JP2000179707A - Passage opening/closing valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a passage opening/closing valve capable of surely closing a fluid passage even if each member expands/contracts due to variation in temperature. SOLUTION: When a first abutting member 32 is seated in a first valve seat 22 and moreover a second abutting member 33 is seated on a second valve seat 28, an EGR(Exhaust Gas REFLUX) valve is closed, cutting off the communication between an exhaust gas inflow passage 100 and an exhaust gas outflow passage 101. A valve housing 20 is made of cast iron. The first valve seat 22 an the first abutting member 32 are formed by pressing a thin stainless steel plate to elastically deformable. The first valve seat 22 is provided with corner parts 22a, 22b forming a step between the outer peripheral side and the inner peripheral side. Thus, even if an outer peripheral annular part 23 deforms due to a difference in the coefficient of thermal expansion between the valve housing 20 and the first valve seat 22, the distorsion of the outer peripheral annular part 23 is prevented from being transmitted to the inner peripheral annular part 24, owing to the elastic deformation of the corner parts 22a, 22b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow passage opening / closing valve, and more particularly to a flow passage opening / closing valve having a pair of valve seats.

[0002]

2. Description of the Related Art As a valve seat of a passage opening / closing valve for opening / closing a fluid passage, a valve housing which forms a fluid passage is formed by cutting and polishing. Instead of such a valve seat, for example, a valve seat formed of a material different from that of the valve housing can be attached to the valve housing. For example, when the valve housing is formed of iron, it is conceivable to form the valve seat with a material such as stainless steel different from that of the valve housing in order to prevent a decrease in seating property when closing the valve due to rust or corrosion.

Further, in an exhaust gas recirculation control valve (hereinafter, referred to as an "exhaust gas recirculation control valve") as a passage opening / closing valve, the force applied to the valve member from the exhaust gas pressure is reduced to open / close the valve member. In order to reduce the driving force of the valve member, it is known that two valve seats are arranged apart from each other in the reciprocating direction of the valve member. When the valve member moves in one direction, the two contact members provided on the valve member are seated on the respective valve seats and cut off the communication between the exhaust gas inflow passage and the exhaust gas outflow passage.
In a state where each valve seat is seated, one contact member of the valve member receives a force from the exhaust gas pressure in the valve opening direction and the other contact member receives the force from the exhaust gas pressure in the opposite direction to the valve closing direction. The force received from the exhaust gas pressure decreases.

In such an EGR valve having two valve seats, one of the valve seats may be formed of a material different from that of the valve housing so as to be elastically deformable. Even if the distance between one contact member and the valve seat and the distance between the other contact member and the valve seat are not set to desired values due to a processing error, an assembly error, or a difference in thermal expansion coefficient, Due to the elastic deformation of the valve seat, the two contact members are securely seated on the respective valve seats, and the fluid flow path can be reliably closed.

[0005]

As described above, in a flow passage opening / closing valve having one or two valve seats, if the valve housing and the valve seat are formed of different materials, the temperature of the fluid flowing through the fluid flow passage becomes lower. If it is high, the valve seat may be distorted due to the difference in the coefficient of thermal expansion between the valve seat and the valve housing.
For example, in the case of an EGR valve, the operating environment temperature is 350 to 400.
° C., if the valve housing and the valve seat are formed of a metal having a different coefficient of thermal expansion, for example, the valve housing is formed of iron and the valve seat is formed of stainless steel, the expansion of the valve seat having a large coefficient of thermal expansion is restricted by the valve housing. When a force is applied to the valve seat, the valve seat may be distorted. Further, when the valve seat exceeds the elastic limit and undergoes plastic deformation, distortion remains in the valve seat even when the temperature decreases. When the valve seat is distorted in this way, even if the contact member of the valve member is seated on the valve seat, a gap may be formed between the contact member and the valve seat, and the fluid may leak. An object of the present invention is to provide a flow path opening / closing valve that reliably closes a fluid flow path even when each member expands and contracts due to a temperature change.

[0006]

According to a first aspect of the present invention, a valve seat formed of a material different from that of a valve housing has a valve seat formed by a difference in thermal expansion coefficient from the valve housing. A distortion suppressing section for suppressing distortion is formed.
Even if, for example, the temperature of each member rises due to the fluid flowing through the fluid flow path and the valve housing and the valve seat having different thermal expansion coefficients thermally expand, the seat portion of the valve seat on which the valve member sits is thermally expanded with the valve housing. Distortion due to a difference in coefficient can be suppressed. Even if each member expands and contracts due to a temperature change, the valve member sits on the valve seat without forming a gap, so that the fluid flow path can be reliably closed.

According to the flow path opening / closing valve of the second aspect of the present invention, the first valve seat is formed of a material different from that of the valve housing so as to be elastically deformable. Therefore, the distance between the first contact member and the first valve seat and the distance between the second contact member and the second valve seat are set to desired values due to a processing error, an assembly error, or a difference in thermal expansion coefficient. Even if not, both contact members are securely seated on each valve seat by the first valve seat being elastically deformed,
The fluid flow path can be reliably closed.

Further, the first valve seat has a distortion suppressing portion for suppressing distortion of the first valve seat caused by a difference in thermal expansion coefficient from the valve housing.
It is formed on the valve seat. Therefore, even if the temperature of each member rises due to the fluid flowing through the fluid flow path and the first valve seat and the valve housing having different thermal expansion coefficients thermally expand, for example, the first valve seat of the first abutment member is seated. Distortion of the seat due to a difference in thermal expansion coefficient from the valve housing can be suppressed. Even if the first contact member and the first valve seat expand and contract due to a temperature change, the first contact member sits on the first valve seat without forming a gap, so that the fluid flow path can be reliably closed.

According to the third aspect of the present invention, since the first valve seat is formed of a thin plate and the thin plate is bent to form the distortion suppressing portion, the distortion suppressing portion can be easily formed by pressing or the like. Can be formed.

According to the flow path opening / closing valve according to the fourth aspect of the present invention, the first contact member and the first valve seat are similarly elastic by the fluid pressure while the first contact member is seated on the first valve seat. Since it is deformed, no gap is formed between the first contact member and the first valve seat when the valve is closed. Therefore, even if the fluid pressure changes, the fluid flow path can be reliably closed.

According to a fifth aspect of the present invention, a plurality of projections extending radially outward are formed on the outer periphery of the first valve seat, and the first valve seat is attached to the valve housing by these projections. ing. Since the outer peripheral edge of the first valve seat other than the projection is not restricted by the valve housing from expansion and contraction due to temperature change, distortion of the first valve seat due to a difference in thermal expansion coefficient from the valve housing is suppressed near the projection, and the first abutment is achieved. The seating portion of the first valve seat on which the member is seated is less likely to be distorted. Since the first contact member is seated on the first valve seat without forming a gap, the fluid flow path can be reliably closed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 3 shows a first embodiment in which the passage opening / closing valve of the present invention is applied to an EGR valve. The valve housing 20 of the EGR valve 10 is formed of cast iron or the like, and the exhaust gas inflow passage 1
00 and an exhaust gas outflow channel 101 are formed. The exhaust gas outflow passage 101 communicates with an intake passage (not shown). Exhaust gas inflow channel 100 and exhaust gas outflow channel 1
01 constitutes a fluid flow path. The valve housing 20 has a valve seat mounting part 21. The first valve seat 22 and the second valve seat 28 are mounted on the valve seat mounting portion 21 so as to be separated from each other in the reciprocating direction of the valve member 30. 1st valve seat 22 and 2nd
The valve seat 28 has openings 110 and 111 through which the exhaust gas inflow channel 100 and the exhaust gas outflow channel 101 can communicate. Both valve seats are formed of a metal having high heat resistance, corrosion resistance and wear resistance, for example, stainless steel.

The first valve seat 22 is formed by pressing a thin plate of stainless steel so as to be elastically deformable, and the second valve seat 28 is formed so as not to be elastically deformed. As shown in FIG.
The first valve seat 22 includes an outer annular portion 23 and an inner annular portion 24.
A connecting portion 25 that connects the outer peripheral annular portion 23 and the inner peripheral annular portion 24 by forming a step; and a diameter of the first valve seat 22 that is disposed at four locations on the outer periphery of the outer peripheral annular portion 23 at 90 ° intervals. And a projection 26 extending outward in the direction. An L-shaped cross-section corner 22a formed by the outer peripheral annular portion 23 and the connecting portion 25 and an L-shaped cross-sectional corner 22b formed by the inner peripheral annular portion 24 and the connecting portion 25 serve as distortion suppressing portions. Are formed. As shown in FIG. 1, the projection 26 is sandwiched between the valve seat mounting portion 21 and the annular member 27, and the annular member 27 is press-fitted into the valve seat mounting portion 21 and then caulked and fixed.
The valve seat 22 is mounted on the valve seat mounting portion 21. The second valve seat 28 is mounted by press-fitting the valve seat mounting portion 21 and then caulking.

As shown in FIG. 3, the valve member 30 has a valve shaft 31, a first contact member 32, and a second contact member 33. The first contact member 32 and the second contact member 33
It is attached to the valve shaft 31 via the collar 34 in the axial direction of the valve shaft 31, that is, in the reciprocating direction of the valve member 30, and reciprocates with the valve shaft 31. Both contact members are made of metal such as stainless steel having high heat resistance, corrosion resistance, and high abrasion resistance as in the case of both valve seats described above. The first contact member 32 is formed by pressing a thin stainless steel plate and is formed in a dish-like shape so as to be elastically deformable.
Seating portion 24 formed on inner annular portion 24 of valve seat 22
a. The second contact member 33 is formed by cutting and polishing stainless steel so as not to be elastically deformed, and can be seated on the seating portion 28 a of the second valve seat 28. The two contact members are seated on the respective valve seats when the valve member 30 moves upward in FIG. 3, that is, when the valve member 30 moves in the valve closing direction.
That is, when it moves in the valve opening direction, it is separated from each valve seat. First
The distance between the contact member 32 and the first valve seat 22 is set to be slightly shorter than the distance between the second contact member 33 and the second valve seat 28. Accordingly, the first contact member 32 is seated on the first valve seat 22 and elastically deforms with each other before the second contact member 33 is seated on the second valve seat 28. The distance between the first contact member 32 and the first valve seat 22 and the distance between the second contact member 33 and the second valve seat 28 do not change due to temperature change.
The valve shaft 31 is formed of a metal having substantially the same coefficient of thermal expansion as both contact members and both valve seats. The spring 35 urges the valve shaft 31 in a direction in which both contact members are seated on the respective valve seats.

The seat diameter of the first valve seat 22 and the second valve seat 2
8 are formed so as to have substantially the same sheet diameter.
Therefore, the pressure receiving area for receiving pressure from the exhaust gas in the exhaust gas inflow passage 100 in a state where both contact members are seated on the respective valve seats is substantially equal for both contact members. However, since the first contact member 32 is elastically deformed by the force received from the exhaust gas pressure of the exhaust gas inflow passage 100 in the valve opening direction when the valve is closed, the pressure receiving area of the first contact member 32 and the exhaust pressure in the valve closed state. A force smaller than the force represented by the product of the gas pressure is applied to the valve shaft 31 from the first contact member 32 in the valve opening direction. Second
Since the contact member 33 is a rigid body, the second
A force represented by the product of the pressure receiving area of the contact member 33 and the exhaust gas pressure is applied to the valve shaft 31 from the second contact member 33 in the valve closing direction. In the closed state, the valve shaft 31 is in the first position.
The force received from the contact member 32 in the valve opening direction is smaller than the force received from the second contact member 33 in the valve closing direction. That is, the effective pressure receiving area of the first contact member 32 is smaller than the effective pressure receiving area of the second contact member 33.

An electric drive section 40 is provided for driving the valve member 30. A spool 4 is provided on the inner periphery of the fixed core 41.
The coil 46 wound around 5 is accommodated. The movable core 42 is disposed so as to face the fixed core 41, and reciprocates with the drive shaft 43. The drive shaft 43 is in contact with the valve shaft 31 and is supported by a bearing 48 so as to be reciprocally movable. The spring 44 includes the fixed core 4
The movable core 42 is urged in a direction in which the movable core 42 approaches 1, that is, in a direction in which both contact members of the valve member 30 separate from the respective valve seats. The shaft 49 of the lift sensor is in contact with the drive shaft 43 and detects the lift amount of the drive shaft 43, that is, the lift amount of the valve shaft 31. Electric power is supplied to the coil 46 from the terminal 51 embedded in the connector 50.

Next, the operation of the EGR valve 10 will be described.
You. When the valve is closed, the following four types of forces F are applied to the valve member 30.
_S1, F_V, F_S2, F_nIs working. A switch for urging the valve member 30 upward in FIG.
Energizing force F of the pulling 35 _S1 Effective receiving pressure from the exhaust gas pressure in the exhaust gas inflow passage 100
The force F that the valve member 30 receives in the valve closing direction due to the area difference_V The valve member 30 is urged downward in FIG. 3, that is, in the valve opening direction.
The biasing force F of the spring 44_S2 The first valve is controlled by the exhaust gas pressure in the exhaust gas inflow passage 100.
When the seat 22 elastically deforms in the valve opening direction, the first contact
The force F which the valve member 30 receives in the valve opening direction via the member 32_n

(1) While power supply to the coil 46 is off, F _S1 + F
A _V> F _S2 + F _n. Therefore, the first contact member 32
Is seated on the first valve seat 22, the second contact member 33 is seated on the second valve seat 28, and communication between the exhaust gas inflow passage 100 and the exhaust gas outflow passage 101 is shut off.

The first valve seat 22 and the first abutment member 32 are formed of thin plates so as to be elastically deformable.
The first contact member 32 is also elastically deformed by the exhaust gas pressure in the exhaust gas inflow passage 100 in a state where the first contact member 32 is seated on the first valve seat 22. Therefore, even if the first contact member 32 and the first valve seat 22 are elastically deformed by the exhaust gas pressure, the exhaust gas does not leak from the contact portion between the first contact member 32 and the first valve seat 22.

[0020] (2) When turning on the energization of the coil 46, is generated a force F _E for attracting the movable core 42 to the fixed core 41.
F _E acts in a direction to open the valve member 30, and F _S1 + F _V <
Since the _{F S2 + F n + F E} , each abutment member is lifted from the valve seat. Then, since the exhaust gas inflow passage 100 and the exhaust gas outflow passage 101 communicate with each other, the exhaust gas flows into the intake passage (not shown). By controlling the energization of the coil 46, the amount of exhaust gas flowing out to the intake passage can be adjusted.

In this embodiment, the first valve seat 2 made of stainless steel is used.
2 has a larger thermal expansion coefficient than the valve housing 20 made of cast iron, so that the exhaust gas temperature of the exhaust gas inflow passage 100 is changed from the ambient temperature before the engine starts to 350 to 350 during the operation of the engine.
The temperature rises to 400 ° C. and the first valve seat 22 and the first contact member 32
Is expanded, the valve housing 20 restricts the first valve seat 22 from extending radially outward. However, in the present embodiment, the connecting portion 25 is connected so as to form a step between the outer peripheral annular portion 23 and the inner peripheral annular portion 24, and the two annular portions and the coupling portion 25 have corners having a substantially L-shaped cross section. Since the portions 22a and 22b are formed, when distortion occurs in the outer peripheral annular portion 23 near the valve housing 20, the corner portions 22a and 22b are elastically deformed as distortion suppressing portions. Therefore, the distortion of the outer peripheral annular portion 23 in the radial direction of the first valve seat 22 and the axial direction of the valve shaft 31 is suppressed from being transmitted to the seating portion 24 a formed in the inner peripheral annular portion 24.

Further, since the first valve seat 22 is restricted from expanding and contracting in the radial direction by the projection 26 instead of the entire circumference of the outer peripheral annular portion 23, the outer peripheral annular portion 23 has a difference in thermal expansion coefficient from the valve housing 20. The resulting distortion is concentrated on the protrusion 26 and the vicinity of the protrusion 26. Therefore, since the ratio of the outer peripheral annular portion 23 that causes distortion is lower than the entire circumference, the distortion of the outer peripheral annular portion 23 is less likely to be transmitted to the inner peripheral side seating portion 24a.

FIG. 4 shows a modification of the first embodiment, and FIG. 5 shows a comparative example of the first embodiment. In the first valve seat 60 of the modified example, the entire outer periphery of the outer peripheral annular portion 61 is attached to the valve housing. The first valve seat 65 of the comparative example is formed in a flat plate shape without a step. FIGS. 6 and 7 show the relationship between the passage of time and the amount of distortion due to thermal expansion and the amount of valve leakage in the first valve seat in the first embodiment, the modification, and the comparative example. Represents the measurement results of the first embodiment, ▲ represents the modified example, and ◆ represents the measurement results of the comparative example. The amount of distortion shown in FIG. 6 indicates an amount of distortion of the seat portion of the first valve seat in the axial direction of the valve shaft.

Although there are some differences between the first embodiment and the modification, the amount of increase in the amount of distortion and the amount of valve leakage is small even with the passage of time. On the other hand, in the comparative example formed in a flat plate shape, since the distortion suppressing portion is not formed, the distortion on the outer peripheral side of the first valve seat due to thermal expansion is transmitted to the inner peripheral side seating portion, and the entire first valve seat undulates. become. Therefore, the amount of distortion and the amount of valve leakage increase with time.

(Second Embodiment) FIG. 8 shows a second embodiment of the present invention.
Shown in The same reference numerals are given to the same components as those in the first embodiment, and the description is omitted. The first valve seat 70 is formed by pressing a thin plate of stainless steel or the like having excellent heat resistance, corrosion resistance, and wear resistance. The outer annular portion 71 and the inner annular portion 72 of the first valve seat 70 are present on the same plane, and a bent portion 73 as a distortion suppressing portion formed in a U-shaped or V-shaped cross section connects the two annular portions. ing.

When the outer peripheral annular portion 71 near the valve housing 20 is distorted, the bent portion 73 is elastically deformed, so that the distortion of the outer peripheral annular portion 71 in the radial direction of the first valve seat 70 and the axial direction of the valve shaft 31 is reduced. Seating part 7 formed in inner peripheral annular part 72
2a.

In the above-described plurality of examples and modifications showing the embodiment of the present invention described above, the outer peripheral side of the first valve seat attached to the valve housing and the first valve seat on which the first contact member is seated. A distortion suppressing unit is provided between the seat and the seat. Therefore, due to the difference in thermal expansion coefficient from the valve housing, the first
Even if distortion occurs on the outer peripheral side of the valve seat, the distortion is not transmitted to the seating portion located on the inner peripheral side due to the elastic deformation of the distortion suppressing portion. Therefore, even when the first contact member is seated on the first valve seat, no gap is formed between the first contact member and the first valve seat. Can be prevented.

In the above-mentioned plural embodiments and modified examples, the corner portions and the bent portions are formed as the distortion suppressing portions. However, the outer peripheral side is easily distorted by making the outer peripheral side thinner and the inner peripheral side thicker. However, transmission of distortion to the inner peripheral side may be suppressed. Further, the first contact member may be formed so as not to be elastically deformed.

In the above embodiments and modifications, E
Although the GR valve has been described, if any one of the valve seats has a pair of valve seats and one of the valve seats may be distorted due to a difference in thermal expansion coefficient between the one valve seat and the valve housing, any flow opening / closing valve may be used. The present invention may be applied to Also, in a flow passage opening / closing valve having one valve seat, if the material of the valve seat and the valve housing are different and the valve seat may be distorted due to a difference in thermal expansion coefficient between the valve seat and the valve housing. It is desirable to apply the flow path on-off valve of the invention.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an EGR valve according to a first embodiment of the present invention.

2A is a perspective view showing a first valve seat of the first embodiment, FIG. 2B is a plan view of the first valve seat, and FIG. 2C is a line CC of FIG. It is sectional drawing.

FIG. 3 is a sectional view showing an EGR valve according to the first embodiment.

FIG. 4 is a perspective view showing a modification of the first embodiment.

FIG. 5 is a perspective view showing a comparative example of the first embodiment.

FIG. 6 is a characteristic diagram showing a relationship between a lapse of time and a distortion amount according to the first embodiment, a modification, and a comparative example.

FIG. 7 is a characteristic diagram showing a relationship between a passage of time and a valve leakage amount according to the first embodiment, a modification, and a comparative example.

FIG. 8A is a perspective view showing a first valve seat of the second embodiment, and FIG. 8B is a sectional view taken along line BB of FIG. 8A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 EGR valve 20 Valve housing 22 1st valve seat 22a, 22b Corner part (distortion suppression part, bending part) 23 Outer ring part 24 Inner ring part 25 Connection part 26 Projection 60 1st valve seat 61 Outer ring part 70 1st Valve seat 71 Outer ring part 72 Inner ring part 73 Bent part (strain suppression part)

Claims (5)

[Claims] A valve housing that forms a fluid flow path; a valve seat attached to the valve housing; a valve that opens and closes the fluid flow path by being separated from the valve seat and seated on the valve seat. A member, wherein the valve seat is formed of a material different from that of the valve housing so as to be elastically deformable, and a distortion suppressing portion for suppressing distortion of the valve seat caused by a difference in thermal expansion coefficient between the valve housing and the valve housing. A flow path opening / closing valve characterized by having: 2. A valve housing forming a fluid flow path; a first valve seat and a second valve seat formed separately; a first contact member capable of being seated on the first valve seat; A valve member having a second contact member capable of being seated on a second valve seat, wherein the first contact member is seated on the first valve seat, and the second contact member is on the second valve seat. A valve member that closes the fluid flow path by seating; the first valve seat is formed of a different material from the valve housing so as to be elastically deformable, and is attached to the valve housing; A flow path opening / closing valve, comprising: a distortion suppressing section that suppresses distortion of the first valve seat caused by a difference in thermal expansion coefficient of the first valve seat. 3. The first valve seat is formed of a thin plate, the distortion suppressing portion is formed by bending the thin plate, and the distortion suppressing portion has a coefficient of thermal expansion between the valve housing and the first valve seat. 3. The flow path on-off valve according to claim 2, wherein the distortion of the first valve seat caused by the difference is suppressed by elastic deformation. 4. The flow path on-off valve according to claim 3, wherein the first contact member is formed of a thin plate so as to be elastically deformable. 5. The valve seat according to claim 2, wherein the first valve seat has a plurality of projections extending radially outward on an outer periphery thereof, and the first valve seat is attached to the valve housing by the projections. 5. The flow path opening / closing valve according to 3 or 4.