EP2884198A1 - Electric heating device - Google Patents

Abstract

The present invention relates to an electric heating device, in particular for heating a tempering medium in a motor vehicle, comprising a housing (2) having pipe connections (10) for connecting pipes carrying the temperature control medium and enclosing a circulation chamber (14) into which heating fins (22), which are each provided with a U-shaped recess (24) which open to a uniform connection chamber (30) from the circulation chamber (14) by one in the region of the open ends of the U-shaped recesses ( 24) provided partition wall (12) is separated, wherein the heating ribs (22) are provided one behind the other and offset from each other and close to the wall, so that in the circulation chamber (14) a meandering flow channel (96) is formed. The present invention seeks to provide an electric heater of the type mentioned above, which allows a high heat output in a compact design, while also taking into account the fact that the pressure loss within the circulation chamber for the temperature control medium to be heated and accordingly the pump pressure and thus the System pressure within the circulation system must not be set too high above the atmospheric pressure. To solve this problem, it is proposed with the present invention that between a the circulation chamber (14) limiting the longitudinal side wall (16) of the housing (2) and the Heizrippe (12) opposite to the flow channel (96 a bypass flow permitting gap (92) is formed is.

Description

The present invention relates to an electric heater, in particular for heating liquid tempering in a motor vehicle. In particular, the present invention relates to a so-called "Coolant Heater", i. an electrical heating device for heating a liquid tempering medium, which heats technical units in a motor vehicle, i. Part of a Temperiermediumkreislaufs is usually includes heat exchange surfaces between the Temperiermediumkreislauf and at least one surface of a technical unit in addition to the electric heater. This technical unit may be the engine block of an internal combustion engine. However, the present invention has but in particular the use of the electric heater in the context of electromobility in view. Thus, in an installation situation of the electric heater according to the invention, in particular heat is exchanged with the surface of a battery, which is heated by means of the heat generated by the electric heater. Herein lies the main application of the electric heater according to the invention.

The present invention is based on the preamble features of claim 1 of an electric heater, which is derived from that of the Applicant EP 2 440 004 A1 is known. This electric heater has a housing with pipe connections, wherein a pipe connection is also formed in the heater according to the invention as an inlet and the other pipe connection as an outlet for the temperature control medium to be heated. The housing encloses a circulation chamber for the temperature control medium. Heating ribs protrude into this circulation chamber, each of which is provided with a U-shaped recess. These U-shaped recesses open to a uniform connection chamber, which is separated from the circulation chamber by a partition wall provided in the region of the open ends of the U-shaped recesses. This results in a secure separation between the temperature control medium leading the circulation chamber and the electrical connections and conductor tracks for receiving terminal chamber.

In the aforementioned prior art, the heating fins extend substantially in a YZ direction, each in the conventional structure of the prior art heater having a planar rectilinear partition wall orthogonal to that plane runs, in which the partition extends. The heating ribs are provided substantially in a plate shape in an X-axis direction orthogonal to the YZ plane one behind the other. They are offset in the prior art to each other and arranged alternately close to the wall. In the aforementioned prior art, the heating ribs each protrude from opposite longitudinal side walls in the circulation chamber, so that the flow in the circulation chamber at the opposite longitudinal side wall opposite the free end face of the heating rib is deflected. This results in a meandering flow channel within the circulation chamber, which ensures that the boundary surface formed by the heating ribs to the circulation chamber as completely as possible flows around the temperature control medium to be heated.

In this respect, the already discussed prior art justifies an improvement over earlier proposals, for example according to EP 1 921 896 A1 respectively. US 1,529,200 from 1925, in which the medium is passed only parallel to the heating ribs from a flow inlet to a flow outlet. In these solutions, the heating ribs do not extend transversely, but longitudinally to that flow direction, with which the flow is introduced into the housing. However, several ribs are provided side by side in this orientation, so that there is a parallel connection of a plurality of juxtaposed flow channels within the circulation chamber.

Although the formation of a meandering flow channel within the circulation chamber changes the heat exchange surface and also the flow conditions so that good heat transfer is possible, there is room for improvement.

The present invention seeks to provide an electric heater of the type mentioned above, which allows a high heat output in a compact design, while also taking into account the fact that the pressure loss within the circulation chamber for the temperature control medium to be heated and accordingly the pump pressure and thus the System pressure within the circulation system must not be set too high above the atmospheric pressure.

To solve this problem, an electric heater with the features of claim 1 is proposed by the present invention. After that is between a the circulation chamber delimiting longitudinal side wall of the housing and the heating fin opposite to the flow channel a bypass flow permitting gap formed.

Practical experiments have shown that, although the main flow in the circulation chamber has to be done alternately and accordingly frontally between the respective heating rib and the side wall of the housing where the respective heating rib allows a larger passage between itself and the housing than on the opposite side. For further explanation of the present invention, a Cartesian coordinate system is introduced to the electric heater. In this case, the plane in which the usually flat plate-shaped heating ribs extend, the Y-Z plane. The partition extends in an X-Y plane as well as a bottom of the circulation chamber. The partition wall as well as the floor are usually formed substantially flat. The longitudinal direction through the housing is given by the X-axis. Since, however, the heating ribs are provided for this purpose, the undisturbed passage of the flow is moved in the X direction by the heating ribs. This results in the meandering flow channel, which leads the main part of the flow of the medium to be heated. This flow channel results in a flow which moves essentially exclusively in the X-Y plane and in this case is guided around the heating ribs in a meandering manner.

However, the present invention allows some direct passage of a small portion of the flow. Thus, part of the main flow from the end face formed between the heating rib and the adjacent longitudinal side wall flow passage through the gap directly pass through the heating rib and reach the flow channel formed in the flow direction behind the corresponding heating fin. In this case, a plurality of heating fins may be provided in parallel succession in a YZ plane, which prevent the free flow passage through the housing in the X direction and impose an alternating flow path on the main flow. The gap thus allows a certain bypass flow on one side opposite to the main flow leading flow channel. This bypass flow usually corresponds to not more than 10% of the volume flow of the main flow at the opposite end face of the heating rib. In other words, only a small part of the flow through the circulation housing as a bypass flow in X-direction led. For this purpose, a gap is provided between a circulation chamber bounding the side wall of the housing and the heating rib, which allows this bypass flow. The gap is - as previously mentioned - provided opposite to the flow channel. In the development discussed here, the heating rib is provided on both sides of the side walls of the housing in the height direction wholly or partially spaced. Usually, a gap is created substantially over the entire height extent of the heating rib, which allows the bypass flow, as well as on the opposite side in comparison to a much larger gap for the main flow. Consequently, both end faces of the heating rib are flowed around. The present invention can for the most part be guided by the idea that only a single heating rib moves the free flow path in the X direction between opposite side walls delimiting the circulation chamber or the circulation compartment chamber. If a plurality of heating ribs are provided in alignment in the YZ plane one after the other, at least one gap allowing a bypass flow should be provided between adjacent heating ribs, so that heat can be dissipated to the heating medium to be heated between two adjacent heating ribs on the end sides. By the measures described above, the heat output of the electric heater is increased without increasing the space considerably. This results in an electric heater with high heat output and low space.

With a view to a good heat transfer to the medium to be heated and to avoid heat loss to the environment, the circulation chamber is preferably surrounded by a housing formed as a plastic part, in particular as a plastic injection molded housing shell, on which a housing cover made of metal is usually placed with the interposition of a sealing ring on which the heating ribs are usually formed in one piece. The housing cover is usually a die-cast part, in particular an aluminum die-cast part. The circulation chamber is limited in this preferred embodiment only on the one hand by the metallic cover and a housing shell forming the lower housing part, which forms the side walls as well as the bottom of the circulation chamber, both housing parts usually each one-piece functional surfaces form, through which the two housing parts directly or via a associated with these functional surfaces fastener are interconnected. The housing pan, ie the lower housing part, usually also integrally forms connecting pieces, which define the aforementioned pipe connections.

According to a preferred embodiment of the present invention, the Heizrippe and / or at least one longitudinal side wall of the housing which defines the circulation chamber, on a side opposite the flow channel side a web which extends between the Heizrippe and the inner wall. The web is accordingly essentially in extension of the heating rib and limits the gap. The web extends in the vertical, i. in the Z direction. The web does not necessarily have to be continuous in this direction from the partition to the bottom of the housing base. Rather, the bridge may also be provided only partially over this height extension. In addition, the bypass flow permitting gap may be partially limited by a web which is arranged on the side wall and preferably integrally formed by the lower housing part and partly by a web which is provided on the front side of the Heizrippe. The ridge is in the X direction, i. The width direction of the heating rib usually much thinner than the heating fin itself. The ratio of width of the heating rib to width of the web is preferably between 7: 1 to 20: 1, preferably between 10: 1 to 15: 1. Thus, the heating rib is only slightly thickened by the front end of the web and thus only slightly increases the heat conduction path from the interior of the heating rib to the outside. Also, a gentle use of the Heizrippe forming material takes place. The web can be machined end, to set exactly the desired gap. In view of the lowest possible flow resistance of the web has curved side walls. There are discontinuities avoided, so that the flow is passed through the circulation housing as possible without abrupt demolition edges. This proviso applies to all possible geometric design details on the one hand, the walls surrounding the circulation chamber including the compartment wall and the Heizrippengestaltung other.

According to a preferred development of the present invention, the lower housing part has a web extending from the floor and the heating rib has a web extending from the partition wall. These two webs limit the height of the floor to the partition usually formed continuously gap of the associated heating rib. However, the outgoing from the ground web ends in about the same height with the outgoing from the partition web preferably at mid-height Circulation chamber. Usually, a bypass flow is allowed between the two webs.

With a view to further improving the heat transfer conditions at the phase boundaries between the heating fin and the circulation chamber, according to a further preferred embodiment of the present invention, a bottom gap is formed between a free end of the heating fin and a bottom of the housing base, allowing a bottom bypass flow. Thus, the heating rib is preferably surrounded on all sides by the temperature control medium to be heated. With a view to the best possible heat dissipation from the surface of the heating rib, a transverse rib projecting from the bottom is provided between adjacent heating ribs, which rib extends parallel to the heating ribs. This transverse rib has a height-wise extension, which usually projects beyond the lower end of the heating rib. In other words, a heating rib protrudes between adjacent transverse ribs deeper than the highest point of the corresponding transverse ribs. The highest point is thus the height-wise distance between a usually flat bottom surface and the end-side distance of the transverse rib. The free end of the transverse rib usually runs parallel to the flat bottom surface and is also flat.

In the electric heating device, the walls of the housing surrounding the heating fins and the circulation chamber are preferably provided so that the flow channel defines a main flow direction of the medium between the pipe connections, which extends solely in the XY plane. In contrast to the prior art according to EP 2 440 004 A1 where the flow of medium between the inlet and outlet ports of the housing has been deflected out of the XY plane and, after this deflection, has been directed back to the inlet port in the XY plane, the present invention allows a meandering flow channel without a corresponding diversion. In this way, we created a flow device that allows for a relatively high pressure loss within the circulation chamber high heat dissipation with little space required for the electric heater. It goes without saying that the flow of the tempering initially distributed on entry into the circulation chamber and transversely to the XY plane, ie in the YZ plane, so that extending between a bottom of the housing and the partition gap filled with the medium as completely as possible. The main flow, ie the direction of movement however, in a plan view of the housing is limited solely to the XY plane. In other words, usually neither the bottom of the housing nor the partition has a flow outlet through which the main flow of the medium to be heated passes.

According to a further preferred development of the present invention, the housing forms at least two circulation chambers, which are separated from one another by a partition wall extending substantially in the X-Z plane. In the preferred embodiment of the present invention, in which a housing pan surrounds the circulation chamber, this compartment wall is usually formed in one piece on the injection-molded housing trough. The compartment wall subdivides the circulation chamber into at least two circulation sub-chambers extending parallel to one another, which are usually each provided with heating ribs. Depending on the desired heat input, however, it may be possible to equip one of the circulation sub-chambers with heating fins and to use the other sub-chamber merely as a return path for the heated tempering medium to one of the pipe connections. The sub-chambers are usually covered by a single housing cover, which integrally forms the heating ribs.

Also with regard to the last-mentioned development, it is preferable to provide the housing with extending in the X direction and the pipe connections predetermining connecting pieces, which are arranged on the same side wall of the housing. It is particularly important that the pipe connections are located on identical side wall of the housing base. They are usually formed in one piece by the lower housing part and are accordingly made of plastic with functional surfaces for fixing the tempering medium-carrying tubes to the electric heater.

According to a further preferred embodiment of the present invention, the compartment wall has a, preferably a single flow passage. This is recessed in a side wall opposite the at least one pipe connection in the compartment wall. According to the development, the flow outlet is adjacent to one of those walls which surrounds the circulation chamber. It has proved advantageous to provide ribs for generating turbulent flows which project from the walls surrounding the circulation chamber. So should also opposite the compartment wall at a near-wall arrangement of the flow passage a rib of protrude the corresponding side wall through which the flow separates from the associated side wall. In this preferred embodiment, the flow passage is therefore basically limited by the associated side wall, however, formed by the projecting from this side wall longitudinal rib slightly spaced from the associated side wall. The longitudinal rib usually passes through from the bottom of the housing base to the partition wall.

Figur 1

eine teilweise geschnittene perspektivische Seitendarstellung eines ersten Ausführungsbeispiels der vorliegenden Erfindung;

Figur 2

eine Explosionsdarstellung des in Figur 1 gezeigten ersten Ausführungsbeispiels der vorliegenden Erfindung;

Figur 3

eine in der X-Y-Ebene liegende Querschnittsansicht des ersten Ausführungsbeispiels von oben;

Figur 4

eine in der X-Z-Ebene liegende Längsschnittsansicht des ersten Ausführungsbeispiels;

Figur 5

eine in der Y-Z-Ebene liegende Querschnittsansicht des ersten Ausführungsbeispiels;

Figur 6

eine perspektivische Darstellung einer in der X-Y-Ebene liegenden Längsschnittansicht von unten, d.h. auf einen Gehäusedeckel;

Figur 7

eine perspektivische Seitenansicht auf ein Leistungsteil des Ausführungsbeispiels;

Figur 8

ein vergrößertes Detail in einer Längsschnittansicht in der X-Y-Ebene von Leistungsteil und Steuerteil;

Figur 9

eine perspektivische Draufsicht auf das offene Steuergehäuse vor dem Einbringen der Leiterplatte;

Figur 10

eine perspektivische Draufsicht nach Figur 9 mit darin montierten Leistungstransistoren und weiteren, der Steuerleiterplatte zugeordneten Elementen innerhalb des Steuergehäuses;

Figur 11

eine perspektivische Draufsicht gemäß den Figuren 9 und 10 nach Montage der Steuerleiterplatte; und

Figur 12

eine perspektivische Explosionsdarstellung des Gehäuses für ein anderes Ausführungsbeispiel der vorliegenden Erfindung.

Further details and advantages of the present invention will become apparent from the following description of two embodiments in conjunction with the drawings. In this show:

FIG. 1

a partially sectioned side perspective view of a first embodiment of the present invention;

FIG. 2

an exploded view of the in FIG. 1 shown first embodiment of the present invention;

FIG. 3

a lying in the XY plane cross-sectional view of the first embodiment from above;

FIG. 4

a lying in the XZ plane longitudinal sectional view of the first embodiment;

FIG. 5

a lying in the YZ plane cross-sectional view of the first embodiment;

FIG. 6

a perspective view of lying in the XY plane longitudinal sectional view from below, ie on a housing cover;

FIG. 7

a perspective side view of a power section of the embodiment;

FIG. 8

an enlarged detail in a longitudinal sectional view in the XY plane of power unit and control part;

FIG. 9

a perspective top view of the open control housing before introducing the circuit board;

FIG. 10

a perspective top view FIG. 9 with power transistors mounted therein and other elements associated with the control board within the control housing;

FIG. 11

a perspective top view according to the Figures 9 and 10 after mounting the control circuit board; and

FIG. 12

an exploded perspective view of the housing for another embodiment of the present invention.

The FIGS. 1 and 2 let recognize the essential components of the first embodiment. In this embodiment, it is an electric heater for controlling the temperature of a liquid tempering, in particular a tempering, which consists of equal parts of water and glycol. The electric heater has a sealed housing 2 with a formed as a plastic injection molded part trough-shaped housing base 4 and a housing lower part 4 sealingly covering the housing cover 6. From a first end face 8 of the lower housing part 4 protrude from two connecting pieces 10, which are integrally formed on the lower housing part 4 and in the present case form the pipe connections of the embodiment. The housing cover 6 defines a partition wall 12, which limits the upper side a circulation chamber 14, which is bounded by walls of the housing lower part 4, namely parallel to the connecting piece 10 extending longitudinal side walls 16 and perpendicular thereto extending end walls 18. By a in FIG. 1 recognizable compartment wall 20, the circulation chamber 14 is divided into two circulation sub-chambers 14a, 14b.

The housing cover 6 is not only provided as a cover for the circulation chamber 14 in the embodiment shown. Rather, the housing cover 6 also forms heating ribs 22, each with U-shaped recesses 24. The heating ribs 18 are integrally provided on the housing cover 6. The housing cover 6 is made as a die-cast part and made of aluminum. In addition to the heating ribs 22 protrude in extension of the connecting piece 10 two Meßfühlerdome 26 in the circulation chamber 14 inside. Each circulation sub-chamber 14a, 14b is assigned a respective sensor dome 26a, 26b.

The filling volume of the circulation chamber in electric fluid heaters of the type described below is between 450 ml and 200 ml, preferably between 400 ml and 220 ml and more preferably between 300 ml and 230 ml. This filling volume also includes the filling volume of the nozzle. Each nozzle itself has a filling volume of about 7 ml. The embodiment shown is usually integrated in a cooling water circuit in a vehicle having a volume of about 5 to 6 liters. In this cooling water circuit, at least one heat exchanger for the heating of air in the passenger compartment can be integrated. Additionally or alternatively, the cooling water circuit heat exchanger surfaces to technical components of an electric vehicle have to bring them to the required operating temperature at cold ambient temperatures. In particular, the electric heater at least also serves to heat a battery in a motor vehicle, which can be driven only electrically. The heater may also be switched so that it can be operated as a parking heater to heat the passenger compartment prior to commissioning of the vehicle to a comfortable temperature for the user. This is done by heating the liquid fluid, which is passed through a heat exchanger, which is illuminated by a blower integrated in the vehicle, so that air passed through the heat exchanger is heated at the heat exchanger and introduced into the passenger compartment. The heat output of the additional electric heater is between 5.0 and 8.0 kW, preferably between 7.0 and 8.0 kW. This heating power is realized with an embodiment in which in each individual U-shaped recess 24, a single electric heating element 28 is provided and a total of between 9 and 16, preferably between 10 and 14 U-shaped recesses in the circulation chamber 14 between 8 and 16, preferably between 10 and 14 heating ribs 22 protrude, each having an electric heating element 28. The surface power density is between 25 and 27 W / cm ² .

In each of the U-shaped recesses 24, an electric heating element 28 is used in the embodiment shown. This electric heating element 28 is in the EP 1 872 986 A1 respectively. EP 1 921 896 A1 designed manner described and in the example in EP 2 440 004 A1 respectively. EP 1 931 176 A1 recorded manner in the U-shaped recess 24 and there applied heat conductively to the associated heating rib 22. In this respect, the disclosure of the aforementioned disclosure of the present applicant is incorporated by reference into the disclosure of the present application. All details of the electrical heating elements 28 described therein are essential to the invention for the embodiment discussed here. This applies not only to the arrangement of the heating elements 28 in the recesses 24 and the heat-conductive contact between the heating elements 28 and the inner surfaces of the heating ribs 22, but also for the below explained in more detail electrical connection of the individual heating elements 28 via their contact tongues 28.1, the form electrical connections of the heating elements 28, in a marked with reference numeral 30 terminal chamber.

In the FIGS. 1 and 2 It can also be seen that the housing cover 6 rests against the lower housing part 4 with the interposition of a sealing element 32. The sealing element 32 is inserted in a groove 34 recessed on the housing lower part 4 and held there. The sealing element 32 projects beyond an end face of the lower housing part 4, on which the housing cover 6 is placed.

In the exploded view to FIG. 2 2, a measuring line section 36 is shown above the electrical heating elements 28 designed as PTC heating elements and is electrically connected to the signal outputs of measuring sensors 37 incorporated in the measuring probe domes 26. The other end of the Meßleitungsstranges 36 is exposed with its Meßleitungsanschlusszungen 38.

Below that is in FIG. 2 a terminal board 40 is shown, which is formed from a plastic plate 42 and a punched and electrical interconnects forming sheet metal blank 44. This terminal board 40 is shown in detail in FIG EP 2 505 931 A1 described, to the disclosure of which reference is made and thereby incorporated in the disclosure of the present application. This embodiment of the terminal board 40 may be essential to the invention for the realization of the invention described herein. The housing cover 6 has a partition wall 12 projecting peripheral edge 45, which surrounds a connection housing 46 for the electrical connection of the contact tongues 28.1 of the heating elements 28 to the terminal board 40. Between the edge 45 and integrally formed on the housing cover 6 webs 49 a semi-circumferential receiving space 51 is provided for the Meßleitungsstrang 36.

At the top is in FIG. 2 a connection housing cover 48 is shown, which consists of a stamped sheet metal plate 50 and a molded edge TPE seal 52 which engages in a recessed on the housing cover 6 sealing groove 54 to Seal the connection housing 46 from the environment. The lid 48 rests on the webs 49.

The components described above are used for mounting the electric heater in the longitudinal direction of the U-shaped recesses, i. Nested in the Z direction, on the one hand form the circulation chamber 14 sealed and on the other hand to use the PTC heating elements 28 in the U-shaped recesses 24 and electrically connect via their upwardly projecting freely projecting contact tongues 28.1 to the terminal board 40. In this joining direction, the thermocouples are also inserted into the sensor domes 26a, 26b and then electrically connected via the measuring line strand 36. Finally, this arrangement is covered by the terminal housing cover 48 and sealed so that the provided in the connection chamber 30 electrical conductor paths are sealed on the upper side from the environment. For this purpose, the plastic plate 42 protruding from its top spacer 56 which are integrally formed on the plastic plate 42 and over which the terminal housing cover 48 is held securely spaced from the electrical traces of the terminal board 40. Also, when the terminal housing cover 48 is pressed in, the terminal board 40 placed on a plastic frame 58 of the PTC heating elements 28 is held down by the spacers 56 and held in the installed position.

That in the FIGS. 1 and 2 embodiment shown further comprises a metallic control housing 60, in which a, inter alia, with semiconductor power switches 62 equipped control circuit board 64 is disposed, as well as a marked with reference numeral 66, injection-molded frame assembly 66 made of plastic, will be discussed in more detail below. Fixing screws 68 are used to attach the metallic control housing 60 to the likewise metallic housing cover 6. Plug fastening screws 70 are used to attach a control plug 72 on the outside of the control housing 60 (see. Fig. 9 . 11 ). With reference numeral 74 marked mounting pins are used to attach the control circuit board 64 in the control housing 60 (see. Fig. 11 ).

Reference numeral 76 denotes a ground connection pin which projects beyond the control housing 60 in the direction of the housing 2 (cf. FIG. 1 ). Reference numeral 78 denotes a control housing cover, which is designed like the connection housing cover 48.

A designated with reference numeral 80 power connector is attached via two locking pins 82 on the outside of the control housing 60. Finally, two elongated rods 84 are in FIG. 2 represented that lock as a form-locking elements opposing abutment surfaces of the lower housing part 4 and housing cover 6 against each other. Housing part 4 and housing cover 6 for this purpose have alternating cross-section attachment portions 86, 88, will be discussed below.

Like the sectional view in the XY plane after FIG. 3 illustrates, the individual heating ribs 22 of each individual circulation sub-chamber 14a, 14b in the X direction, ie, the longitudinal direction of the housing 2 are provided one behind the other. In each of the sub-chambers 14a, 14b is located in the X direction in each case a single heating rib 22 behind a single other heating rib 22. The heating ribs 22, however, provided alternately offset in the Y direction. This results in a meandering flow channel designated by reference numeral 90 within the circulation subchambers 14a, 14b, which defines a main flow (arrow H). However, the individual heating ribs 22 with their side opposite the flow channel 90 for the main flow H do not directly adjoin the longitudinal side wall 16 or the compartment wall 20 delimiting the circulation sub-chamber 14a or 14b. Rather, there is a gap 92, which allows a bypass flow marked B. As FIG. 3 can be seen, the gap 92 has a gap width corresponding to 5% to 20%, preferably 7% to 15% of the clear width between the opposite end face of the corresponding Heizrippe 22 and the longitudinal side wall 16 and the compartment wall 20. The gap width is preferably between 3 , 0 and 0.5 mm, more preferably between 2.0 and 0.7 mm. Most preferably, the gap has a width of between 1.5 and 0.8 mm. Setting the respective gap width in relation to the width B of the flow channel 90 results in ratios of width to gap width of between 4 and 15, preferably between 6 and 10.

In the exemplary embodiment shown, the partition wall 20 in the flow channel 90 has longitudinal ribs 94 upstream of the gap in the flow direction, by means of which separation of the main flow H from the otherwise flat and straight compartment wall 20 is relieved. Like the others FIG. 3 can be seen, the heating ribs 22 are slightly towards its front end towards the central region thickened. In the central region, the heating ribs 22 form on the inside flat contact surfaces 22. 1 for the electrical heating elements 28.

In extension of the compartment wall 20 and opposite to the connecting piece 10, a flow passage 96 is provided, which allows passage of the flow between the two circulation sub-chambers 14a, 14b. However, the main flow H remains in the XY representation plane FIG. 3 , The flow passage 96 is close to the wall by a longitudinal rib 98 which protrudes from the otherwise flat end wall 18 and is formed in the height direction of a bottom 100 to the partition wall 12 continuously.

In FIG. 3 and in particular the FIGS. 4 and 5 Furthermore, transverse ribs 102 projecting from the bottom 100 can be seen, which are provided between adjacent heating ribs 22. The transverse ribs 102 project beyond the free lower end of the heating ribs 22 (cf. FIG. 4 ) and also provide for flow separation from the floor 100. As further out FIG. 4 it can be seen that the free end 22.2 of the heating rib 22 only a small distance of 8 mm to 10 mm to the bottom 100, so that there is a bottom gap 103, which allows a bottom bypass flow BB.

In the figures described above and in FIG. 6 Cartesian coordinates X, Y and Z are entered. It follows from the previous description that the main flow H extends solely in the XY plane (cf. Fig. 3 ). The connecting pieces 10 are at a height in the Z direction, see. Fig. 2 , A deflection of the main flow H around the respective heating ribs 22 takes place solely around deflecting edges which extend essentially in the Z direction, such as the end faces of the heating ribs 22 or the wall parts of the housing lower part 4 bounding the flow passage 96. Specifically, the main flow H does not transferred between the two circulation sub-chambers 14a, 14b in another, separate from the previous flow level in the Z direction flow plane.

Details of the bypass current B limiting walls of the housing base 4 and the housing cover 6 are described below, in particular the Figures 3 . 5 and 6 can be seen. In this case, the heating ribs 22 protrude from the basically flat and straight continuously extending partition wall 12. In the Y direction adjacent and different circulation sub-chambers 14a, 14b associated heating ribs 22 are connected via a partition wall 12 superior connecting web 104 with each other, for which the partition wall 20 forms a corresponding thereto formed connecting web receptacle 106. A complete seal between the circulation sub-chambers 14a, 14b is not necessary. However, it is desired to substantially avoid a leakage flow by appropriate design of the compartment wall 20 and to pass the main flow between the circulation sub-chambers 14a, 14b as completely as possible through the flow passage 96.

The heating ribs 22 have a heating rib web 108 delimiting the gap 92, which extends approximately over 3/5 of a height HZ of the circulation chamber (cf. FIG. 5 ). In continuation of this Heizrippenstege 108 a projecting from the bottom 100 and integrally formed by the lower housing part 4 housing web 110 is provided. Between the respective webs 108, 110 and the opposite mating surface of the heating rib 22 and the lower housing part 6, the aforementioned gap 92 is formed. The webs 108, 110 terminate in approximately the same height, but in the height direction with a small distance, so that between the webs 108, 110, a bypass flow B enabling gap 92 is provided.

Hereinafter, the particular configuration of the terminal board 40 and the joining of power unit L and control part S are explained in more detail. The power unit L consists of the FIG. 2 , Left superimposed components, namely the lower housing part 4, the sealing element 32, the housing cover 6, the electrical heating elements 28 housed therein, the Meßleitungsstrang 36 and the terminal board 40 and this covering terminal housing cover 48. The power unit L also includes the joining of housing base The control part S essentially comprises the control housing 60, the control circuit board 64 received therein, the frame arrangement 66 provided between the control housing 60 and the control circuit board 64, and finally the metal control housing cover 78. It should be noted that the respective covers 48 and 78 are made of stamped sheet metal and by punching and bending thereon integrally formed metallic claws 112 which cooperate with the associated walls of the housing cover 6 and the control housing 60 to a circumferential shield z form u, on the one hand encloses the terminal board 40 and on the other hand, the control circuit board 64th

When manufacturing the power part L of the housing cover 6 is placed under compression of the sealing element 32 on the lower housing part 4. The alternating, interlocking attachment portions 86, 88 slide past each other. Opposing abutment surfaces of these attachment portions 86, 88 are so far apart from each other by the external pressure, that the rods 84 from the in FIG. 2 , Position shown on the right in the X direction between the contact surfaces of the mounting portions 86, 88 can be brought. Thereafter, the external force is relieved. The elastically compressed sealing element 32 pushes the two parts 4, 6 apart in the Z direction. The opposing abutment surfaces of the attachment portions 86, 88 are finally applied to the rods 84, which prevent further movement of the parts 4, 6. Thereafter, the lower housing part 4 and the housing cover 6 are positively connected with each other. This results in a simple positive connection of the essential components of the power section L.

This push the rods 84 in FIG. 2 , left against formed by the lower housing part 4 stop surfaces. Thus, the rods 84 are fixed on one side in their longitudinal direction in the X direction. After application of the control housing 6, 84 forms the mating surfaces for the rods 84 in the axial extension of the rods, the rods 84 are positively secured in the other direction and thus in the X direction between two opposing attacks, so that they remain in place.

How the particular FIG. 8 can be seen, the terminal board 40 dominates both with their formed by punching the sheet metal plate 44 terminal board terminal lugs 114 as well as by an end portion 116 of the plastic plate 42, the power part L, ie the housing 2. For this purpose, the housing cover 6 in the edge 45, a terminal board Through-opening 117 (see. Fig. 4 ). On this exposed end of the terminal board 40, the control part L is pushed after to be described below pre-assembly of the recorded in the control housing 60 components. Of the FIG. 10 Furthermore, an embodiment can be seen in which the end portion 116 of the plastic plate 42 is also still surmounted by positioning pins 119 which project beyond the connection lugs 114.

As in particular from FIG. 9 As can be seen, the control housing 60 has a terminal board connection opening 118 whose dimension is exactly adapted to the contour of the end portion 116 of the terminal board 40, so that a sliding guide results. This also includes a slightly thickened region of the plastic plate 42, which - in FIG. 9 , shown on the left - has Meßzungenaufnahmen 120 for the previously mentioned Meßleitungsanschlusszungen 38. In these Meßzungenaufnahmen 120 Meßleitungsanschlusszungen 38 are kept positioned so that their free ends as well as the terminal board terminal lugs 114 project beyond the plastic plate 42.

FIG. 9 also illustrates the previously mentioned frame assembly 66. It is an assembly of four frames 124, which is made as an injection-molded unit made of silicone and connected to the control housing via connectors. The control housing 60 has projections 122 each surrounded by a single frame 124 of the frame assembly 66. Integrally formed on the frame assembly 66 retaining webs 126 project inwardly from the frame 124 from. This holding webs 126 are on the front side of the respective projections 122 formed flat contact surfaces 128.

The frames 124 surround the power transistors 62 in a manner to be described below. The control circuit board 64 is first inserted into the control housing 60 after being equipped with all electronic and electrical components and controls. The control circuit board 64 is then attached to the mounting posts 74 opposite the control housing 60. The thus preassembled unit of control housing 60, frame assembly 66 and control circuit board 64 is then slid onto the power unit in a direction transverse to the direction of insertion of the heating elements 28 into the U-shaped receptacles 24. Here, first, the positioning pins 119 hit the plane of the control circuit board 64. Corresponding to the positioning pins 119 are at predetermined locations and in FIG. 11 provided with reference numeral 129 positioning pin recordings. In these recordings 129 of the control circuit board 64, the positioning pins 119 engage with little play in the transverse direction. In the embodiment shown, these positioning pin receptacles 129 are formed as longitudinal slots and accordingly only exactly present a positioning in a direction transversely thereto. Of course, the corresponding openings may also be formed circular and according to a kind of fit for the positioning pins 119, to specify the relative position between the terminal board 40 and the control circuit board 64 unambiguously. In the embodiment shown is However, the pre-positioning is significantly influenced by the fit between the dimensions of the plastic plate 42 and the dimension of the connection opening 118, so that a fit in the present case between the positioning pin receptacle 129 and the associated positioning pin 119 must specify the position exactly in the Y direction only. Upon further pushing on the control part S on the power unit L, the exposed Meßleitungsanschlusszungen 38 engage in recessed on the control PCB 64 holes 64.1, as is apparent from FIG. 11 is apparent. Furthermore, the terminal board terminal lugs 114 pass through holes 64.2 in the control board 64. This situation is also in FIG. 11 shown. In the corresponding holes 64.1; 64.2 of the control circuit board 64 are female contact elements 64.3 introduced, which are mechanically connected to the control circuit board 64 and thereby electrically connected to tracks of the control circuit board 64, as shown in the EP 2 236 330 A1 the present applicant are described. The disclosure of this earlier application is incorporated by reference into the disclosure of the present application. (The female contact elements 64.3 are in FIG. 10 without the associated control circuit board 64 shown for reasons of illustration isolated.) Thus, the control circuit board 64 is electrically connected to the terminal board 40 after pushing the preassembled control housing 60 in the X direction against the power unit L. Usually before the sliding of the control housing 60, the control part S is completely pre-assembled, ie the control housing 60 is closed to the control housing cover 78.

Next, the particular configuration of the control case 60 and the assembly of the semiconductor power switch 62 realized therein will be described.

The control housing 60 formed from metal in the present case has four rectangular contact surfaces 128, which are each formed by the housing projections 122 projecting from a basically planar control housing bottom 130 in the direction of the control circuit board 64. Laterally adjacent to the upper three housing projections 122, each of the control housing bottom 130 projecting mounting pins are integrally formed by the control housing 60 forming material, which are provided with a bore into which mounting pins of the frame assembly 66 engage and secured there. A corresponding embodiment results to the left of the lower housing projection 122 as shown by FIG. 9 , As further shown in this figure, each frame 124 of the frame assembly 66 has four retaining webs 126 located on top of the abutment surface 128 and protrude from a circumferentially surrounding the bearing surface 128 edge inwards. The frames 124 enclose the housing projection 128 at a certain distance. The frame 124 also have - as in particular from FIG. 8 seen - in the direction of the control housing bottom 130 projecting lower edge 124.1, which projects beyond the holding web 126 and at least partially surrounds a peripheral surface 132 of the housing projection 122, and projecting in the opposite direction upper edge 124.2, between the circuit breaker 62 and the frame 124 defines a gap 133. The arrangement of the lower edge 124.1 at a distance from the housing projection 122 results between the frame 124 and this housing projection 122, a circumferential, ie annular adhesive gap 134th

The FIG. 8 shows the situation after installation of the first preassembled and introduced as a structural unit in the control housing 60 control circuit board 64. Here are the semiconductor power transistors 62 frontally against the holding webs 126, which accordingly a defined distance between the semiconductor power transistors 62 and the contact surface 128th pretend. Any gap between the abutment surface 128 and the semiconductor power transistor 62 is filled by a silicone adhesive 136, which in the present case represents an exemplary embodiment of the adhesive mass. The silicone adhesive 136 has good thermal conductivity, but is electrically insulating. The upper edge 124.2 encloses a mounting space 137 for the semiconductor power switch 62, which is completely filled by the introduction of the same in the frame 124 of the silicone adhesive 136. As in particular from FIG. 8 it can be seen, the silicone adhesive 136 even towers over the end of the upper edge 124.2 projecting toward the control circuit board 64

For assembly, the silicone adhesive 136 is first applied to the contact surface 128. Thereafter, the preassembled control circuit board 64 is inserted into the control housing 60. At the end of this insertion movement, the front face of the respective semiconductor power transistors 62 strikes the silicon adhesive 136. This is displaced in the plane as the insertion movement of the control circuit board 64 progresses and is evenly distributed on the contact surface 128. However, there is so much silicone adhesive 136 on each one the abutment surfaces 126 applied, that the contact surface 128 respectively surrounded by the frame 124 not only completely wets in the circumferential direction with the silicone adhesive 136 becomes. Rather, by displacing the volume between the contact surface 128 and the semiconductor power transistor 62 toward both the control board 64 and the glue gap 134, the silicone adhesive 136 increases. Thus, there is good sealing of the semiconductor power transistor 62. Also, the frame 124 relatively large area with the silicone adhesive 136 and thus adhesion-promoting and firmly connected to the control housing 60. Furthermore, due to its good thermal conductivity, the silicone adhesive 136 provides a good dissipation of the power loss generated by the semiconductor power transistor 62. On the side opposite the semiconductor power transistor 62 side, the control housing 60 forms integrally formed thereon cooling fins 138. These are provided at least exactly opposite to the respective semiconductor power transistors 62.

The FIG. 12 shows a modification to the previously discussed embodiment. This may be equipped with the same components as described above to form the power unit L. Also, the control part S may be formed in an identical manner and flanged laterally to the line part L. This in FIG. 12 shown embodiment of the housing 2 differs only by the power unit L after the previous figures, that the housing cover 4 only has a number of heating ribs 22a provided in the direction one behind the other. These are provided in extension of the inlet nozzle 10. In the other circulation sub-chamber 14b there are no heating ribs 22. This circulation sub-chamber 14b serves only for the return of the fluid to be heated. The circulation sub-chamber 14a is accordingly constructed as in the previously discussed embodiment; the circulation sub-chamber 14b but serves only the flow return to the outlet port 10, left in Fig. 12 , So has the embodiment after FIG. 12 also only about half of the heat output compared to that with reference to the FIGS. 1 to 11 discussed first embodiment.

LIST OF REFERENCE NUMBERS

2

casing

4

Housing bottom

6

housing cover

8th

first end face

10

spigot

12

partition wall

14

circulation chamber

14a, 14b

Circulation partial chamber

16

Longitudinal side wall

18

End wall

20

compartment wall

22

heating ridge

22.1

level contact surface of the heating rib

22.2

free end of the heating rib

24

U-shaped recesses

26a, 26b

Messfühlerdom

28

electric heating element

28.1

contact tongue

30

terminal chamber

32

sealing element

34

groove

36

Measuring wiring harness

37

probe

38

Measuring line connection tongue

40

Termination PC

42

Plastic plate

44

sheet metal blank

45

edge

46

connection housing

48

Connection cover

49

web

50

sheet metal plate

51

accommodation space

52

TPE gasket

54

sealing groove

56

spacer

58

Plastic frame

60

control housing

62

Semiconductor circuit breaker / power transistor

64

Control board

64.1

Bore for test lead terminal 38

64.2

Bore for connection board connection lug 114

64.3

female contact elements

66

frame assembly

68

fixing screw

70

Plug mounting screw

72

control plug

74

fastening pin

76

Mass pin

78

Timing cover

80

power connector

82

safety pin

84

pole

86

Attachment section of the housing base

88

Attachment section of the housing cover

90

flow channel

92

gap

94

Longitudinal rib (compartment wall 20)

96

Control passage

98

Longitudinal rib (flow passage 96)

100

ground

102

transverse rib

103

ground clearance

104

connecting web

106

Connecting web recording

108

Heizrippensteg

110

housing web

112

claw

114

Connection PCB connection flag

116

end

117

Connection PCB through-opening

118

Connection PCB connection opening

119

positioning

120

Measuring tongue receiving

122

housing projection

124

frame

124.1

lower edge

124.2

upper edge

126

holding web

128

contact surface

129

Positioning Recording

130

Control housing bottom

132

peripheral surface

133

gap

134

bonding gap

136

silicone adhesive

137

mounting space

138

cooling fin

B

bypass flow

BB

Floor bypass flow

H

mainstream

HZ

Height of the circulation chamber 14

L

power unit

S

control part

Claims (13)

Electric heating device, in particular for heating a tempering medium in a motor vehicle, having a housing (2) which has pipe connections (10) for connecting pipes carrying the temperature control medium and enclosing a circulation chamber (14) into which heating ribs (22) protrude, which are each provided with a U-shaped recess (24) which open to a uniform connection chamber (30) of the circulation chamber (14) by a provided in the region of the open ends of the U-shaped recesses (24) partition ( 12), wherein the heating ribs (22) are provided one behind the other and offset from one another and are arranged alternately close to the wall, so that a meandering flow channel (96) is formed in the circulation chamber (14),
characterized,
in that a gap (92) permitting a bypass flow is formed between a longitudinal side wall (16) of the housing (2) delimiting the circulation chamber (14) and the heating rib (12) opposite to the flow channel (96). Electric heating device according to claim 1, characterized in that the gap (92) is formed substantially completely extending between the partition wall (12) and a bottom (100) of the housing (2). Electric heating device according to claim 1 and 2, characterized in that the heating rib (22) and / or at least one the circulation chamber (14) of the housing (2) delimiting longitudinal side wall (16) on a flow channel (90) opposite side of a web (108 , 110) extending between the heating fin (22) and the longitudinal side wall (16). Electric heating device according to claim 3, characterized in that the lower housing part (4) has a web (110) projecting from the bottom (100), that the heating rib (22) has a web (108) projecting from the dividing wall (12) and the extending from the bottom (100) web (110) ends approximately at the same height with the outgoing from the partition wall (12) web (108). Electric heating device according to one of the preceding claims, characterized in that between a free end of the heating rib (22) and a bottom (100) of the housing lower part (4) has a bottom bypass flow (BB) permitting bottom gap (103) is formed. Electric heating device according to claim 5, characterized in that between adjacent heating ribs (22) from the bottom (100) projecting transverse rib (102) is provided, which extends parallel to the heating ribs (22). Electric heating device according to one of the preceding claims, characterized in that between adjacent heating ribs (22) one of at least one of the side walls (16, 18) and / or a circulation chamber (14) in at least two circulation sub-chambers (14a, 14b) dividing Abteilungswand (20) projecting longitudinal rib (94, 98) is provided. Electric heating device according to one of the preceding claims, characterized in that the gap (92) has a gap width (SW) of between 3.0 and 0.5 mm, preferably between 2.0 and 0.7 mm, particularly preferably between 1 , 5 and 0.8 mm. Electric heating device according to one of the preceding claims, characterized in that the heating ribs (22) extend substantially in a YZ plane and along an orthogonal thereto provided X-axis behind the other and offset from each other and arranged alternately close to the wall, so that in the Circulation chamber (14) of the meandering flow channel (96) is formed, and that the heating ribs (22) and the circulation chamber (14) surrounding walls (16, 18, 20) of the housing (2) are provided, the flow channel (19) a only in the XY plane extending main flow (H) of the medium between the pipe connections (10) pretends. Electric heating device according to one of the preceding claims, characterized in that the housing (2) extending in the X direction and the pipe connections (10) predetermining connecting piece (10) arranged on the same side wall (8) of the housing (2) are. Electric heating device according to one of the preceding claims, characterized in that the compartment wall (20) at one of the at least one pipe connection (10) opposite side adjacent to a circulation chamber (14) surrounding wall (16) provided flow passage (96) spared. Electric heating device according to one of the preceding claims, characterized in that the circulation chamber (14) is surrounded by a trough-shaped housing lower part (4) formed of plastic, of a heating ribs (22) integrally forming housing cover (6) made of a good heat conductive material is sealed. Electric heating device according to one of the preceding claims as far as dependent on claim 2 and 5, characterized in that the housing lower part (4) integrally forming the partition wall (12) and the pipe connections (10) predetermining connecting piece (10).

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