CN203774010U - Cable shield improving structure for preventing common-mode interference - Google Patents
Cable shield improving structure for preventing common-mode interference Download PDFInfo
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- CN203774010U CN203774010U CN201420132644.1U CN201420132644U CN203774010U CN 203774010 U CN203774010 U CN 203774010U CN 201420132644 U CN201420132644 U CN 201420132644U CN 203774010 U CN203774010 U CN 203774010U
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Abstract
Provided is a cable shield improving structure for preventing common-mode interference. The cable shield improving structure comprises an inner shielding layer, at least two power lines, at least one group of signal lines, at least one inner ground wire, an inner insulating layer, an outer shielding layer, and a surface protection layer. The inner shielding layer is used in shielding. The at least two power lines are used for transmitting electric energy. The outer rim of each signal line is provided with an insulating layer and the signal lines are used for transmitting signals. The at least one inner ground wire is arranged beside the signal lines. The inner insulating layer wraps a same group of signal lines or wraps a same group of signal lines and the inner ground wire. The outer shielding layer is arranged on the periphery of the inner shielding layer and is used in shielding. The surface protection layer is arranged on the periphery of the outer shielding layer. A mylar slice with an electric insulation effect is arranged between the inner shielding layer and the outer shielding layer such that the inner shielding layer and the outer shielding layer are electrically insulated and not communicated.
Description
Technical field
The utility model relates to a kind of electric cable shield structure field, espespecially a kind of cable shield structure-improved that prevents that common-mode signal from disturbing.
Background technology
As shown in Figure 3, existing difference mode signal (Differential-Mode Single) is called again induction and symmetric signal etc. between norm, string mould, line, and in two line cable transmission loops, each line-to-earth voltage represents with symbol V1 and V2.Difference mode signal component is VDIFF.Pure difference mode signal is V1=-V2, its equal and opposite in direction, and 180 ° of phase phasic differences, VDIFF=V1-V2, because V1 and V2 are symmetrical over the ground, so ground does not have electric current to flow through online, the circuit of difference mode signal is as shown in Figure 3.Load is flow through in all differential-mode currents (IDIFF) entirely.Differential mode interference invade to come and go two signal line, and direction is square consistent with signal code, and it is a kind of is to be produced by signal source, and another kind is by electromagnetic induction, to be produced in transmitting procedure, and it is together with train of signal and same-phase, and such interference is generally difficult to inhibition.
Common-mode signal (Common-Mode Single) is called again induced signal or asymmetric signal over the ground, and common-mode signal components is Vcom, and pure common-mode signal is: Vcom=V1=V2, and equal and opposite in direction, phase difference is 0 °.V3＝0。The circuit of common-mode signal as shown in Figure 4.Interference signal is invaded between circuit and ground connection, and disturbance current respectively flows through 1/2nd online at two, take ground as common return, and in principle, this interference is eliminated than being easier to.In side circuit, because line impedance is uneven, make common-mode signal disturb (Common-mode Interference) can be converted into the crosstalk interference that is difficult for elimination.
The variation of electric current and voltage has two kinds of forms during by wire transmission; we are called this power line of " common mode " and " differential mode " equipment; the order wire of phone etc.; the communication line mutually exchanging with miscellaneous equipment or ancillary equipment; have two wires at least; these two wires transmit electric power or signal as round circuit. but outside these two wires, conventionally also have the 3rd conductor, and Here it is " ground wire ".Interference voltage and electric current are divided into two kinds: a kind of is that two wires are respectively as round circuit transmission; Another kind is that two wires are done outlet, and ground wire returns to road transmission.The former is " differential mode " (Differential-Mode), and the latter is " common mode " (Common-Mode).
It is different that interference type is pressed jamming pattern conventionally, can be divided into common mode disturbances (Common-Mode Interference) and differential mode interference (Differential-Mode Interference).Common mode disturbances and differential mode interference are a kind of more conventional sorting techniques.Touching altogether interference is signal earth potential difference, mainly by electrical network seal in, epd and spacing electromagnetic radiation formed at common-mode (equidirectional) voltage superposition of the online induction of signal, common-mode voltage is sometimes larger, particularly adopt the poor distributor power supply chamber of isolation performance, the common-mode voltage that transmitter is carried is generally higher.Common-mode voltage is convertible into differential mode voltage by unsymmetric circuit, directly affects measurement and control signal, causes components and parts to damage (the higher main cause of some system I/0 module spoilages that Here it is), and this common mode disturbances can be direct current, also can be interchange.Differential mode interference refers to the interference voltage that acts on signal two interpolars, mainly by external electromagnetic field formed voltage of inductive coupling and unbalanced circuit conversion common mode disturbances between signal, thisly allows direct superposition on signal, directly impact measurement and control precision.
Shielding is exactly carrying out the isolation of metal between two area of space, with control electric field, magnetic field and electromagnetic wave by a region to the induction in another region and radiation.Specifically, with shield, the interference source of component, circuit, sub-assembly, cable or whole system is surrounded exactly, prevents that interfere with electromagnetic field is to outdiffusion; With shield, receiving circuit, equipment or system are surrounded, prevent that they are subject to the impact of external electromagnetic field.Because shield all produces and absorbs energy (eddy current loss), reflected energy (boundary reflection of electromagnetic wave on shield) and counteracting energy (electromagnetic induction produces reverse electromagnetic field on screen the interference electromagnetic wave from outsides such as wire, cable, component, circuit or systems and internal electrical magnetic wave, can offset part and disturb electromagnetic wave) effect, so shield has the function that weakens interference.
(1) when the frequency of interfere with electromagnetic field is higher, utilize the eddy current producing in the metal material of low-resistivity, form and externally carry out electromagnetic negative function, thereby reach the effect of shielding.
(2) when disturbing electromagnetic frequency lower, adopt the material of high permeability, thereby make the magnetic line of force be limited in shield inside, prevent that the space that is diffused into shielding from going.
(3), under some occasion, if while requiring high and low frequency electromagnetic field all to there is good shield effectiveness, often adopt different metal materials to form multilayer screen body.
What is called on the construction of cable " shielding " is in fact a kind of measure that improves Electric Field Distribution.Cable conductor forms by multiple conducting wires is stranded, easily forms air gap between it and insulating barrier, and conductive surface is rough, can cause electric field to concentrate.The screen that adds one deck semiconductive material at conductive surface, the conductor equipotential of it and conductively-closed and with insulating barrier good contact, thereby avoid, between conductor and insulating barrier, partial discharge occurs, this one deck shielding is internal shield; At insulating surface and sheath contact position, also may there is gap equally, it is the factor that causes partial discharge, therefore add the screen of one deck semiconductive material at surface of insulating layer, the insulating barrier of it and conductively-closed has good contact, with metallic sheath equipotential, thereby avoid, between insulating barrier and sheath, partial discharge occurs, this one deck shielding is outer shielding layer; The cables with extruded insulation that there is no metallic sheath, except semiconductive shielding layer, also to increase with copper strips or the wrapped metal screen layer of copper wire, metallic shield has two Main Functions, the one, what when cable is switched on, produce is electromagnetic-field-shielded in insulated wire cores, to reduce, produces to external world electromagnetic interference; The 2nd, the fault current in the scope of design that system is produced is introduced safely grounding system, protection system safe operation.This metal screen layer passes through capacitance current when normal operation; When system is short-circuited, as the passage of short circuit current, also play the effect of electric field shielding simultaneously.Visible, if this layer of outer semiconductor layer and copper shield do not exist in cable, the possibility that insulation breakdown occurs between three-core cable SMIS and core is very large.While making cable termination or joint, divesting a bit of screen main purpose is for guaranteeing high pressure creepage distance over the ground, and this shielding incision position stress is very concentrated, is weak link! Must take adequate measures to carry out length that stress processing (with stress cone or stress tube etc.) divests screen to guarantee creepage distance; The anti-creepage ability in reinforced insulation surface is foundation.Screen stripping is long will increase the difficulty of construction, and the cost that increases electric cable accessories there is no need completely.
Summary of the invention
For addressing the above problem, the utility model provides a kind of cable shield structure-improved that prevents that common-mode signal from disturbing.
For achieving the above object, the utility model adopts following technical scheme to be: a kind of cable shield structure-improved that prevents that common-mode signal from disturbing, comprising: internal shield, for shielding, in described internal shield, be provided with: at least two power lines, described power line is used for transmitting power supply; At least one group of holding wire, described every signal line outer rim is provided with insulating barrier, for signal transmission; At least one interior ground wire, described interior ground wire is located at the side of holding wire; And inner insulating layer, outside the periphery of holding wire on the same group described in described inner insulating layer holds or on the same group holding wire and interior ground wire, enclose; And outer shielding layer, described internal shield is arranged with outer shielding layer outward, for shielding; Appearance protective layer, the outer appearance protective layer that is arranged with of described outer shielding layer; Between described internal shield and outer shielding layer, setting tool has the wheat of electric insulation usefulness to draw, and makes to present each other electric insulation relation and not conducting mutually between internal shield and outer shielding layer.
Preferably, described interior ground wire is from copper covered steel or copper-clad copper or gun-metal.
The beneficial effects of the utility model are: the utility model is simple in structure, and low cost of manufacture has the Mai Lake of electric insulation usefulness effectively to eliminate common-mode signal by setting tool between internal shield and outer shielding layer and disturbs, and reduce the spoilage of components and parts.
Accompanying drawing explanation
Fig. 1 is the utility model generalized section.
Fig. 2 is the generalized section of existing cable shielding construction.
Fig. 3 is the schematic diagram of existing difference mode signal.
Fig. 4 is the schematic diagram of existing common-mode signal.
Mark explanation:
11. power lines; 12 (12'). holding wire; 13. interior ground wires; 14. inner insulating layers; 15. internal shields; 16. outer shielding layers; 17. appearance protective layers; 18. wheats are drawn.
Embodiment
Refer to shown in Fig. 1, the utility model is about a kind of cable shield structure-improved that prevents that common-mode signal from disturbing, and a kind of cable shield structure-improved that prevents that common-mode signal from disturbing, comprising: internal shield 15, for shielding, is provided with in described internal shield 15:
Article at least two, power line 11, and described power line 11 is for transmitting power supply;
At least one group of holding wire 12, described every signal line 12 outer rims are provided with insulating barrier, for signal transmission;
At least one interior ground wire 13, described interior ground wire 13 is located at the side of holding wire 12;
With inner insulating layer 14, outside the periphery of holding wire on the same group described in described inner insulating layer holds or on the same group holding wire and interior ground wire, enclose; And outer shielding layer, described internal shield is arranged with outer shielding layer outward, for shielding; And
Outer shielding layer 16, the outer outer shielding layer 16 that is arranged with of described internal shield 15, described outer shielding layer 16 and internal shield 15 are for shielding;
Appearance protective layer 17, the outer appearance protective layer 17 that is arranged with of described outer shielding layer 16; Between described internal shield 15 and outer shielding layer 16, setting tool has the wheat of electric insulation usefulness to draw 18, makes to present each other electric insulation relation and not conducting mutually between internal shield 15 and outer shielding layer 16.Preferably, described interior ground wire is from copper covered steel or copper-clad copper or gun-metal
Refer to shown in Fig. 1, a kind of cable shield structure-improved that prevents that common-mode signal from disturbing, comprises that (11) ﹝ red lines and Hei Xian ﹞ are used for transmitting power supply to two power lines.Every signal line (12) (12') outer rim all holds insulating barrier, for the defeated Xin ﹝ of Chuan for example: the 2P holding wire (12') of USB2.0 is white line and green line; As for the 2P holding wire (12) in USB3.0 (purple line, orange line, yellow line, blue line) ﹞.And above-mentioned interior ground wire (13) is the side that is adjacent to the 2P holding wire (12) in USB3.0.As for inner insulating layer (14), be respectively to surround on the same group holding wire (12) ﹝ are that the 2P holding wire (12) in USB3.0 (encloses outside purple line, orange line, yellow line, blue line) ﹞ and interior ground wire (13); Or (12') ﹝ is that the 2P holding wire (12') in USB2.0 (encloses outside white line and green line) ﹞ only to surround on the same group holding wire.Internal shield (15) be surround all power line (11), holding wire (12) (12') and outside interior ground wire (13) encloses so as shielding.Outer shielding layer (16) is to surround outside internal shield (15) to enclose.And appearance protective layer (17) is the periphery that surrounds whole screens (16); between above-mentioned internal shield (15) and outer shielding layer (16); Jie's setting tool has the wheat of electric insulation usefulness to draw (18), makes to present each other electric insulation relation and not conducting mutually between internal shield (15) and outer shielding layer (16).
In addition, when when wiring, the utility model should be away from high-voltage line, more high-voltage power-line and holding wire (12) (12') can not be tied together to cabling.
Above execution mode is only that preferred implementation of the present utility model is described; not scope of the present utility model is limited; do not departing under the prerequisite of the utility model design spirit; various distortion and improvement that the common engineers and technicians in this area make the technical solution of the utility model, all should fall in the definite protection range of claims of the present utility model.
Claims (2)
1. prevent the cable shield structure-improved that common-mode signal is disturbed, comprising:
Internal shield, for shielding, is provided with in described internal shield:
Article at least two, power line, described power line is used for transmitting power supply;
At least one group of holding wire, described every signal line outer rim is provided with insulating barrier, for signal transmission;
At least one interior ground wire, described interior ground wire is located at the side of holding wire;
And inner insulating layer, outside the periphery of holding wire on the same group described in described inner insulating layer holds or on the same group holding wire and interior ground wire, enclose; And
Outer shielding layer, described internal shield is arranged with outer shielding layer outward, for shielding;
Appearance protective layer, the outer appearance protective layer that is arranged with of described outer shielding layer;
It is characterized in that: between described internal shield and outer shielding layer, setting tool has the wheat of electric insulation usefulness to draw, make to present each other electric insulation relation and not conducting mutually between internal shield and outer shielding layer.
2. a kind of cable shield structure-improved that prevents that common-mode signal from disturbing according to claim 1, is characterized in that: described interior ground wire is from copper covered steel or copper-clad copper or gun-metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420132644.1U CN203774010U (en) | 2014-03-21 | 2014-03-21 | Cable shield improving structure for preventing common-mode interference |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420132644.1U CN203774010U (en) | 2014-03-21 | 2014-03-21 | Cable shield improving structure for preventing common-mode interference |
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| Publication Number | Publication Date |
|---|---|
| CN203774010U true CN203774010U (en) | 2014-08-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420132644.1U Expired - Fee Related CN203774010U (en) | 2014-03-21 | 2014-03-21 | Cable shield improving structure for preventing common-mode interference |
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| CN (1) | CN203774010U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106961541A (en) * | 2017-04-07 | 2017-07-18 | 信利光电股份有限公司 | A kind of camera device |
-
2014
- 2014-03-21 CN CN201420132644.1U patent/CN203774010U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106961541A (en) * | 2017-04-07 | 2017-07-18 | 信利光电股份有限公司 | A kind of camera device |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140813 |