DE102023106460A1 - Electric heater - Google Patents

Abstract

The present invention relates to a compact electrical heating device with a housing (2) which has a heating chamber (8) for passing a medium to be heated through the housing (2) and a connection chamber (14) for the electrical connection of at least one PTC heating device (24), wherein the PTC heating device (24) has at least one PTC element (28) and conductor tracks (30) which are electrically conductively connected to the PTC element (28) for supplying current to the PTC element (28) with different polarity, and wherein the PTC heating device (24) is introduced into a heating device housing (20) which is open at its upper end and towards the connection chamber (14) and closed at its lower end and towards the heating chamber (8) and protrudes from the partition wall (12) in the direction of the heating chamber (8). In the heating chamber (8), a supply branch (64) and a discharge branch (66) for the medium to be heated are formed, which are connected to one another via a transverse channel (62) which is provided opposite an inlet (16) of the supply branch (64) or an outlet (18) and the discharge branch (66). The supply branch (64) and the discharge branch (66) each form a meandering flow path (69) which has flow channels (70) extending between main side surfaces of the heating device housings (20), wherein the flow channels (70) of the supply branch (64) and the discharge branch (66) are each aligned obliquely relative to a substantially rectangular base area (R) of the housing (2) and in a herringbone pattern relative to one another, and wherein the flow channel (70.6) of the supply branch (64) and the discharge branch (66) arranged furthest from the inlet (16) or the outlet (18) opens into the transverse channel (62).

Description

The present invention relates to an electric heating device having the preamble features of claim 1.

Such an electric heating device is made, for example, of EP 1 872 986 A1 or EP 2 797 381 A1 known.

This previously known electric heating device has a multi-part housing which has a heating chamber for passing the medium to be heated through the housing and a connection chamber for the electrical connection of at least one PTC heating device. The housing has inlet and outlet openings for introducing the medium to be heated into the housing or discharging it from the housing. In the solution according to the invention, there is preferably a partition between the circulation chamber and the connection chamber, from which heating device housings protrude, forming receiving pockets into which PTC heating devices are inserted on the connection side. These heating device housings protrude into the heating chamber like heating ribs, which is completely separated from the connection chamber in terms of fluids via the partition. The connection chamber usually also has a control device for the PTC heating devices which are electrically connected within the connection chamber and may also be grouped there into heating circuits.

In case of a different state of the art according to EP 2 884 817 A1 The heating fins are formed by plug-in elements that are sealed into plug-in element receptacles that are recessed in the partition wall, with contact tongues of the PTC heating devices being extended and transferred through the partition wall into the connection chamber. The heating device housing is formed by a frame and an insulating layer joined to it, which surround the PTC heating device in such a way that its current-carrying components do not come into direct contact with the medium to be heated.

The heating device housing is closed towards the heating chamber and at its lower end and is open at its upper end and towards the connection chamber so that at least the electrical contacting of the conductor tracks can take place in the connection chamber. This does not exclude the provision of a fluidic seal between the connection chamber and the receptacle for the PTC heating device formed by the heating device housing. The previously mentioned features of the prior art can also be essential to the present invention.

The electric heating device according to the present invention has - like the prior art - at least one PTC element, which is usually a cuboid-shaped ceramic stone, which is provided with a metallization on opposite sides to introduce the power current. This PTC element is connected to different polarity via conductor tracks. Both the conductor tracks and the PTC element

The present invention aims to create an electric heating device of the type mentioned at the beginning, which is compact in construction, but nevertheless allows good heating of the usually liquid medium and enables the flow of such a medium through the heating chamber with the lowest possible flow resistance. The electric heating device is intended to be used in particular as a heater in a motor vehicle.

In view of this, the present invention proposes providing a supply branch and a discharge branch for the medium to be heated in the heating chamber. An inlet is provided for the supply branch and an outlet for the discharge branch. The inlet and outlet are arranged on one side in relation to the housing. On the opposite side of the housing, the supply branch is connected to the discharge branch via a transverse channel. The supply branch thus forms a main flow direction from the inlet to the transverse channel and the discharge branch a main flow direction in the opposite direction. The supply branch and the discharge branch each form a meandering flow path. This meandering flow path flows around heating device housings that protrude from the partition wall into the heating chamber. The flow path is formed by flow channels that are provided between main side surfaces of the heating device housings and connecting channels that transfer the flow from one flow channel to the other. The flow path in the supply branch and the flow path in the discharge branch are designed in this way. The flow channels of the supply path and the flow channels of the discharge path are each arranged obliquely relative to a substantially rectangular base area of the housing. They are aligned in a herringbone pattern relative to one another. The flow channels of the supply branch are usually arranged strictly parallel relative to one another. The same applies to the flow channels of the discharge branch. Usually, all flow channels of the supply branch are arranged relative to all flow channels of the discharge supply branch of the arranged diagonally. The arrangement is in the form of a herringbone pattern. A central longitudinal axis of the housing extending between the supply branch and the discharge branch can form the axis of symmetry for this design of the flow channels and possibly also the connecting channels.

The flow channels are formed in a straight line. The transition between the flow channels and the connecting channels is usually rounded to enable the flow to be diverted from one flow channel to the next as uniformly and as little loss as possible. The flow channel of the supply branch that is furthest from the inlet and the flow channel of the discharge branch that is furthest from the outlet open into the cross channel. The two flow channels that are furthest away form the inlet and outlet to the cross channel. Here, too, the flow is diverted around radii and is therefore smooth.

The cross channel can be connected directly to an inward-facing flow channel of the supply branch and the discharge branch. In this case, the cross channel is arranged at a distance from a side surface of the housing. The cross channel can be formed slightly curved between the flow channels connected to it in order to create the lowest possible flow resistance for the flowing medium at the transition between the supply branch and the discharge branch.

This design requires less deflection than a preferred development of the present invention, in which the transverse channel runs parallel to a side surface of the housing and absorbs the power loss of a circuit breaker, thereby cooling the circuit breaker and at the same time heating the medium to be heated with the power loss. For this purpose, the electrical heating device preferably has a control housing that surrounds a control device comprising the at least one circuit breaker and is mechanically connected to the housing. The control housing can be welded to the rest of the housing, in particular the upper part of the housing, in particular laser welded. The control housing is usually arranged transversely to the housing. In other words, the control housing extends in its main flow direction essentially parallel to the transverse channel and rests on the side surface of the housing provided adjacent to the transverse channel.

According to a preferred development of the present invention, the PTC element has a rectangular base area with a height and a width in a manner known per se. The width is smaller than the height. The ratio of width to height is between 8 to 14 and 12 to 14, in particular 11 to 14. In this preferred embodiment, the width extends along a direction that connects the lower end of the heater housing with the upper end thereof. The smaller extension of the rectangular base area accordingly runs between the connection chamber and the lower end of the heater housing. Contrary to the usual arrangement, the PTC element is installed "transversely". This allows the heater housing to be manufactured with a smaller depth. The heating fin formed by the heater housing protrudes less far into the heating chamber. This makes the heater housing easier to manufacture, in particular by casting as a structural unit with the partition wall and preferably as a component of a housing upper part made of metal, which usually only has to be covered with a sheet metal plate as a cover in order to seal the connection chamber from the environment. Such a design has also proven to be advantageous in the case where the control device is provided in the connection chamber, which is accommodated in a shielded manner in the connection chamber due to the walls of the upper housing part and the metallic cover.

In this preferred embodiment, the larger extent of the base area of the PTC element extends parallel to the flow within the flow channel. This means that more of the surface area of the PTC element is swept over by the flow path, which improves the heat transfer to the medium to be heated.

In order to ensure that the flow is passed through with as little loss as possible, a preferred development of the present invention proposes that the flow channel of the supply branch or the discharge branch that is arranged furthest from the inlet or the outlet forms an angle of 30 degrees to 40 degrees with the transverse channel. This angular alignment of these flow channels, which are usually arranged parallel to the other flow channels of the supply branch or the discharge branch, also applies in particular to the relative arrangement of the corresponding flow channels relative to the housing, which is essentially rectangular in its base area.

However, a low-loss flow within the heating chamber is not only achieved by the arrangement of the flow channels or the connecting channels and their design. Rather, the present invention Dimensions of the flow channels are also specified, which have proven to be particularly preferred with regard to the transfer of heat to the medium with the lowest possible flow resistance within the flow channels.

In this preferred embodiment, the heating device housings usually taper towards their lower end. The flow channel provided between adjacent heating device housings is accordingly wider adjacent to the partition than at the lower end of the heating device housing. There, adjacent heating device housings preferably have a distance of between 4 mm and 8 mm, preferably between 5 and 6 mm. In the area of the partition, i.e. where the heating device housings merge into the partition, the distance between adjacent heating device housings is approximately 2 mm and 6 mm, preferably between 4 and 5 mm. All heating device housings of the electric heating device generally protrude from a partition extending in one plane and protrude into the heating chamber with the same extent. All heating device housings are preferably provided identically and formed in one piece with the partition.

The invention discussed above has various advantages that allow a compact electric heating device to be designed with low losses but still effectively in terms of heat extraction. Due to the two-row structure with a supply branch and a discharge branch, the inlet and outlet of the housing can be positioned on the same side. This makes it easier to connect the electric heating device to the medium to be heated. The electric heating device of the present invention is used in particular in a motor vehicle, where the installation space is naturally limited.

The heating device housings and thus the PTC elements are arranged at an angle relative to the base area of the housing and thus the main flow direction within the heating chamber. The herringbone pattern in particular results in a compact design with a sufficiently extended heat path within the heating chamber.

The arrangement of the PTC element "transversely" results in a reduced depth of the receiving pocket formed by the heating device housing. This allows the partition wall, any walls protruding from it and surrounding the connection chamber, as well as several heating device housings molded onto the partition wall in one piece, to be manufactured in a simplified manner using die casting.

The design, in which the transverse channel runs parallel to a side surface of the housing and forms an angle of between 30 and 40 degrees with the last flow channel, enables a basically triangular recess within the connection chamber. This recess is limited by walls that protrude into the heating chamber like a heating rib and accordingly limit the flow path within the heating chamber. The triangular recess is suitable for accommodating drying granulate, which can bind moisture within the connection chamber. If the connection chamber is connected to the inside of a control housing in a fluid-tight manner, any moisture present there is also bound by the drying granulate. However, additional PTC heating devices can also be accommodated in the triangular recess to increase the heating output. The triangular recess also saves material for the construction of the housing. In primary forming processes for producing the housing, the area would otherwise be completely filled with material.

• 1: eine erste perspektivische Seitenansicht eines Ausführungsbeispiels einer elektrischen Heizvorrichtung ohne Steuerstecker;
• 2: eine zweite perspektivische Ansicht des Ausführungsbeispiels nach 1 ohne Steuerstecker;
• 3: eine perspektivische Ansicht der Unterseite des Gehäuseoberteils des Ausführungsbeispiels;
• 4: eine Querschnittsansicht des Ausführungsbeispiels in der der Ebene IV-IV nach 1 mit Steuerstecker;
• 5: ein vergrößertes Detail der Schnittansicht gemäß 4;
• 6: eine anschlusskammerseitige Draufsicht auf das Gehäuseoberteil des Ausführungsbeispiels ohne Verdrahtungsmodul und
• 7: eine Querschnittsdarstellung des Strömungsweges innerhalb der Heizkammer.

Further details and advantages of the present invention will become apparent from the following description of an embodiment in conjunction with the drawing, in which:

• 1 : a first perspective side view of an embodiment of an electric heating device without control plug;
• 2 : a second perspective view of the embodiment according to 1 without control plug;
• 3 : a perspective view of the underside of the upper housing part of the embodiment;
• 4 : a cross-sectional view of the embodiment in the plane IV-IV according to 1 with control plug;
• 5 : an enlarged detail of the sectional view according to 4 ;
• 6 : a connection chamber side top view of the housing top of the embodiment without wiring module and
• 7 : a cross-sectional view of the flow path within the heating chamber.

The 1 and 2 show a heating device with a housing, which is identified overall by reference number 2, with the housing cover partially removed. The housing 2 has a housing upper part 4 made of metal, a housing lower part 6 made of plastic, which is tightly connected to the housing upper part 4 to form a heating chamber 8 and a 4 shown housing cover 10, which is fluid-tight with the housing upper part 4. The heating chamber 8 is in the 3 and 4 marked with reference number 8, although the housing lower part 6 is not shown there. Between the housing cover 10 and a partition wall marked with reference number 12, the housing upper part 4 forms a connection chamber 14. The partition wall 12 separates the connection chamber 14 from the heating chamber 8.

The housing lower part 6 forms inlet and outlet nozzles formed thereon in one piece, which form an inlet 16 and an outlet 18 to the heating chamber 8 and can be connected to the hoses for guiding the liquid medium to be heated.

The nozzles open into the heating chamber 8. Heating device housings 20 protrude into this heating chamber 8 as heating ribs, which are formed by die-casting in one piece on the partition wall 12 and thus the housing upper part 4. Each heating device housing 20 forms a 4 with reference number 22, which is closed towards the heating chamber 8 and open towards the connection chamber 14. In each receiving pocket 22, at least one, possibly several PTC heating devices 24 are provided. Each PTC heating device 24 has a frame 26, which accommodates a PTC element 28 and joins two conductor tracks in the form of contact plates 30 to form a unit, which lie directly on the main side surfaces of the PTC element 28 in an electrically conductive manner and form contact tongues 32 that extend into the connection chamber 14. The contact plates 30 are provided on the outside with an insulating layer 34, for example an aluminum oxide plate or an electrically insulating film. The contact plates 30 are thereby supported in an insulating manner in the receiving pocket 22. A good heat-conducting contact of the main side surfaces of the PTC element 28 can be achieved, for example, by wedging the PTC element 28 together with the contact plates and the insulating layers 34 in the receiving pocket 22 by means of a wedge element 36, which can also be implemented as a U-shaped element; compare EN 10 2020 201 571 A1 .

The 1 and 2 show a power connector 38 with a power connector housing 40. A control connector 44 to be inserted into a control connector receptacle 42 marked there with reference number 42 is shown in 4 shown in section with its control plug housing 46. The power current is fed to a control device via the power plug 38 and control signals are fed to a control device via the control plug 44.

In the embodiment of an electric heating device shown, this control device 50 is provided in a separate metallic control housing 52; cf. 4 and 5 . The electrical connection of the PTC heating devices 24 to the control device 50 is made via a wiring module 53 arranged in the connection chamber 8, which groups several PTC heating devices 24 into heating circuits. The busbars of this wiring module 53 are plugged into the circuit board 54; cf. 5 .

The control device 50 essentially comprises a printed circuit board 54 with which the power connector 38 and the control connector 46 as well as the wiring module 53 are plugged in and which has the power switches 56, which each rest in a heat-conducting manner with an electrically insulating film in between on a cooling surface 58 which is formed by the housing base 6 and in 5 is shown.

The control housing 52 is welded, soldered or glued to the housing upper part 4. For this purpose, the housing upper part 4 has a 5 outer surface marked with reference number 60. As the sectional view according to the 4 and 5 In order to convey heat, the control housing 52 lies at the level of the circuit breaker 56 directly against this outer surface 60 of the metallic housing upper part 4, so that there is good heat conduction between the circuit breaker 56 and the medium to be heated and this medium can cool the circuit breaker 56.

The flow of the medium to be heated within the electric heating device results in particular from 3 and 7 , whereby the 7 in a cross-sectional view, the flow channels within the lower housing part 6, partially separated by components assigned to the upper housing part 4, are illustrated.

The flow guidance is symmetrical relative to a central longitudinal axis L, which is defined in the heating chamber 8 by a transverse wall 62 of the upper housing part 4 extending from the partition wall 12. Reference numeral 64 in the 7 a supply branch; reference numeral 66 denotes a discharge branch. The supply branch 64 and the discharge branch 66 are connected to one another via a transverse channel 68 opposite the inlet 16 and the outlet 18, respectively. The transverse channel 68 runs parallel to an outer wall 76 of the housing base 6.

The supply branch 64 and the discharge branch 66 each define a flow path 69, which is formed by straight flow channels 70 between the individual heating device housings 20 and deflection sections 72, 74 provided therebetween, the outer deflection sections 72 being formed by opposite Outer walls of the housing base 6 and the inner deflection sections 74 are delimited by the transverse wall 62.

The flow channels 70 of the supply branch 64 run parallel to each other; the flow channels 70 of the discharge path 64 run parallel to each other. Due to the opposing inclination of the flow channels 70, the cross-sectional view according to 7 a herringbone-like design of the flow channels 70 within the substantially rectangular housing base 6 in plan view. 7 The rectangular base area marked R is formed by the outer deflection sections 72, the transverse channel 68 and the design of the flow path 69 opposite it. The flow channel 70.6 of the supply branch 64 or the discharge branch 66 which is furthest away from the inlet 16 or the outlet 18 encloses an angle α of approximately 40 degrees between itself and the transverse channel 68.

This transverse channel 68 defines an outer wall of the upper housing part 4, which 4 is identified with reference number 76. On the side of the connection chamber 14, there is a recess 76 which is open to the connection chamber 14 and has a substantially triangular base. The thickness of the walls of the upper housing part 4 surrounding this recess 76 corresponds substantially to the wall thickness of the transverse wall 62. The upper housing part 4 can thus be designed with relatively thin walls. The recess 76 which is open to the connection chamber 14 can accommodate drying granules. Alternatively, at least one PTC heating device can also be provided therein to increase the heating output of the electrical heating device as a whole.

How 4 As illustrated in the drawing, ribs 82 protrude from a base 86 of the lower housing part 6 in the direction of the heating chamber 8. These ribs 82 extend parallel to the heating device housings 20 and are located in the width direction centrally within the flow channels 70. The ribs 82 surround the free ends of the heating device housings 20 with little play and thus significantly limit the flow around this free end at a height at which the PTC element 28 is no longer located within the receiving pocket 22 and at which the release of heat to the outside of the heating device housing 20 is accordingly low.

The 4 shows a thermocouple holder 84 tapering towards the heating chamber 8, which is closed at the bottom and open to accommodate a thermocouple connected in the connection chamber 14 (not shown). The thermocouple holder 84 is connected - as 3 shows - a flow guide wall 86 which directs the flow from the inlet 16 around the thermocouple holder 84 to the beginning of the first heater housing 20. The same applies to flow paths between the last heater housing 20 and the outlet 18.

The PTC elements 28 are - as usual - made of ceramic semiconductor stones, which are provided with a metallization on the outside, which lies electrically conductively on the contact plates 30. The PTC elements 28 have a rectangular base with a height H and a width B. The width B is smaller than the height H. The extension in the direction of the height H is in 6 the extension in the direction of width B is in 4 The width B extends along the direction that connects the lower free end of the heating device housing 20 with the upper end open towards the connection chamber 14. The PTC elements 28 thus lie transversely in the receiving pocket 22.

The dimensions H and B specify the main side surfaces of the PTC element 28. The outer main side surface of the heater housing 20, which delimits the adjacent flow channel 70, also extends parallel to this.

The heating device housings 20, which act as heating fins, have a relatively low height compared to a conventional structure. How 4 conveyed, a projection surface onto the PTC element 28 is completely exposed in the flow path 69, while in the vertical direction below the PTC element 28 by the ribs 82 and above the PTC element 28 by the upper end of the receiving pocket 22 no free flow channel 70 is formed any more. In this way, the heat is coupled out of the PTC element 28 in the best possible way.

List of reference symbols

2

Housing

4

Housing top

6

Housing base

8

Heating chamber

10

Housing cover

12

partition

14

Connection chamber

16

inlet

18

Outlet

20

Heating device housing

22

Recording pocket

24

PTC heating device

26

Frame

28

PTC element

30

Contact plate

32

Contact tongues

34

Insulation layer

36

Wedge element

38

Power connector

40

Power connector housing

42

Control plug receptacle

44

Control plug housing

46

Control plug

50

Control device

52

Control housing

54

Circuit board

56

Circuit breaker

58

Cooling surface

60

Exterior surface

62

Cross wall

64

Supply branch

66

Derivative branch

68

Cross channel

69

Flow path

70

Flow channel

72

outer deflection section

74

inner deflection section

76

Exterior wall

78

Recess

80

Floor

82

Ribs

84

Thermocouple holder

86

Flow guide wall

L

Central longitudinal axis

R

rectangular base

α

angle

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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 accepts no liability for any errors or omissions.

Cited patent literature

• EP1872986A1 [0002]
• EP 2797381 A1 [0002]
• EP 2884817 A1 [0004]
• DE 102020201571 A1 [0024]

Claims (7)

Electric heating device with a housing (2) which has a heating chamber (8) for passing a medium to be heated through the housing (2) and a connection chamber (14) for the electrical connection of at least one PTC heating device (24), wherein the PTC heating device (24) has at least one PTC element (28) and conductor tracks (30) which are electrically connected to the PTC element (28) for supplying current to the PTC element (28) with different polarity, and wherein the PTC heating device (24) is introduced into a heating device housing (20) which is open at its upper end and towards the connection chamber (14) and closed at its lower end and towards the heating chamber (8) and protrudes from the partition wall (12) in the direction of the heating chamber (8), characterized in that in the heating chamber (8) there is a supply branch (64) and a discharge branch (66) for the medium to be heated is formed, and are connected to one another via a transverse channel (62) which is provided opposite an inlet (16) of the supply branch (64) or an outlet (18) and the discharge branch (66), and wherein the supply branch (64) and the discharge branch (66) each form a meandering flow path (69) which has flow channels (70) extending between main side surfaces of the heating device housings (20), wherein the flow channels (70) of the supply branch (64) and the discharge branch (66) are each aligned obliquely relative to a substantially rectangular base area (R) of the housing (2) and in a herringbone pattern relative to one another, and wherein the flow channel (70.6) of the supply branch (64) and the discharge branch (66) arranged furthest from the inlet (16) or the outlet (18) is in the Cross channel (62) flows into it. Electric heating device according to Claim 1 characterized by a control housing (52) which surrounds a control device (50) comprising at least one circuit breaker (56) and is connected to the upper housing part (4), wherein the transverse channel (68) runs parallel to an outer wall (76) of the housing (2) and the circuit breaker (56) is bonded to the transverse channel (68) in a heat-conducting manner. Electric heating device according to Claim 1 or 2 , characterized in that the PTC element (28) has a rectangular base with a height (H) and a width (B), wherein the width (B) is smaller than the height (H) and that the width (B) extends along the direction connecting the lower end of the heater housing (20) to its upper end. Electric heating device according to at least one of the preceding claims, characterized in that the flow channels (70) of the supply branch (64) and the flow channels (70) of the discharge branch (66) are each provided parallel to one another and that the flow channel (70.6) of the supply branch (64) or of the discharge branch (66) arranged furthest from the inlet (16) or the outlet (18) encloses an angle (α) of 30° to 40° with the transverse channel (68). Electric heating device according to Claim 4 , characterized in that a triangular recess (76) opening towards the connection chamber is provided between the flow channels (70.6) of the supply branch (64) and the discharge branch (66) arranged furthest from the inlet (16) or the outlet (18) and the transverse channel (68). Electric heating device according to at least one of the preceding claims, characterized in that adjacent heating device housings have a distance of between 4 mm and 8 mm at their lower end and that the distance between the adjacent heating device housings (20) in the region of the partition wall (12) is between 2 and 6. Electric heating device according to at least one of the preceding Claims 2 until 5 , characterized in that the control housing (52) is welded to the housing upper part (4).

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