WO2019180110A1

WO2019180110A1 - Arrangement of strand heating elements and method for limiting magnetic and electromagnetic fields

Info

Publication number: WO2019180110A1
Application number: PCT/EP2019/057021
Authority: WO
Inventors: Jörg Marktscheffel
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2018-03-22
Filing date: 2019-03-21
Publication date: 2019-09-26
Also published as: DE102018204412A1; EP3769584A1

Abstract

The invention relates to an arrangement and to a method for generating heat on a predetermined heating surface (A) of a component, by means of at least one heating element (H; n=1) in wire form which is arranged on or in a support element (100) of the component, in which for the predetermined heating surface (A) a target heating power (P_Soll) is achieved at a predetermined operating voltage (U_B) with a predetermined current strength (I_H). According to the invention, the target heating power (P_Soll) is generated by arranging at least two heating element sections (HA; n>1) on or in a support element (100), the at least two heating element sections (HA; n>1) being connected in parallel to one another, and a component current strength (I_HA) is switched to each of the heating elements (HA; n>1); the sum of the component current strengths (I_HA) of the heating element sections (HA; n>1) corresponds to the predetermined current strength (I_H), such that the respective measured value (<B_max; n>1), reduced by a predeterminable amount, of the electromagnetic fields (B; n>1) each of the at least two heating elements (H; n>1) in wire form by comparison with a previous maximum value (B_max; n=1) of the electromagnetic field (B; n=1) of a single heating element (H; n=1) in wire form is reduced with the proviso that the single heating element (H; n=1) in wire form and the at least two heating element sections (HA; n>1) are arranged and operated on or in a support element (100) taking account of the same predetermined heating surface (A) and the same predetermined (P_Soll) and the same operating voltage (U_B).

Description

description

Arrangement of stranded heating elements and methods for limiting magnetic and electromagnetic fields

The invention relates to an arrangement and a method for generating heat on a predetermined heating surface of a component, by means of at least one wire-shaped

Heating element, which is arranged on or in a carrier element of the component, wherein for the given heating surface, a desired heating power at a predetermined

Operating voltage is achieved with a predetermined current.

Seat heaters with wire-shaped heating elements are now among the most popular features of vehicles. Seat heaters are now regarded not only as additional comfort equipment, but as standard equipment. The increasing electrification of automobiles and the constant advancing displacement of the classic internal combustion engine also eliminates the use of waste heat in the passenger compartment. The waste heat of a battery and the electric motors is too low, so as to provide the passenger compartment with sufficient heat. This means that more and more electrically powered components must be used to generate heat in vehicles, which in turn leads to an increase in the electromagnetic fields. Currently, there is a trend to look for ways to provide electrically operated heating zones based on electric heating elements within electrically powered vehicles - where no use of waste heat in the passenger compartment is possible. Thus, to achieve a pleasant interior climate of the vehicle increasingly cladding elements, such as door panels, the cockpit and the vehicle sky, and the steering wheel, the shift knob and armrests, center armrests and even floor mats and / or the like and as hitherto seat heaters equipped with heating elements. In this way, in particular the seat heating is becoming a more and more indispensable comfort component. All enumerated heat generating measures, in which electrical currents flow, provide for an increase of the fields in which electromagnetic radiation acts in the passenger compartment. In the future, this will be greatly reduced by meaningful measures in order to protect health, in particular to protect carriers of cardiac pacemakers, insulin pumps, etc. according to the ICNIRP guideline. As far as possible no additional costs should be incurred. For the purposes of the present invention are thus additional cost generating components, such as

Shielding material or additional electronic control devices are not taken into account.

It has also been found that all known Schirmungsmaterialien can indeed shielding, but the seating comfort by the unsatisfactory

Strain behavior of very rigid shielding is severely limited, so that under this aspect shielding materials are not taken into account. Finally, there is a problem in that the durability of the shielding materials is difficult to ensure over the life of a vehicle life, so also for this reason, a solution providing shielding is dispensed with.

With regard to the idea explained below, the necessary basics are first summarized. The magnetic field is a field of electromagnetic energy. Everywhere where electricity flows, creates a magnetic field, as in seat heaters, where

For example, a backrest or a seat part, which are to be heated components.

The object of a stranded component heating, for example a stranded-seat heating or strand-back heating, is to electrically heat the seat part or the backrest.

It is understood that the solutions according to the invention explained below also apply to other components, such as a stranded door panel heating, a stranded cockpit heating, a stranded vehicle overhead heating, a stranded wire heating and a stranded switching knob heating and a stranded armrest heating, etc.

The document DE 10 2007 019 891 A1 has already set itself the task of creating a heating device and a corresponding method for heating a device of a vehicle, in particular a seat, a steering wheel, an exterior mirror or a window pane, which makes it possible with negligible minimal additional costs and also a negligible effort to heat the devices mentioned and thereby reduce the electromagnetic radiation. It is provided to arrange at least one first wire-shaped heating element of a first group and at least one second heating element of a second group of heating elements, preferably of the same construction, this second heating element of the second group being in the opposite direction to the first Heating element of the first group of heating elements is energized. These two oppositely energized heating elements are preferably arranged axially parallel and closely adjacent to each other or one above the other, so that they have a bifilar arrangement of

Form heating elements. The heating elements can be designed as individual heating wires or as a heating line in which two or more heating wires are firmly connected together with an insulator. The heating elements can also as

superimposed heating mats, heating foils or heating coatings are performed, wherein the power supply to the heating mats, heating foils or heating layers and the arrangement of the heating mats, heating foils or heating layers are matched to each other so that the heating elements mutually bifilar arrangements, resulting in the electromagnetic emissions of heating mats, heating foils or heating layers weaken or compensate each other. It will be appreciated that additional line lengths are disadvantageously required in this solution to achieve the compensation effect. In addition, a bifilar installation works only in the two - dimensional plane, because one with some distance to the bifilar laying of the

Heating wires measured electromagnetic field caused by the superposition of the currents a distance-dependent other field. Thus, a bifilar installation in a seat portion or backrest portion of a vehicle seat is not efficient because the distance between a passenger for built-in seat heating is so large that another, so to speak mixed electromagnetic field is effective.

The invention is based on the object, a reduction of the magnetic radiation of the heating elements used in a vehicle in strand technology for compliance with limits of exposure to variable electrical and magnetic and

In particular, the directive ICNIRP is considered, which is to be implemented while maintaining the full range of comfort and functionality of the component heaters formed from the heating elements. Moreover, the object is that the safety and durability of a component heating formed from at least one heating element are not reduced, and in addition the production costs do not increase significantly.

The starting point of the invention is the arrangement of at least one wire-shaped

Heating element on or in a carrier element of a component for generating heat on a predetermined heating surface of the component, wherein for the predetermined heating surface, a desired heating power is achieved at a predetermined operating voltage with a predetermined current. According to the invention, it is provided that the desired heating power is generated by arranging at least two heating element sections on or in a carrier element, wherein the at least two heating element sections are connected to one another via a parallel circuit, and each of the heating element sections is switched to a partial current intensity, wherein the sum of the partial current strengths of the Heizelementabschnitte the predetermined current corresponds, whereby the measured in each case by a predeterminable amount reduced value of the electromagnetic fields of each of the at least two wire-shaped heating elements in

Compared to a previous maximum value of the electromagnetic field of a single wire-shaped heating element is reduced on the assumption that the single wire-shaped heating element and the at least two Heizelementabschnitte on or in a carrier element taking into account the same predetermined heating surface and the same nominal heating power and the same operating voltage (UB) are arranged and operated.

It is preferably provided that the at least two heating element sections have an equal length or different lengths, the respective length being selected such that the respective measured reduced value of the electromagnetic fields of each of the at least two wire-shaped heating elements compared to the previous maximum value of the single wire-shaped heating element is reduced by the predetermined amount.

Further, it is preferably provided that the partial current strengths of each of the Heizelementabschnitte depending on the number of Heizelementabschnitte and / or their length is less than the current of the single wire-shaped heating element.

The user of this invention will determine the substream strengths of the heater sections in FIG

Adjust the dependence of the number of Heizelementabschnitte and / or their length by changing the electrical resistance of the Heizelementabschnitte to generate the predetermined current.

It is preferably provided that the arrangement of the heating element sections is optimized by determining the number of heating element sections and / or determining their length such that the value of the magnetic fields of each of the heating element sections which is reduced compared to the previous maximum value does not exceed a predefinable limit value of a maximum permissible magnetic field , The arrangement is characterized in that the arrangement of the heating element sections is optimized by determining the number of heating element sections and / or determining their length such that the limit value in each of the heating element sections is undershot by a predeterminable percentage. In other words, the predetermined limit of the maximum permissible magnetic field is undershot by the predetermined percentage, so that a safety threshold or a safety range between the maximum permissible limit of the magnetic field and the undershooted by the predetermined percentage maximum permissible limit of the magnetic field is effected.

The starting point of the inventive method for generating heat on a given heating surface of a component is that at least one wire-shaped heating element is arranged on or in a carrier element of the component, wherein in operation of the wire-shaped heating element for the given heating surface, a desired heating power at a predetermined Operating voltage is achieved with a predetermined current.

According to the invention, it is provided that the desired heating power is generated by arranging at least two heating element sections on or in a carrier element, the at least two heating element sections being connected in parallel, and each of the

Heizelementabschnitte a partial current is switched, the sum of the

Partial current strengths of the Heizelementabschnitte the predetermined current, whereby the measured in each case by a predetermined amount reduced value of the electromagnetic fields of each of the at least two wire-shaped heating elements is reduced, the reduction considered compared to a previous maximum value of the electromagnetic field of a single wire-shaped heating element under the condition is that the only wire-shaped heating element and the at least two Heizelementabschnitte are operated on or in a carrier element, taking into account the same predetermined heating surface and the same desired heating power and the same operating voltage.

The invention will be explained below with reference to the accompanying drawings. Show it:

Figure 1 is a classic strand heating for heating a seat part and / or a

Lean with a single continuous heating strand arranged per heating field;

FIG. 2 shows a strand heating according to the invention for heating the seat part and / or the backrest with a plurality of heating strands arranged per heating field; Figure 3 shows the classic strand heating according to Figure 1 in a representational

Representation with nine reference measuring points distributed on the heating surface; and

Figure 4 shows the strand heating according to the invention in a according to Figure 2 in a

representational representation with nine arranged analogously to Figure 3 comparison measuring points.

According to FIG. 1, heald heaters have hitherto been used for heating a component,

For example, a backrest (backrest heater) or a seat part (seat part heater) used, the per heating field, with a heating surface A a single (number n = 1) continuous heating H, n = 1 have.

This heating strand H is energized in the conventional design per heating field, for example, with a current IH of 4A.

FIG. 1 shows by way of example, representative of other possible carrier elements, a carrier element 100 with the single heating strand H; n = 1, which is arranged on or in the carrier element 100.

The surface of the carrier element 100 corresponds to the heating surface A. Such

Carrier element 100 is part of a component, in particular a backrest and / or a seat part of a vehicle seat and arranged below the cover or below the cover and a lamination of the seat part and / or the back, to name just two of the possible arrangement options.

With an operating voltage U _B of, for example, 13V applied to the heating strand H and an energization of the heating strand H with a current IH of 4A, a power of 52W thus results for the area A (= heating surface) to be heated. In other words, relatively high currents are required to produce a blanket heat for the heating surface A, so that a relatively high magnetic field is formed, whereby the strand length, thereby only one strand H; n = 1 is used is relatively high, to ensure a homogeneous heat distribution of the heating surface A, which also causes a high electromagnetic field. Upon energization of the heating strand H with an even higher current intensity IH and an even higher length of the heating strand H, this results in an even higher one

electromagnetic field. High electromagnetic fields are undesirable. Therefore, in order to reduce the electromagnetic energy of a component heater according to the ICNIRP directive, various considerations have been made.

From the general school physics it is known that with increasing current strength the

Magnetic field rises around the conductor. Decreasing the current strength also reduces the magnetic field. In short, the higher the current I is, the larger it is

magnetic field B.

It is also known that with increasing cable length also increases the magnetic field, such as the number of turns in an electromagnet strengthens the magnetic field.

Shortening the conductor reduces the magnetic field. In short, the longer the conductor through which flows, the larger the electromagnetic field.

As a result of the above explanations, the causes of the high magnetic fields in classical Litzenheizungen be seen in the fact that high currents are required to generate in the respective component, a blanket heat and relatively long strand lengths are needed to in the corresponding component or the associated to be heated surface to ensure a homogeneous heat distribution.

The measures according to the invention thus follow the fundamental principle that the current is reduced within the heating strands, whereby a reduction of

electromagnetic field is achieved. A second measure is the

Litz length to reduce, which also achieves a reduction of the electromagnetic field.

Preferably, these measures are carried out in combination, so that the object of the present invention is achieved by at least one of the measures or by both measures.

FIG. 2 shows an example which is used for further detailed explanation of FIG

Invention serves.

In the present exemplary embodiment according to FIG. 2, the existing strand length according to FIG. 1 is divided into heating element sections HA; n> 1 divided. Thus, in the exemplary embodiment, four heating element sections HA; n = 4 arranged. By comparison of FIGS. 1 and 2, it becomes clear the carrier element 100 has the same area A, so that the surface A to be heated of the components to be compared is the same size.

According to the invention it is provided that with the inventive division of a single wire-shaped heating element H; n = 1 in at least two heating element sections HA; n> 1 an equal desired heating power Psoii is effected.

By dividing into the at least two heating element sections HA; n> 1, the electromagnetic fields B associated with each of the heater sections HA are given by the

Reduction of the current intensity IHA per heating element section HA compared to the current intensity I _H (see Figure 1) and reduced by reducing the length of the Heizelementabschnitte HA compared to a single heating H (see Figure 1) on the entire heating surface A.

If these heating element sections HA are then switched in parallel and the heating field A is again set to the same current intensity IH of FIG. 4A as explained with reference to FIG. 1, consequently the respective magnetic fields B of the heating element sections HA are also reduced.

In the embodiment according to FIG. 2, for example, four heating element sections HA; n = 4 arranged, which have the same length in the embodiment and are each energized with a current of 1A, the operating voltage UB with respect to the example in Figure 1 remains unchanged.

It is understood that the heating element sections HA; n> 1 need not necessarily have the same length but that different lengths can be chosen, the same lengths and the different lengths being chosen such that at each of the heating element sections HA; n> 1 a reduced value 1 compared to an assumed maximum value B _m ax; n = 1 of the only one

wire-shaped heating element H; n = 1 according to FIG.

In other words, the maximum value B _max ; n = 1, in addition to the choice of the number n of

Heating element sections HA; n> 1, depending on the length designation of the heating element sections HA; n> 1 can be reduced by a predefinable amount.

FIG. 3 shows, for a further explanation according to FIG. 1, a carrier element 100 shown in the figure with a single circuit of a single heating element H; n =. 1 This structure represents a so-called reference heating element, wherein nine reference measuring points 1 to 9 are shown, in which the values of those acting there

electromagnetic fields B have been measured.

By means of a known Narda ELT-400 measuring device, the electromagnetic fields B acting on the surface of the heating element H having a single heating wire H were measured in a grid-like manner at the reference measuring points 1 to 9.

The mentioned measuring device is used for the safety assessment of the radiation exposure of humans through magnetic fields and for the acceptance measurement of electrically operated products. For further explanation please refer to the website www.narda-sts.com.

Each of the new reference measurement points 1 to 9 is thus a certain value of one

attributable to electromagnetic field B.

These values of the electromagnetic fields B in the reference measuring points 1 to 9 are either below or above a guideline limit value, which is defined in the aforementioned guideline ICNIRP.

In FIG. 4, in comparison with FIG. 3, the corresponding arrangement is shown in which a support element 100 is likewise arranged, whose predetermined heating surface A corresponds to the heating surface A in FIG. In addition, the target heating power Ps _oii and the

Operating voltage UB in Figure 4 compared to Figure 3 be the same size, so that the

Boundary conditions between the solution of the prior art according to Figure 3 and the inventive solution according to Figure 4 are the same.

In contrast to FIG. 2, in this exemplary embodiment in FIG. 4, in contrast to FIG. 2, it is not a quadruple parallel connection but a sixfold parallel circuit in which six heating element sections HA; n = 6 are arranged.

In Figure 4 are in local analogy to the reference measuring points 1 to 9 the

Comparison measuring points 1 to 9 arranged and the corresponding experimental evaluation was determined by measurements with the Narda ELT-400, that in each of the comparison points 1 to 9 of Figure 4, the associated electromagnetic fields B compared to the reference measuring points 1 to 9 in FIG 3 are substantially reduced. The experiments thus confirmed that the formation of at least two heating element sections HA, n> 1 of the same length or different lengths achieves a proven reduction of the electromagnetic fields B in the nine comparative measuring points 1 to 9 chosen by way of example only.

Depending on which height the electromagnetic fields should have in the comparison measuring points 1 to 9, it is possible according to the invention, the partial current strengths IHA each of

Heating element sections HA; n> 1 depending on the number n of Heizelementabschnitte HA and / or depending on their length to reduce.

The maximum value adopted to Erläutertungszwecken B _max; n = 1 can thus be reduced to the reduced value 1, wherein it is possible in the invention to take into account a predeterminable limit value B enz _Gr, which is defined for example as guidelines limit value in the aforesaid ICNIRP. In other words, the limit value B _limit is assigned to a maximum permissible electromagnetic field B, wherein the limit value B _{limit should} not be exceeded at any point of the heating surface A of the carrier element 100.

In addition, it can be provided that the predefinable limit value B _{limit is} even undershot by a predefinable percentage p%.

In other words, it can be specified according to the invention that the limit value B _{limit should be} 50% or 75% of a maximum permissible value B _{max of} the electromagnetic field B, that is to say fall below by a certain percentage p% by 50% or 25% is to give a personal protection compared to a policy-limit in the said Directive ICNIRP is further enhanced by the limit B _limit is set well below the policy limit.

LIST OF REFERENCE NUMBERS

100 carrier element

A heating surface

n number

H heating wire

UB operating voltage

l _H current of a heating element H

IHA amperage of a heating element section HA

Psoii desired heat output

Bmax assumed maximum value of an electromagnetic field B

<Bmax reduced value of an electromagnetic field B

1 to 9 reference and comparison measuring points

B _G rence limit

p% percentage

Claims

claims

1. Arrangement of at least one wire-shaped heating element (H; n = 1) on or in a carrier element (100) of a component for generating heat on one

predetermined heating surface (A) of the component, wherein for the given heating surface (A) a desired heating power (Psoii) is achieved at a predetermined operating voltage (UB) with a predetermined current (IH),

characterized in that

the desired heating power (Psoii) by arranging at least two

Heating element sections (HA; n> 1) is generated on or in a carrier element (100), wherein the at least two heating element sections (HA; n> 1) are interconnected via a parallel connection, and each of the heating element sections (HA; n> 1) a partial current intensity (IHA) is connected, the sum of the partial current strengths (I HA) of the heating element sections (HA; n> 1) corresponding to the predetermined current intensity (IH), whereby the respectively measured value reduced by a predefinable amount ( 1) of the electromagnetic fields (B; n> 1) of each of the at least two wire-shaped heating elements (H; n> 1) compared to a previous maximum value (B _m ax; n = 1) of an electromagnetic field (B; n = 1) of a single wire-shaped heating element (H; n = 1) on the premise that the single wire-shaped heating element (H; n = 1) and the at least two heating element sections (HA; n> 1) on or in a carrier element (100) considering the same predetermined heating surface (A) and the same desired heating power (Psoii) and the same operating voltage (UB) are arranged and operated.

2. Arrangement according to claim 1, characterized in that the at least two

Heizelementabschnitte (HA; n> 1) have the same or different lengths, wherein the respective length is selected so that each measured reduced value ( ^< 'Bmax! N> 1) of the electromagnetic fields (B; n> 1) of each of at least two wire-shaped heating elements (H; n> 1) compared to the previous maximum value (B _max ; n = 1) of the single wire-shaped heating element (H; n = 1) is reduced by the predeterminable amount.

3. Arrangement according to claim 2, characterized in that the partial current strengths (IHA) of each of the Heizelementabschnitte (HA; n> 1) as a function of the number (n) of

Heating element sections (HA; n> 1) and / or their length is less than the current (IH) of the single wire-shaped heating element (H; n = 1).

4. An arrangement according to at least one of claims 1 to 3, characterized in that the relative to the maximum value (B _m ax; n = 1) reduced value ( 1) of the magnetic fields (B; n> 1 ) each of the Heizelementabschnitte (HA; n> 1) does not exceed a predetermined limit (B _Gr enz) of a maximum permissible magnetic field (B).

5. Arrangement according to claim 4, characterized in that the limit value (B _Gr enz) in each of the Heizelementabschnitte (HA; n> 1) by a predetermined percentage (p%) is exceeded.

6. A method for generating heat on a given heating surface (A) of a

Component, by means of at least one wire-shaped heating element (H; n = 1), which is arranged on or in a carrier element (100) of the component, wherein for the given heating surface (A) a desired heating power (Psoii) at a predetermined operating voltage (UB ) is achieved with a predetermined current (IH), characterized in that

the desired heating power (Psoii) by arranging at least two

Heating element sections (HA; n> 1) is generated on or in a carrier element (100), wherein the at least two heating element sections (HA; n> 1) are connected in parallel, and each of the heating element sections (HA; n> 1) has a partial current intensity ( IHA), wherein the sum of the partial current strengths (IHA) of the heating element sections (HA; n> 1) corresponds to the predetermined current intensity (IH), whereby the respectively measured maximum value ( 1) reduced by a predeterminable amount electromagnetic fields (B; n> 1) of each of the at least two wire-shaped heating elements (H; n> 1) compared to a previous maximum value of the electromagnetic field (B _max ; n = 1) of a single wire-shaped heating element (H; n = 1) provided that the only wire-shaped heating element (H; n = 1) and the at least two

Heating element sections (HA; n> 1) on or in a carrier element (100) below

Consideration of the same predetermined heating surface (A) and the same nominal heating power (Psoii) and the same operating voltage (UB) are operated.

7. The method according to claim 6, characterized in that the partial current strengths (IHA) of the Heizelementabschnitte (HA; n> 1) as a function of the number (n) of

Heating element sections (HA; n> 1) and / or their length by means of changing the electrical resistance of the Heizelementabschnitte (HA; n> 1) are adapted to generate the predetermined current (IH).