EP2293648B1 - Heat exchanger - Google Patents

Description

The invention relates to a heat exchanger according to the preamble of claim 1.

The electric auxiliary heating in consumption-optimized vehicles, which provide, for example, in the start-up phase or at low outside temperatures too little waste heat for heating the interior of a motor vehicle, is carried out in the prior art, for example by means of so-called PTC heaters.

Such a PTC heating device essentially comprises two main components: on the one hand heating strands or heating registers and on the other hand power supply elements. The heating registers essentially comprise PTC heating elements, contact plates and heat dissipation elements. The power supply elements comprise electrical cables or busbars which are connected to the contact plates of the heating coils and connect them to a power supply.

In a motor vehicle air conditioning system, such a PTC heating device is arranged behind or behind the evaporator in the air flow direction. For operating phases with air conditioning switched to "cold", forms are on the evaporator condensation, which can be forwarded to the heating registers of the PTC heater. In a high-voltage PTC device, however, it is important that this water does not reach the power supply elements or only to the smallest possible extent in order to avoid disturbances.

In addition, it is possible for dust to accumulate on the PTC heater. This is especially the case after a long break in operation. The accumulation of dust particles on the heating registers and the power supply elements can lead to creepage distances.

Out EP 1 182 908 B1 a heating device is known in which the PTC elements are held in a "clamping package" with the other elements of the heating device. The clamp acts to hold all the elements together and stands vertically on the contact surfaces of the PTC element. The outer heating stages each have a PTC row, wherein electrode sheets of the middle assemblies are connected by means of a bridge. The modules are held in a frame of side rails and longitudinal beams, wherein electrical connection lugs laterally protrudes through one of the two side rails for contacting the contact plates. Thus, this side rail forms a partition between the Heizregistem and the power supply elements.

EP 2 063 683 A1 and EP 1 768 457 A1 also describe heating devices according to the prior art. However, in such a configuration, the power supply elements are not protected against moisture and dust and, as already mentioned, a build-up of dust between the contact components and the partition may create a bridge, which is the risk of breakdown due to the accumulation of dust and moisture on the surface of the partition elevated.

Therefore, it is the object of the present invention to provide a heat exchanger in which the risk of breakdown is minimized due to dust accumulation and moisture on the components of the heat exchanger.

The object of the present invention is achieved by a heat exchanger with the features of claim 1. Advantageous developments of the present invention are defined in the subclaims.

According to the invention, a heat exchanger, in particular an electric heater for a motor vehicle, with at least one at least one heating element and at least two contact plates having heater, wherein the at least one heater is disposed in a frame, wherein on the at least one heater an insulation profile is provided in potential-free arrangement wherein the at least one heating coil comprises a substantially plate-like insulating member, wherein the insulating member on opposite surfaces each having an insulating layer and is disposed between the insulating layers, wherein on the insulating layer in each case a heat conducting plate is provided, wherein adjacent to the heat conducting rib members, which the the heat register provided heat conducting contacted, wherein the insulating profile is in contact with the insulating layer and the insulating profile has at least one opening through which the zuminde a heater is inserted therethrough and wherein the insulation profile is a separate component which is fastened via fastening means to the frame. In order to protect the power supply elements against moisture and dust, the insulation profile is arranged on the floating components of the at least one heating register or the heating register, with this arrangement, no bridges between the contact members or plugs can be formed, the risk of breakdown due to dust accumulation and moisture would increase on the insulation profile.

Preferably, the at least one opening is U-shaped.
According to a further preferred embodiment, the insulation profile has a thickness which lies in a range of 2 to 3 mm.

According to yet another preferred embodiment, the insulation profile is formed as a separate component.

Alternatively, the insulation profile may also be cast in the frame.

It is particularly preferred if the insulation profile is made of silicone. This material is particularly preferred because it can withstand temperatures of about 140 ° C to 170 ° C.

Preferably, the contact plates protrude from the heat exchanger on the opposite side of the insulation profile of this.

It is furthermore preferred if a cover element, which is in particular made of plastic, is provided on the heat exchanger, which covers the contact plates and power supply elements connected to the contact plates, such as cables or busbars. The cover element, which covers the contact sheets and the wiring or busbars, these are not exposed and thus can not be touched or contacted in any other way. This increases the electrical safety. In addition, the power-conducting elements are protected by providing the cover from dust and moisture.

In yet another preferred embodiment, a first seal, in particular a rubber profile or a foam profile, is provided between the cover element and the heat exchanger, and a second seal is provided between the cover element and a supply plug.

By tightly connecting the cover element with the heat exchanger or with the insulation profile, the cover element forms a sealed box and can thus act as a second seal for an electrically insulating potting compound. In this embodiment, an electrical insulating element is provided which electrically insulates an electrical resistance heating element and / or electrical conductors of the heating register in that they are arranged in a cavity which is filled by an electrically insulating potting compound. In case of failure of the seal on a resistance heating element and / or electrical conductor, the potting compound is collected in the cover element. Due to the first seal between the cover element and the upper edge of the heat exchanger and the second seal between the supply plug and the cover element, the inner region of the cover element thus forms a sealed box from which the potting compound can not leak - for example into the passenger compartment. Although in such a case, the heating capacity of this heater may be reduced, but no operating hazard is caused. The box remains relatively cool during normal operation as well as when the potting compound drains. The seals also protect the electrical components inside the box from the ingress of external moisture and from dust.

Fig.1

eine Explosionsansicht eines Heizregisters gemäß dem Stand der Technik;

Fig. 2

eine perspektivische Ansicht eines Wärmeübertragers gemäß einer Ausführungsform;

Fig. 3

eine Detailansicht eines unteren Abschnitts des Wärmeübertragers von Fig. 2;

Fig. 4

eine schematische Schnittansicht eines Wärmeübertragers gemäß einer Ausführungsform;

Fig. 5

eine schematische Schnittansicht eines Wärmeübertragers gemäß einer weiteren Ausführungsform.

In the following the invention will be explained in detail by means of an embodiment with reference to the drawing. In the drawing show:

Fig.1

an exploded view of a heating register according to the prior art;

Fig. 2

a perspective view of a heat exchanger according to an embodiment;

Fig. 3

a detailed view of a lower portion of the heat exchanger of Fig. 2 ;

Fig. 4

a schematic sectional view of a heat exchanger according to an embodiment;

Fig. 5

a schematic sectional view of a heat exchanger according to another embodiment.

In Fig. 1 an exploded view of a heating register 1 according to the prior art is shown. The heating register 1 comprises a receiving frame 2, in which three heating elements 3 are arranged or fixed in the form of PTC elements. The PTC elements 3 are PTC thermistors made of ceramic and represent a very strong temperature-dependent semiconductor resistance. This means that with increasing temperature, the resistance of the ceramic element increases very greatly. This raises regardless of the boundary conditions such. B. applied voltage, nominal resistance, amount of air above the PTC element a very uniform surface temperature at the PTC element, wherein with increasing temperature, the electrical resistance increases proportionally strong.

Further, on both opposite sides of the receiving frame 2 printed circuit boards 4, 4 'are arranged, which at a respective first end 5, 5' with respective contact plates 6, 6 'are provided, via which they are connected to a power supply (not shown) to to conduct electrical current through the circuit boards 4, 4 'to the heating elements 3. Respectively adjacent to the circuit boards 4. 4 ', respective insulating elements in the form of insulating layers 7, 7' are arranged, to which, in turn, respective Heat conducting plates 8, 8 'for transferring the heat to the adjoining respective rib elements 9, 9' in the form of corrugated fins.

Fig. 2 shows a perspective view of a heat exchanger 10 according to an embodiment. The not visible here heating register 1 are received in a frame 11. The frame 11 has on its front side 12 and on its rear side 13 respective grid elements 14, through which an air flow can enter or exit the heat exchanger 10. On an underside 15 of the heat exchanger 10, an insulating profile 16 is provided, which rests only on potential-free components of the heat exchanger 10, as further below in connection with Fig. 3 will be explained in more detail. The insulating profile 16 here has a thickness of 2 mm and is made of silicone, so that it withstands temperatures in a range of 140 ° C to 170 ° C. In the embodiment, the insulating profile 16 is made as a separate component and is fastened to the frame 11 via fastening devices 17. The insulating profile 16 is positioned on the Heizregistem 1, wherein the respective contact plates 6, 6 'protrude through U-shaped openings 16 formed in the insulating profile 16 therethrough.

Fig. 3 shows a detailed view of a lower portion of the heat exchanger 10 of Fig. 2 , wherein only a lower half of the insulation profile 16 is shown and the upper half has been omitted for illustrative purposes. As can be seen in the figure, each heating register 1 on both sides of the insulating layers 7, 7 'and disposed thereon heat conducting plates 8, 8', to which the ribbing elements 9 adjacent. Between each two insulating layers 7, 7 ', an insulating member 19 is arranged centrally, in which the not visible here PTC elements are housed. By providing the insulating layers 7, 7 'and the insulating member 19, it is possible that the insulation profile 16 is only in contact with potential-free components of the heat exchanger 10 and each heater 1. At the respective openings 18 in the insulating profile 16, only the periphery of the insulated portion of the heating coil 1 is contacted, namely, laterally or on the long sides of the openings 18, the insulating layers 7, 7 'and on the short sides of the insulating member 19. According to this embodiment the insulation profile 16 does not form a bridge between the contact components or plugs, which would increase the risk of breakdown due to dust accumulation and moisture precipitation.

Fig. 4 shows a schematic sectional view of a heat exchanger 10 according to another embodiment. In the figure, the individual heating registers 1 are only indicated schematically, on which the insulation profile 16 on the above in connection with Fig. 2 and Fig. 3 described manner is arranged floating. The contact sheets 6, 6 'protrude from the top of the insulation profile 16. Each heating register 1 in this case has at least two conductor tracks 17 which have different electrical potentials (high-voltage minus "HV" and high-voltage plus "HV ⁺ "). By cable 20, the conductor tracks 17 are connected to a power plug 21. In order to protect the electrical components from dust particles and moisture, according to the embodiment, a cover element 22 is placed tightly on the heat exchanger 10 or on the insulation profile 16 by means of a first seal 23. A second seal 24 is provided between the cover member 22 and the power plug 21. By the cover member 22, the current-carrying electrical components of the heat exchanger 10 are not exposed, so that they can not be touched from the outside or damaged by moisture or dust particles. Also, the cover member 22 together with the insulation profile 16 forms a sealed box, so that potting compound, which is filled in respective cavities, not shown, of the heating coil 1, for example, in the event of a failure, can not leak into the passenger compartment.

Fig. 5 Finally, shows a schematic sectional view of a heat exchanger 10 according to a further embodiment, which differs from the in Fig. 4 shown embodiment differs only in that instead of the cable 20 busbars 26 are provided, which connect the contact plates 6, 6 'of each heater 10 with the power connector 21.

Overall, with the heat exchanger 1 designed in this way, it is possible to provide a particularly reliable electrical heater which is protected against interference.

LIST OF REFERENCE NUMBERS

1

heater

2

mounting frame

3

heating element

4,4 '

PCBs

5.5 '

first end

6.6 '

contact sheet

7,7 '

insulating

8,8 '

heat conduction

9.9 '

rib element

10

Heat exchanger

11

frame

12

front

13

back

14

grid element

15

bottom

16

insulation profile

17

fastening device

18

opening

19

insulation component

20

electric wire

21

power connector

22

cover member

23

first seal

24

second seal

25

box

26

conductor rail

Claims (8)

1. An electric auxiliary heater for a motor vehicle, with at least one heating register (1) which has at least one heating element (3) and at least two contact sheets (6, 6'), wherein the at least one heating register (1) is arranged in a frame (11), wherein an insulation profile (16) in a potential-free arrangement is provided on the at least one heating register (1), wherein the at least one heating register (1) has a substantially plate-like insulation component (19) in which the at least one heating element is housed, wherein the insulation component (19) has one insulation layer (7, 7') each on opposite surfaces and is arranged between the insulation layers, wherein one heat-conducting plate (8, 8') each is provided on the insulation layers (7, 7'), wherein rib elements abut on the heat-conducting plates and contact the heat-conducting plate (8, 8') provided on the heating register (1), wherein the insulation profile (16) is in contact with the insulation layer (7, 7') and the insulation profile (16) has at least one opening (18) through which the at least one heating register (1) is inserted and wherein the insulation profile is a separate component which is fastened to the frame by means of fastening devices.
2. An electric auxiliary heater according to claim 1, characterised in that the at least one opening (18) is U-shaped.
3. An electric auxiliary heater according to one or more of claims 1 to 2, characterised in that the insulation profile (16) has a thickness which is in a range between 2 to 3 mm.
4. An electric auxiliary heater according to one or more of claims 1 to 3, characterised in that the insulation profile (16) is cast into the frame (11).
5. An electric auxiliary heater according to one or more of claims 1 to 4, characterised in that the insulation profile (16) is made from silicone.
6. An electric auxiliary heater according to one or more of claims 1 to 5, characterised in that the contact sheets (6, 6') protrude from a side of the insulation profile (16) which faces away from the heat exchanger (10).
7. An electric auxiliary heater according to one or more of claims 1 to 6, characterised in that a cover element (22), which is in particular made from plastic material, is provided on the heat exchanger (10) and covers the contact sheets (6, 6') and power supply elements connected to the contact sheets (6, 6'), in particular cables (20) or current bars (26).
8. An electric auxiliary heater according to claim 7, characterised in that a first seal (23), in particular a rubber profile or a foam profile, is provided between the cover element (22) and the heat exchanger (10) and a second seal (24) is provided between the cover element (22) and a supply connector (21).

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