DE102018222817A1 - Stoker - Google Patents

Abstract

The invention relates to an electric heater (1) with at least one heating module (2). The at least one heating module (2) has a row of elements (3) aligned in the longitudinal direction (LR) and comprising a plurality of heating elements (6) and two corrugated fins (4) aligned in the longitudinal direction (LR). The corrugated fins (4) can be flowed through transversely to the longitudinal direction (LR) in the flow direction (SR) by a fluid to be heated. The heating elements (6) in the element row (3) can also be electrically contacted on both sides to generate heat. The row of elements (3) and the two corrugated fins (4) are arranged next to one another transversely to the longitudinal direction (LR) and transversely to the flow direction (SR) in the stacking direction (ST). According to the invention, the two electrically conductive corrugated fins are located in the at least one heating module (2) (4) directly and on both sides of the row of elements (3) on electrically conductive and heat transfer. Furthermore, contact plates (5) are located on the respective corrugated fins (4) of the at least one heating module (2) facing away from the row of elements (3), so that the contact plates (5) are the heating elements (6) of the at least one heating module ( 2) Contact electrically and heat-conducting indirectly via the respective corrugated fins (4).

Description

The invention relates to an electric heater with at least one heating module according to the preamble of claim 1.

A generic electric heater usually comprises several heating modules with several heating elements. The heating elements are, for example, PTC elements (PTC: Positive Temperature Coefficient), which are arranged between two contact plates and are electrically contacted by them. In order to increase heat dissipation, corrugated fins are attached to the contact plates in a heat-transferring manner. The heat generated in the PTC elements is then released to the contact plates and further to the corrugated fins. Air can flow through the corrugated fins, so that the heat can be emitted from the corrugated fins to air and this can thereby be heated. Several heating modules can be arranged in the heater. For example, the corrugated fins of the adjacent heating modules can be fixed to one another directly or by means of an intermediate plate to transfer heat, or two adjacent heating modules can have a common corrugated fin.

In the case of air-side electric heaters in motor vehicles, in order to save space and reduce the weight, it is necessary to realize a high power density, also in relation to the air-side pressure drop. This applies to the air-side electric heaters in both the low-voltage and high-voltage range. A small air pressure drop also reduces the noise level in the heater. The aim is also to use the PTC elements efficiently. The PTC elements regulate themselves during heating by increasing their electrical resistance. Since the heat is conducted, among other things, to the neighboring PTC elements via the contact plates, the PTC elements in the heating module influence one another and regulate one another. This can adversely affect the efficiency of the heater.

The object of the invention is therefore to provide an improved or at least alternative embodiment for an electric heater of the generic type, in which the disadvantages described are overcome. In particular, the heat emission and thereby the efficiency of the electric heater are to be improved. Furthermore, the pressure loss and the noise level in the electric heater are to be reduced.

This object is achieved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea of improving the efficiency of the electric heater by directly emitting heat from heating elements in corrugated fins. An electric heater has at least one heating module. The at least one heating module has a row of elements aligned in the longitudinal direction, which has a plurality of heating elements arranged at a distance from one another in the longitudinal direction. The heating elements are electrically contacted on both sides and are preferably resistance elements or PTC heating elements. Furthermore, the at least one heating module has two corrugated fins aligned in the longitudinal direction, through which a fluid to be heated can flow in the direction of flow transversely to the longitudinal direction. The row of elements and the two corrugated fins are arranged transversely to the longitudinal direction and transversely to the flow direction in the stacking direction to one another to form the at least one heating module. According to the invention, in the at least one heating module on the row of elements, the two electrically conductive corrugated fins are directly and electrically conductive and heat-transferring on both sides. Contact sheets of the heater are located on the respective corrugated fins of the at least one heating module so as to be electrically conductive and thermally conductive, facing away from the row of elements. As a result, the respective contact plates contact the heating elements of the at least one heating module indirectly in an electrically conductive and heat-conducting manner via the respective corrugated fins.

In the heater according to the invention, the heat generated in the heating elements is dissipated directly to the corrugated fins, which are directly and heat-transferring to the heating elements. In this context, “immediately” means that no further self-supporting or rigid elements, such as contact plates, are arranged between the respective corrugated fin and the heating elements. However, it is conceivable that thermally conductive or electrically conductive layers are arranged between the heating elements and the corrugated fins in order to improve the electrical or thermally conductive contact and / or to firmly attach the heating elements to the corrugated fins. Both the corrugated fins and the contact plates are made of an electrically conductive material, so that the heating elements are electrically contacted with the contact plates indirectly via the corrugated fins. In this context, “indirect” means that the current applied to the respective contact plate can only flow from the contact plate to the heating elements of the respective row of elements via the respective corrugated fin. In the heater according to the invention, each contact plate can form a contact electrode that can be electrically contacted with an external power source.

The corrugated ribs have a wavy, zigzag-shaped or folded structure with several in Wrinkles through which flow can flow, so that the heat conduction in the respective corrugated fin into the fold and thus takes place close to the stacking direction. The adjacent heating elements in the respective row of elements can thus be thermally decoupled from one another in the longitudinal direction. In comparison to conventional heaters, in which the heat conduction between the individual heating elements takes place in the longitudinal direction via the contact plates adjoining them, the thermal interaction between the adjacent heating elements is reduced in the heater according to the invention. This can prevent mutual curtailment of PTC elements and overall improve the heat dissipation from the heating elements in the corrugated fins. This can significantly increase the efficiency of the electric heater.

The respective contact plates can be formed, for example, from aluminum or from a non-ferrous metal alloy and are preferably stamped, rolled or drawn. The respective contact plates can have an electrically conductive coating. The thickness of a material forming the respective contact plate can be between 0.25 mm and 1.0 mm. The respective corrugated fin can be formed from aluminum and is preferably stamped or rolled. The thickness of a material forming the corrugated fin can be between 0.06 mm and 0.2 mm. The thickness of the respective heating element in the respective row of elements can be between 1 mm and 3 mm.

In an advantageous embodiment of the electric heater, it is provided that the heater has a plurality of heating modules which are arranged one above the other in the stacking direction. The respective heating modules that are adjacent in the stacking direction are each electrically and heat-exchanged via a common contact plate in the heater. The respective heating modules adjacent in the stacking direction are thus in contact with the common contact plate with the corrugated fins, so that the number of elements in the heater and its weight are reduced. Furthermore, the ratio of the flowable area to the total area of the heater transverse to the flow direction is advantageously increased. As a result, the power density in the electric heater can also be increased with respect to the pressure drop. In the electric heater with several heating modules, the number of corrugated fins is then twice as large as the number of rows of elements and the number of rows of elements corresponds to the number of heating modules. The number of contact plates in the heater can then be one higher than the number of heating modules in the heater. For this purpose, all of the adjacent heating modules are in each case in contact with a common contact plate which, on the one hand, bears on the corrugated fin of one heating module and, on the other hand, on the corrugated fin of the other heating module in a heat-transmitting and electrically conductive manner. In this advantageous embodiment, each of the respective contact plates can then be a contact electrode which is directly electrically contacted with an external current source. In comparison to conventional heaters with several heating modules, there are no contact plates that are not directly contacted, which disadvantageously reduce the area through which the heater can flow.

In an advantageous development of the heater, it is provided that the respective corrugated fin is composed alternately of warm areas and cold areas in the longitudinal direction. The heating elements of the adjacent row of elements lie against the corrugated fin in the respective warm areas. In the respective cold areas, however, there are no heating elements of the adjacent row of elements on the corrugated fin to transmit heat. The heat then spreads preferably from the heating elements over the warm areas in the stacking direction to the respective contact plate, in the respective contact plate in the longitudinal direction and then from the respective contact plate in the stacking direction into the cold areas. As a result, the respective corrugated fin is tempered at a comparable temperature in the warm areas and in the cold areas, so that the heat is given off to the fluid to be heated in the respective corrugated fin almost uniformly. Due to this advantageous embodiment of the heater, the heat can be efficiently transferred to the corrugated fin and from there to the fluid to be heated, so that the efficiency of the heater can be increased. The heat conduction takes place in the corrugated fin, preferably in the stacking direction, so that the two adjacent heating elements in the row of elements are thermally decoupled. If the heating elements are PTC elements, this can prevent them from mutually reducing.

Advantageously, it can be provided that the respective corrugated rib has on both sides a contact surface extending transversely to the stacking direction. The respective corrugated fin rests with the one contact surface on the heating elements of the row of elements and with the other contact surface on the respective contact plate. In order to enlarge the contact areas of the respective corrugated fin, the corrugated fin can be formed from a meandering folded band material. As a result, the corrugated fin has a plurality of loops through which flow can flow. The respective loop then runs together on the one hand and on the other hand forms the respective contact surface of the corrugated fin in some areas. This advantageous embodiment of the corrugated fin enables the contact surface to be increased, so that the heat-transmitting contact and the electrically conductive contact between the respective corrugated fin and the adjacent heating elements and between the respective corrugated fin and the respective contact plate are improved.

In summary, the heat emission and thereby the efficiency are improved in the heater according to the invention. Furthermore, the number of contact plates and thereby the weight and the cost of the heater can advantageously be reduced. Since the contact plates cannot be flowed through, the number of flowable areas of the heater can also be increased by reducing their number. In addition, the pressure loss and the noise level in the electric heater can be advantageously reduced.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, the same reference symbols referring to the same or similar or functionally identical components.

• 1 eine Ansicht eines erfindungsgemäßen Heizers mit drei Heizmodulen;
• 2 eine Ansicht einer Wellrippe in dem erfindungsgemäßen Heizer;
• 3 eine Explosionsansicht des erfindungsgemäßen Heizers mit zwei Heizmodulen;
• 4 eine Ansicht eines Ausschnitts des erfindungsgemäßen Heizers mit schematisch angedeuteter Strom- und Wärmeleitung.

It shows, each schematically

• 1 a view of a heater according to the invention with three heating modules;
• 2nd a view of a corrugated fin in the heater according to the invention;
• 3rd an exploded view of the heater according to the invention with two heating modules;
• 4th a view of a section of the heater according to the invention with schematically indicated current and heat conduction.

1 shows a view of an electric heater according to the invention 1 . The heater 1 has three heating modules here 2nd on, each from a row of elements 3rd and two corrugated fins 4th are formed. In the respective heating module 2nd are the element series 3rd and the two corrugated fins 4th aligned in the longitudinal direction LR. Furthermore, the heater points 1 four contact plates 5 on, which extend in the longitudinal direction LR and on the heating modules 2nd are arranged. The corrugated fins 4th can be flowed through in the flow direction SR by the fluid to be heated - for example air - which is transverse to the longitudinal direction LR. The row of elements 3rd has several - only two shown here - heating elements 6 on, the PTC elements arranged side by side here 6a are. In the respective heating module 2nd are the element series 3rd and the two corrugated fins 4th transverse to the longitudinal direction LR and transverse to the flow direction SR in the stacking direction ST arranged one above the other. The respective heating modules 2nd alternate with the respective contact plates 5 in the stacking direction ST . The two electrically conductive corrugated fins 4th are in the respective heating module 2nd on both sides of the element row 3rd electrically conductive and heat transfer. The electrically conductive contact plates 5 then lie on the two corrugated ribs 4th of the respective heating module 2nd from the row of elements 3rd turned away from electrically conductive and heat transfer. This makes the PTC elements 6 of the respective heating module 2nd with the two contact plates 5 of the heater 1 indirectly via the corrugated ribs 3rd contacted electrically and heat transfer.

The heater shown here 1 has a total of three heating modules 2nd on that in the stacking direction ST are arranged one above the other. The are in the stacking direction ST neighboring heating modules 2nd on a common contact plate 5 on. The number of corrugated fins 4th is in the heater 1 twice the number of element rows 3rd , the number of element rows 3rd corresponds to the number of heating modules 2nd and the number of contact plates 5 is one more than the number of heating modules 2nd . The total number of contact plates 5 in the heater 1 and its weight is also reduced compared to conventional heaters. Furthermore, there is also the ratio of the area through which the flow direction SR can flow, to the total area of the heater 1 advantageously increased compared to conventional heaters. In the heater 1 is also each of the respective contact plates 5 a contact electrode 5a that can be electrically contacted directly with an external power source. In comparison to conventional heaters, there are no contact plates that are not directly connected to the power source.

The respective corrugated fin 4th has contact surfaces on both sides 4a and 4b on that is transverse to the stacking direction ST extend. The respective corrugated rib lies here 4th with one contact surface 4a on the PTC elements 6a the row of elements 3rd and with the other contact surface 4b on the contact plate 5 on. The investment area 4a and thereby the corrugated fin 4th are in themselves in warm areas 10 and in cold areas 11 divided. In the warm areas 10 are the respective PTC heating elements 6a on the contact surface 4a on. In the cold areas 11 there are no PTC heating elements 6a on the contact surface 4a on. The warm areas 10 and the cold areas 11 alternate due to the structure of the row of elements 3rd in the longitudinal direction LR.

2nd now shows a view of the corrugated fin 4th in the electric heater 1 . The corrugated fin 4th is made from a meandering folded band material 7 shaped so that several loops through which flow can flow 8th are shaped. The respective loop 8th runs on the one hand in a closing point 9 on one contact surface 4a or 4b together and forms on the other hand - or the closing point in the stacking direction ST opposite - area by area the other contact surface 4b or 4a the corrugated fin 4th . This makes the contact surfaces 4a and 4b compared to conventional corrugated fins larger, so that the heat transfer contact and the electrically conductive contact between the corrugated fin 4th and the adjacent PTC elements 6a and between the corrugated fin 4th and the contact plate 5 are improved.

3rd shows an exploded view of the electric heater 1 with two heating modules 2nd . The heater 1 is to the stoker 1 in 1 constructed the same way and only has a different number of heating modules 2nd and the contact plates 5 on. It goes without saying that the number of heating modules shown here 2nd and the contact plates 5 in the heater 1 to 1 and 3rd is only exemplary. The heater 1 can both multiple heating modules 2nd as even a single heating module 2nd and a correspondingly adjusted number of contact plates 5 include. Also the number of heating elements 6 in the respective row of elements 3rd may vary.

4th shows a view of a section of the electric heater 1 with power line I indicated by arrows and heat conduction indicated by arrows Q . The power line I takes place in the heater 1 from the one contact electrode 5a to the other contact electrode 5a , as indicated by arrows. In the heater 1 is each of the respective contact plates 5 the contact electrode 5a that is directly contacted with an external power source. In comparison to conventional heaters, there are no contact plates that are not directly connected to the power source 5 left.

In the heater 1 will be in the PTC elements 6a generated heat directly to the adjacent corrugated fins 4th derived the heat transfer on the PTC elements 6a issue. Through the loops 8th - see in particular 2nd - The heat conduction takes place Q from the PTC elements 6a close to the stack direction ST to the respective neighboring contact plates 5 . This will make the corrugated fin 4th first in the warm areas 10 warmed up. Via the contact plates 5 the heat conduction takes place Q in the longitudinal direction LR to the neighboring cold areas 11 the respective corrugated fin 4th . This will make the corrugated fin both in heat areas 10 as well as in cold areas 11 heated to a comparable extent and the heat evenly emitted to the fluid flowing through. In particular, takes place in the heater 1 no heat conduction Q between the adjacent PTC elements directly in the longitudinal direction LR, as is the case in conventional heaters. This can reduce the mutual regulation of the PTC elements 6a prevents and overall the heat output in the heater 1 be improved. The efficiency of the electric heater 1 can be significantly improved.

The respective contact plates 5 can be formed from aluminum or a non-ferrous metal alloy, for example, and are preferably stamped, rolled or drawn. The respective contact plates 5 can also have an electrically conductive coating. The thickness of the respective contact plate 5 forming material can be between 0.25 mm and 1.0 mm. The respective corrugated fin 4th can be formed from aluminum and is preferably stamped or rolled. The thickness of a the corrugated fin 4th forming material can be between 0.06 mm and 0.2 mm. The thickness of the respective PTC element 6a in the respective row of elements 3rd can be between 1 mm and 3 mm.

In summary, the heat emission and thereby the efficiency in the heater according to the invention 1 improved compared to conventional heaters. In addition, the number of contact plates 5 and thereby the weight and cost of the heater 1 reduced. Furthermore, the area through which the heater can flow is also 1 increases, causing pressure loss and noise level in the heater 1 are advantageously reduced.

Claims (10)

Electric heater (1) with at least one heating module (2), - the at least one heating module (2) having a row of elements (3) oriented in the longitudinal direction (LR), - the row of elements (3) spacing several apart in the longitudinal direction (LR) arranged heating elements (6), preferably a plurality of resistance elements or a plurality of PTC elements (6a), which can be electrically contacted on both sides to generate heat, the at least one heating module (2) having two corrugated fins (4) aligned in the longitudinal direction (LR) which can be flowed through transversely to the longitudinal direction (LR) in the flow direction (SR) by a fluid to be heated, and - the element row (3) and the two corrugated fins (4) transversely to the longitudinal direction (LR) and transversely to the flow direction (SR) are arranged in the stacking direction (ST) next to one another to form the heating module (2), characterized in that - in the at least one heating module (2) on the row of elements (3), the two electrically conductive corrugated fins (4) directly and nd are electrically conductive on both sides, and - that the respective corrugated fins (4) of the at least one heating module (2) have contact plates (5) on both sides facing away from the row of elements (3), so that the respective contact plates (5) are electrically conductive Heating elements (6) of the Contact at least one heating module (2) indirectly via the respective corrugated fins (4) in an electrically conductive and thermally conductive manner. Heater after Claim 1 , characterized in that - the heater (1) has a plurality of heating modules (2) which are arranged one above the other in the stacking direction (ST), and - that the respective heating modules (2) adjacent in the stacking direction (ST) each have a common contact plate (5 ) are contacted with each other electrically and heat transfer. Heater after Claim 2 , characterized in that the number of contact plates (5) in the heater (1) is one more than the number of heating modules (2). Heater according to one of the preceding claims, characterized in that the respective corrugated fin (4) in the longitudinal direction (LR) is composed alternately of warm areas (10) and cold areas (11), the heating elements (6) in the respective warm areas (10) the adjacent row of elements (3) and in the respective cold areas (11) no heating elements (6) of the adjacent row of elements (3) rest on the corrugated fin (4) in a heat-transferring manner, and - that the heating elements (6), the corrugated fin (4) and the Contact plates (5) are arranged such that heat from the heating elements (6) in the stacking direction (ST) via the warm areas (10) to the respective contact plate (5), in the respective contact plate (5) in the longitudinal direction (LR) and from spreads the respective contact plate (5) in the stacking direction (ST) into the cold areas (11), so that the respective corrugated fin (4) in the warm areas (10) and in the cold areas (11) is at a comparable temperature. Heater according to one of the preceding claims, characterized in that each of the respective contact plates (5) has or is a contact electrode (5a) which can be electrically contacted with an external power source. Heater according to one of the preceding claims, characterized in that - the respective contact plates (5) are formed from aluminum or a non-ferrous metal alloy, preferably stamped, rolled or drawn, and / or - that the respective contact plates (5) have an electrically conductive coating have, and / or - that the thickness of the respective contact sheet (5) forming material is between 0.25 mm and 1.0 mm. Heater according to one of the preceding claims, characterized in that the respective corrugated fin (4) has on both sides in each case a contact surface (4a, 4b) extending transversely to the stacking direction (ST), the respective corrugated fin (4.) In the at least one heating module (2) ) with one contact surface (4a) on the heating elements (6) of the row of elements (3) and with the other contact surface (4b) on the respective contact plate (5). Heater after Claim 7 , characterized in that - the corrugated fin (4) is formed from a meandering folded material band (7) so that the corrugated fin (4) has a plurality of loops (8) through which flow can flow (SR), and - that the respective loop (8 ) converges on the one hand and on the other hand forms the respective contact surface (4a, 4b) of the corrugated fin (4) in some areas. Heater according to one of the preceding claims, characterized in that - the respective corrugated fin (4) is formed from aluminum, preferably punched or rolled, and / or - that the thickness of a material forming the corrugated fin (4) is between 0.06 mm and 0.2 mm. Heater according to one of the preceding claims, characterized in that the thickness of the respective heating element (6) in the respective row of elements (3) is between 1 mm and 3 mm.

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