EP2161514B1 - Heat exchanger - Google Patents

Description

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

Such a heat exchanger is known from the patent DE 4404345 A1 known.

Consumption-optimized vehicles generate less and less waste heat, which is available for warming up the interior. Especially in the starting phase and at low outside temperatures it is necessary to heat up.

There are various options available for this. The auxiliary heating can be effected, for example, via fuel heaters, electric heaters, exhaust gas heat exchangers, etc. Of the above options, however, the electric heater has proved to be particularly useful because it is cost-effective and spontaneously noticeable. In particular, electric heaters can also be easily integrated or installed in an air conditioning unit and air ducts.

Preferably, so-called PTC heaters are used for this purpose. In electric auxiliary heaters, which use this type of heaters, the conversion of electrical energy from the vehicle electrical system of the vehicle takes place in heat in a PTC element ( Positive Temperature Coefficient ). This ceramic thermistor is a very temperature-dependent Semiconductor resistor. This means that with increasing temperature the resistance of the ceramic element increases very much. This raises regardless of the boundary conditions - such. Applied voltage, nominal resistance, air flow above the PTC element - a very uniform surface temperature at the PTC element. This prevents overheating, as z. B. could occur with a normal heat-emitting heating wire, since regardless of the boundary conditions always the same resistance and thus electrical heating power is introduced. That is, with increasing temperature, the electrical resistance increases proportionally strong.

In order to achieve a performance increase in terms of heating power, it is known in the art to use two or more PTC heaters simultaneously. The respective heating registers are arranged in two independent frames and are placed one behind the other in the air conditioner.

However, the use of PTC heaters or PTC heating coils in two independent frames requires a larger space, which is problematic due to the existing in the air conditioning small space, which is limited to the air duct cross-section. Also, when using two frames, the distance between the PTC ceramics of the respective heater registers increases. For example, with two heaters arranged one behind the other with two separate frames, the rear heater, which is remote from a fan, is heated more than the front heater, which is closer to the fan.

This is z. B. off JP 62080122 A known to use an electric heater, wherein at least two PTC heaters with mutually different Curie temperatures to increase the efficiency are used, which are arranged in a frame. In doing so, the higher Curie temperature PTC heater tab is located away from a fan port through which warm air exits, and the lower Curie temperature PTC heater tab is positioned in front of the fan port.

In this configuration, however, it is also problematic that there is no reliable physical separation between the PTC heater registers arranged one behind the other. This can be problematic, especially in high voltage applications.

Therefore, it is the object of the present invention to provide a heat exchanger for motor vehicles, which achieves a heating capacity increase in space-saving manner.

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, having at least one at least one heating element exhibiting first heater, and at least one at least one heating element exhibiting second heater, which in a frame having a front and a back, are arranged, the at least one first heating register on the front side and the at least one second heating register on the rear side of the frame offset from each other, wherein in the frame at least a first and a second through-flow grating element are provided, wherein at least a first grid element at the front of the frame and at least a second grid element is provided on the rear side of the frame, the first and the second grid elements respectively between the first and the second grid elements second heating element / fin element arrangements are positioned, wherein the heat exchanger has first rib elements, which are each arranged between two of the first heating registers and the heat exchanger has second rib elements, which are each arranged between two of the second heating registers provided. By providing a first and a second heater in only one frame space is saved in an advantageous manner. Particularly in comparison with heating devices which use independent heating elements in separate frames, the configuration according to the invention has a smaller installation space (air duct cross-section). In addition, a significant increase in efficiency can be achieved by the configuration according to the invention, since a plurality of Heizregistem can be arranged side by side and in succession. The fact that a physical separation of the first and second heating coils is also provided by the frame, a higher security is also given especially in the high voltage range.

Preferably, the frame is a plastic frame. On the one hand, this ensures insulation of the individual heating elements mounted on both sides and, moreover, such a plastic frame can be produced in a simple and cost-effective manner.

According to a further preferred embodiment, a plurality of first heating registers and a plurality of second heating registers can be received in the frame. This further increases the efficiency of the heat exchanger or its heating power.

According to yet another preferred embodiment, the frame is in several parts, in particular in two parts, formed. In particular in the upper region of the frame, a two- or multi-part design is preferred for leading out the cables from the heat exchanger.

The heat exchanger has first rib elements, which are each arranged between two of the first Heizregistem. This results in a first heating network with alternating sequence of first Heizregistem and first rib elements.

The heat exchanger has second rib elements, which are each arranged between two of the second heating registers. This results in a second heating network with alternating sequence of second Heizregistem and second rib elements.

According to the invention, in the frame, the first rib members on the front face the second heating register on the back side of the frame.

It is even more preferable if, in the frame, the second rib elements on the rear side are also opposite the first heating register on the front side.

Preferably, the at least one first and the at least one second heating coil is designed as a PTC heating coil, each having at least one PTC heating element.

It is also preferred if the frame has at least two latching elements, wherein a latching element is provided on a first edge portion, which is arranged asymmetrically to a further latching element on a second edge portion which is opposite to the first edge portion. By providing the asymmetrically arranged latching elements on the frame, demolding of the frame is allowed.

According to the invention, grid elements are provided in the frame. The grid elements are arranged in the frame at a position where no PTC heating elements or PTC heating coils are arranged. This results in a pressure drop. As the air enters the heat exchanger, the air passes from the front of the heat exchanger to its rear without mixing with air already heated by the PTC heaters on the front of the heat exchanger.

According to the invention, at least one grid element is provided on the front of the frame.

According to the invention, grid elements are provided at the rear of the frame. The first and second grid members are respectively positioned between first and second heater / fin element arrays and first and second heating networks, respectively.

It is even more preferable if the first and second grid elements are integrated in the frame. This facilitates the production or assembly of the heat exchanger and thus reduces the cost.

Most preferably, the first and second grid elements are formed as a honeycomb grid.

According to yet another preferred embodiment, the frame together with a front cover plate and a rear cover plate together form a housing.

Fig. 1

eine perspektivische Ansicht eines Rahmens eines Wärmeübertragers gemäß einer Ausführungsform;

Fig. 2

eine Draufsicht auf einen Rahmen eines Wärmeübertragers gemäß einer Ausführungsform;

Fig. 3

eine perspektivische Ansicht einer Anordnung von ersten und zweiten Heiznetzen;

Fig. 4

eine perspektivische Ansicht der Vorderseite des Rahmens mit darin montierten ersten Heiznetzen;

Fig. 5

eine perspektivische Ansicht der Rückseite des Rahmens mit darin montierten zweiten Heiznetzen;

Fig. 6

eine perspektivische Ansicht einer Abdeckplatte;

Fig. 7

eine perspektivische Ansicht eines zusammengebauten Wärmeübertragers gemäß einer 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

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

Fig. 2

a plan view of a frame of a heat exchanger according to an embodiment;

Fig. 3

a perspective view of an arrangement of first and second heating networks;

Fig. 4

a perspective view of the front of the frame with mounted therein first heating networks;

Fig. 5

a perspective view of the back of the frame with mounted therein second heating networks;

Fig. 6

a perspective view of a cover plate;

Fig. 7

a perspective view of an assembled heat exchanger according to an embodiment.

Fig.1 shows a perspective view of a frame 2 according to one embodiment. The frame 2 has a front 3 and a back 4, which is opposite to the front 3. Integrated into the frame 2, three grid elements 5 in the form of honeycomb gratings are provided here. In addition, the frame has on the front side 3 a plurality of first receiving elements 6, in which respective first heating coil (not shown) are receivable in the form of PTC heating registers and are held and fixed therein. On the back 4, the frame also has a plurality of second receiving elements (not shown). It can also be seen in the figure that two respective latching elements 8 arranged in pairs are provided on a first edge section 7, which here corresponds to a longitudinal side of the heat exchanger 1. At a second edge portion 9, two latching elements 8 are also provided, which are arranged with respect to the longitudinal axis L of the frame 2 asymmetrically to the latching elements 8 at the first edge portion 7.

Fig. 2 shows a plan view of a frame 2 according to one embodiment. Here it can be seen that the plurality of first receiving elements 6 on the front side 3 of the frame 2, which are the installation areas of the first Limit PTC heating elements (not shown), a plurality of second receiving elements 10 on the back 4 of the frame 2 is opposite, which limit the installation areas of the second PTC heating elements (not shown). In this case, the first receiving elements 6 on the front side 3 are in each case not mirror-symmetrically arranged with respect to a center line M of the frame 2 but offset relative to the second receiving elements 10 on the rear side 4. The center line M indicates the center between the front 3 and the back 4 of the frame 2.

Fig. 3 1 shows a perspective view of an arrangement of first heating networks 11 and second heating networks 12. The first heating networks 11 each comprise first heating registers 13 and first rib elements 14, wherein the first heating registers 13 are arranged between in each case two first rib elements 14. In the embodiment, two first heating networks 11 are provided. The first rib members 14 are formed as corrugated ribs. Each heating network 11 is constructed from four first heating registers 13 and five first rib elements 14 in each case. The first heating networks 11 are constructed to be arranged in a frame (not shown) of the type which e.g. B. already in connection with Fig. 1 or Fig. 2 has been described. The second heating networks 12 comprise respective second heating registers 15, which are arranged between in each case two second rib elements 16. The second rib members 16 are also formed as corrugated ribs. In the embodiment, two second heating networks 12 are provided. The first and second heating networks 11, 12 are essentially the same here, but are offset from each other in succession. In particular, the PTC ceramic elements of the first heating register 13 are arranged offset from the PTC ceramic elements of the second heating register 15. In this case, the first heating register 13, which are mounted on the front of the frame (not shown), the second rib members 16 of the second heating network 12, which at the back of the frame (not shown) is mountable, opposite. The contact plates 17 of the first and second heating registers 13, 15 protrude from the illustrated arrangement upwards.

Fig. 4 shows a perspective view of the front side 3 of the frame 2 with mounted therein first heating networks 11, each of which in turn consist of an alternating sequence of first fin elements 14 and first heating registers In the embodiment, two first heating networks 11 are provided, which are integrated by a grid element 5 in the form of honeycomb grids, which is integrated in the frame 2. are provided. In the embodiment, two grid elements 5 are provided.

Fig. 5 shows a perspective view of the back 4 of the frame 2 with two mounted therein second heating networks 12, each consisting of a second heating register 15 with both sides adjacent thereto second rib members 16. There are three grid elements 5 are provided in the form of honeycomb gratings, each second heating network 12 adjacent to one of the three grid elements 5 on each longitudinal side.

Fig. 6 shows a perspective view of a cover plate 18 which is composable with the frame (not shown). The cover plate 18 also has engaging elements 19, here four, two of which are provided on opposite longitudinal sides of the cover plate 18, on. The engagement elements 19 of the cover plate 18 are also arranged asymmetrically corresponding to the latching elements 8 on the first edge portion 7 and the second edge portion 9 of the frame 2 on the front side 3 thereof. When assembling the frame 2 with the cover plate 18, it is engaged with the front side 3 of the frame 2 by engaging the latching members 8 with the engaging members 19. Similarly, a second cover plate 18, which is constructed substantially identical, on the back 4 of the frame 2 attachable, so that the frame 2 with two cover plates 18 in the assembled state, which in Fig. 7 is shown, a housing 20 of the heat exchanger 1 forms. Here it can be seen that the respective cover plates 18 are also provided with a honeycomb-like structure 19, so that a plurality of air passage openings 21 is respectively provided on the front 3 and the back 4. In the housing 20, the first heating networks 11 are arranged in the manner already described offset to the second heating networks 12, wherein the first heating coil 13 of the first heating network 11 on the front side 3 of the frame 2 in each case the second rib members 16 of the second heating network 12 the back 4 of the frame 2 are opposite. The grid elements 5 in the form of honeycomb gratings are arranged in the configuration in each case at positions where there are no PTC heating elements, ie where no first or second heating registers 13, 15 are arranged, so that a pressure drop across the first and second heating registers 13, 15 he follows. The entering into the heat exchanger 1 at the front 3 fresh air is passed through the heat exchanger 1 and exits at the back 4 again, without thereby entering upon entering the heat exchanger 1 on the front 3 with already heated by the first heating coil 13 air ,

Overall, can be provided with the thus designed heat exchanger 1, an electric heater especially for high-voltage designs with increased efficiency and low space requirement.

LIST OF REFERENCE NUMBERS

1

Heat exchanger

2

frame

3

front

4

back

5

grid element

6

first receiving elements

7

first edge section

8th

latching

9

second edge section

10

second receiving elements

11

first heating network

12

second heating network

13

first heating register

14

first rib element

15

second heating register

16

second rib element

17

contact sheet

18

cover

19

honeycomb structure

20

casing

21

Air passage openings

Claims (10)

1. A heat exchanger (1), in particular an electric auxiliary heater for a motor vehicle, with at least one first heating register (13) having at least one heating element and at least one second heating register (15) having at least one heating element, which are arranged in a frame (2) having a front side (3) and a back side (4), wherein the at least one first heating register (13) is arranged on the front side (3) and the at least one second heating register (15) is arranged on the back side (4) of the frame (2), offset to one another, characterised in that at least one first and one second grid element (5), which can be flowed through, are provided in the frame (2), wherein at least one first grid element is provided on the front side of the frame and at least one second grid element is provided on the back side of the frame, wherein the first and the second grid elements are respectively positioned between first and second heating element/rib element arrangements, wherein the heat exchanger (1) has first rib elements (14) which are respectively arranged between two of the first heating registers (13) and the heat exchanger (1) has second rib elements (16) which are respectively arranged between two of the second heating registers (15).
2. The heat exchanger (1) as claimed in claim 1, characterised in that the frame (2) is a plastic frame.
3. The heat exchanger (1) as claimed in claim 1 or 2, characterised in that a plurality of first heating registers (13) and a plurality of second heating registers (15) is receivable in the frame (2).
4. The heat exchanger (1) as claimed in one or more of claims 1 to 3, characterised in that the frame (2) is formed of several parts, in particular two parts.
5. The heat exchanger (1) as claimed in claims 1 to 4, characterised in that in the frame (2), the first rib elements (14) on the front side (3) are opposite the second heating registers (15) on the back side (4) of the frame (2).
6. The heat exchanger (1) as claimed in claims 1 to 5, characterised in that in the frame (2), the second rib elements (16) on the back side (4) are opposite the first heating registers (13) on the front side (3).
7. The heat exchanger (1) as claimed in one or more of claims 1 to 6, characterised in that the at least one first and the at least one second heating register (13, 15) are formed as PTC heating registers, each having at least one PTC heating element.
8. The heat exchanger (1) as claimed in one or more of claims 1 to 7, characterised in that the frame (2) has at least two latching elements (8), wherein one latching element (8), provided on a first edge portion (7), is arranged asymmetrically to a latching element (8) on a second edge portion (9) which is opposite the first edge portion (7).
9. The heat exchanger (1) as claimed in one or more of claims 1 to 8, characterised in that the at least one grid element (5) is integrated in the frame (2).
10. The heat exchanger (1) as claimed in one or more of claims 1 to 9, characterised in that the at least one grid element (5) is formed as honeycomb grid.

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