DE20021566U1 - Device for heating gases for heating interiors and lamella of such a device - Google Patents

Description

Device for heating gases for heating interior spaces and fin of such a device

The invention relates to a device for heating gases, in particular air, for the purpose of heating interiors, in particular those of motor vehicles or the like, with a heating register with heating fins traversed by heating elements, as well as a heating fin for a heating register for heating gases with openings for the passage of heating elements.

In the past, when heating interiors, especially vehicle interiors, the waste heat from the engine was used in air-filled engines through appropriate exhaust heat exchangers or in water-cooled engines by using the thermal energy in the cooling water. However, this waste heat is no longer sufficient in modern engines, especially in the cold season. For this reason, devices for heating vehicle interiors have been developed.

B1000245

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which ensure that the interior is heated regardless of the available waste heat from the engine.

Such heating devices are usually compact electrical heating elements that are assembled into a heating block and held in a frame.

The auxiliary heaters described above are now usually installed in complicatedly shaped air conditioning boxes that are molded onto the passenger compartment and offer very limited installation space. The differently shaped air conditioning boxes have the disadvantage of generating an inhomogeneous flow velocity across their flow cross-section and, as a result, inhomogeneous air heating with a constant heat exchanger thickness. In particular, it is not possible to generate a desired, defined heat distribution.

Known heating devices do not adequately address this problem. This is mainly due to the fact that the most commonly used solutions (e.g. DE 44 36 613 Al and DE 44 04 345 Al) only allow a rectangular air passage and a constant thickness of the register. DE 196 07 122 Al also clearly shows the unsatisfactory solution to the problem, with an almost triangular longitudinal section of the housing.

DE 19 8 4 8 169 Al also shows a cuboid-shaped auxiliary heater in which PTC components are clamped into the interior of a profile tube made of a material with good heat conduction, such as aluminum, and fins are placed on the outside of the tube to dissipate heat.

The invention is based on the object of avoiding the aforementioned disadvantages by providing an improved device for

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Heating of gases and fins intended for such a heating device.

According to the invention, the above-mentioned object is achieved in a heating device of the type mentioned in that the shape of each heating fin is such that the outlet temperature of the heated gas on the outlet side of the heating fins is essentially constant. A preferred embodiment provides that the shape of each heating fin (3a-3n) is such that the outlet temperature of the heated gas on the outlet side of the heating fins (3a-3n) is essentially constant. In a preferred embodiment, it is provided that the height of the heating fins is greater in the region of higher gas flow speed than in the region of lower gas flow speed. Accordingly, the invention further provides a heating fin of the type mentioned in order to achieve the object, in which the height of the heating fin is greater in the region of higher air flow speed than in the region of lower air flow speed.

The invention therefore provides that in zones of higher flow velocity the effective heat exchanger height is greater than in zones of lower velocity.

The heating fins of a heating register are designed in such a way that the outlet temperature of the heated gas is essentially constant on the outlet side of the heating fins, both across their width and in the case of a heating register in the direction of the stacking of several heating fins. According to the invention, the different flow speeds of the gas flowing through the heating register, which may occur due to external circumstances, are taken into account across the width of the heating fin and the depth of its stacking, as well as due to the influence of the flow and heating speed of the gas.

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by the design of the heating register itself. If, due to previous changes in direction of the gas flowing into a heating register having heating fins, this has a different flow speed across the width of the fins and in the direction of the stacking of the fins, the invention provides that the height of the heating fins is greater in the area of higher gas flow speed than in the area of lower gas flow speed. This ensures that, due to the extension of the heating path in the area of higher gas flow speed, the outlet temperature in such areas is essentially the same as in areas of lower gas flow speed, in which the gas is heated more strongly in a given flow section, in particular in areas in which heating fins are interspersed with resistance heating elements, where the gas flowing through is swirled and thus its global average speed or passage time is reduced.

Furthermore, excessive heating at the location of a resistance heating element, which usually contains a PTC thermistor, will result in a loss of performance of the same, as would be the case if the PTC thermistor exceeded its temperature and entered the high-resistance range due to excessive heating.

Overall, the measures according to the invention make it easy to ensure that the temperature difference on the outlet side of the heating register, towards the outlet surface of the same, does not exceed 2°C.

Within the scope of the device according to the invention, it can be taken into account that the outer shape of each heating fin corresponds to the inner contour of a housing enclosing the heating fins.

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housing in the cross-sectional plane in which the heating fin is arranged. This allows the limited space available to be used optimally by ensuring that the external shape of the auxiliary heater follows the complex shape of the air conditioning box into which it is installed as closely as possible in order to accommodate the required high electrical output in the available volume, and to prevent zones from forming in which the air passes through the auxiliary heater without being heated, so-called "bypass zones".

Furthermore, in the stacking direction of the heating fins or in the longitudinal direction of the heating elements passing through them, the design of the device according to the invention, in particular of the heating register, can include the heating elements having different lengths.

In a further embodiment of the invention, it can be provided that the heating register is fixed to the housing by screw connections, with at least the outer heating fins in particular having tabs that overlap parts of the housing and are screwed into the housing by means of the screws. This means that the fastening of the fins via plastic flanges that are attached to the beginning and end of heating rods can be omitted. This is particularly advantageous when the heating rods are of different lengths. Such plastic flanges have the additional disadvantage that they no longer hold reliably at temperatures above 13 0 ⁰ C. In order to keep the individual heating fins at a distance from one another, the invention also provides spacers for the heating fins. These can initially be formed by tabs bent out of the planes of the heating fins. In an additional or alternative manner, it can be provided that the heating fins are mutually supported by at least parts of two

opposite edges are bent inwards by at least 180°, whereby the distance between the heating fins is specified and the end section rests resiliently against the adjacent heating fin. In addition, the inner area of the spacer can be punched out.

In a preferred embodiment, the heating fins are secured to the heating elements by means of clamping tabs bent out of the heating fins, which are held frictionally on the heating elements. A device according to the invention can further provide that air inlet and air outlet channels are arranged upstream and downstream of the heating register.

Finally, the individual heating fins do not have to be flat, but can be twisted, i.e. bent or curved, to adapt to the conditions such as inflow conditions, spatial conditions, etc.

Further advantages and features of the invention emerge from the claims and from the following description, in which embodiments are explained in detail with reference to the drawing. In this drawing:

Fig. 1a is a perspective view of a heating device according to the invention;

Fig. 1b is a plan view of a heating device according to the invention according to the arrow I in Fig. 2;

Fig. 2 is a plan view of a single lamella according to arrow II of Fig. 1b;

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Fig. 3a is a perspective view of a heating device arranged in the housing;

Fig. 3b is a view of the heating device of Fig. 3a according to the arrow II of Fig. 1b;

Fig. 4 is an enlarged view of a spacer corresponding to that of detail B of Fig. 3a;

Fig. 5a,b Side view and top view according to the

Arrow III of an alternative embodiment of a spacer to Fig. 4;

Fig. 6a-d various perspective views of a curved slat; and

Fig. 6 the resistance-temperature characteristic of a PTC heating element.

Figures 1a and 1b show a heating device according to the invention. In the embodiment shown, it has electrical heating elements 2a, 2b, 2c in the form of profile tubes. Lamellas 3a...3n for dissipating heat to the surrounding air or gas are frictionally and thermally seated on the heating elements 2a-c. In the embodiment shown, the lamellas have three openings 4a, 4b, 4c, which are delimited on each of their sides by clamping tabs 5a, 5b, 5c, by means of which the heating lamellas 3a-3n are held on the heating elements 2a-c. Between the openings 4a-c, the heating lamellas 3a-3n have tabs 6a, 6b bent out of their main plane, which resiliently support adjacent lamellas 3a-3n at a distance from one another.

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For further detailed design of such a heating device per se, reference is made by way of example to EP 379 837 B1 and DE 198 48 169 A1, the disclosure of which is each made the subject matter of the present application.

What is essential to the invention, however, is that, in contrast to the prior art, the fins 3a-3n of the heating device according to the invention are not rectangular, but are designed in such a way that the escaping gas has an almost constant outlet temperature at every point on the outlet side of the heating fins. This means first of all that if, due to the introduction conditions of the gas to be heated, this gas is not guided through the fins over a sufficiently long distance without a change of direction, for example in front of the heating register 3 formed by the heating fins 3a-3n, but instead experiences a direction diversion, for example in front of the heating register 3, which means that the flow speed on one side of a fin is lower than on the other side and/or in the area at one end of the heating register (perpendicular to the direction of extension of the fin) is higher than at the other end, the fin height is also correspondingly larger, so that the faster-flowing gas components are nevertheless heated to essentially the same outlet temperature as slower-flowing gas components (in whose area the fin height is lower).

In areas where heating elements 2a-2c in the form of profile tubes extend through the slats (which usually have PTC elements as effective heating elements), the heating elements cause turbulence and thus a reduction in the global passage speed through the slats or an increase in the passage time 5 (compared to areas between the heating elements in which

the gas can flow freely through). In order to achieve essentially the same output speed over the outlet surface of the register 3 here too, the fins in areas of the heating elements have a lower height than in areas between the heating elements, in which the gas can flow freely, so that the flow time and accordingly the outlet temperature are essentially the same over the entire outlet surface of the heating register. In this case, the reduction in the height of the heating fin also takes into account the fact that in the area of a heating element, the gas flowing through is not only heated by the heating fin itself (as is the case in areas far away from the heating elements) but also by the heating element itself. This design also prevents local overheating in the area of the heating elements, which could lead to a loss of performance in the case of PTC thermistors according to their heating characteristics, as shown in Figure 7, if the critical temperature ob is exceeded.

The above is illustrated in particular by the figure. Due to external housing conditions (redirection of the incoming air), the inlet flow speed V _e increases continuously from the left with V _e i to the right V _e7 in this exemplary embodiment. In order to adapt to these flow conditions, the slat 3a shown is therefore higher on the right side than on the left side. In the area of the openings 4a-c through which the heating elements 2a-c are guided, turbulence occurs through the latter, as already mentioned. This reduces the flow speed and thus the exit speed V _a2 , V _a4 , V _a6 compared to the corresponding inlet speed V _e 2 , V _e4 , Ve6. The disadvantageous temperature increase mentioned above

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The increase in temperature in these areas compared to intermediate areas can be compensated by reducing the height of the slats 3a-3n in the area of the heating elements 2a-c, as shown in Figures 1a and 2a, in that the slat is designed here on the outlet side in a wave-like manner, with the height continuously increasing with regard to the mentioned inflow conditions.

In this way, regardless of different inlet velocities and different global flow times (and global flow velocities) as well as local stronger heating of the gas flowing through (in the area of the heating elements), an essentially uniform outlet temperature distribution can be achieved over the entire outlet surface of the heating register, both in the direction of the width of the fins and in the direction of the stacking of the fins.

Figures 3a,b show representations of a complete heating device 1 according to the invention in which the heating register is installed in a housing 6. In this exemplary embodiment, the slats 3a-3n are shaped in their main plane in such a way that they completely fill the space available to them in the housing. The housing is inclined in its main axis between an air inlet channel 7 and an air outlet channel 8 by an angle α. The heating device 1 thus has a section of a right-angled triangle available in the main plane of the slats 3a-3n, which can be fully used due to the adapted slats 3a-3n 0. In the longitudinal direction of the heating device, the shape in this exemplary embodiment is shown as constant for reasons of illustration, the slats can also be designed in a wavy, rising manner, as shown in Figures

la and 2. Instead of or in addition to the mutual support of the slats, as described above by bent tabs 6a, 6b punched out of the main plane of the slats 3a-3n, the slats can be supported in their edge region in a manner as shown in Figure 4. Lateral edges 9 of a slat 3a are bent at right angles, the first right-angled section 10 corresponding to the desired distance between two adjacent slats and thus specifying this, while the second section 11 rests resiliently against the adjacent slat and thus each individual heating slat is resiliently supported by its tab on its adjacent heating slat (for example 3a).

Fig. 5a and 5b show another possible design of spacers using bent edges (9), in which, in contrast to Fig. 4, the edges (9) run obliquely to the direction of air flow. In order to obtain an additional passage area (15) for the air flow, the interior of the spacer (14) is punched out.

Figure 3 also shows an example of a design for fastening the outer fins 3a, 3n to the housing 6 using a screw connection. For this purpose, an individual fin, for example 3a, has two tabs 12a, 12b with an opening on its long side. The tabs 12a, 12b and the fin 3a can either be formed as one piece or the tabs are attached to the heating fin 3a, for example by rivets. The heating fin 3a is attached to the housing 6 using screws 13a, 13b via these tabs 12a, 12b, whereby the entire heating register is immovably fixed relative to the housing due to the clamping mutual support of all the fins.

Figures 6a-6b show different views of a heating fin 3a, whereby Figure 6a shows a heating register of identical fins 3a-3n. The heating fins 3a-3n are provided with the heating fins 3a-3n shown in more detail in Figures 6b-6d.
Heating fin 3a is not flat, but twisted, and thus bent or curved. Otherwise, heating fins 3a-3n have the additional detailed designs explained above.

Claims (23)

1. Device for heating gases, in particular air, for the purpose of heating interiors, in particular those of motor vehicles or the like, with a heating register with heating fins traversed by heating elements, characterized in that the shape of the heating fin ( 3 a - 3 n) is such that the distribution of the outlet temperature of the heated gas over the outlet surface on the outlet side of the heating fins ( 3 a - 3 n) essentially corresponds to a predetermined distribution. 2. Device according to claim 1, characterized in that the shape of each heating fin ( 3 a - 3 n) is such that the outlet temperature of the heated gas on the outlet side of the heating fins ( 3 a - 3 n) is substantially constant. 3. Device according to claim 1 or 2, characterized in that the height of the heating fins ( 3 a - 3 n) is greater in the region of higher gas flow velocity than in the region of lower gas flow velocity. 4. Device according to claim 1, 2 or 3, characterized in that the height of the heating fins in the region of heating elements ( 2 a-c) is lower than in regions where no heating elements are present. 5. Device for heating gases, in particular air, for the purpose of heating interiors, in particular those of motor vehicles or the like, with a heating register with heating fins traversed by heating elements, in particular according to one of claims 1 to 4, characterized in that the external shape of each heating fin ( 3 a - 3 n) corresponds to the internal contour of a housing ( 6 ) enclosing the heating fins ( 3 a - 3 n) in the cross-sectional plane in which the heating fin ( 3 a - 3 n) is arranged. 6. Device according to one of claims 1 to 5, characterized in that the heating elements ( 2 a-c) have different lengths. 7. Device according to one of claims 1 to 6, characterized in that the heating register ( 3 ) is fixed to a housing ( 6 ) by screw connections. 8. Device according to claim 7, characterized in that at least outer heating fins ( 3 a, 3 n) have tabs ( 12 a, b) which overlap parts of the housing ( 6 ) and are screwed into the housing by the screws ( 13 a, b). 9. Device according to one of the preceding claims, characterized by spacers ( 6 a, 6 b; 10 , 11 ) of the heating fins ( 3 a- 3 n). 10. Device according to claim 9, characterized by tabs ( 6 a, 6 b) bent out of the planes of the heating fins ( 3 a - 3 n) as spacers. 11. Device according to claim 8, characterized in that the heating fins ( 3 a - 3 n) are mutually supported in that at least sections ( 10 , 11 ) of two opposite edges are bent inwards by approximately 180°, the first section ( 10 ) defining the distance between the heating fins ( 3 a - 3 n) and an end section ( 11 ) resting resiliently on the adjacent heating fin ( 3 a - 3 n). 12. Device according to claim 11, characterized in that the inner region ( 14 ) of the spacer ( 9 ) is rigid. 13. Device according to one of claims 5 to 12, characterized in that the heating fins ( 3 a- 3 n) are held on the heating elements ( 2 a-c) in a frictionally engaged manner by means of clamping tabs ( 5 a-c) bent out of them. 14. Device according to one of claims 5 to 13, characterized in that air inlet and air outlet channels ( 7 , 8 ) are arranged upstream and downstream of the heating register ( 3 ). 15. Device according to one of claims 5 to 14, characterized in that the heating fins ( 3 a - 3 n) are not flat, but curved or bent. 16. Heating fin for a heating register for heating gases, with openings for the passage of heating elements, characterized in that the height of the heating fin is greater in the region of higher air flow velocity than in the region of lower air flow velocity. 17. Heating fin according to claim 16, characterized by a curved or curved design. 18. Heating fin according to claim 16 or claim 17, characterized by fastening tabs ( 12 a, 12 b). 19. Heating fin according to one of claims 16 to 18, characterized by spacers ( 6 a, 6 b). 20. Heating fin according to claim 19, characterized by tabs ( 6 a, 6 b) bent out of the plane of the heating fin ( 3 a - 3 n) as spacers. 21. Heating fin according to claim 19 or 20, characterized in that the heating fins ( 3 a - 3 n) are mutually supported in that at least sections ( 10 , 11 ) of two opposite edges are bent inwards by approximately 180°, the first section ( 19 ) defining the distance between the heating fins ( 3 a - 3 n) and an end section ( 11 ) resting resiliently on the adjacent heating fin ( 3 a - 3 n). 22. Heating fin according to claim 21, characterized in that the inner region ( 14 ) of the spacer ( 9 ) is rigid. 23. Heating fin according to one of claims 16 to 23, characterized by punched and bent-out clamping tabs ( 5 a-c) for the heating elements.