JP4298375B2 - Seal structure and safety valve using the seal structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seal structure and a safety valve using the seal structure.
[0002]
[Prior art]
For example, in a safety valve that protects equipment such as a hydraulic circuit or piping from destruction, an O-ring is generally widely used as a seal structure (see, for example, Patent Document 1).
[0003]
FIG. 8 shows a safety valve having a conventional seal structure using an O-ring.
[0004]
In this safety valve A, an O-ring 2 inserted between the valve body 4 and the valve seat 16 for ensuring airtightness surrounds the outer periphery of the valve body 4 and the valve seat 16 with its inner wall. And is mounted in a free state without being fixed in a space defined by the valve body 4 and the valve seat 16.
[0005]
In this safety valve A, when the pressure in the passage 13 of the main body 1 rises above a predetermined level, the valve body 4 is pushed upward against the urging force of the valve spring 7 to increase the pressure in the passage 13 of the main body 1. This fluid flows out to the blowing portion 14 through the valve body 4 and the gap between the main body 1 and the auxiliary wheel 3 and is discharged from the discharge port 15.
[0006]
By the way, in such a safety valve A, the auxiliary wheel 3 is provided between the valve body 4 and the valve seat 16, and the O-ring 2 is accommodated on the inner peripheral side of the auxiliary wheel 3.
[0007]
In this safety valve A, the O-ring 2 is in a closed state as shown in FIG. 8, and when the pressure in the passage 13 rises from this state, the O-ring 2 is first deformed in the direction of expanding the diameter by the pressure. Will receive the power to do. That is, when the pressure in the passage 13 increases, the outer peripheral surface of the O-ring 2 comes into contact with the inner peripheral surface of the auxiliary wheel 3 and further deformation is prevented. Thus, the safety valve A has a structure in which the outer peripheral side of the O-ring 2 is restrained by the auxiliary wheel 3. However, when the outer peripheral side of the O-ring 2 is constrained, a slight distortion occurs in the O-ring 2, and as a result, there is a problem that the sealing performance is deteriorated in a low pressure region.
[0008]
When this state is judged from the test results, in the safety valve A, when the set pressure is set in the low pressure region, the difference between the blow start pressure and the blow pressure is large. Furthermore, there was a large variation among products.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-31345 (see FIG. 1 and paragraph number [0009])
[0010]
[Problems to be solved by the invention]
As shown in FIG. 8, when a safety valve in which at least the outer peripheral side of the O-ring 2 is constrained is used, for example, for protecting the pneumatic circuit of an oxygen concentrator, it is sufficient for use in a low pressure region due to the characteristics of the valve. In some cases, there is a problem that even if the valve is closed and airtightness is maintained, airtight leakage occurs. In addition, when the safety valve is mass-produced, there is a problem that the characteristics are not constant depending on the product and the seal characteristics vary.
[0011]
In view of such a situation, the present invention does not have a complicated structure of the first member that constitutes the valve body and the second member that constitutes the valve seat, and particularly has good sealing characteristics in a low pressure region, In addition, the present invention provides a seal structure with little variation in valve characteristics when mass-produced, and a safety valve using this seal structure.
[0012]
[Means for Solving the Problems]
To achieve the above object, the seal structure according to the present invention comprises:
A valve chamber 42 is defined between the first member 22 and the second member 24 that reciprocates relative to the first member 22 , and an O-ring 38 is provided at the tip of the second member 24. In the seal structure for sealing the passage 40 formed in the first member 22 by mounting,
The O-ring 38 is mounted on the outer peripheral surface of a small-diameter shaft portion 24a formed to protrude from the distal end portion of the second member 24 .
In the passage 40 formed in the first member 22, a valve seat 36 in which a flat surface P is formed at the tip portion and an inclined surface Q is formed on the outer diameter side of the flat surface P is projected and formed.
A substantially central portion of the O-ring 38 is brought into contact with an outer diameter side corner portion R of the valve seat 36 .
[0013]
With such a configuration, when pressure is applied to the O-ring, the O-ring can be freely deformed outward. As a result, good sealing performance was exhibited under the operating conditions in the low pressure region.
[0014]
Further, it was confirmed that there was little variation in the seal characteristics when mass production was performed.
[0016]
The safety valve according to the present invention is a safety valve having the above-described seal structure. The first member 22 is a valve housing 22 , the second member 24 is a valve body 24, and protrudes from the distal end portion of the valve body 24. An O-ring 38 is attached to the outer peripheral surface of the formed small-diameter shaft portion 24a ,
The primary passage 40 formed in the valve housing 22 is formed with a valve seat 36 in which a flat surface P is formed at the tip and an inclined surface Q is formed on the outer diameter side of the flat surface P.
A substantially central portion of the O-ring 38 is brought into contact with an outer diameter side corner portion R of the valve seat 36 .
[0017]
In the case of a safety valve having such a configuration, it was confirmed that there is little variation in the start and discharge pressures in the low pressure region, and the operation characteristics are stabilized. In addition, when mass-produced, there was little variation due to products.
[0019]
In addition, with such a configuration, it is possible to more accurately control the start of blowing, blowing out, and blowing off.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
FIG. 1 shows a safety valve having a seal structure according to an embodiment of the present invention, and particularly shows a safety valve used for protecting a pneumatic circuit of an oxygen concentrator. In addition, the safety valve 20 used in such an application is used at a relatively low set pressure, for example, a pressure of 250 kPa or less.
[0022]
In the safety valve 20, a valve body 24 is accommodated in a valve housing 22 formed in a substantially cylindrical shape so as to be reciprocally movable. That is, the valve housing 22 is formed with a valve body accommodation hole 26 for slidingly guiding the valve body 24, and a passage 40 connected to the pneumatic circuit is formed below the valve body accommodation hole 26. In the passage 40, the pressure in the pneumatic circuit is transmitted. A valve seat 36 is formed to protrude between the valve element housing hole 26 and the passage 40 by an inner cylindrical portion. As shown in FIGS. 2 and 3, the distal end portion (inner diameter side of the pressure receiving diameter a) of the valve seat 36 formed by the inner cylindrical portion is a flat surface P, and the outer diameter side of the flat surface P An inclined surface Q is formed on the surface.
On the other hand, a screw hole 28 is formed at the opening end of the valve housing 22. For example, an adjustment screw member 30 in which two pressure equalizing holes 30 a are formed is screwed into such a screw hole 28, and the push-in depth of the adjustment screw member 30 is adjusted, whereby the valve spring 32. The biasing force is adjusted.
[0023]
A discharge hole 34 that is open to the outside is formed in the side wall of the valve body accommodation hole 26 of the valve housing 22, and a pressure medium that has accumulated pressure in the passage 40 is discharged outward from the discharge hole 34. The Further, a space 35 is provided between the valve body 24 and the discharge hole 34 so that a differential pressure between the valve chamber 42 and the atmospheric pressure is not applied to the valve body 24.
[0024]
Further, a small diameter shaft portion 24 a is formed at the distal end portion of the valve body 24. Further, as shown in an enlarged view in FIG. 2, a flange portion 24b having a slightly larger diameter is formed at the tip of such a small diameter shaft portion 24a.
[0025]
An O-ring 38 made of synthetic rubber or the like is attached to the outer periphery of the small diameter shaft portion 24a of the valve body 24. The O-ring 38 is prevented from coming off by the flange 24b of the valve body 24 described above.
[0026]
The outer peripheral surface of the O-ring 38 is accommodated away from the inner wall 42a of the valve chamber 42. In other words, the outer peripheral surface of the O-ring 38 is attached to the outer peripheral surface of the small diameter shaft portion 24a in a state where it does not contact anywhere.
[0027]
Further, as shown in an enlarged view in FIG. 3, the O-ring 38 is in contact with the valve seat 36 only at the substantially central portion of the wire diameter. That is, the O-ring 38 is in contact with the outer-diameter-side corner portion R of the valve seat 36 only at the substantially central portion of the wire diameter. Thereby, it is possible to more accurately control the start of blowing, blowing out, and blowing stop.
[0028]
Here, as shown in FIG. 3, when the force F acts on the pressure receiving part S from the inside of the passage 40, the force F can be decomposed into a force Fa for pushing up the valve and a force Fb for pushing the valve.
[0029]
In order to counter the component force Fb at this time, the O-ring 38 is attached to the valve body 24 with an appropriate tension within the elastic limit.
[0030]
The safety valve 20 according to this embodiment is configured as described above, and the operation thereof will be described below.
[0031]
First, such a safety valve 20 is used, for example, for protecting a pneumatic circuit of an oxygen concentrator. In a normal state, as shown in FIG. 1, the O-ring 38 is in contact with the valve seat 36 and the valve is closed. Here, for example, when the pressure on the primary side in the passage 40 connected to the pneumatic circuit rises to a predetermined level or more, the valve body 24 having the O-ring 38 attached to the tip end thereof is changed to the valve as shown in FIG. Separate from the seat 36. That is, the valve is opened. Then, the pressure in the primary side passage 40 is instantaneously released to the discharge hole 34 through the valve chamber 42. This prevents the pressure in the passage 40 from rising beyond the set pressure.
[0032]
On the other hand, when the inside of the passage 40 drops below the set pressure, the valving force of the valve spring 32 returns the valve body 24 to the state shown in FIG. That is, the valve is closed.
[0033]
When only the inner peripheral side of the O-ring 38 is constrained by the small-diameter shaft portion 24a as in the present embodiment, the sealing performance in the low pressure region was good. That is, even when the valve was repeatedly opened and closed, the sealing performance was good. Moreover, even when the set pressure of the safety valve was set to a low pressure, the test confirmed that the difference between the blow start pressure and the blow pressure was small and that there was little variation among products. Thereby, the safety valve 20 can be preferably used at a low set pressure.
[0034]
The seal structure according to one embodiment of the present invention and the safety valve using the seal structure have been described above, but the present invention is not limited to the above-described embodiment. For example, such a safety valve 20 is not limited to a safety valve used in a low pressure region, and can also be used in a high pressure region. When used in a high pressure region, it is preferable to provide the valve housing 22 with a stopper portion 37 that prevents excessive deformation of the O-ring 38, as shown in FIG.
[0035]
Further, in the seal structure according to this embodiment, since the structure for mounting the O-ring 38 is simple, the workability of the valve body 24 is good and the mounting is easy. Further, since the valve body 24 only needs to be processed by a shaft, the processing cost is low.
[0036]
Below, the test result which investigated how the seal | sticker structure based on this invention and the safety valve using this seal | sticker structure show favorable operation | movement in a low-pressure range is demonstrated.
[0037]
FIG. 6 shows a test result of a safety valve using an O-ring as a so-called outer restraint as in the prior art. FIG. 7 shows test results of a safety valve in which an O-ring is a so-called inner restraint as in the present invention.
[0038]
6 and 7, the horizontal axis indicates the number of samples used in the test. In the conventional product, 40 samples were manufactured, and in the present invention, 25 samples were investigated. Then, the set pressure of the safety valve is set to 245 kPa, and the blowing pressure, the blowing start pressure, and the blowing stop pressure are measured, and the rhombus (♦), square (■), and triangle (△) are respectively measured in the upper, middle, and lower stages. ). The vertical axis represents pressure (kPa).
[0039]
As shown in FIG. 2, when the primary side pressure (pressure in the passage 40) exceeds the set pressure, the blow start pressure (■) is a load equivalent to the pressure receiving diameter (a). This is the pressure at which the urging force of 32 is exceeded and leakage occurs from the valve.
[0040]
The blowout pressure (♦) is the pressure when the amount of leakage from the valve exceeds the amount leaking from the discharge hole 34. At this time, the valve body 24 is subjected to a load corresponding to the diameter (b) of the valve body. In response, the valve body 24 rises instantaneously.
[0041]
The blow-off pressure (Δ) is a pressure when the pressure in the primary passage 40 decreases and the spring force of the valve spring 32 overcomes a load corresponding to the diameter (b) of the valve body 24 and the valve closes. is there.
[0042]
As is clear from the test results shown in FIGS. 6 and 7, the present invention shown in FIG. 7 has a smaller difference between the blow start pressure and the blowout pressure than the conventional product shown in FIG. Was confirmed. In addition, the present invention had less variation among products in terms of blowing, starting blowing, and stopping. In particular, the blowing pressure showed a substantially constant value.
[0043]
As described above, it was confirmed that, particularly in a low pressure region of about 250 kPa, there was little variation in the sealing performance of mass-produced products, and a stable sealing performance was obtained. Therefore, the safety valve according to the present invention can be preferably used for a safety valve used in a relatively low pressure region of 250 kPa or less.
[0044]
As mentioned above, although one Example of this invention was described, the seal structure which concerns on this invention is not limited to a safety valve, It can apply to another seal structure. That is, in the said Example, although the 1st member was made into the valve housing and the 2nd member was made into the valve body, the 1st member and the 2nd member are not limited to these, If it is a member with which an O-ring is mounted, It can be anything. Moreover, the fluid flowing through the piping path is not limited to compressed air, and can be applied to other inert gases. Further, the fluid is not limited to gas, and can be applied to liquids such as water.
[0045]
【The invention's effect】
As described above, according to the seal structure of the present invention, when pressure is applied to the O-ring, the O-ring can be freely deformed outward, so that the occurrence of minute distortion is eliminated. . In particular, good sealing performance was exhibited in the low pressure region. In addition, there was less variation due to products when mass-produced.
[0046]
Furthermore, when the seal structure according to the present invention is employed in a safety valve, good sealing performance is ensured particularly when the operating pressure is in a low pressure region.
[0047]
Further, in the safety valve according to the present invention, since the substantially central portion of the O-ring is in contact with the valve seat, it is possible to more accurately control the start of blowing, blowing, and blowing.
[Brief description of the drawings]
FIG. 1 is a sectional view of a safety valve having a seal structure according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a part of FIG.
3 is an enlarged schematic view showing a contact relationship between the O-ring shown in FIG. 2 and the valve seat.
4 is a cross-sectional view when the safety valve shown in FIG. 1 is opened. FIG.
FIG. 5 is a schematic view showing a modification when the safety valve shown in FIG. 1 is used in a high pressure region.
FIG. 6 is a test result of a conventional example, and is a test result showing a relationship between a blowing start pressure, a blowing pressure, and a blowing stop pressure of the safety valve when the outside of the O-ring is constrained.
FIG. 7 is a test result of the present invention, showing the relationship between the blow start pressure, the blow pressure and the blow stop pressure of the safety valve when the inside of the O-ring is restrained.
FIG. 8 is a cross-sectional view of a safety valve disclosed in Japanese Patent Application Laid-Open No. 11-31345 having a conventional seal structure.
[Explanation of symbols]
20 Safety valve 22 Valve housing (first member)
24a Small-diameter shaft 24 Valve body (second member)
36 Valve seat 38 O-ring 40 Passage 42 Valve chamber
P flat surface
Q inclined surface
R Inflection point

Claims (2)

A valve chamber (42) is defined between the first member (22) and the second member (24) reciprocally moved relative to the first member (22) , and the second member ( In the sealing structure for sealing the passage (40) formed in the first member (22) by attaching an O-ring (38) to the tip of 24) ,
The O-ring (38) is attached to the outer peripheral surface of a small-diameter shaft portion (24a) formed to protrude from the distal end portion of the second member (24) ,
The passage (40) formed in the first member (22) has a flat surface (P) at the tip and an inclined surface (Q) on the outer diameter side of the flat surface (P). A seat (36) is formed protrudingly;
A seal structure characterized in that a substantially central portion of a wire diameter of the O-ring (38) abuts on an outer diameter side corner (R) of the valve seat (36) . A safety valve having the seal structure according to claim 1, wherein the first member (22) is a valve housing (22) , the second member (24) is a valve body (24) , and the valve body (24) An O-ring (38) is mounted on the outer peripheral surface of the small-diameter shaft portion (24a) formed to protrude from the tip portion,
The primary passage (40) formed in the valve housing (22) has a flat surface (P) at the tip and an inclined surface (Q) on the outer diameter side of the flat surface (P). A seat (36) is formed protrudingly;
The substantially central portion of the wire diameter of the O-ring (38) is a safety valve, wherein the this abutting outside diameter side corner (R) of the valve seat (36).

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