VARIABLE BACK-UP RING AND A SEALING STRUCTURE HAVING THE SAME
A variable back-up ring includes: a first half shell; a second half shell having a symmetrical shape to the first half shell; and an inner cavity defined by the first half shell and the second half shell. The first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.
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This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2020-0165648, filed on Dec. 1, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
TECHNICAL FIELDThe present disclosure relates to a variable back-up ring, and more particularly, to a variable back-up ring which is deformable in a radial direction depending on a fluid pressure, i.e., the amount (magnitude) of force acting on an O-ring and/or a back-up ring, and a sealing structure having the same.
BACKGROUNDA fuel cell is an electrochemical cell that converts the chemical energy of a fuel (hydrogen) and an oxidizing agent (oxygen) into electrical energy through redox reactions.
As the perception of environmental crisis and depletion of oil resources has increased, research and development of eco-friendly vehicles such as electric vehicles (EVs) and fuel cell electric vehicles (FCEVs) have actively been conducted.
A fuel cell system is made up of: a fuel cell stack generating electrical energy; a fuel supply system supplying a fuel (hydrogen) to the fuel cell stack; an air supply system supplying oxygen of the air as an oxidizing agent required for electrochemical reaction to the fuel cell stack; and a thermal management system (TMS) removing heat of reaction from the fuel cell stack out of the system and controlling the operating temperature of the fuel cell stack. The fuel cell system generates electricity through the electrochemical reaction between the fuel (hydrogen) and oxygen in the air and removes heat and water as reaction by-products.
The hydrogen supply system is configured to supply hydrogen, which is a relatively high-pressure fluid, to the fuel cell stack. In the hydrogen supply system, a sealing structure including an O-ring and a back-up ring for holding the O-ring may be provided between two connector bodies (e.g., a valve housing and a valve fitting) that match each other, thereby preventing leakage of the high-pressure fluid. The O-ring may create a seal between the two connector bodies, and the back-up ring may minimize a clearance gap between the two connector bodies to prevent the O-ring from entering the clearance gap between the two connector bodies.
When high-pressure hydrogen of 700 bar flows in such a high-pressure fluid system (the hydrogen supply system), a permeation leakage may occur as small-sized hydrogen molecules penetrate into a rubber (polymer) material of the O-ring, A leakage may also occur as cracks are generated in the O-ring due to pressurization/decompression. Specifically, as the hydrogen molecules penetrate into the rubber (polymer) material of the O-ring in the high-pressure hydrogen environment, O-ring swelling may occur. Accordingly, as the O-ring gets caught within the clearance gap, external cracks (extrusion) of the O-ring may occur. In addition, when the volume of hydrogen expands as hydrogen evaporates due to rapid decompression after the swelling of the O-ring, internal cracks (blister) of the O-ring may occur.
The clearance gap between the two connector bodies may be created due to manufacturing tolerances, assembly tolerances, and the like. In order to prevent damage to the sealing structure in the high-pressure fluid system, the back-up ring may minimize the clearance gap between the two connector bodies to thereby prevent damage to the O-ring.
However, as the back-up ring is mainly made of a rigid material such as a synthetic resin material, it is difficult for the back-up ring to minimize the clearance gap between the two connector bodies.
The above information described in this background section is provided to assist in understanding the background of the inventive concept. The background section may include any technical concept which is not considered as the prior art that is already known to those having ordinary skill in the art.
SUMMARYThe present disclosure has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact.
An aspect of the present disclosure provides a variable back-up ring having a shape that is variable or deformable in a radial direction and provides a sealing structure having the same.
According to an aspect of the present disclosure, a variable back-up ring may include: a first half shell; a second half shell having a symmetrical shape to the first half shell; and an inner cavity defined by the first half shell and the second half shell. The first half shell and the second half shell may be deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.
The first half shell and the second half shell may have a reference shape when the fluid pressure is lower than a reference pressure. and
The first half shell and the second half shell may have an expanded shape when the fluid pressure is higher than a reference pressure.
The shape of the first half shell and the second half shell may vary between the reference shape and the expanded shape as the magnitude of the fluid pressure varies. The reference shape may be a shape in which the first half shell and the second half shell contract radially inward. The expanded shape may be a shape in which the first half shell and the second half shell expand radially outward.
According to another aspect of the present disclosure, a sealing structure may include: a first connector body having a groove; a second connector body encompassing the first connector body; an O-ring partially received in the groove of the first connector body; and a variable back-up ring partially received in the groove of the first connector body, holding the O-ring. The variable back-up ring may be deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.
The variable back-up ring may include an inner circumferential surface contacting the groove of the first connector body and an outer circumferential surface facing an inner circumference of the second connector body. A position of the outer circumferential surface of the variable back-up ring may be variable or deformable in the radial direction of the variable back-up ring depending on the magnitude of the fluid pressure.
The shape of the variable back-up ring may be variable or deformable so that the outer circumferential surface of the variable back-up ring may be brought into contact with the inner circumference of the second connector body when the magnitude of the fluid pressure is higher than a reference pressure.
The groove of the first connector body may include a base surface recessed radially inward from an outer circumference of the first connector body, a first side relatively close to a source of the fluid pressure, and a second side opposing the first side. The O-ring may be relatively close to the first side, and the variable back-up ring may be relatively close to the second side.
The above and other objects, features, and advantages of the present disclosure should be more apparent from the following detailed description taken in conjunction with the accompanying drawings:
Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used throughout to designate the same or equivalent elements. In addition, a detailed description of well-known techniques associated with the present disclosure has been omitted in order not to unnecessarily obscure the gist of the present disclosure.
Terms such as first, second, A, B, (a), and (b) may be used to describe the elements in the embodiments of the present disclosure. These terms are only used to distinguish one element from another element, and the intrinsic features, sequence or order, and the like of the corresponding elements are not limited by the terms. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those having ordinary skill in the field of art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings consistent with the contextual meanings in the relevant field of art. Such terms are not to be interpreted as having ideal or excessively formal meanings unless clearly defined as having such in the present application.
The present disclosure relates to a sealing structure for preventing leakage of a high-pressure fluid from a high-pressure fluid system such as a hydrogen supply system of a fuel cell and relates to a back-up ring holding an O-ring in the sealing structure. In particular, according to embodiments of the present disclosure, an outer diameter of the back-up ring may be variable or deformable in a radial direction depending on the magnitude of a force or fluid pressure acting on the O-ring and the back-up ring.
Referring to
The first connector body 1 may have an outer circumference 11. The annular groove 12 may be defined in the outer circumference 11 and the first connector body 1 may have a cylindrical shape. The groove 12 may have a base surface 15 recessed radially inward from the outer circumference 11 of the first connector body 1, a first side 13 relatively close to a source of a fluid pressure, and a second side 14 opposing the first side 13. The base surface 15 may be located between the first side 13 and the second side 14. The groove 12 may have a predetermined depth d. The depth d of the groove 12 may be a distance between the base surface 15 and the outer circumference 11.
The second connector body 2 may have an inner circumference 21 tightly encompassing the outer circumference 11 of the first connector body 1 and the second connector body 2 may have a cylindrical shape. The outer circumference 11 of the first connector body 1 and the inner circumference 21 of the second connector body 2 may face each other. the inner circumference 21 of the second connector body 2 may be spaced apart from the outer circumference 11 of the first connector body 1 by a clearance gap cg. In other words, the clearance gap cg may be defined between the outer circumference 11 of the first connector body 1 and the inner circumference 21 of the second connector body 2.
For example, the first connector body 1 may be a valve fitting of a high-pressure hydrogen valve having a cylindrical shape. The second connector body 2 may be a valve body of the high-pressure hydrogen valve having an opening into which the valve fitting is tightly fitted.
Alternatively, the first connector body 1 and the second connector body 2 may be part of a pressure regulator, a shut-off valve, a check valve, a flow valve, or a pipe fitting.
The O-ring 5 may be an annular seal at least partially received in the groove 12 of the first connector body 1. The O-ring 5 may be relatively close to the first side 13 of the groove 12. The O-ring 5 may be made of at least one material or a mixture of two or more materials among various materials such as acrylonitrile butadiene rubber (NBR), hydrogenated acrylonitrile butadiene rubber (HNBR), fluorocarbon (FPM, FKM, Viton™), ethylene propylene diene monomer (EPDM), neoprene chloroprene (CR), silicone (VMQ, PVMQ), acrylate (ACM) and polyurethane (AU).
The back-up ring 6 may be an annular ring at least partially received in the groove 12 of the first connector body 1. The back-up ring 6 may be relatively close to the second side 14 of the groove 12. Referring to
The outer diameter of the back-up ring 6 may be variable or deformable in the radial direction of the back-up ring 6 depending on the magnitude of the force or fluid pressure acting on the back-up ring 6. Specifically, when the fluid pressure applied between the outer circumference 11 of the first connector body 1 and the inner circumference 21 of the second connector body 2 acts on the O-ring 5 and the back-up ring 6, the back-up ring 6 may expand or contract in a width direction of the back-up ring 6 while contracting or expanding in the radial direction of the back-up ring 6 depending on the magnitude of the fluid pressure.
The back-up ring 6 may include an inner circumferential surface 9a facing the center of the back-up ring 6 and an outer circumferential surface 9b located away from the center of the back-up ring 6. The inner circumferential surface 9a may contact the base surface 15 in the groove 12 of the first connector body 1 and the outer circumferential surface 9b may face the second connector body 2. When the back-up ring 6 contracts or expands in the radial direction of the back-up ring 6 depending on the magnitude of the fluid pressure, the inner circumferential surface 9a of the back-up ring 6 may be supported to the base surface 15 of the groove 12. Accordingly, the position of the inner circumferential surface 9a of the back-up ring 6 may not change and the position of the outer circumferential surface 9b of the back-up ring 6 may be varied. Specifically, the outer circumferential surface 9b of the back-up ring 6 may be spaced apart from the inner circumference 21 of the second connector body 2 (see
Referring to
Referring to
Referring to
The first half shell 6a may face the first side 13 and the second half shell 6b may face the second side 14. In other words, the first half shell 6a and the second half shell 6b may oppose each other. The first half shell 6a may contact the O-ring 5 and the second half shell 6b may contact the second side 14 of the groove 12. As the inner cavity 6c is defined by the first half shell 6a and the second half shell 6b, the inner cavity 6c may be a closed cavity.
When the force or fluid pressure acting on the first half shell 6a and the second half shell 6b is lower than the reference pressure, the first half shell 6a and the second half shell 6b may have a reference shape (see
When the force or fluid pressure acting on the first half shell 6a and the second half shell 6b is higher than the reference pressure, the first half shell 6a and the second half shell 6b may have an expanded shape (see
As described above, the shape of the first half shell 6a and the second half shell 6b may vary between the reference shape and the expanded shape as the magnitude of the force or fluid pressure varies.
Referring to
The first half shell 6a may include a first outer surface 31 facing the outside of the back-up ring 6 and a first inner surface 32 facing the inner cavity 6c. The first outer surface 31 may partially contact the O-ring 5 and the first inner surface 32 may define at least a portion of the inner cavity 6c.
In an initial state in which no fluid pressure or low fluid pressure acts on the back-up ring 6, the first half shell 6a may have the reference shape, which is convex toward the outside of the inner cavity 6c. Referring to
The second half shell 6b may include a second outer surface 33 facing the outside of the back-up ring 6 and a second inner surface 34 facing the inner cavity 6c. The second outer surface 33 may partially contact the second side 14 of the groove 12 and the second inner surface 34 may define at least a portion of the inner cavity 6c.
In the initial state in which no fluid pressure or low fluid pressure acts on the back-up ring 6, the second half shell 6b may have the reference shape, which is convex toward the outside of the back-up ring 6. Referring to
Referring to
The back-up ring 16 may include a first half shell 16a facing the first side 13, a second half shell 16b facing the second side 14, and an inner cavity 16c defined by the first half shell 16a and the second half shell 16b.
The first half shell 16a may contact the O-ring 5 and the second half shell 16b may contact the second side 14 of the groove 12. As the inner cavity 16c is defined by the first half shell 16a and the second half shell 16b, the inner cavity 16c may be a closed cavity.
The first half shell 16a may include a first outer surface 41 facing the outside of the back-up ring 16 and a first inner surface 42 facing the inner cavity 16c. The first outer surface 41 may partially contact the O-ring 5 and the first inner surface 42 may define at least a portion of the inner cavity 16c.
In an initial state in which no fluid pressure or low fluid pressure acts on the back-up ring 16, the first half shell 16a may have a reference shape, which is convex toward the outside of the back-up ring 16. Referring to
The second half shell 16b may include a second outer surface 43 facing the outside of the back-up ring 16 and a second inner surface 44 facing the inner cavity 16c. The second outer surface 43 may partially contact the second side 14 of the groove 12 and the second inner surface 44 may define at least a portion of the inner cavity 16c.
In the initial state in which no fluid pressure or low fluid pressure acts on the back-up ring 16, the second half shell 16b may have a reference shape, which is convex toward the outside of the back-up ring 16. Referring to
As described above, as the first half shell 6a or 16a and the second half shell 6b or 16b are convex in the opposite direction, the shape of the back-up ring 6 or 16 may be easily variable in the radial direction.
As set forth above, according to embodiments of the present disclosure, the shape of the back-up ring may be variable or deformable in the radial direction depending on the magnitude of the fluid pressure acting on the back-up ring and/or the O-ring. The variable back-up ring may expand radially outward in the condition in which the fluid pressure is higher than the reference pressure, thereby completely blocking or minimizing the clearance gap between the first connector body and the second connector body. Thus, the sealing performance between the first connector body and the second connector body may be maximized.
Hereinabove, although the present disclosure has been described with reference to several embodiments and the accompanying drawings, the present disclosure is not limited thereto. The present disclosure and the embodiments may be variously modified and altered by those having ordinary skill in the art to which the present disclosure pertains without departing from the spirit and scope of the present disclosure claimed in the following claims.
Claims
1. A variable back-up ring, comprising:
- a first half shell;
- a second half shell having a symmetrical shape to the first half shell; and
- an inner cavity defined by the first half shell and the second half shell,
- wherein the first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.
2. The variable back-up ring according to claim 1, wherein the first half shell and the second half shell have a reference shape when the fluid pressure is lower than a reference pressure, and
- wherein the reference shape is a shape in which the first half shell and the second half shell contract radially inward.
3. The variable back-up ring according to claim 1, wherein the first half shell and the second half shell have an expanded shape when the fluid pressure is higher than a reference pressure, and
- wherein the expanded shape is a shape in which the first half shell and the second half shell expand radially outward.
4. The variable back-up ring according to claim 2, wherein the shape of the first half shell and the second half shell varies between the reference shape and an expanded shape as the magnitude of the fluid pressure varies.
5. A sealing structure, comprising:
- a first connector body having a groove;
- a second connector body encompassing the first connector body;
- an O-ring partially received in the groove of the first connector body; and
- a variable back-up ring partially received in the groove of the first connector body, holding the O-ring, the variable back-up ring being deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.
6. The sealing structure according to claim 5, wherein the variable back-up ring includes an inner circumferential surface contacting the groove of the first connector body and an outer circumferential surface facing an inner circumference of the second connector body, and
- wherein a position of the outer circumferential surface of the variable back-up ring is variable in the radial direction of the variable back-up ring depending on the magnitude of the fluid pressure.
7. The sealing structure according to claim 5, wherein the shape of the variable back-up ring is variable so that the outer circumferential surface of the variable back-up ring is brought into contact with the inner circumference of the second connector body when the magnitude of the fluid pressure is higher than a reference pressure.
8. The sealing structure according to claim 5, wherein the groove of the first connector body includes a base surface recessed radially inward from an outer circumference of the first connector body, a first side relatively close to a source of the fluid pressure, and a second side opposing the first side,
- wherein the O-ring is relatively close to the first side, and
- wherein the variable back-up ring is relatively close to the second side.
Type: Application
Filed: Oct 13, 2021
Publication Date: Jun 2, 2022
Applicants: HYUNDAI MOTOR COMPANY (Seoul), KIA CORPORATION (Seoul)
Inventor: Byung Ryeol Lee (Yongin-si)
Application Number: 17/500,693