DE102019129739B3 - Radiant heating element and radiant heater for a vehicle - Google Patents

Abstract

The invention relates to a radiant heating element for a vehicle comprising: a first layer (101) with a knitted fabric, a scrim, a knitted fabric or a fabric made from a first electrical conductor (102), a second layer (103) with a knitted fabric, a scrim, a knitted or woven fabric made of a second electrical conductor (104), and a third layer (105) which is arranged between the first layer (101) and the second layer (103) connecting them, the first conductor (102) and the second conductor (104) for generating thermal radiation through the first (101) and second (102) layers can be connected to a power source (111), and the third layer (105) is elastic in such a way that it is in a mechanically unloaded first State the first layer (101) and the second layer (103) spaced apart by a distance A and, in a mechanically loaded second state, local electrical contact between the first layer (101) and the second layer (10 3) allows.

Description

The invention relates to a radiant heating element, a radiant heater for a vehicle with such a radiant heating element and a vehicle with such a radiant heater, in particular a road vehicle, a rail vehicle, a watercraft or an aircraft.

Due to the changing types of drive in future vehicles, especially road vehicles, towards electric drives, waste heat from internal combustion engines can no longer be used to heat the vehicle interior, as has been the case up to now. For an increasing number of hybrid and electric vehicles, alternative heating systems need to be developed that are both efficient and comfortable.

In addition to heating by convection (air circulation), heating can be implemented by generating radiant heat (infrared radiation). Here, the thermal effect is generated by incident (infrared) radiation, for example directly on the skin surface of a vehicle occupant.

From the WO 2013/020627 A1 a functionalized interior trim component, a method for its production and a motor vehicle with the interior trim component are known. The interior lining component is a sandwich component with a layer arrangement, the at least one honeycomb core, two cover layers, which comprise at least one reinforcement fiber arrangement embedded in a thermoplastic plastic matrix and between which the honeycomb core is arranged, at least one surface heating textile that on a side facing away from the honeycomb core at least one of the Cover layers is arranged, and has at least one decorative layer which covers the surface heating textile and forms a surface of the interior trim component.

Heating elements can also be found in the following documents: DE 10 2012 012 285 A1 , DE 10 2013 212 831 A1 , as US 2018/0201095 A1 .

The object of the invention is to provide a radiant heating element as a heat source of a radiant heater for a vehicle which, on the one hand, achieves a high surface temperature in order to generate a desired high radiant power and, on the other hand, enables low contact temperatures, whereby there is a risk of injury to human skin in particular upon contact with the radiation heating element is minimized.

The invention results from the features of the independent claims. Advantageous further developments and refinements are the subject matter of the dependent claims.

A first aspect of the invention relates to a radiant heating element for a vehicle comprising: a first layer with a knitted fabric, a scrim, a knitted fabric or a fabric made of a first electrical conductor, a second layer with a knitted fabric, a laid fabric, a knitted fabric or a woven fabric a second electrical conductor, and a third layer which is arranged between the first layer and the second layer, connecting them, wherein the first conductor and the second conductor can be connected to a power source for generating thermal radiation through the first and second layers.

The invention is based on the following findings of the inventors.

The surface temperature of a heat-radiating body enters the generated heat radiation with the fourth power and is therefore the most important parameter with regard to the generation of heat radiation.

• • Temperatur der Oberfläche
• • Material der Oberfläche
• • Dauer des Kontaktes
• • Struktur der Oberfläche
• • Empfindlichkeit der Haut des Menschen

For the surfaces inside the vehicle, it must be ensured that vehicle occupants cannot burn themselves if they touch a radiant heater. In DIN EN ISO 13732-1, which describes the ergonomics of the thermal environment and thus the evaluation method for human reactions to contact with surfaces, it emerges that the following parameters determine whether there is a burn / damage to the skin on contact with a surface come or not:

• • Surface temperature
• • Material of the surface
• • Duration of contact
• • Structure of the surface
• • Human skin sensitivity

Investigations have shown that low temperatures, for example around 40 ° C, are rather unsuitable for radiant heating, since the radiated heat can only be perceived at a distance of a few centimeters. There is no generally applicable, maximum permissible surface temperature in the vehicle interior. However, maximum temperatures can be specified for certain materials and contact times. For plastics, for example, they are in contact for 8 hours and longer at a maximum of 43 ° C.

stellt sich entsprechend eine geringe Kontakttemperatur ein. Beispielsweise kann Holz $\left(\text{b=0}\text{,4}-\mathrm{0,5}\left[\frac{kJ}{K{m}^2\sqrt{s}}\right]\right)$

mit 90°C (z.B. in einer Sauna) ohne Gefahr einer Hautverbrennung berührt werden, wohingegen Stahl $\left(\text{b}=14\left[\frac{kJ}{K{m}^2\sqrt{s}}\right]\right)$

bei dieser Temperatur nicht berührt werden sollte.The decisive factor in avoiding skin damage is that Contact temperature between the passenger's skin and the radiating surface. This is described by the temperatures of the two surfaces (skin - radiating surface) and, crucially, by the heat penetration coefficient b. For materials with a low coefficient of thermal penetration $\text{b <1}\left[\frac{kJ}{K{m}^2\sqrt{s}}\right],$

a correspondingly low contact temperature is established. For example, wood can $\left(\text{b = 0}\text{, 4}-0.5\left[\frac{kJ}{K{m}^2\sqrt{s}}\right]\right)$

at 90 ° C (e.g. in a sauna) without risk of skin burns, whereas steel $\left(\text{b}=\mathrm{14th}\left[\frac{kJ}{K{m}^2\sqrt{s}}\right]\right)$

should not be touched at this temperature.

The proposed radiant heating element consists of at least three layers (first layer, second layer, third layer), the first layer and the second layer serving to generate radiant heat, provided that electrical current flows through them accordingly. In the proposed radiant heating element, thermal radiation is thus generated from both the first layer and the second layer, with heat transfer, for example, to the skin of a person taking place only through the first layer when it is touched (it is assumed in the present case that the first layer is that layer which is arranged directed towards the interior of the vehicle when the radiant heating element is arranged in a vehicle). This ensures that heating power is generated in the form of radiant heat from both the first and the second layer, while the contact heat is only transmitted through the first layer (the layer facing the interior), for example by touching a person, so that through the proposed radiant heating element on the one hand achieves a high efficiency of the radiant heating and on the other hand minimizes the risk of injury to a person when touching the radiant heating element.

A lamination layer can advantageously be applied to the first layer, i.e. on the side of the radiant heating element facing the interior of a vehicle, which meets the visual and / or haptic requirements of the vehicle interior and thus separates the radiant heating element from the corresponding vehicle interior after installation in a vehicle. The lamination layer is advantageously made of a material which allows thermal radiation to pass essentially unhindered.

According to the invention, the proposed radiant heating element is characterized in that the third layer is designed to be elastic in such a way that it separates the first layer and the second layer by a distance A in a mechanically unloaded first state and a reduction in the distance A in a mechanically loaded second state generated or even enables a local electrical contacting of the first layer with the second layer. The term “mechanically loaded second state” is understood to mean, in particular, the application of an external force to the first layer. This can be done, for example, by pressing a human extremity against the first layer. The third layer is thus elastic in that when external forces are applied to the radiant heating element, the layer thickness of the third layer can be variably adjusted.

The third layer is advantageously designed as a knitted fabric, the scrim, the knitted fabric or the woven fabric made of one or more synthetic fibers. The non-electrically conductive knitted fabric, scrim, knitted fabric or woven fabric of the third layer is advantageously composed of a polymer, in particular of polyester.

In one embodiment of the third layer, it is designed such that when a correspondingly high external force is applied, the first and second layers come into contact, so that in particular at least local electrical contacting of the electrical conductors of the first and second layer results.

The knitted fabric, the scrim, the knitted fabric or the woven fabric of the first layer and / or the second layer advantageously additionally has one or more synthetic fibers.

In a particularly preferred variant, the first layer and / or the second layer consists of a knitted fabric, a scrim, a knitted fabric or a woven fabric exclusively made from an electrically conductive material.

In another variant, the first and second electrical conductors are covered with an electrically non-conductive layer or wrapped with one or more electrically non-conductive synthetic fibers. In this variant, no electrical contact can be made between the first electrical conductor and the second electrical conductor. In this respect, no disconnection device, as described below, is required in this variant.

The first and / or the second electrical conductor can in particular consist of a plurality of electrically conductive individual fibers. The first and / or the second electrical conductor preferably consist of metal, a metal alloy or an electrically conductive fiber material.

An advantageous development of the proposed radiant heating element is characterized in that the first and / or the second conductor each electrically have an electrical contact interface on an opposite side of the respective layer, which can be connected to the power source. The contact interface is advantageously designed as an electrical-mechanical plug connection.

An advantageous development of the proposed radiant heating element is characterized in that a reflector layer is arranged on the second layer on the side facing away from the third layer, which reflector layer consists of a heat radiation-reflecting material, preferably an aluminum layer coated with polypropylene. The reflector layer serves to deflect the thermal radiation hitting the reflector layer so that it leaves the radiant heating element via the first layer, so that a heat output radiated in the direction of the vehicle interior is increased.

An advantageous development of the proposed radiant heating element is characterized in that a spacer layer made of a material with low thermal capacity and low thermal conductivity is arranged between the second layer and the reflector layer, so that the spacer layer is penetrated by thermal radiation. The spacer layer serves in particular to decouple the heat conduction between the second layer and the reflector layer.

In one configuration, the spacer layer is designed as an air gap between the second layer and the reflector layer. Alternatively, the spacer layer can be designed as a knitted fabric, a scrim, a knitted fabric or a woven fabric or have a honeycomb-like or corrugated honeycomb-like structure or consist of a reticulated foam.

An advantageous development of the proposed radiant heating element is characterized in that a thermal insulation layer made of a material with low thermal conductivity is arranged on the reflector layer on its side facing away from the second layer. The heat insulation layer serves to insulate the radiant heating element as far as possible with regard to heat conduction from the installation location in the vehicle.

In an advantageous embodiment, the radiant heating element has three layers, two layers (first layer and second layer) made of a metallic (stainless steel) knitted fabric with the third layer made of a plastic material in between. Due to the low density and the low heat capacity of the conductive metallic knitted fabric, high surface temperatures can be achieved without causing burns on contact with the human skin. In this way, in particular, rapid heating and cooling speeds can also be achieved.

Another aspect of the invention relates to a radiant heater with a radiant heating element, as described above, and a power source.

An advantageous development of the radiant heater is characterized in that there is a disconnection device which is connected to the first electrical conductor and the second electrical conductor as well as the power source, the disconnection device being designed for this purpose in the event of an electrical connection between the first being detected electrical conductor and the second electrical conductor to switch off the power supply to the first electrical conductor and to the second electrical conductor from the power source. The cut-off device is used in particular for safety. The disconnection device is advantageously designed in such a way that as soon as there is no electrical connection between the first conductor and the second conductor, a disconnection from the power source that has previously occurred is canceled.

Another aspect of the invention relates to a vehicle, in particular a road vehicle, a rail vehicle, a watercraft or an aircraft with a radiant heater installed in the vehicle as described above. The proposed radiant heating element is advantageously installed in the footwell of a vehicle.

Further advantages, features and details emerge from the following description, in which at least one exemplary embodiment is described in detail - possibly with reference to the drawing.

• 1 einen schematisierten Aufbau einer Strahlungsheizung mit einem erfindungsgemäßen Strahlungsheizungselement (dargestellt in einer schematisierten Querschnittsansicht), einer Stromquelle und eine Abschalteinrichtung.

It shows

• 1 a schematic structure of a radiant heater with a radiant heating element according to the invention (shown in a schematic cross-sectional view), a power source and a cut-off device.

1 shows a schematic structure of a radiant heater with a radiant heating element according to the invention (shown in a schematic cross-sectional view), a power source and a switch-off device. The radiant heating element shown generates thermal radiation which is radiated in the direction of the arrow, for example into a vehicle interior, that is to say upward in the image.

The radiant heating element comprises a first layer 101 with a knitted fabric made of a first electrical conductor made of a stainless steel material, a second layer 103 with a knitted fabric made of a second electrical conductor made of a stainless steel material and a third layer 105 that between the first layer 101 and the second layer 103 , this is arranged connecting. The first layer 101 is on the side facing the vehicle interior with a cladding layer 110 whose surface meets the corresponding requirements for the interior design of the vehicle in terms of visual and haptic properties. The lamination layer 110 advantageously has a low thermal capacity and is made of a material that allows thermal radiation to pass essentially unhindered.

Furthermore, the radiant heating element comprises a reflector layer 106 working on the second shift 103 on which the third layer 105 is arranged facing away from the side and which consists of a heat radiation-reflecting material, in particular is designed as an aluminum layer coated with polypropylene. Between the second shift 103 and the reflector layer 106 is also a spacer layer 107 arranged with a knitted fabric made of a material with low thermal capacity and low thermal conductivity, so that the spacer layer 107 is penetrated by thermal radiation essentially unhindered. Finally, the radiant heating element comprises a thermal insulation layer 108 attached to the reflector layer 106 on the second layer 103 is arranged facing away from the side and consists of a material with low heat conduction. The radiant heating element thus consists of seven layers in this exemplary embodiment.

The first electrical conductor and the second electrical conductor are connected to a power source 111 connected. Furthermore, the first and second electrical conductors are on opposite sides of the respective layer 101 / 103 via an electrical contact interface 112 with the power source 111 connected.

The third layer 105 is designed to be elastic in such a way that it forms the first layer in a mechanically unloaded first state 101 and the second layer 103 at a distance A and, in a mechanically loaded second state, a local electrical contacting of the first layer 101 with the second layer 103 enables.

The radiant heater shown also includes a shutdown device 109 is present with the first electrical conductor 102 and the second electrical conductor 104 as well as the power source 111 is connected, the disconnection device 109 is designed for this purpose in the event of an electrical connection between the first electrical conductor being detected 102 and the second electrical conductor 104 the power supply to the first electrical conductor 102 and to the second electrical conductor 104 from the power source 111 switch off.

With the proposed radiant heating, skin burns are avoided because of the low density and the low heat capacity of the conductive knitted fabric of the first layer 101 high surface temperatures can be achieved without burns occurring on contact because of the low contact temperature between the skin of a passenger of a vehicle in which the radiant heater is integrated and the surface of the radiant heater. The small amount of heat is quickly absorbed when it comes into contact with the hand, for example, but the desired heat radiation is still noticeably noticeable even at greater distances from the passenger to the surface.

The radiant heating element described can be integrated into an interior structure of a vehicle, which improves the efficiency of the radiant heating. A reflector layer is used to direct the infrared rays that propagate against the vehicle interior into the vehicle interior 106 integrated (e.g. a polypropylene coated aluminum foil -> reflective, non-conductive surface).

The structure and material of the cladding layer 110 is advantageously chosen in such a way that the thermal radiation generated in the radiation element covers the cladding layer 110 Happened as unhindered as possible. As materials for the lamination layer 110 are for example: a polyester knit, fabric, knitted fabric, dilours, velor, Maliwatt, Malivlies -> with low grammage). This lamination can, for example, with a thin adhesive layer with the first layer 101 be connected (e.g. adhesive fabric, adhesive lamination, film).

The multi-layer structure of the radiant heating element with the reflector layer advantageously doubles the radiating area, which is also a factor in the equation for thermal radiation, whereby the thermal radiation is also doubled.

In the case of a single-layer structure, the base area would have to be doubled for comparable thermal radiation, the radiating area increased (higher mass -> contact temperature critical) or the temperature correspondingly increased. Due to the limited space available in the vehicle interior and the requirements with regard to burns, this property represents a significant advantage. The mass that is touched in the event of contact is also advantageously halved, which reduces the contact temperature.

• • Aufgrund der geringen Dichte und der geringen Wärmekapazität des leitenden Gestricks der ersten Schicht 101 können hohe Oberflächentemperaturen realisiert werden, ohne dass es bei Kontakt zu Verbrennungen kommt. Es stellt sich daher eine geringe Kontakttemperatur zwischen der Haut eines Passagiers und der Oberfläche der Strahlungsheizung ein. Die geringe Wärmemenge wird bei Kontakt schnell aufgenommen (bspw. durch die Hand). Die begrenzte Temperatur bspw. bei Kunststoff von 43°C kann durch den Aufbau des Gestrickes deutlich übertroffen werden, sodass die Wärmestrahlung auch bei größeren Entfernungen merklich spürbar ist.
• • Durch den mehrlagigen Aufbau des Strahlungsheizungselements mit dem Reflektor wird die abstrahlende Fläche, die ebenfalls ein Faktor in der Gleichung der Wärmestrahlung darstellt, verdoppelt, wodurch sich die Wärmestrahlung ebenfalls verdoppelt. Bei einem einlagigen Aufbau müsste die Grundfläche zur Erzeugung einer vergleichbaren Wärmestrahlung demnach verdoppelt, die abstrahlende Fläche erhöht (höhere Masse -> Kontakttemperatur kritisch) oder die Temperatur entsprechen erhöht werden. Aufgrund der begrenzt zur Verfügung stehenden Flächen im Fahrzeuginterieur und den Anforderungen bzgl. Verbrennungen, stellt diese Eigenschaft einen wesentlichen Vorteil dar.
• • Durch den mehrlagigen Aufbau halbiert sich die Masse, die im Falle eines Kontaktes berührt wird, wodurch sich die Kontakttemperatur reduziert (im Vergleich zu einem einlagigem Aufbau bei gleicher Fläche und gleicher Wärmestrahlung ergibt sich daher eine höhere Temperatur).
• • Durch die geringe Dichte und geringe Wärmekapazität der ersten und zweiten Schicht sind schnelle Aufheiz- und Abkühlzeiten realisierbar. Folglich kann ein hoher Komfort erreicht werden, da ein Fahrzeugpassagier nach kurzer Zeit Wärme wahrnimmt. Außerdem kann die Oberflächentemperatur des Strahlungsheizungselements mit integrierter Abschalteinrichtung (Sensorik) schnell reduziert werden, sodass die Verbrennungsgefahr ausgeschlossen werden kann.
• • Die flexible/elastische dritte Schicht ermöglicht das Zusammendrücken der beiden leitenden Schichten 101 und 103, wodurch ein Fehlstrom bei Berührung detektiert werden und bspw. als Abschaltsignal genutzt werden kann. Das System des Heizelements kann dementsprechend zusätzlich als Sensor verwendet werden.
• • Gute Drapiereigenschaften

The described structure of the proposed radiant heating element results in the following advantages:

• • Due to the low density and the low heat capacity of the conductive knitted fabric of the first layer 101 high surface temperatures can be achieved without burns on contact. There is therefore a low contact temperature between the skin of a passenger and the surface of the radiant heater. The small amount of heat is quickly absorbed upon contact (e.g. by the hand). The limited temperature of 43 ° C for plastic, for example, can be significantly exceeded by the structure of the knitted fabric, so that the heat radiation is noticeably noticeable even at greater distances.
• • Due to the multi-layer structure of the radiant heating element with the reflector, the radiating surface, which is also a factor in the equation for thermal radiation, is doubled, which also doubles the thermal radiation. In the case of a single-layer structure, the base area would have to be doubled in order to generate comparable thermal radiation, the radiating area increased (higher mass -> contact temperature critical) or the temperature correspondingly increased. Due to the limited space available in the vehicle interior and the requirements with regard to burns, this property represents a significant advantage.
• • The multi-layer structure halves the mass that is touched in the event of a contact, which reduces the contact temperature (compared to a single-layer structure with the same area and the same heat radiation, this results in a higher temperature).
• • Due to the low density and low heat capacity of the first and second layers, quick heating and cooling times can be achieved. As a result, a high level of comfort can be achieved because a vehicle passenger feels heat after a short time. In addition, the surface temperature of the radiant heating element with an integrated switch-off device (sensor system) can be reduced quickly so that the risk of burns can be excluded.
• • The flexible / elastic third layer enables the two conductive layers to be pressed together 101 and 103 , whereby a fault current can be detected when touched and can be used, for example, as a switch-off signal. The system of the heating element can accordingly also be used as a sensor.
• • Good draping properties

List of reference symbols

101

first layer

102

first electrical conductor

103

second layer

104

second electrical conductor

105

third layer

106

Reflector layer

107

Spacer layer

108

Thermal insulation layer

109

Shutdown device

110

Lamination layer

111

Power source

112

electrical contact interface

Claims (9)

Radiant heating element for a vehicle comprising: - A first layer (101) with a knitted fabric, a scrim, a knitted fabric or a woven fabric made of a first electrical conductor (102), - A second layer (103) with a knitted fabric, a scrim, a knitted fabric or a woven fabric made of a second electrical conductor (104), and - A third layer (105) which is arranged between the first layer (101) and the second layer (103) connecting them, wherein - the first conductor (102) and the second conductor (104) can be connected to a power source (111) for generating thermal radiation through the first (101) and second (102) layers, and - The third layer (105) is elastic in such a way that in a mechanically unloaded first state it separates the first layer (101) and the second layer (103) by a distance A and, in a mechanically loaded second state, local electrical contacting of the first Layer (101) with the second layer (103) allows. Radiant heating element according to Claim 1 , in which the third layer (105) consists of one or more synthetic fibers as a knitted fabric, as a scrim, as a knitted fabric or as a woven fabric. Radiant heating element according to one of the Claims 1 to 2 , in which the knitted fabric, the scrim, the knitted fabric or the woven fabric of the first layer (101) and / or the second layer (103) additionally has one or more synthetic fibers. Radiant heating element according to one of the Claims 1 to 3 , in which the first (102) and / or the second (104) conductor each have an electrical contact interface (112) on opposite sides of the respective layer, which can be connected to the power source (111). Radiant heating element according to one of the Claims 1 to 4th , in which a reflector layer (106) is arranged on the second layer (103), on the side thereof facing away from the third layer (105), which reflector layer consists of a thermal radiation-reflecting material. Radiant heating element according to Claim 5 , in which a spacer layer (107) made of a material with low thermal capacity and low thermal conductivity is arranged between the second layer (103) and the reflector layer (106). Radiant heating element according to Claim 5 or 6th in which a thermal insulation layer (108) made of a material with low thermal conductivity is arranged on the reflector layer (106) on its side facing away from the second layer (103). Radiant heating with a radiant heating element according to one of the Claims 1 to 7th , a current source (111) and a disconnection device (109) which is connected to the first electrical conductor (102) and the second electrical conductor (104) and the power source, the disconnection device (109) being designed for this in the event of a detection an electrical connection between the first electrical conductor (102) and the second electrical conductor (104) to switch off the power supply to the first electrical conductor (102) and to the second electrical conductor (104) from the power source (111). Vehicle, in particular road vehicle, watercraft, aircraft, or rail vehicle with a radiant heater installed therein, in particular in a footwell of the vehicle Claim 8 .

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