CN212303177U - Wire capable of forming heat conducting network - Google Patents

Abstract

The utility model discloses a to current when piling up use or coiling and become multilayer coil, because thermal contact resistance leads to the serious bad problem of heat dissipation of inside wire between the wire of mutual contact, provide a wire that can constitute heat conduction network. The cable comprises a conductive wire core and an insulating layer, wherein a thermal expansion layer is wrapped outside the insulating layer, the thermal expansion layer comprises a thermal expansion base layer and thermal expansion filler dispersed in the thermal expansion base layer, the melting point of the thermal expansion filler is not higher than 90 ℃, and the thermal expansion coefficient of the thermal expansion filler is 20-50 times that of the thermal expansion base layer. The utility model discloses can reduce the thermal contact resistance between the wire that piles up by a wide margin, and then obviously improve the heat-sinking capability of the bad wire of serious heat dissipation among the prior art, the thermal diffusivity through strengthening the whole resistance heat of wire harness has increased substantially the allowable electric current of these wires, finally reduces the production of devices such as motor, generator, inductance coils, transformer, electro-magnet, mutual-inductor, use cost and spare part volume.

Description

Wire capable of forming heat conducting network

Technical Field

The utility model relates to a wire and cable correlation technique field, specifically speaking relates to one kind and when piling up the use or coiling and become multilayer coil, each wire can constitute the wire of space heat conduction network.

Background

In the field of electronic equipment, wires are used not only for conducting electricity, but also in a large number of devices such as motors, generators, induction coils, transformers, electromagnets, and transformers.

In the prior art, resistance exists in any wire, so that resistance heat, also called ohmic heat, is inevitably generated when the conductive fiber core works. The insulation of the insulating layer is obviously reduced due to resistance heat generated by the wire; the barrier property of the insulating layer to water vapor and oxygen is greatly reduced, and the chemical reducibility of the conductive metal is obviously enhanced, so that the conductive wire core is rapidly oxidized; in addition, when the temperature of the wires in various coils is too high, the plasticity and the fluidity of the fixing glue for fixing the wires are increased, so that the wires vibrate under the action of alternating electromagnetic force to generate sharp high-frequency noise, and the insulating layers are gradually abraded to finally cause short-circuit accidents inside components. The continuous accumulation and increase of the resistance heat of the conducting wire in the circuit or the electronic device are one of the main reasons of gradual failure or sudden burnout of the conducting wire or the electronic device in use.

Especially for the coil conducting wires wound inside the devices such as motors, generators, inductance coils, transformers, electromagnets, mutual inductors, etc., because of the miniaturization of the devices or the need of reducing skin effect in high frequency alternating current circuits, the coil conducting wires must be bundled into a conducting wire bundle composed of a large number of parallel conducting wires, and each turn of the coil needs to be wound by tens of even hundreds of thin conducting wires in a laminating way. At this time, each conductive core generates resistance heat, the stacked wire bundles are equal to a large number of bundled resistance heating wires, and the heat needs to be conducted and dissipated to the outside. Therefore, in the design of a circuit or an electric device, ensuring the balance between the resistance heat and the heat dissipation of the coil is often the most difficult design bottleneck. For this reason, in the field of "motor drive" technology design, the thermal balance check requirements for continuously operating motors are often many times higher than the power and power requirements. That is to say, when the type of the motor is selected, the motor with power reserve several times higher than that actually needed is often selected to ensure that the motor works under the light load condition for a long time, and further ensure that the motor does not overload and burn down when the motor continuously runs, which obviously brings unnecessary use cost. This problem is also present in the field of design of inductors and transformers for the same reason.

For the above problems, the technical solution of trying to improve the heat dissipation capability of a single wire is simple. For example, the applicant has previously developed several technical patents of the conductive wire capable of effectively improving the thermal conductivity of the insulating layer, and can significantly improve the allowable current value of the conductive wire by greatly improving the resistance heat generated by the conductive fiber core conducted to the outside by the insulating layer. However, when the wires are stacked or wound into a coil, the heat conductivity of the single guide insulating layer is simply improved, and the effect of improving the overall heat dissipation performance of the wire bundle consisting of a large number of wires is very limited. This is because a large number of gaps are always present between the conductor insulating layers stacked on top of each other, and a large amount of air that does not easily flow freely is distributed in the gaps. Under standard conditions, air, which is flow limited (i.e., not free to convect heat), has a thermal conductivity of only 0.0262W/mk. In contrast, pure copper, which is often used as wire stock, has a thermal conductivity of 401W/mk (thermal conductivity many times fifteen thousand times that of confined air). At this time, because the wires and the wire insulating layers cannot be compacted completely (the insulating layers are easily damaged under the pressure change of repeated expansion and contraction), the insulating layers of different wires can only form line contact and even suspend without contact, so that very large contact thermal resistance can be generated between the wires and the wire due to the huge thermal resistance of air (the actual thermal resistance is often one or two orders of magnitude higher than the thermal conductivity of the insulating layers). In this case, the farther the wire is from the outside of the coil, the more difficult it is for the resistance heat to dissipate to the outside during operation, and the more severe the operating state, the more likely it is for the failure accidents such as short circuit due to dielectric breakdown or oxidation of the conductive core to occur first due to overheating. At this time, no matter whether the outermost coil is guaranteed by forced heat dissipation such as air cooling heat dissipation, serious thermal contact resistance exists between each layer or each circle of wires on the heat conduction path, and the wires at the innermost circle are always in a serious heat dissipation difficult state which is most prone to failure.

Therefore, in a stacked wire bundle or coil, the allowable power load for various electronic devices can only be determined by the wires that dissipate the least heat internally. Although the heat conductivity coefficient of the metal conductive wire core is theoretically high, the metal conductive wire core is a heating body and has no heat dissipation capacity, the heat conduction performance of the wire insulation layer is improved greatly, and the metal conductive wire core is also influenced by the heat dissipation bottleneck of the contact thermal resistance among different wire insulation layers. This greatly limits the allowable power load increase of the electronic device, resulting in significant cost and material waste. In actual use, air between the wires is partially expelled by means of soaking fixing glue and the like sometimes, but the fixing glue belongs to a high polymer material which needs to give priority to mechanical strength, high temperature resistance and insulating property after curing, the heat conductivity of the fixing glue is very limited, residual air between dense wires cannot be effectively expelled by a glue dipping process, and plastic flow (high-temperature creep) is easy to occur under long-term high-temperature work of the coils to generate heat conduction gaps again. The heat dissipating design of the wire bundle and coil is therefore very unreliable and can fail over time if one wants to rely on the potting compound over a long period of use.

Therefore, the wire which can form a heat conducting network in a wire bundle or a multilayer coil by itself is designed and invented to eliminate or greatly weaken the contact thermal resistance between insulating layers, so that the allowable current of the wire which is the most unfavorable for heat dissipation of the innermost layer of the wire bundle or the coil can be greatly improved, the working performance and the service life of a large number of devices such as a motor, a generator, an inductance coil, a transformer, an electromagnet, a mutual inductor and the like are greatly improved, and the production and use cost of the devices is reduced.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a to current when piling up use or coiling and become multilayer coil, because thermal contact resistance leads to the serious bad problem of heat dissipation of inside wire between the wire of mutual contact, provide a wire that can constitute heat conduction network.

The utility model discloses the technical problem that needs to solve can realize through following technical scheme:

a conducting wire capable of forming a heat conducting network comprises a conductive wire core and an insulating layer wrapped outside the conductive wire core, and is characterized in that a thermal expansion layer is wrapped outside the insulating layer, the thermal expansion layer comprises a thermal expansion base layer and a thermal expansion filler dispersed in the thermal expansion base layer, the melting point of the thermal expansion filler is not higher than 90 ℃, and the thermal expansion coefficient of the thermal expansion filler is 20-50 times that of the thermal expansion base layer.

The utility model discloses in, the thermal energy basic unit is through the modified macromolecular material layer of heat conduction filler.

The heat conducting filler is silicon dioxide powder or boron nitride or silicon carbide or magnesium oxide or aluminum oxide.

In the utility model, the thermal expansion filler is modified paraffin.

The utility model discloses in, the conductive core is copper wire or aluminium wire or silver-colored wire or aluminium copper facing wire or copper silvering wire.

The utility model discloses in, the insulating layer is polyvinyl chloride insulating layer or polyester insulating layer or crosslinked polyethylene insulating layer or fluoroplastics insulating layer or rubber class insulating layer or ethylene propylene rubber insulating layer or polyamide insulating layer or silicon rubber insulating layer or polyurethane insulating paint layer.

The utility model discloses a can constitute the wire of heat conduction network, can reduce the thermal contact resistance between the wire that piles up by a wide margin, and then obviously improve the heat-sinking capability of the bad wire of serious heat dissipation among the prior art, the thermal diffusivity through strengthening the whole resistance heat of wire harness has increased substantially the allowable electric current of these wires, finally reduces the production of devices such as motor, generator, inductance coils, transformer, electro-magnet, mutual-inductor, use cost and spare part volume.

Drawings

The invention is further described with reference to the following drawings and detailed description.

Fig. 1 is a schematic structural diagram of the present invention.

Detailed Description

In order to make the technical means, creation features, achievement purposes and functions of the present invention easy to understand, the present invention will be further described with reference to the following specific drawings.

Referring to fig. 1, the utility model discloses a can constitute heat conduction network's wire, the wire is outside by the center respectively by electric conductor core 1, insulating layer 2 and disperse have thermal expansion filler 4's thermal expansion basic unit 3 to constitute in the radius direction of cross section, and thermal expansion basic unit 3 and thermal expansion filler 4 constitute the thermal expansion layer, and insulating layer 2 wraps up wire core 1, and thermal expansion layer wraps up insulating layer 2.

The conductive wire core 1 is a copper wire, an aluminum wire, a silver wire, an aluminum copper plated wire or a copper silver plated wire, and these materials are all conventional technologies and are not described again. The insulating layer 2 is made of high molecular polymer, and is made of common insulating materials in the prior art, such as insulating paint layers of polyvinyl chloride (PVC), Polyester (PE), cross-linked polyethylene (XLPE), fluoroplastic, rubbers, ethylene propylene rubber, FORMVAR, polyamides, silicone rubber, polyurethane, and the like. In the conductor of the present patent, the insulating layer 2, which has its conventional insulating and mechanical protecting functions, can be used along with the conventional conductor manufacturing process and equipment, and since it is covered with the thermal expansion layer, which is also a matrix of a polymer material, the thickness of the insulating layer can be appropriately reduced as required.

The utility model discloses in, thermal energy basic unit 3 is the macromolecular material layer through the heat conduction filler modification, and its heat conduction modified packing is conventional silica powder, boron nitride, carborundum, magnesium oxide or aluminium oxide, and such packing can effectively improve the thermal conductivity of polymer substrate in certain weight proportion (generally be less than 25%) and do not obviously reduce insulating nature and mechanical strength.

The thermal expansion filler 4 is modified paraffin, which is uniformly dispersed in the thermal expansion base layer 3. The thermal expansion filler 4 absorbs a large amount of heat in a set temperature range required by modification and then undergoes phase change, so that the thermal expansion base layer 3 is driven to expand greatly by large expansion, thermal shock generated by sudden large current of the conductive wire core 1 can be absorbed, a thermal buffering effect is achieved, and air gaps and thermal contact resistance among wires are reduced.

The thermal conductivity of the common solid paraffin is about 0.56W/mk, which is obviously higher than that of the common high molecular material, and the common solid paraffin is also a high molecular material with improved thermal conductivity, and the liquid paraffin can provide higher thermal conductivity (which can be higher than that of pure water by 0.62W/mk) through thermal convection. The specific heat capacity of the solid paraffin was about 2.6J/(kg. ℃ C.) and that of the liquid paraffin was about 2.89J/(kg. ℃ C.), and the influence of the comparative heat capacity of the modification treatment was not great. For comparison, the specific heat capacity of the vulcanizate is about 1.7J/(kg. ℃ C.). That is, the modified paraffin wax of the same weight has a significantly higher heat storage capacity than the high molecular material. More importantly, the heat of dissolution of paraffin wax is about 60 kcal per kg. That is, when one kilogram of paraffin is dissolved in a phase change manner, the paraffin can absorb heat generated by heating 1 kilogram of water to 60 ℃ and keep the temperature of the paraffin solid-liquid mixture unchanged, and the heat absorption capacity of the dissolved heat is considerable. And the modification treatment of the paraffin wax can change the specific phase transition temperature of the paraffin wax from solid to liquid.

The melting point of normal paraffin wax is about 45-65 ℃, which can meet the temperature control requirement of many wires or elements. For a wire which needs to work at a higher temperature (such as 90 ℃) in a short time, paraffin needs to be modified (a large number of papers can be found on a specific modification treatment process, particularly a paper on a modified paraffin heat storage technology of an interlayer in a wall of an environment-friendly building, which belongs to the known technical field), so that the dissolving temperature of the modified paraffin is further increased or reduced. The lead can pass large current for a short time, and the temperature of the thermal expansion base layer 3 is kept to be about the expected temperature (such as 90 ℃) without rising. Near this temperature point, the modified paraffin wax has a very large specific heat capacity as does the ice-water mixture. For many devices which are not under long-term thermal overload conditions, the economy of use can be effectively improved.

For example, the short-term heat absorption performance can significantly improve the economy of the power motor of high-performance electric sports cars, high-speed rails, subways and other equipment which need short-term acceleration performance. Because the coil current of the power motor is the largest in the process from rest to acceleration, the resistance heat release of the lead is the largest, but after the vehicle stops accelerating and enters a constant-speed running state, the output power of the motor can be greatly reduced. Under the condition, the motor adopts the lead with the short-term heat storage function, so that the power reserve margin of the heat load in the process of checking and selecting the heat balance of the motor can be effectively reduced. The motor capable of short-term thermal overload can greatly improve the economy and effectively reduce the volume and the dead weight of the vehicle. The same is true for the motors of food processors (including cell wall breaking machines, high-speed mixers and the like) which work intermittently, soybean milk machines and other electrical appliances. The same is true of the increased economy and safety of components such as transformers and electromagnets for inductors needed in circuits that are subject to occasional overloads with low loads for long periods of time.

As described above, the melting point of the thermally expandable filler is preferably not higher than 90 degrees celsius, and when the thermally expandable filler 4, for example, the modified paraffin is dissolved in a liquid state entirely by heat absorption, the volume of the modified paraffin is greatly increased by the difference in density between the solid state and the liquid state. At this time, the thermal expansion filler 4 dispersed in the thermal expansion base layer 3 can drive the thermal expansion layer 3 to expand greatly, and simultaneously, the density and the surface hardness of the thermal expansion base layer 3 are reduced, so that the thermal expansion base layer 3 becomes softer and more flexible. At this point, the gaps and air gaps between the multiple wires that are originally tightly bundled, or self-twisted, or tightly wound, are expelled and filled by the expanding thermal expansion substrate 3. When the temperature of the thermal expansion base layer 3 is sufficiently high, the soft polymer material is sufficient to fill up the microscopic level of voids on the surface between the different wires. This effectively eliminates the otherwise extremely severe thermal contact resistance between the wires. The space heat conduction network is formed among the inner layer lead, the middle layer lead and the outer layer lead through respective thermal expansion base layers 3, so that the heat dissipation capability of the lead which has the most volatile effect and the least adverse heat dissipation effect in a lead bundle or a multilayer coil in the prior art is obviously improved. That is, when the thermal expansion filler 4 is completely melted and can no longer absorb the melting heat, the temperature of the thermal expansion base layer 3 will continue to rise, but at this time, the wires will automatically form a completely new space heat conducting network, and the heat dissipation capability of the whole wire system has been improved by several times or even tens of times (the specific improvement number is related to the pre-tightening force of the wire system or the contact pressure between the wires, and the heat dissipation efficiency of the outermost wire — if there is no forced air cooling heat dissipation, the actual heat conductivity of the thermal expansion base layer 3, etc.).

More specifically, for example, the thermal expansion coefficient of the thermal expansion filler 4 is preferably 20 to 50 times that of the thermal expansion base layer 3. For example, if the thermal expansion coefficient of the thermal expansion filler 4 is 30 times that of the thermal expansion base layer 3 and modified paraffin having a volume ratio of about 33% is uniformly dispersed in the thermal expansion base layer 3 as the thermal expansion filler 4, the thermal expansion volume of the thermal expansion base layer 3 increases by 10 times as compared with the case where the thermal expansion filler 4 is not added after the temperature of the wires exceeds the phase transition temperature (melting temperature) of the modified paraffin, and at this time, problems such as an air gap between the wires, an air contact area, and a line contact area being too small are eliminated. Experimental tests show that the method for eliminating the thermal contact resistance by expelling air and the surface microscopic peaks and valleys of the contact surface through the large-scale expansion of the thermal expansion base layer 3 has the efficiency which is dozens of times or even hundreds of times higher than that of the heat-conducting silicone grease which is commonly used in the field of semiconductor heat dissipation or the improvement of the thermal contact resistance by the lead fixing glue, and the reliability of the method is far superior to that of the latter.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (6)

1. A conducting wire capable of forming a heat conducting network comprises a conductive wire core and an insulating layer wrapped outside the conductive wire core, and is characterized in that a thermal expansion layer is wrapped outside the insulating layer, the thermal expansion layer comprises a thermal expansion base layer and a thermal expansion filler dispersed in the thermal expansion base layer, the melting point of the thermal expansion filler is not higher than 90 ℃, and the thermal expansion coefficient of the thermal expansion filler is 20-50 times that of the thermal expansion base layer.

2. A wire configurable into a thermally conductive network as claimed in claim 1, wherein: the thermal expansion base layer is a high polymer material layer modified by a heat-conducting filler.

3. A wire configurable into a thermally conductive network as claimed in claim 2, wherein: the heat conducting filler is silicon dioxide powder or boron nitride or silicon carbide or magnesium oxide or aluminum oxide.

4. A wire configurable into a thermally conductive network as claimed in claim 1, wherein: the thermal expansion filler is modified paraffin.

5. A wire configurable into a thermally conductive network as claimed in claim 1, wherein: the conductive wire core is a copper wire or an aluminum wire or a silver wire or an aluminum copper plated wire or a copper silver plated wire.

6. A wire configurable into a thermally conductive network as claimed in claim 1, wherein: the insulating layer is a polyvinyl chloride insulating layer or a polyester insulating layer or a crosslinked polyethylene insulating layer or a fluoroplastic insulating layer or a rubber insulating layer or an ethylene propylene rubber insulating layer or a polyamide insulating layer or a silicone rubber insulating layer or a polyurethane insulating paint layer.

Images