Composite material for resistance heating and system for resistance heating with at least one heating element based on this composite material

Abstract

The invention relates to a composite material (1) for resistance heating, comprising a heating layer (2) formed by a planar layer of electrically conductive carbon multifilaments or rovings with a basis weight of 50 to 850 g / m² 2 is formed, wherein an insulating layer (3) is deposited on both sides of the heating layer (2), which is formed by a planar layer of electrically non-conductive fiber material with a basis weight of 200 to 600 g / m². 2 is formed, wherein the heating layer (2) and the insulating layers (3) are stored in a matrix (4) formed by a resin, the resin content corresponding to 20 to 35 wt.% of the heating layer (2). The invention further relates to a system (5) for resistance heating, which has at least one heating element (6) formed by the composite material (1) according to the invention, which is connected to an electrical voltage source (7), wherein a temperature controller (8) is arranged between the heating element (6) and the electrical voltage source (7).

Description

field of technology

[0001] The technical solution involves a composite material for resistance heating.

[0002] The technical solution also relates to a resistance heating system with at least one heating element based on this composite material, which is intended in particular for heating the electrical cells of a battery of a battery electric vehicle. State of the art

[0003] Resistance heating is a type of electrical heating in which an electric current flows through a heating resistor. The moving carriers of electric charge (usually electrons) collide with particles (usually ions) in the material lattice of the heating resistor, transferring some of their kinetic energy to them. This energy is then converted into heat energy, increasing the temperature of the heating resistor (Joule heating). Heating resistors are primarily used today in large industrial plants such as glass furnaces. Their disadvantage lies in their relatively large dimensions and high mass, which results in relatively high thermal inertia.This makes the use of resistance heating difficult or completely impossible in applications with limited space for installing heating resistors and / or in applications where the heating system needs to react as quickly as possible to the prevailing conditions and therefore exhibit minimal thermal inertia. A typical example is preheating the electrical cells of batteries, such as those in battery-electric vehicles, before charging at low temperatures, etc.

[0004] The aim of the technical solution is to propose a composite material for resistance heating that would eliminate the disadvantages of the state of the art.

[0005] Furthermore, the aim of the technical solution also includes a system for resistance heating with at least one heating element based on this composite material. Explanation of the nature of the technical solution

[0006] The technical solution achieves its objective through a composite material featuring a heating layer formed by a planar layer of electrically conductive carbon multifilaments or rovings with a fineness of 800 to 3000 tex and a basis weight of 50 to 850 g / m². 2 is formed, wherein an insulating layer is deposited on both sides of the heating layer, which is formed by a planar layer of electrically non-conductive fiber material with a basis weight of 200 to 600 g / m². 2 is formed, wherein the heating layer and the insulating layers are embedded in a resin-formed matrix, the resin content corresponding to 20 to 35 wt.% of the heating layer.

[0007] In an advantageous embodiment, the heating layer is formed by a layer of a carbon multifilament or roving applied to one side, with a total fineness of 800 to 3000 tex, wherein the basis weight of the heating layer is 50 to 150 g / m².2 amounts.

[0008] In another advantageous embodiment, the heating layer is formed by a fabric made of carbon multifilament or roving with a total fineness of 800 to 3000 tex, wherein the basis weight of this layer is 120 to 850 g / m². 2 The amount is [amount missing]. A suitable type of fabric is a twill weave fabric.

[0009] In the advantageous embodiment, the insulating layer is formed by a fabric made of glass multifilaments or rovings or fabric made of aramid fibers with a total fineness of 300 to 2300 tex, wherein the basis weight of this layer is 200 to 600 g / m². 2 The amount is [amount missing]. A suitable type of fabric is a twill weave fabric.

[0010] The matrix is ​​preferably formed by an epoxy resin or a melamine-formaldehyde resin.

[0011] Furthermore, the objective of the technical solution is also achieved by a resistance heating system comprising at least one heating element formed by the composite material according to the technical solution, which is connected to an electrical voltage source, wherein a temperature controller, e.g. a bimetallic controller, is arranged between the heating element and the electrical voltage source. Explanation of the drawings

[0012] The enclosed drawing schematically depicts: on Fig. 1 a cross-section of the composite material for resistance heating according to the technical solution and on Fig. 2 a scheme of a system for heating with a heating element based on this composite material. Examples of the technical solution

[0013] The composite material 1 for resistance heating according to the technical solution has a heating layer 2 formed by a planar layer consisting of electrically conductive carbon multifilaments or rovings, i.e., a linear structure composed of several hundred to thousands of continuous carbon fibers with a diameter typically of 4 to 9 micrometers, which is not reinforced by twisting or the twisting is minimal. An insulating layer 3, formed by a planar layer of electrically non-conductive, preferably fibrous, material, is deposited on both sides of the heating layer 2. All three layers 2, 3 of the composite material 1 are jointly embedded in a matrix 4, which binds them together and simultaneously imparts stiffness and advantageous mechanical properties to the composite material 1 thus produced, while also protecting the individual layers 2, 3 from mechanical damage.

[0014] Depending on the intended use, the heating layer 2 is formed by a layer of a single-sided carbon multifilament or roving, or by a fabric woven from this multifilament or roving in a suitable weave. For low power outputs in the range of a few tens of watts, the heating layer 2 is formed by a layer of single-sided carbon multifilaments or rovings with a total fineness of 800 to 3000 tex and a basis weight of 50 to 150 g / m². 2 , preferably 90 to 120 g / m² 2 For higher power outputs in the range of several hundred watts, the heating layer 2 is made of a fabric consisting of these carbon multifilaments or rovings with a basis weight of 150 to 850 g / m². 2 , preferably in the range of 200 to 700 g / m³ 2 formed. A suitable type of fabric is a twill weave fabric.

[0015] The heating layer 2 has means for connection to an electrical voltage source at its two opposite ends, e.g., in the form of conductive interfaces 20. The interfaces 20 preferably consist of an electrically conductive, silver-containing epoxy paste, which is encapsulated by pressing copper or aluminum foil onto the carbon filaments. In other embodiments, however, these interfaces 20 can also be configured differently.

[0016] The insulating layers 3 are formed from an electrically non-conductive, preferably fibrous material. These layers protect the heating layer 2 from mechanical damage and simultaneously provide electrical insulation from the environment. Suitable materials for the insulating layers 3 are fibers with high heat resistance (preferably non-combustible) and suitable mechanical and electrical insulating properties, such as woven fabrics made of glass multifilaments or rovings with a total fineness of 300 to 2300 tex or woven fabrics made of aramid fibers. The insulating layer 3 has a basis weight of 200 to 600 g / m². 2 , preferably 250 to 400 g / m² 2 . A suitable type of fabric for the insulating layer 3 is then a twill weave fabric.

[0017] The two insulating layers 3 on the opposite surfaces of the heating layer 2 can be identical, or they can differ from each other in their material and / or structure and / or basis weight.

[0018] The heating layer 2 and the insulating layers 3 are embedded together in a matrix 4, which provides stiffness to the resulting composite material and simultaneously protects these layers 2 and 3 from mechanical damage. A suitable matrix 4 is, for example, an epoxy-based resin matrix with a glass transition temperature (Tg) above 100 °C, such as a dispersion epoxy resin with potassium thiocyanate (KSCN) as a catalyst or a melamine-formaldehyde resin. Generally, other types of resins available for bonding carbon and glass composites with a heat resistance above 220 °C can also be used. In an advantageous preparation method, the matrix 4 is introduced into the structure of the composite material in its liquid state by impregnating the dry sandwich, which consists of the heating layer 2 and the electrically insulating layers 3.The matrix fills the voids between the individual layers 2 and 3, encapsulates their fibers, and bonds these layers 2 and 3 into a single unit. After curing, it imparts stiffness to the resulting composite material and protects its layers 2 and 3 from mechanical damage. At the same time, this matrix does not prevent heat transfer from the heating layer to the surroundings. The matrix content corresponds to 20 to 35 wt.% of the heating layer 2.

[0019] Suitable fabrics made from carbon multifilaments or rovings, as well as fabrics made from glass multifilaments or rovings, are currently widely available on the market (see, for example, the company Havel composites CZ).

[0020] If required, the composite material 1 for resistance heating can have more than one heating layer 2 according to the technical solution, in which case each heating layer 2 is covered from its outside with an insulating layer 3.

[0021] In each embodiment, the composite material 1 for resistance heating can be supplemented on at least one of its sides with an additional suitable material layer, which gives it an additional function. Such a layer can, for example, be a layer of reflective material for reflecting or concentrating the heat generated by the heating layer(s) 2.

[0022] Fig.Figure 2 shows a schematic of a system 5 for resistance heating, which includes a heating element 6 formed by this composite material 1. This heating element 6 is connected to an electrical voltage source 7 via an interface 20 of the heating layer 2. A suitable known controller 8, e.g., a bimetallic temperature controller, is arranged between the heating element 6 and the electrical voltage source 7, which opens or closes the circuit depending on the actual temperature. When the electric current flows through the material of the heating layer 7, this material is heated.

[0023] If required, several heating elements 6 can be arranged within a system 5 for resistance heating.

[0024] Due to the low mass of the composite material 1 for resistance heating according to the technical solution, this material, or the heating element 6 made from it, has a low thermal inertia, so that it heats up or cools down quickly as required.

Claims

[1] Composite material (1) for resistance heating, characterized by , that it has a heating layer (2) which is formed by a planar layer of electrically conductive carbon multifilaments or rovings with an areal weight of 50 to 850 g / m² 2 is formed, wherein an insulating layer (3) is deposited on both sides of the heating layer (2), which is formed by a planar layer of electrically non-conductive fiber material with a basis weight of 200 to 600 g / m². 2 is formed, wherein the heating layer (2) and the insulating layers (3) are stored in a matrix (4) formed by a resin, the resin content corresponding to 20 to 35 wt.% of the heating layer (2). [2] Composite material (1) according to claim 1, characterized by, that the heating layer (2) is formed by a layer of a carbon multifilament or roving applied to one side with a total fineness of 800 to 3000 tex, wherein the basis weight of the heating layer (2) is 50 to 150 g / m² 2 amounts. [3] Composite material (1) according to claim 1, characterized by , that the heating layer (2) is formed by a fabric of carbon multifilament or roving with a total fineness of 800 to 3000 tex, wherein the basis weight of the heating layer (2) is 120 to 850 g / m² 2 amounts. [4] Composite material (1) according to claim 3, characterized by , that the heating layer (2) is formed by a twill weave fabric. [5] Composite material (1) according to claim 1, characterized by , that the insulating layer (3) is formed by a fabric of glass multifilaments or rovings with a total fineness of 300 to 2300 tex, wherein the basis weight of the insulating layer (3) is 200 to 600 g / m² 2amounts. [6] Composite material (1) according to claim 1, characterized by , that the insulating layer (3) is formed by a fabric of aramid fibers with a total fineness of 300 to 2300 tex, wherein the basis weight of the insulating layer (3) is 200 to 600 g / m² 2 amounts. [7] Composite material (1) according to claim 5 or 6, characterized by , that the insulating layer (3) is formed by a twill weave fabric. [8] Composite material (1) according to claim 1, characterized by that the matrix is ​​formed by an epoxy resin or a melamine-formaldehyde resin. [9] System (5) for resistance heating, characterized by , that the system has at least one heating element (6) formed by the composite material (1) according to one of claims 1 to 8, which is connected to an electrical voltage source (7), wherein a temperature controller (8) is arranged between the heating element (6) and the electrical voltage source (7).

Images