FR2846477A1 - Cable entry gland with external sealing ring protected by a locking ring for use in explosive environments, uses seal clamped over cable entry to gland and sealing ring under locking ring to seal gland assembly - Google Patents

Abstract

The cable gland (100) has a hollow body (110) that attaches to the wall of an electrical equipment housing, and an outer sleeve (120) that screws onto the hollow body. A seal (191,192) fits over the cable where it enters the gland, and is covered by a nut (122). A sealing ring (130) fits between the locking ring (140) and the outer sleeve to seal the gland mounting.

Description

i The present invention relates generally to the inputs of

  cable, i.e. devices intended to equip all types of devices

  electrical for the passage of electrical cables necessary for their service.

  The invention relates more particularly to those of these devices which, commonly known as cable glands, comprise a hollow body to be secured

  to said device, a cap device, screwed onto the hollow body, having a drilled bottom for the passage of the cable, sealing and cable holding means positioned in said pierced bottom of the cap device and intended to be applied to said cable passing through the assembly, as well as an outer sealing ring 10.

  The invention finds a particularly advantageous application in the

  field of the chemical, petroleum or sugar industry to produce sealed cable entries in electrical devices, such as electrical boxes or cabinets, operating in an explosion risk atmosphere where the flash point is relatively low.

  In these areas of application, electrical devices can be

  designed in such a way that their envelope resists a possible explosion occurring inside it. They can also be designed in such a way that their content, placed inside their external envelope, itself resists possible explosion.

  In the first case, the cable gland allowing the connection of the cable to the electrical device must also resist an explosion occurring at the level of the electrical device so as to avoid propagation of the explosion. The external sealing ring of such a cable gland makes it possible to avoid possible corrosion of the internal parts of the latter, and in particular of the metal reinforcement of the cable, by the aggressive external environment in which it operates. Already known, in particular from documents EP 0 945 947 and WO 01/54245, a cable gland of the aforementioned type in which the outer sealing ring is secured to said hollow body and has a lip which is applied freely against the surface. external of said hat device to

  near an edge of one of its ends.

  The main drawback of such a cable gland is that its easily accessible outer sealing ring is in no way protected from

  the external environment and can easily degrade.

  There are also known cable glands in which the outer sealing ring 5 is housed in an annular groove provided on the outer surface of said hollow body, and, when the cap device is screwed onto it, it engages in the inside said hat device by applying against

the inner surface of it.

  Here, the outer sealing ring is well protected from the aggressiveness of the external environment in which the cable gland operates, but it is difficult to access and requires the complete dismantling of the cable gland to check its condition, which represents a cost. maintenance and labor

not negligible.

  In order to remedy the drawbacks of the aforementioned prior art, the invention provides a new cable gland, as defined in the introduction, in which the outer sealing ring is protected from the aggressive external environment. in which the cable gland operates while being easily

accessible to the user.

  More particularly, according to the invention, the cable gland is characterized in that said outer sealing ring is housed in a nut screwed onto said cap device so that said outer sealing ring

  is applied against an edge of said end of the cap device.

  Thus, the user can easily check the condition of the outer seal ring during use of the cable gland by simply unscrewing the nut which permanently protects the outer seal ring from

external aggressions.

  In particular, when the stuffing box is used at sea, on an oil platform, the outer sealing ring avoids the introduction of water inside the stuffing box and the nut protects said sealing ring 30 for mechanical attack, ultraviolet rays and

chemical flows.

  Other non-limiting and advantageous characteristics of the invention are as follows: - said cap device comprises an intermediate hollow body screwed onto said hollow body and a cap, screwed to one end of said intermediate hollow body, provided with said drilled bottom, said nut housing said outer seal ring being screwed onto the other end of said intermediate hollow body so as to apply said outer seal ring against the edge of said other end of the intermediate hollow body; - Said intermediate hollow body projecting from its external surface an annular rim forming a stop for screwing said nut so as to limit the compression of the outer sealing ring when screwing said nut; - Said annular rim is formed by the edge of a ring with cut sides formed on the external surface of said intermediate hollow body; - said hollow body and said intermediate hollow body are substantially tubes whose axes are aligned; - Said nut has a knurled outer surface;

  - Said nut is made of metallic material.

  the intermediate hollow body internally houses a male element axially pierced for the passage of the cable and a part of the external surface of which is conical, and a female element whose internal surface is conical complementary to that of said male element, said internal surface of said female element pressing against said part of the external surface of said male element to pinch said metallic armature of the stripped cable, and said hollow body has internally a funnel surface against which an internal conical sealing ring is supported pushed by said male element; - An anti-friction ring is provided interposed between said inner sealing ring and said male element. 30 - the intermediate hollow body internally houses a male element axially pierced for the passage of the cable and of which a part of the external surface is of conical shape, and a female element whose internal surface is of conical shape complementary to that of said male element, said internal surface of said female element pressing against said part of the external surface of said male element to pinch said metal frame of the stripped cable, and said hollow body internally houses a tubular sleeve, for the passage of the conductors of said stripped cable, one of which funnel-shaped end accommodates one end of said male member, said hollow body having internally a funnel surface against which bears said funnel-shaped end of said tubular sleeve; - Said female element is in the form of a ring; and

  - Said sealing and cable holding means comprise an O-ring seal with which is associated an anti-friction ring.

  Furthermore, according to a particularly advantageous characteristic of the cable gland according to the invention, said hollow body has an interior arrangement adapted to receive either a conical interior sealing ring, or

  a tubular socket for the passage of the conductors of said stripped cable.

  Preferably, said hollow body is generally a tube of axis X

  with a cylindrical inner surface of revolution around the X axis which opens at one end onto an inner funnel surface.

  Thus, advantageously, with the invention, the user can easily transform a cable gland with a conical inner sealing ring into a cable gland with mass filling, and vice versa, by simply interchanging two elements of the cable gland, know the inner conical sealing ring 25 and the male element on the one hand, and the tubular sleeve and the element

male on the other hand.

  Moreover, with this same idea of interchangeability, the invention proposes a range of cable glands comprising, on the one hand, a cable gland in which the intermediate hollow body internally houses a male element pierced axially for the passage of the cable and of which a part of the external surface is of conical shape, and a female element whose internal surface is of conical shape complementary to that of said male element, said internal surface of said female element pressing against said part of the external surface of said male element for pinching said metal armature of the stripped cable, and in which said hollow body internally has a funnel surface against which an internal conical sealing ring pressed by said male element, and, on the other hand, a press mass-filled packing in which the intermediate hollow body internally houses a male element pierced axially in. ur the passage of the cable and of which a part of the external surface is of conical shape, and a female element whose internal surface is of conical shape complementary to that of said male element, said internal surface of said female element pressing against said part of the external surface of said male element for pinching said metallic armature of the stripped cable, and in which said hollow body internally houses a tubular sleeve for the passage of the conductors of the stripped cable, one funnel-shaped end of which receives one end of said male element, said hollow body having internally a funnel surface against which said funnel-shaped end of the tubular sleeve bears, the two cable glands comprising a set of identical parts of which the hollow body, the intermediate hollow body, the hat, the means of sealing and maintaining

  cable positioned in the pierced bottom of the cap and the female element.

  Such a range of cable glands is economical to produce.

  The description which follows with reference to the appended drawings, given at

  title of nonlimiting examples, will make it clear what the invention consists of

  and how it can be achieved.

  In the accompanying drawings: - Figure 1 is a schematic exploded perspective view of a first embodiment of the cable gland according to the invention; - Figure 2 is a schematic exploded perspective view of a second embodiment of the cable gland according to the invention; - Figure 3 is a schematic perspective view of the assembled gland of Figure 1; - Figure 4 is a schematic view in axial section of the gland of Figure 1 assembled, secured to a wall of an electrical device and crossed by a cable; and - Figure 5 is a schematic view in axial section of the gland of Figure 2 assembled, secured to a wall of an electrical device and

crossed by a cable.

  The figures show two embodiments of a cable gland according to the invention. Each cable gland 100, 100 'is intended for the connection of a cable to an electrical appliance 1 of which only part of its casing

  external is shown in Figures 4 and 5.

  The two cable glands 100, 100 'shown in Figures 1 and 2 10 are particularly suitable for connecting a cable 10 to armature

metallic 12.

  Advantageously, these two cable glands 100, 100 ′ have common identical elements which will be described below with reference to

Figures 1, 3 and 4.

  More particularly, in FIGS. 1, 3 and 4, there is shown a cable gland 100 intended for connecting a cable 10 to an electrical appliance 1, for example an electrical cabinet or cabinet, the external envelope of which is designed so to resist a possible explosion occurring inside

of it.

  Here the cable gland 100 shown in Figures 1, 3 and 4 is a

  cable gland said to internal seal.

  More particularly, the cable gland 100 shown in FIGS. 1, 3 and 4 comprises a hollow body 110 to be secured to the electrical appliance 1. This hollow body 110 is generally a tube of axis X. It internally has a surface cylindrical of revolution around the X axis which opens at one end

on a funnel surface 115.

  The hollow body 110 comprises, at one end 111, a thread intended to be screwed into a thread 2 carried by the outer casing of the device

electric 1 considered.

  The hollow body 110 carries, on its external surface, a ring 114 with cut sides, here a hexagon ring formed on said external surface, of which a section 11A, located on the side of its end 111, forms a screwing stop.

  of the hollow body 110 in the internal thread 2 of the electrical appliance 1.

  The hollow body 110 has, at its other end, on the one hand, on its

  external surface, a thread 112, and, on the other hand, on its internal surface, a thread 113 for its attachment to the other elements of the cable gland 100.

  In this regard, the cable gland 100 includes a cap device 120 screwed onto the hollow body 110. This cap device 120 here consists of two parts, namely an intermediate hollow body 121 screwed onto said hollow body 110 and a screw cap 122 on one end 121B of said intermediate hollow body 121 and provided with a

  bottom 122A drilled for cable passage 10.

  More particularly, the intermediate hollow body 121 is generally a tube whose axis coincides with the axis of the hollow body 110 when the latter is screwed onto said hollow body 110. This intermediate hollow body 121, also commonly called press nut -throat, comprises, on its internal surface, at a distance from its end edges, a thread (not visible in the figures) 15 intended to cooperate with the thread 112 provided on the external surface of the body

  hollow 110 for its connection by screwing to the latter.

  In addition, the cap device 120 comprises a cap 122 which has the overall shape of a nut, this is why it is commonly called chamber nut, and which is screwed to one end 121B of said intermediate hollow body 121 For this, the end 121B concerned of said body

  intermediate hollow 121 has, on its external surface, a thread.

  The cap 122 has, internally, a chamber intended for

  accommodate sealing and cable retention means 191, 192.

  Here, said cable sealing and holding means comprise a toric sealing ring 191 housed in said cap and surrounding the outer sheath of the cable 10 with which is an anti-friction ring 192, here conical in shape, intended to be position in a conical seat

  complementary formed in the bottom 122A of the cap 122.

  As shown more particularly in FIG. 4, when the cap 30 122 is screwed onto the intermediate hollow body 121, the toric sealing ring 191, positioned in abutment against the anti-friction ring 192, is applied against the edge 121 E of the corresponding end 121 B of said intermediate hollow body

  121 so as to be compressed against the outer sheath 11 of the cable 10.

  Of course, the cap 122 has an axis coincident with the axis X

  when it is screwed onto the intermediate hollow body 121.

  Furthermore, the cable gland 100 includes an outer sealing ring 130, positioned on said hollow body 110, capable of establishing a seal at one end of said cap device 120. In particular said outer sealing ring 130 establishes a seal at

  level of one end 121A of the intermediate hollow body 121.

  This outer sealing ring 130 is here an O-ring washer which is advantageously housed in a nut 140 screwed onto the cap device so that said outer sealing ring 130 is pressed against an edge 121D of said end 121A of the hollow body. intermediate 121 of said device

hat 120.

  More particularly, the nut 140 has, on its internal surface, an annular groove (not visible in the figures) receiving the outer sealing ring 130 as well as a thread 141 allowing its screwing on the end

  121A of the intermediate hollow body 121.

  The intermediate hollow body 121 projecting from its external surface an annular flange 121F constituted by the edge of a cut-edge ring 121C formed on said external surface of said intermediate hollow body 121, this annular flange 121F forming a screwing stop for said nut 140 so as to limit the compression of the outer sealing ring 130 when said nut is screwed against the edge 121D of the end 121A of the hollow body

intermediate 121.

  Thus, advantageously, the outer sealing ring 130 ensures by compression a perfect seal between the outside and the inside of the cable gland while being protected by the nut 140. A simple unscrewing of the nut 140 allows a user to check the condition of the outer sealing ring 130 during operation of the cable gland 100 without having to

  intervene on the other parts of it.

  The nut 140, like the hollow body 110, the intermediate hollow body and the cap 122, is made of metallic material, for example brass

nickel plated.

  Said nut 140 has a knurled outer surface 142 to allow the user to take it in hand more easily for its

  screwing on said intermediate hollow body 121.

  Furthermore, according to the particular embodiment shown in FIGS. 1, 3 and 4, the cable gland 100 includes a male element 150 housed at

  the interior of the intermediate hollow body 121.

  This male element 150 is pierced axially for the passage of the cable 10 and has an external surface of which a part 151 is of conical shape. Another part 154 of its cylindrical external surface has a thread 10 intended to cooperate with the thread 113 of said hollow body 110 for its attachment to the latter. The cylindrical external surface 154 is separated from the conical external surface 151 of said male element 150 by a hexagonal ring 153 formed on said external surface of said male element. The front edge of this hexagonal ring 153 forms a stop for screwing said male element 150 into said hollow body 110 while coming to bear against the edge 11 2A of the end

  112 corresponding to said hollow body 110.

  As shown in FIGS. 1 and 4, the intermediate hollow body 121 of the cable gland 100 also houses a female element 160 whose internal surface 161 is of conical shape complementary to the conical external surface 20 151 of said male element 150. Said internal surface 161 of said female element is intended to be applied against the conical external surface 151 of said

  male element 150 for pinching said metal frame 12 of the stripped cable.

  To increase the pinching effect of the metal frame 12 produced by the cooperation of the female element 160 with the male element 150, the conical external surface 151 of the male element 150 has annular grooves 152, and the internal conical surface 161 of said female element 160 also comprises at least one annular groove 161A which comes to bear against the metal frame 12 of the cable 10 when the female element 160 is engaged

on the male element 150.

  Pinching the metal frame 12 of the cable 10 by the male 150 and female 160 elements, made of metallic material, makes it possible to connect the said cable to earth via the various metallic elements of the cable gland.

  themselves electrically grounded.

  In addition, an internal conical sealing ring 170 pushed by the male element 150 screwed into said hollow body 110 bears against the

  funnel surface 115 inside the latter.

  An annular anti-friction ring 180 5 is advantageously provided interposed between said conical inner sealing ring 170 and said male element 160 to prevent, when the latter is screwed into said hollow body 110,

  damage the inner sealing ring 170.

  The internal conical sealing ring 170 pushed by said male element 150 screwed into said hollow body comes to apply tightly against the internal sheath of the stripped cable 10 to establish an internal sealing at the

  cable inner sheath level 10.

  Of course, inside the inner sheath of the cable 10 run the

  conductors (not shown in Figure 4) which will be connected to the various electrical devices placed inside the electrical device 1 15 concerned.

  The stripped part of the cable 10 therefore runs from the entry of the male element 150 to the exit of the hollow body 110 to open out inside

the electrical appliance 1.

  The female element 160 is here in the form of a ring but, according to another embodiment not shown, it could be provided that it is formed in one piece with the cap device, and, in particular, with the

intermediate hollow body 121.

  In FIGS. 2 and 5, an alternative embodiment of the cable gland according to the invention is shown, which constitutes a cable gland 100 ′ with mass filling particularly suitable for being connected to an electrical appliance 1 in which the electrical equipment are imprisoned in

  a resin type material to avoid exploding.

  This cable gland 100 ′ advantageously includes elements identical to the cable gland 100 which will not be described here again 30 times. These identical elements include the hollow body 110, the intermediate hollow body 121, the cap 122, the sealing and cable holding means 191.192 positioned in the bottom 122A pierced with the cap 122 and the element

female 160.

  On the other hand, the cable gland 100 'comprises, in place of the conical inner sealing ring 170, a tubular sleeve 170' for the passage of the conductors 14 of the cable 10 completely stripped (from which the internal sheath 13 has been removed ), one end 171 'of which is funnel-shaped comes to bear against the funnel surface 115 formed inside the hollow body 110. The interior of this tubular sleeve 160 is intended to be filled with

  the resin so as to trap the conductors 14 circulating in it and avoid the propagation of a possible explosion produced inside the electrical appliance 1 o the conductors 14 will be connected to the electrical equipment 10 concerned.

  In addition, the cable gland 100 'has another male element 150' also pierced axially for the passage of the cable and one end 154 'of cylindrical shape is intended to engage in the end 171' in shape

  of funnel of the tubular sleeve 170 '.

  This male element 150 ′ also has a part 151 ′ of its external surface, situated beyond a ring formed on the external surface of this, which has a conical shape complementary to the internal conical surface 161 of the female element 160 in the form of a ring, the female element 160 and the male element 150 'being intended to cooperate with each other to pinch, as in the case of the cable gland 100, the metal frame 12 of the cable

  stripped for connection to earth.

  Said conical external surface 151 'of the male element 150' comprises

  also annular grooves 152 ′ intended, with the annular groove 161A of the conical internal surface 161 of the female element, to reinforce the pinching effect 25 of the metal frame 12 of the cable 10.

  The male elements 150, 150 'as well as the female element 160 are also made of metallic material, for example brass plated with nickel, just like the other metallic elements of the cable glands 100,'. The various seals or sealing rings are made of material

  rubber type elastomer as usual.

  Thus, quite advantageously said hollow body 110 of the cable gland according to the invention has an interior arrangement adapted to receive either an interior conical sealing ring 170, or a tubular sleeve 170 ′ for the passage of the conductors of said stripped cable. A user can then easily transform a cable gland 100 with an inner sealing ring

  tapered into a stuffing box 100 'tube fitting with mass filling.

  Moreover, particularly advantageously, the two cable glands 100, 100 'are part of a range; they are easily transformable by interchanging their different elements, namely the O-ring seal 170 and the male element 150 for one, and the tubular bush 170 'and the male element 150' for the other, the elements common of these cable glands 100, 100 '10 being intended to cooperate with the specific elements thereof. Finally, the anti-friction rings 180, 192 are made of material

  synthetic, for example based on polyamide resin.

  The present invention is in no way limited to the embodiments

  described and shown, but a person skilled in the art will know how to make any variant 15 in accordance with his spirit.

Claims (15)

  1. Cable gland (100; 100 ') for the connection of a cable (10) to an appliance (1), comprising a hollow body (110) to be secured to said appliance (1), a cap device (120), screwed onto the hollow body (110), having a bottom (122A) pierced for the passage of the cable, sealing and cable holding means (191, 192) positioned in said bottom (122A) pierced with the cap device ( 120) and intended to be applied to said cable passing through the assembly, as well as an outer sealing ring (130), positioned on said hollow body (110), capable of establishing a seal at one end ( 121A) of said cap device (120), characterized in that said outer sealing ring (130) is housed in a nut (140) screwed onto said cap device (120) so that said outer sealing ring (130 ) applies against   an edge (121D) of said end (121A) of the cap device (120).   2. Cable gland (100; 100 ') according to claim 1, characterized in that said cap device (120) comprises an intermediate hollow body (121) screwed onto said hollow body (110) and a cap (122), screwed at one end   (121B) of said intermediate hollow body (121), provided with said drilled bottom (122A), said nut (140) housing said outer sealing ring (130) being screwed onto the other end (121A) of said intermediate hollow body (121 ) so as to apply said outer sealing ring (130) against the edge (121D) of said other end (121A) of the intermediate hollow body (121).   3. Cable gland (100; 100 ') according to claim 2, characterized in   that said intermediate hollow body (121) projecting from its external surface an annular flange (121F) forming a screw stop for said nut (140) so as to limit the compression of the outer sealing ring 25 (130) during screwing said nut.   4. Cable gland (100; 100 ') according to claim 3, characterized in that said annular flange (121F) is formed by the edge of a cut-off ring (121C) formed on the external surface of said intermediate hollow body (121).   5. Cable gland (100; 100 ') according to one of claims 2 to 4,   characterized in that said hollow body (110) and said intermediate hollow body   (121) are substantially tubes whose axes are aligned.   6. Cable gland (100; 100 ') according to one of claims 1 to 5, 5 characterized in that said nut (140) has an external surface (142) knurled.   7. Cable gland (100; 100 ') according to one of claims 1 to 6,   characterized in that said nut (140) is made of metallic material.   8. Cable gland (100) according to one of claims 1 to 7, for a cable (10) with a metal frame (12), characterized in that the hollow body   intermediate (121) internally houses a male element (150) pierced axially, for the passage of the cable and of which a part (151) of the external surface is of conical shape, and a female element (160) of which the internal surface (161) is of conical shape complementary to that of said male element (150), said internal surface (161) of said female element (160) pressing against said part (151)   of the external surface of said male element (150) for pinching said metal frame (12) of the stripped cable, and in that said hollow body (110) has internally a funnel surface (115) against which a sealing ring is supported inner (170) conical pushed by said male element 20 (150).   9. Cable gland (100) according to claim 8, characterized in that there is provided an anti-friction ring (180) interposed between said sealing ring   interior (170) and said male element (150).   10. Cable gland (100 ') according to one of claims 1 to 7, for a cable (10) with a metal frame (12), characterized in that the hollow body   intermediate (121) internally houses a male element (150 ') pierced axially for the passage of the cable and of which a part (151') of the external surface is conical in shape, and a female element (160) whose internal surface is of conical shape complementary to that of said male element, said internal surface (161) of said female element (160) pressing against said part (151 ') of the external surface of said male element (150') to pinch said metal frame (12 ) of the stripped cable, and in that said hollow body (110) internally houses a tubular sleeve (170 '), for the passage of the conductors of said stripped cable, one end (171') of which is funnel-shaped receives one end ( 154 ') of said male element (150'), said hollow body (110) having internally a funnel surface (115) against which said end (171 ') bears   funnel-shaped of said tubular sleeve (170 ').   11. Cable gland (100; 100 ') according to one of claims 9 or 10,   characterized in that said female element (160) is in the form of a ring.   12. Cable gland (100; 100 ') according to one of claims   above, characterized in that said cable sealing and holding means 10 comprise a toric sealing ring (191) to which is   associated with an anti-friction ring (192).   13. Cable gland (100; 100 ') according to one of claims 8 and 10,   characterized in that said hollow body (110) has an internal arrangement adapted to receive either an internal conical sealing ring (170) or a tubular sleeve (170 ') for the passage of the conductors of said stripped cable.   14. Cable gland (100; 100 ') according to claim 13, characterized in that said hollow body is generally a tube of axis X with a cylindrical inner surface of revolution around the axis X which opens to a   end on an inner funnel surface (115).   15. Range of cable glands including a cable gland (100)   according to claim 8 and a mass-filled cable gland (100 ') according to claim 10 which comprise a set of identical parts which include the hollow body (110), the intermediate hollow body (121), the cap (122 ), the sealing and cable holding means (191, 192) positioned in the pierced bottom of the cap and the female element (160).