GB2158529A

GB2158529A - Compound sealing ring for threaded closure

Info

Publication number: GB2158529A
Application number: GB08511908A
Authority: GB
Inventors: Adriano Albertini
Original assignee: Metal Work SpA
Current assignee: Metal Work SpA
Priority date: 1984-05-10
Filing date: 1985-05-10
Publication date: 1985-11-13
Also published as: FR2564168A3; GB8511908D0; IT8421749V0; DE8513179U1; ES286515U; FR2564168B3; ES286515Y

Abstract

A seal assembly for components of pneumatic or hydraulic circuits, said components being provided with a threaded protruding portion and annular generally flat abutment projecting part, said seal assembly being comprised of an annular element with a generally square-shaped cross- section, said annular element having the inwardly faced side provided with a peripheral projecting portion located near one of the flat faces so as to provide an abutment for an O-ring seated around said threaded protruding portion and within said annular element, the transversal thickness of said annular element being same as the height of said O-ring received in said annular element when said O-ring is compressed to effect the sealing between two brought closer surfaces. <IMAGE>

Description

SPECIFICATION Seal for components of pneumatic or hydraulic circuits Various types of seals to be interposed between two elements, in particular a threaded member to be screwed into a corresponding seat, are known.

One type of such seal is known under the name of "O-ring" because of its toroidal shape, and is very commonly used for its excellent behaviour from several points of view, as is well known to those skilled in the art.

A correct utilization of this type of seal on threaded members, such as spigots, plugs, etc.

requires however a machined seat to partially receive the O-ring, in order that said O-ring is not allowed to get out the correct position and it is not expelled by the approaching surfaces which are rotating, and thus originate a mutual movement which causes shearing stress on the seal which is liable to shift owing to its circular cross section. In addition, a requirement of this type of seal is the need of a correct tightening of the elements holding the seals therebetween, in order to avoid on one side deformations insufficient and unable to guarantee the required fluid tightness, and on the other side excessive deformations liable to damage or even break the elastomeric material of the seal.

The aim of the invention is to provide a composite seal which permits to obtain an optimum exploitation of the excellent sealing characteristic of O-rings on threaded elements, without requiring any special configuration for said elements in order to receive this type of seal.

According to the invention, the sealing assembly is comprised on an annular element with a generally square-shaped cross-section, said annular element having the inwardly face side provided with a peripheral projecting portion located near one of the flat faces so as to provide an abutment for an O-ring located within the annular element, the transversal thickness of said annular element being same as the height of said O-ring received in said annular element when said O-ring is compressed to effect the sealing between two brought closer surfaces.

The objects and characteristics of the invention will appear more clearly from the following description of one embodiment therof, taken together with the accompanying drawing, in which: Fig. 1 and Fig. 2 show a diametral sectional view of a plug on which a seal according to the invention is mounted, in a free position and in a working and compressed position, respectively.

A plug 10, conventional per se, is shown in the figures. This plug is to be considered as a general example of a threaded element to be screwed in a seat with an interposed seal; any other type of union or nipple has in fact similar configuration, as far as the existence of a threaded cylindrical part 11, recessed near an abutment surface 12, is concerned.

According to the invention, it is thus provided an annular element 13 of a relatively rigid material, metallic or non metallic, with a projecting part 14 on its inner face. On said annular element a conventional O-ring 15 is seated. It is to be noted that the thickness of the annular element 13 is less than the diameter of the cross-section of the O-ring, said thickness being equal to the corresponding dimension the O-ring will take in order to produce a satisfactory seal without any harmful excess of deformation. Such compressed condition of the 0ring is illustrated in Figure 2, and in this figure the plug is shown only partially screwed on a seat 16 of a typical member 17 (only partially shown).

The advantages of the above described seal assembly will easily appear.

The O-ring maintains the rigid element 13 in the correct position by means of the inner peripheral projection 14 provided on said element, and the installation of the assembly on a typical threaded cylindrical part of current production is simple and very fast.

During the tightening operation the element 13 contains the O-ring peripherically, avoiding any undue displacement and equalizing the compression, thus implementing a limiting device against deformations by restraining the potential approaching of the two surfaces holding the seal therebetween. The user can therefore tighten the threaded part up to the sudden increase of resistance due to the abutment of the element 13, without any need to evaluate, with inherent difficulty, the small and graduated increases of resistance due to the elastic deformation of the 0ring during the screwing operation. It is thus assured both the correct deformation of the O-ring and the complete screwing on.

It is obvious that the specific shape and dimensions of the elements comprising the seal can be varied, as well as the materials utilized therefor, without departing from the spirit and object of the invention.

1. A seal assembly comprising an O-ring and an annular element surrounding and in contact with the outer periphery of the O-ring, the annular element having an inwardly directed projection with which one side of the O-ring is engaged, the other side of the O-ring protruding axially from the annular element when the O-ring is uncompressed.

2. A seal assembly according to claim 1, wherein said projection is annular.

3. An assembly according to claim 2, wherein said projection has a generally conical surface which engages the O-ring.

4. An assembly according to claim 1,2 or 3, wherein the inward extent of the projection is less than the radial thickness of the O-ring when the 0ring is uncompressed.

5. An assembly according to claim 1, 2 or 3, wherein the inward extent of the projection is less than half the radial thickness of the O-ring when the O-ring is uncompressed.

6. An assembly according to any preceding claim, wherein said projection is located at an end of the annular element, said end of the annular element having a plane radial surface comprised partly by a surface of the projection.

7. An assembly according to any preceding claim,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Seal for components of pneumatic or hydraulic circuits Various types of seals to be interposed between two elements, in particular a threaded member to be screwed into a corresponding seat, are known. One type of such seal is known under the name of "O-ring" because of its toroidal shape, and is very commonly used for its excellent behaviour from several points of view, as is well known to those skilled in the art. A correct utilization of this type of seal on threaded members, such as spigots, plugs, etc. requires however a machined seat to partially receive the O-ring, in order that said O-ring is not allowed to get out the correct position and it is not expelled by the approaching surfaces which are rotating, and thus originate a mutual movement which causes shearing stress on the seal which is liable to shift owing to its circular cross section. In addition, a requirement of this type of seal is the need of a correct tightening of the elements holding the seals therebetween, in order to avoid on one side deformations insufficient and unable to guarantee the required fluid tightness, and on the other side excessive deformations liable to damage or even break the elastomeric material of the seal. The aim of the invention is to provide a composite seal which permits to obtain an optimum exploitation of the excellent sealing characteristic of O-rings on threaded elements, without requiring any special configuration for said elements in order to receive this type of seal. According to the invention, the sealing assembly is comprised on an annular element with a generally square-shaped cross-section, said annular element having the inwardly face side provided with a peripheral projecting portion located near one of the flat faces so as to provide an abutment for an O-ring located within the annular element, the transversal thickness of said annular element being same as the height of said O-ring received in said annular element when said O-ring is compressed to effect the sealing between two brought closer surfaces. The objects and characteristics of the invention will appear more clearly from the following description of one embodiment therof, taken together with the accompanying drawing, in which: Fig. 1 and Fig. 2 show a diametral sectional view of a plug on which a seal according to the invention is mounted, in a free position and in a working and compressed position, respectively. A plug 10, conventional per se, is shown in the figures. This plug is to be considered as a general example of a threaded element to be screwed in a seat with an interposed seal; any other type of union or nipple has in fact similar configuration, as far as the existence of a threaded cylindrical part 11, recessed near an abutment surface 12, is concerned. According to the invention, it is thus provided an annular element 13 of a relatively rigid material, metallic or non metallic, with a projecting part 14 on its inner face. On said annular element a conventional O-ring 15 is seated. It is to be noted that the thickness of the annular element 13 is less than the diameter of the cross-section of the O-ring, said thickness being equal to the corresponding dimension the O-ring will take in order to produce a satisfactory seal without any harmful excess of deformation. Such compressed condition of the 0ring is illustrated in Figure 2, and in this figure the plug is shown only partially screwed on a seat 16 of a typical member 17 (only partially shown). The advantages of the above described seal assembly will easily appear. The O-ring maintains the rigid element 13 in the correct position by means of the inner peripheral projection 14 provided on said element, and the installation of the assembly on a typical threaded cylindrical part of current production is simple and very fast. During the tightening operation the element 13 contains the O-ring peripherically, avoiding any undue displacement and equalizing the compression, thus implementing a limiting device against deformations by restraining the potential approaching of the two surfaces holding the seal therebetween. The user can therefore tighten the threaded part up to the sudden increase of resistance due to the abutment of the element 13, without any need to evaluate, with inherent difficulty, the small and graduated increases of resistance due to the elastic deformation of the 0ring during the screwing operation. It is thus assured both the correct deformation of the O-ring and the complete screwing on. It is obvious that the specific shape and dimensions of the elements comprising the seal can be varied, as well as the materials utilized therefor, without departing from the spirit and object of the invention. CLAIMS

2. A seal assembly according to claim 1, wherein said projection is annular.

7. An assembly according to any preceding claim, wherein the annular element is of generally square cross-section.

8. An assembly according to any preceding claim, wherein the annular element is rigid relative to the O-ring.

9. An assembly according to claim 8,wherein the annular element is metal.

10. An assembly according to claim 8, wherein the annular element is non-metal.

11. A component having a protrusion and a generally flat radially extending abutment surface surrounding said protrusion, and a seal assembly according to any preceding claim surrounding said protrusion with the projection of the annular element adjacent the abutment surface.

12. A component according to claim 11, wherein said protrusion is threaded.

13. A seal assembly for components of pneumatic or hydraulic circuits, said components being provided with threaded protruding portion and an annular generally flat abutment projecting part, said seal assembly being comprised of an annular element with a generally square-shaped crosssection, said annular element having its inwardly facing side provided with a peripheral projecting portion located near one of the flat faces so as to provide an abutment for an O-ring seated around said threaded protruding portion and within said annular element, the transverse thickness of said annular element being the same as the height of said O-ring received in said annular element when said O-ring is compressed to effect sealing.

14. A seal assembly substantially as herein described with reference to the accompanying drawings.

15. A oomponent having a seal assembly mounted thereon substantially as herein described with reference to the accompanying drawings.