DE102021004123A1 - Electric heater - Google Patents

Abstract

The present invention relates to an electrical heating device, in particular for heating a fluid in a motor vehicle, having a housing with first and second fluid-carrying heat exchanger elements arranged parallel to one another, characterized in that a first and a second heating zone are formed between the first and the second heat exchanger element , wherein in the first heating zone at least one heating element, which generates heat through an ohmic resistance of a passive component, and in the second heating zone at least one electrical semiconductor power switch generating a power loss are arranged.

Description

The invention relates to an electrical heating device, in particular for heating a fluid in a motor vehicle with a semiconductor circuit breaker that generates power loss, and a motor vehicle according to the species of the independent patent claims.

In electrical heating devices, semiconductor power switches are used to electrically switch heat-generating heating elements. In the process, the semiconductor power switches generate a power loss that has to be dissipated in order to ensure proper functioning and a long service life of the semiconductor power switches.

Such a generic electric heater is for example from EP 2884817 A1 known wherein here power loss generating semiconductor power switches are arranged on one side of a housing to allow heat dissipation.

The electrical heating device according to the invention with the features of the independent patent claims has the advantage that the dissipation of the power loss is carried out to a fluid with which the electrical heating device is applied during operation and which should also be heated by the electrical heating device. In this way, the power loss emitted by the semiconductor power switches is not released unused to a housing or to the environment, but instead is discharged to the tempering fluid. The heating of the fluid is thus supported by the power loss of the semiconductor power switches and an advantageous gain in efficiency of the device according to the invention is achieved. Due to the arrangement between two fluid-carrying heat exchanger elements, two-sided heat dissipation can also be achieved, which is even more efficient. In addition, this results in an advantageous arrangement that makes complex constructions for fixing the semiconductor power switches unnecessary.

Therefore, an electrical heating device according to the features of claim 1 and the dependent claims is proposed here. The electrical heating device is used in particular for heating a fluid in a motor vehicle, a liquid fluid, in particular a coolant used in a cooling circuit, or a gaseous fluid, in particular air, being able to be used as the fluid. In the case of a coolant as the fluid, the electric heating device is used to heat a cooling or heating circuit in which the electric heating device is arranged in a motor vehicle, the cooling or heating circuit being used, for example, to heat a vehicle interior by means of a radiator or to control the temperature of a battery in a Motor vehicle can be used to enable an optimized supply or removal of energy into the battery when it is cold outside.

The electrical heating device has a housing that accommodates at least parts of the electrical heating device. In this case, a predominantly enclosed space can be assumed to be the housing, which includes, for example, electrical connections, contains control circuit boards, or, depending on the embodiment, encloses the entire electrical heating device. In this case, the housing is largely sealed against the undesired ingress of liquids and has appropriate openings for the introduction or discharge of fluids, electrical contacts or other components belonging to the electrical heating device. The housing can expediently consist of several individual parts which can form a closed housing when connected to one another. In particular, a housing can consist of a base body and a cover, with the housing being able to consist of plastic and/or metal materials, in particular cast or sheet metal materials.

Furthermore, the electrical heating device has first and second fluid-carrying heat exchanger elements arranged parallel to one another, between which first and second heating zones are formed, with at least one heating element in the first heating zone that generates heat through an ohmic resistance of a passive component and in the second heating zone at least one a power loss generating semiconductor power switch is arranged.

The first and the second heating zones are used to generate heat and give off the generated heat to the adjacent fluid-carrying heat exchanger elements and thus expediently heat the fluid circulating or flowing through them.

The heating elements arranged in the first heating zone generate heat through an ohmic resistance when an electrical voltage is applied. The components function as passive components. Depending on the embodiment, the heating elements can be designed as thick-film heating elements, as PTC resistance heating elements or as heating foils. Thick-film heating elements are conventional heating elements that generate and emit heat when electrical energy flows through them due to an ohmic resistance. In this case, preformed heating elements can be used, which are then placed in the first heating zone between the two fluid-carrying heat exchangers lementen are arranged or at least partially applied to the first and / or second heat exchanger element coating of a thick-film material that has heat-generating properties by applying a voltage. The selection of materials for this is extensive and can include metal alloys and/or also materials having ceramic or semiconductor properties and is not intended to be presented here conclusively.

However, the heating element can also be designed as a PTC heating element and thus act as a PTC thermistor with a positive temperature coefficient. In this case, however, an ohmic resistance is used to generate heat, except that the ohmic or electrical resistance of the heating element is temperature-dependent, so that the electric current is conducted better at low temperatures than at high temperatures. Characteristic of PTC heating elements are non-linear resistance curves, which enable self-regulating behavior of the heating elements, with the resistance increasing rapidly if the temperatures of the PTC heating elements are too high and the heating element can thus regulate itself. Particularly characteristic of this are ceramic-based PTC heating elements, e.g. based on BaTiO3, which are available as preformed components and can therefore be easily arranged between two fluid-carrying heat exchanger elements.

The heating element can also be designed as a heating foil. Different configurations are possible. The heating foils are usually thin plastic foils that contain a coating or a thin electrically conductive material that generates heat when an electrical voltage is applied. This coating or layer of material can be embedded between two plastic films, which then serve as a carrier material for the heating film on both sides. The coating or material layer can be designed as a PTC thermistor with a positive temperature efficiency or act as a conventional ohmic resistor. An advantage of this heating foil as a heating element is the very thin design, which allows it to be attached flexibly to surfaces of different shapes, e.g. flat or curved. The heating foils can also be used advantageously as an electrically insulating heating element against the adjacent components due to the structure with foils as the carrier material. Additional insulating layers can be omitted. The at least one semiconductor power switch arranged in the second heating zone serves essentially to control the heating elements arranged in the first heating zone. In this case, all the usual semiconductor power switches can be used that are suitable for being able to switch the high loads that are generated by the heating elements. In particular, IGBTs or MOSFETs should be mentioned here, both of which are semiconductor-based transistor elements that make it possible to switch large currents. Even if these semiconductor power switches work with comparatively little loss due to the semiconductor design, the high switched loads result in power loss that quickly heats up the components and, without dissipating the heat, leads to losses in the performance and service life of the semiconductor power switches.

According to the invention, the fluid-carrying heat exchanger elements can be designed in various ways. For example, the heat exchanger elements can be formed as tubes, in particular as flat tubes, with these flat tubes usually being made of aluminum. The aluminum flat tubes can be produced as extruded or continuously cast aluminum profiles with one or more fluid-carrying chambers, or they can also be formed from aluminum sheet metal that is folded and finally tightly welded or soldered. Here, too, designs with one or more fluid-carrying chambers are possible. The cross-section of the flat tubes is designed with two long sides and two narrow sides that are significantly shorter in relation to the long sides. The transitions are usually provided with radii, whereby the radius can be selected so large that the entire narrow side assumes a curved shape and is therefore completely rounded off. The long sides of the flat tubes expediently form the contact surfaces for the first and second heating zones. A liquid fluid circulates through the flat tubes, in particular a coolant, which is heated during operation of the electrical heating device by the heat introduced into the first and second heating zones.

According to the invention, however, the fluid-carrying heat exchanger elements can also be formed from stacked disk plates composed of aluminum half-shells through which fluid can flow. At least two half-shells are placed one on top of the other and, by means of embossed structures, form at least one fluid channel through which a fluid, in particular a coolant, can flow. Such stacks can be stacked in multiple layers and then tightly connected to one another by means of a soldering or gluing process. These stacked disk plates can in turn be arranged parallel to one another and between the individual stacked disk plates form the first and second heating zones in which the heating elements and semiconductor circuit breakers can be arranged.

In a further solution according to the invention, it is conceivable that the fluid-carrying heat exchanger elements are formed by ribs through which a fluid, in particular air, can flow wherein the ribs are stacked on top of each other, with a region being formed between each two ribs in which the first and second heating zones are formed, in which the heating elements and semiconductor power switches are arranged. An electrical heating device formed in this way is used in a motor vehicle as an air heating device, in particular for heating the passenger compartment. The heating elements and semiconductor power switches generate heat and give it off to the air via the ribs and heat it up.

In a further advantageous solution according to the invention, a first indentation is provided on at least one of the fluid-carrying heat exchanger elements in the area of the second heating zone, with a semiconductor circuit breaker being arranged in this first indentation. The embossing makes it possible to use heating elements and semiconductor power switches that have different thicknesses in the first and second heating zones. In order to also be able to use thicker semiconductor power switches, the embossing can therefore expediently also be embossed on both sides in the fluid-carrying heat exchanger elements. Particularly thin heating elements can be used in combination with powerful, thick semiconductor circuit breakers. In this way, it can be ensured in a particularly advantageous manner that the heat-emitting elements are in thermal contact with the fluid-carrying heat exchanger elements on both sides, thus enabling optimum heat dissipation into the fluid.

In a further advantageous solution, the embossing is shaped in such a way that at least two flanks of the embossing receive the semiconductor circuit breaker in a form-fitting manner and this is thus held securely between the two fluid-carrying heat exchanger elements. For optimal fixation of the semiconductor circuit breaker, even with strong vibrations in the vehicle, a clamping element can be arranged between the first and/or second fluid-carrying heat exchanger element and at least one side of the semiconductor circuit breaker, which securely positions the semiconductor circuit breaker. This clamping element is expediently designed to be elastically resilient and thus tightens the semiconductor circuit breaker. Typically, such a metal clamping element is formed in particular from sheet metal or spring steel that has good thermal conductivity, so that a good thermal transfer into the fluid-carrying heat exchanger elements is made possible despite the use of a clamping element. By using such a clamping element, tolerances between the arrangement of the fluid-carrying heat exchanger elements and the semiconductor circuit breaker can also be compensated.

In a further advantageous solution according to the invention, an electrically insulating layer is arranged between the first and/or second fluid-carrying heat exchanger element and at least one side of the semiconductor circuit breaker in order to prevent electrical current from flowing away from or to the semiconductor circuit breaker. Such an electrically insulating layer can expediently be an adhesive layer, in particular a silicone adhesive layer or a layer of thermally conductive paste or a thermally conductive pad. In this way, in addition to electrical insulation, the heat transfer from the semiconductor power switch to the fluid-carrying heat exchanger element can also be advantageously improved and/or an improved fixation of the semiconductor power switch can also be achieved. In addition, the positioning of such an insulating layer can also enable tolerance compensation between the fluid-carrying heat exchanger elements and the semiconductor circuit breaker.

• 1 eine erfindungsgemäße elektrische Heizeinrichtung zur Erwärmung eines Fluids, insbesondere von Kühlmittel
• 2 eine perspektivische Detaildarstellung der Wärmetauscherelemente mit Halbleiter-Leistungsschalter
• 3 eine Detaildarstellung eines Halbleiter-Leistungsschalters auf einem Wärmetauscherelement
• 4 eine Detailansicht eines Halbleiter-Leistungsschalters zwischen zwei Wärmetauscherelementen
• 5 eine Detailansicht eines Halbleiter-Leistungsschalters zwischen zwei Wärmetauscherelementen mit einem Klemmelement
• 6 eine erfindungsgemäße elektrische Heizeinrichtung zur Erwärmung eines Fluids, insbesondere von Luft

Further advantageous configurations of the invention are described by the following figure descriptions. In this show:

• 1 an electric heating device according to the invention for heating a fluid, in particular a coolant
• 2 a detailed perspective view of the heat exchanger elements with semiconductor circuit breakers
• 3 a detailed view of a semiconductor power switch on a heat exchanger element
• 4 a detailed view of a semiconductor power switch between two heat exchanger elements
• 5 a detailed view of a semiconductor circuit breaker between two heat exchanger elements with a clamping element
• 6 an electric heating device according to the invention for heating a fluid, in particular air

Preferred embodiment of the invention

The 1 shows a sectional side view of a first exemplary embodiment of an electrical heating device 1 according to the invention for heating a fluid FL. A coolant or heating medium based on water with an optional addition of glycol can be used here as fluid FL, in order to ensure the frost resistance of the mixture, or also on oil or other fluids suitable for heat transfer. Such electrical heating devices can be arranged in a motor vehicle in a cooling circuit and are used for the targeted heating of the fluid FL used in the cooling circuit. The heated fluid FL can be used, for example, to bring a cooling circuit to an optimal minimum temperature - such as the temperature control of a battery or electronic cooling circuit - or also for the sole or supporting heating of a cooling or heating circuit for temperature control of an interior of a motor vehicle. Here, the heat introduced into the cooling or heating circuit is given off to the interior via a suitable radiator.

For this purpose, the electrical heating device 1 has inlets and outlets for the fluid FL, which correspondingly direct the fluid FL to be heated in and out of the housing 2 of the electrical heating device 1 . The fluid FL reaches a first collector 12 and is then distributed there to individual heat exchanger elements 3,3'.

The heat exchanger elements 3, 3' consist of extruded aluminum flat tubes, but can also be designed as folded and seal-welded or seal-soldered flat tubes. Such folded tubes are usually formed from an aluminum material, but it is also conceivable that another metallic material such as stainless steel is used here. The heat exchanger elements 3,3' are inserted into corresponding openings in the collector 12,12' and sealed. The seal can be realized by separate sealing elements or by joint soldering or welding of collectors 12,12' and heat exchanger elements 3,3'. In the case of soldering or welding, the collector 12, 12' must also be made of aluminum or of another metallic material, such as stainless steel. The use of a collector 12, 12' made of plastic is also conceivable without the thermal joining process. It is also possible for the pipes to be glued into the collector 12, 12'. Conventional sealants such as silicone or other industrial adhesives suitable for the relevant application can be used for this purpose.

From the first collector 12, the fluid FL passes via the heat exchanger elements 3, 3' into the second collector 12' and then leaves the electric heating device 1 there via an outlet 14. Via between a first heat exchanger element 3 and a second heat exchanger element 3', in a first Heating zone 4, arranged heating elements 5,6,20 is heated in the heat exchanger elements 3,3 'out fluid FL. For this purpose, the heating elements 5, 6, 20 are energized and switched on and off via corresponding semiconductor power switches 7. As a result, the heating elements 5,6,20 heat up accordingly and transfer the heat generated to the heat exchanger elements 3,3' and the fluid FL conducted therein. The semiconductor power switches 7 are arranged in a second heating zone between a first heat exchanger element 3 and a second heat exchanger element 3'.

PTC heating elements 5, for example, can be provided as heating elements 5, 6, 20, which consist of a ceramic material, for example based on BaTiO ₃ , which have a temperature-dependent ohmic resistance. This means that the ohmic resistance increases as the temperature of the PTC heating element 5 rises, and the PTC heating element 5 is therefore automatically regulated. Usually, this resistance profile is not linear in the case of PTC heating elements 5, but increases suddenly when a specific limit temperature is exceeded. This creates an advantageous control effect that protects the electrical heating device from overheating.

Thick-film heating elements 6 represent a further possibility, via an ohmic resistance, of generating heat and dissipating it to the heat exchanger elements 3, 3'. Such thick-film heating elements 6 usually consist of heat conductor or resistance alloys that offer a relatively constant electrical resistance over a wide temperature range. These thick-film heating elements 6 can be printed or applied as solid components adapted to the shape of the heat exchanger elements 3, 3', as heating wires or also on a carrier material, e.g. a heating foil 20 or a PCB.

The heating elements 5,6,20 can be held mechanically between the heat exchanger elements 3,3' or can also be glued. It is conceivable that between the heating elements and the heat exchanger elements 3, 3' there is also a particularly good heat-transferring layer, which is formed for example by a thermally conductive pad, an adhesive layer or a TIM layer (thermal interface material).

For special protection of the electrical elements, the heating elements 5,6,20 and the heat exchanger elements 3,3' can be encapsulated with a suitable material at least in the area of the heating elements 5,6,20, so that protection against moisture is created.

The heating elements 5,6,20 are controlled via a corresponding control device device 15, which regulates the electric heater 1 as needed. It is conceivable that the control device 15 receives corresponding instructions via corresponding sensors or via a control device arranged outside of the electrical heating device 1 . Such electrical heating devices 1 usually also contain protective circuits in order to prevent damage or overheating.

2 is a perspective detailed view of a further embodiment of an electrical heating device 1 with extruded aluminum flat tubes as a heat exchanger element 3,3 'through which a fluid FL flows and between which first and second heating zones 4,4' are arranged. Arranged in the first heating zone 4 are heating elements 5,6,20 which can be electrically connected by means of contact plates 18, the contact plates also being responsible for the electrical insulation of the heating elements 5,6,20 from the heat exchanger element 3,3'. Suitable coatings or other layers are conceivable for this purpose, which on the one hand ensure good thermal contact with the heat exchanger element 3, 3′ but also have an electrical effect. The semiconductor power switches 7 arranged in the second heating zones 4' are arranged in impressions 8 which are formed by the heat exchanger elements 3, 3'. As a result, semiconductor power switches 7 can be used which are thicker than the heating elements 5,6,20 used. Depending on the installation situation, the embossing can be formed on one side or on both sides of the heat exchanger element 3,3'. This means that very thick semiconductor circuit breakers 7 can also be used. Depending on the type of semiconductor circuit breaker 7 used, a layer 10 that is electrically insulating on one or both sides can also be applied between the heat exchanger elements 3 , 3 ′ and the semiconductor circuit breaker 7 . Such layers can compensate for manufacturing tolerances of the heat exchanger elements 3, 3′ and the indentations 8 made, and in all cases a tight fit and optimum thermal contact can be ensured. The electrically insulating layer 10 can also advantageously have particularly good thermal conductivity. The heating elements 5,6,20 as well as the semiconductor power switches 7 are electrically contacted by connection terminals 19, which are brought out between the heat exchanger elements 3,3'.

The 3 shows the detailed illustration of an electrical heating device 1 according to the invention, wherein the heat exchanger element 3, 3' has an indentation 8 in the region of the second heating zone 4', in which a semiconductor circuit breaker 7 is arranged. An electrically insulating layer 10 is applied between the heat exchanger element 3, 3' and the semiconductor power switch 7, which ensures electrical separation of the two components, with the layer 10 also being able to ensure particularly good heat conduction between the semiconductor power switch 7. In this case, the electrically insulating layer 10 can be applied to only one side of the semiconductor circuit breaker 7, but it can also be applied to both sides. As a rule, however, at least one side of the semiconductor circuit breaker 7 must be electrically insulated due to the design. However, it is also conceivable to use fully encapsulated semiconductor circuit breakers 7 and thus dispense with the electrical insulation. But even in these cases, the attachment of a particularly good thermally conductive layer 10, for example a thermally conductive pad or gluing with a silicone or other adhesive can be expedient.

The embossing 8 can be made by mechanically forming the heat exchanger element 3,3', for example by pressing, stamping, stamping, embossing, or by mechanically machining the heat exchanger element 3,3', such as milling, or by other suitable manufacturing processes. Due to the embossing, the bearing surface of the second heating zone 4' is brought to a different level than the bearing surface of the first heating zone 4, so power half-switches 7 can be used which are thicker than the heating elements 5,6,20.

In the 4 a further embodiment according to the invention is shown, which shows a semiconductor circuit breaker 7 arranged between two heat exchanger elements 3,3' in a second heating zone 4'. The semiconductor circuit breaker 7 is arranged in two indentations 8 made in the heat exchanger elements 3 , 3 . An electrical, insulating layer 10 electrically separates the semiconductor circuit breaker 7 from the heat exchanger elements 3,3. The embossing 8 has these flanks 9, 9', which are dimensioned in such a way that the semiconductor power switch 7 is fixed at least on one side. In addition, an adhesive layer, for example made of silicone or another suitable adhesive, can also be used. It is also conceivable that up to four flanks 9, 9' are used in order to fix the semiconductor circuit breaker 7 in place. The first heating zone 4, in which the heating elements 5,6,20 are accommodated, is arranged next to the second heating zone 4'.

The 5 is a further embodiment according to the invention, in which the semiconductor power switch 7 is arranged in an indentation 8 in a heat exchanger element 3, the second side of the semiconductor power switch 7 being in contact with the heat exchanger element 3' without an indentation, but by means of an electrically insulating layer 10. In the embossing 8, the semiconductor power circuit ter 7 fixed with a prestressed clamping element 11. The clamping element 11 is designed as a metal clamp and on the one hand enables secure fixing and on the other hand a good thermal contact of the semiconductor circuit breaker 7 with the heat exchanger element 3.

The 6 as a further exemplary embodiment of an electric heating device 1 according to the invention for heating air in a motor vehicle. Such an electrical heating device 1 can be arranged, for example, in the air conditioning system of a motor vehicle and can be used there to heat the air flowing into the interior of the motor vehicle. By using such an electrical heating device 1, an advantageous, particularly fast and efficient heating of the inflowing air can be achieved, as is absolutely necessary, for example, in electrically operated motor vehicles, since there is no longer an internal combustion engine here that, with its relatively large heat loss, generates sufficient thermal energy provided to heat the interior. However, such electrical heating devices 1 can also be used to support the heating of the interior of motor vehicles with efficient diesel engines or to achieve a particularly comfortable driving experience with a warm interior as soon as the motor vehicle is started.

The electrical heating device 1 according to the invention consists of a housing 2, which contains electrical connections, control boards and other necessary components that are required for the installation and operation of the electrical heating device. Arranged on the housing is the heating network 17, which has several heat exchanger elements 3,3' in the form of corrugated fins and between individual heat exchanger elements 3,3' several PTC heating elements 5 or thick-film heating elements 6 in the first heating zones 4 and semiconductor power switches 7 in the second Heating zones 4 'records.

Air flows through the heat exchanger elements 3,3' as a fluid FL and in the process releases the heat generated by the heating elements 5,6,20 to the air. The heat exchanger elements 3, 3' are expediently formed as corrugated fins, which consist of a folded, thin aluminum sheet and form the largest possible surface area for dissipating heat.

In the embodiment shown, the PTC heating elements 5 or thick-film heating elements 6 and the semiconductor power switches 7 are arranged between two contact plates 18, which have the necessary electrical connections for controlling the heating elements 5,6,20 and the semiconductor power switches 7 and thus contiguous heating rods 16 form.

The heating rods 16 and the heat exchanger elements 3, 3' in the form of corrugated fins are stacked alternately one on top of the other. Each heating rod 16 does not have to have first and second heating zones 4, 4', but could only be equipped with PTC heating elements 5 or thick-film heating elements 6, for example.

Reference List

1

Electrical heating device

2

Housing

3, 3'

heat exchanger element

4, 4'

heating zone

5

PTC heating element

6

thick film heating element

7

semiconductor circuit breaker

8th

imprint

9.9'

flanks

10

electrically insulating layer

11

clamping element

12,12'

collector

13

inlet

14

outlet

15

control device

16

heater

17

heating network

18

contact plate

19

terminals

20

heating foil

FL

Fluid

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2884817 A1 [0003]

Claims (11)

Electrical heating device (1), in particular for heating a fluid (FL) in a motor vehicle, with a housing (2), with first and second fluid-carrying heat exchanger elements (3, 3') arranged parallel to one another, characterized in that between the first and the second heat exchanger element (3, 3') a first and a second heating zone (4, 4') are formed, wherein in the first heating zone (4) at least one heating element (5, 6) which generates heat through an ohmic resistance of a passive component , and in the second heating zone (4') at least one electrical semiconductor power switch (7) generating a power loss are arranged. Electrical heating device (1) after claim 1 characterized in that the first and/or the second heat exchanger element (3, 3') has at least one indentation (8) in the area of the second heating zone (4, 4') and in the area of the indentation (8) the electrical semiconductor circuit breaker ( 7) is arranged. Electrical heating device (1) after claim 2 characterized in that the at least one embossing (8) in the area of the second heating zone (4, 4') is shaped in such a way that on at least two flanks (9,9') the electrical semiconductor arranged in the at least one embossing (8). - Circuit breaker (7) positively accommodates. Electrical heating device (1) after claim 1 , 2 or 3 characterized in that the at least one electrical semiconductor power switch (7) is in thermal contact with the first and second heat exchanger element (3, 3') in the region of the second heating zone (4, 4') on both sides. Electrical heating device (1) according to one of the preceding claims, characterized in that an electrically insulating layer (10) is arranged between the first and/or second heat exchanger element (3, 3') and at least one side of the electrical semiconductor circuit breaker (7). Electrical heating device (1) after claim 5 characterized in that the electrically insulating layer (10) is an adhesive layer, in particular a silicone adhesive layer or a layer of thermally conductive paste or a thermally conductive pad. Electrical heating device (1) according to one of the preceding claims, characterized in that a clamping element (11) is arranged between the first and/or second heat exchanger element (3, 3') and at least one side of the electrical semiconductor circuit breaker (7). Electrical heating device (1) according to one of the preceding claims, characterized in that the first heating zone (4) has a heat output which is at least half as high as that of the second heating zone (4'). Electrical heating device (1) according to one of the preceding claims, characterized in that the heat exchanger elements (3, 3') are extruded aluminum flat tubes, folded and tightly welded aluminum flat tubes or stacked disk plates composed of at least two aluminum half-shells through which fluid can flow. Electrical heating device (1) according to one of the preceding claims, characterized in that the at least one heating element (5,6,20) is a PTC heating element (5), a thick-film heating element (6) or a heating foil (20). Motor vehicle with an electric heating device (1) according to one of the preceding claims.

Images