[Brief description of drawings]

FIG. 1 is a system diagram of an engine including an EGR valve.

FIG. 2 is a cross-sectional view of the EGR valve showing the first embodiment of the present invention.

FIG. 3 is a view showing a state in which the EGR valve of the above embodiment has foreign matter caught therein.

FIG. 4 is a view showing a state in which a conventional EGR valve has caught a foreign matter.

FIG. 5 is a sectional view of an EGR valve showing a second embodiment of the present invention.

[Explanation of symbols]

1 engine 2 combustion chamber 3 exhaust passage 4 Intake passage 5 EGR passage 6 EGR valve 10 motors 11 Passage wall structure 12 seat 13 valve shaft 14 valve umbrella 15 Coil spring (elastic body) 16 retainer 17 cover 18 coil spring 20 ECU

Claims (6)

[Claims] 1. An annular valve seat provided in an EGR passage that recirculates a part of engine exhaust gas to an intake side, and an annular valve seat supported by a passage wall structure, and an axis line disposed on a center line of the valve seat. In an EGR valve including a valve shaft driven in a direction and a valve head supported by the valve shaft and facing a valve seat, the valve head is tiltably supported by the valve shaft. EGR valve characterized by. 2. The EGR valve according to claim 1, wherein the valve umbrella is tiltably supported by the valve shaft by an elastic body. 3. The EGR valve according to claim 1, wherein a gap between the valve umbrella and the valve shaft is covered with a cover member in an airtight state. 4. The EGR valve according to claim 3, wherein the cover member has a convex curved surface shape on the upstream side in the EGR gas flow direction. 5. An annular valve seat provided in an EGR passage that recirculates a part of exhaust gas of an engine to an intake side, and an annular valve seat supported by a passage wall structure, and an axis line disposed on a center line of the valve seat. In an EGR valve including a valve shaft driven in a direction and a valve umbrella supported by the valve shaft and facing a valve seat, the valve seat is tiltably supported by the passage wall structure. An EGR valve that is characterized by 6. The EGR valve according to claim 5, wherein the valve seat is supported by the passage wall structure by an elastic body so as to be tiltable.