ELECTRIC FLUID HEATER

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of, and claims priority to, International Application Number PCT/EP2023/066671, filed Jun. 20, 2023, entitled ELECTRIC FLUID HEATER, which claims priority to German Application Number 10 2022 128 258.9, filed Oct. 25, 2022, and German Application Number 10 2022 115 736.9, filed Jun. 24, 2022, the entire disclosures of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electric heater for fluids, specifically for liquids and more specifically for coolants.

BACKGROUND

In WO 2011/054970 A2, an electric fluid heater of this type is disclosed. Each of three tubular heating elements forms a plurality of coils along a joint coil axis, the coils being arranged in a housing through which the fluid flows. Thus, the fluid flows around the coils while being heated.

An embodiment with a fluid conduct is shown in which a tubular member is arranged in the housing inside the coils along the coil axis. The fluid to be heated first flows inside the tubular member along the coil axis, from there through passage recesses radially outwardly to the outer circumference of the tubular member and finally flows back at the outer circumference of the tubular member. Since the coils of the tubular heating elements are arranged at the outer circumference of the tubular member, also there the fluid for the first time contacts the coils. At the circumference of the tubular member, outer strips are provided which extend along the tubular member and against which the tubular heating elements can bear. The outer strips can also take over a flow conducting function.

SUMMARY

A drawback of those electric fluid heaters is the transverse flow and the resulting limited performance density.

It is the object of the present disclosure to increase the performance density of electric fluid heaters of this type.

The object is achieved by an electric fluid heater comprising the features of an independent claim. Further advantageous configurations are the subject matter of the dependent claims.

The claimed electric fluid heater has a fluid-conducting housing in which at least one tubular heating element each with a plurality of coils is arranged. An inner region extending preferably along a coil axis is delimited by the coils. According to the disclosure, a displacer body arrangement having at least one displacer body at the outer circumference of which a flow region for the fluid is formed is provided in the inner region. In the flow region, also the coils are arranged. An interior space arrangement having at least one interior space of the displacer body arrangement is largely or completely separated from the flow region of the fluid in a fluid-tight manner. Largely separated means, for example, that at least 90%, preferably 95% of the interior space arrangement are surrounded by fluid-tight walls. A transverse flow (i.e., transversely with respect to the longitudinal axis of the coil) is largely or completely avoided. The active principle according to the disclosure thus is a minimization of the dead volume and a reduction of the flow cross-section. This results in an increase of the flow speed. The performance density of the fluid heater according to the disclosure is thus increased, consequently an increase of the heat transfer to the fluid is possible and/or a reduction of the available space and the device-related effort, resp., is possible. Thus, in a variant of the disclosure, the number of the tubular heating elements known from prior art is reduced.

In terms of manufacture, it is simple when the coils result in a circular-cylindrical shape, thus also allowing the inner region to take a circular-cylindrical shape.

In terms of device, it is simple when the displacer body arrangement bears against the coils.

When the housing has two opposite housing end walls which are preferably formed on a trough-like housing part, the displacer body arrangement extends over at least 90%, preferably over at least 95% of the distance of the two housing end walls to largely prevent the transverse flow. The displacer body arrangement can also bear against the two housing end walls.

In a first configuration variant of the disclosure simple in terms of manufacture, the (preferably exactly one) displacer body is a tube. The tube may be cylindrical, that is, it may have a uniform cross-section over its length, or it may have a reduction of diameter (constriction). If more than two tubular heating elements are provided, also more than one diameter reduction (constriction) can be provided.

If each of the end sections of the tube has a distance from the two opposite housing end walls, then two end-face lids each facing one of the two housing end walls are required to form the largely or completely fluid-tight wall according to the disclosure. As an alternative, an inner partition may also be present inside the tube. If more than two tubular heating elements are provided, even more than one inner partition can be provided.

In a second configuration variant of the disclosure, two or more displacer bodies are provided. The displacer bodies can be substantially equal in terms of simple manufacture, and can be arranged mirror-inverted to each other, for example, in the case of two displacer bodies.

In an embodiment of the second configuration variant, the displacer bodies are respective cups each of which has a bottom.

In the case of two cups, the two bottoms can face each other. In this case, the interior space arrangement has two separate interior spaces. Deviating therefrom, each bottom can also be arranged adjacent to a respective housing end wall. In this case, the two cups can be fastened to each other at their respective peripheral edges and/or can be nested. In this case, the two cups jointly form a tubular displacer body arrangement with the interior space arrangement in this case having exactly one interior space.

For particularly preferred developments, the at least one displacer body (e.g., a tube or cup) includes plural longitudinal ribs distributed over the cover. In the case of the cylindrical tube or in the case of the cup, the longitudinal ribs can extend over the entire length of the displacer body, e.g., when they form contact sections with all coils of the tubular heating elements, or when they form flow elements of maximum length. As an alternative, the longitudinal ribs may extend only over a partial length of the displacer body, for example when they form only contact sections for several coils of the tubular heating element.

There may also be provided exactly two opposite longitudinal ribs which, in a concrete embodiment, are shaped (are made uniform) so that an oval cross-section of the tube results.

In order to enable or improve the heat transfer to the fluid even from the inner faces of the coils, it is important that inner flow regions, for example in the form of longitudinal channels, through which the fluid can flow between the coils and the cover of the respective displacer body and can absorb heat are retained between the longitudinal ribs. Those inner flow regions also help reduce the undesired heat input into the interior space.

According to a preferred first basic principle of the disclosure, the interior space of the displacer body arrangement is a rest chamber into which the fluid penetrates. For this purpose, the displacer body arrangement has at least one opening. At least one of the openings may be an oblong hole or a slit.

For example, when taking into operation or after dismantling the fluid heater, it is important that air can escape from the housing and, in the case of the first principle of the disclosure, also from the rest chamber for the fluid, that consequently the rest chamber, too, is completely vented through the at least one opening.

The oblong hole and/or the slit can be introduced into the cover of the displacer body (tube or cup) and/or can extend approximately in parallel to a coil axis.

In the case of the cup, at least one of the openings can also be arranged on the bottom of the cup. In the case of the tube, at least one of the openings can also be arranged at the end-face cover of the tube so that the fluid can penetrate into and fill the rest chamber from a region between the end-face lid and the adjacent housing end wall. Said openings may be formed by slits disposed between triangular or circle segment-shaped sections of the lid.

According to a second principle of the disclosure, the displacer body arrangement can also be constituted by a fluid-tight tube so that the interior space of the tube is delimited against the fluid. In this case, the tube must be connected in a fluid-tight manner to the two housing end walls, and at least one of the housing end walls has an opening so that the interior space is connected to the ambient air.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an electric fluid heater according to the disclosure in a perspective view from below;

FIG. 2 shows the fluid heater of FIG. 1 with a first variant of the displacer body arrangement in a longitudinal section;

FIG. 3 shows the fluid heater of FIG. 1 with a second variant of the displacer body arrangement in a longitudinal section;

FIG. 4 shows the fluid heater of FIG. 1 with a third variant of the displacer body arrangement in a longitudinal section;

FIG. 5 shows the electric fluid heater of FIG. 1 with a first embodiment of a two-part displacer body arrangement in a longitudinal section;

FIG. 6 shows the fluid heater of FIG. 5 in cross-section;

FIG. 7 shows one of the two displacer bodies of the FIGS. 5 and 6;

FIG. 8 shows a deviating embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 9 shows another embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 10 shows another embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 11 shows another embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 12 shows another embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 13 shows another embodiment of a one-part displacer body arrangement for use in the fluid heater of FIG. 1; and

FIG. 14 shows an embodiment of a two-part displacer body arrangement for use in the fluid heater of FIG. 1;

FIG. 15 shows another embodiment of a two-part displacer body arrangement for use in the fluid heater of FIG. 1; and

FIG. 16 shows another embodiment of a two-part displacer body arrangement for use in the fluid heater of FIG. 1.

DESCRIPTION

FIG. 1 illustrates an electric fluid heater 100 according to the disclosure in a perspective view from below. The fluid heater 100 has a housing in the fluid space of which the variants and embodiments of the displacer body arrangement according to the disclosure described with reference to the following FIGS. 2 to 16 can be realized.

The housing is composed of a trough-like housing part 6 and a substantially flat housing lid 10. In order to seal the fluid space delimited in the trough-like housing part 6 and the housing lid 10 in a fluid-tight manner, said two housing parts 6, 10 are joined cohesively, such as welded or soldered, to each other.

On a lower side of the trough-like housing part 6 (at the top in FIG. 1), two ports 8 for the fluid are formed spaced apart from each other, one port 8 thereof acting as an inlet and the other port 8 thereof acting as an outlet. Further, two mounting tabs 6a by which the fluid heater 100 can be mounted in a vehicle, for example, whose coolant is to be heated, are attached to the trough-like housing part 6.

The housing lid 10 projects on one side (on the right in FIG. 1) from the trough-like housing part 6. An electric high-voltage plug 10a for voltage supply of the fluid heater 100 is screwed to and a ground stud 10b is welded to said projection. Moreover, an electric low-voltage plug 10c through which the LIN communication with the fluid heater 100 is performed is screwed to the projection.

An electronic housing 11 which is mounted tightly to the housing lid 10 by means of crimped tabs is provided on an upper side of the housing lid 10 in the operating position remote from the fluid space. The crimped tabs are formed uniformly along the edge of the electronics housing 11 and encompass the edge of the housing lid 10 around the full circumference. An electronics space is delimited by the housing lid 10 and the electronics housing 11. In said electronics space, an electronic system, power busbars and circuit elements such as IGBT are installed (not visible).

On the basis of FIGS. 2 to 16, general variants and more concrete embodiments of the displacer body arrangement are described according to the first principle of the disclosure. The first principle excels by the fact that at least one rest chamber 25 into which the fluid penetrates is formed in the at least one interior space of the displacer body arrangement.

Each of the FIGS. 2 to 4 illustrates the housing of the fluid heater 100 of FIG. 1. The respective coils of two tubular heating elements 2 extend along a coil axis 4. Two end sections with electrical connections of the two tubular heating elements 2 extend in a sealed state through the housing lid 10 into the electronic space of the electronic housing 11 (shown in FIG. 1), only one end section with the electrical connection being shown in each of the FIGS. 2 to 4.

FIG. 2 illustrates the housing of the fluid heater 100 of FIG. 1 with a first variant of the displacer body arrangement. The latter consists of a tube 101; 201; 301; 401; 501; 601 that is radially spaced apart from the coils of the tubular heating elements 2 and at the end face is in preferably sealing contact with the two housing end walls 12 of the preferably trough-like housing part 6. For this purpose, the tube 101; 201; 301; 401; 501; 601 is clamped between the two housing end walls 12. Initial filling of the rest chamber 25 created in this way takes placed via radial openings 22 of the tube 101; 201; 301; 401; 501; 601. During operation of the fluid heater 100, a transverse flow is largely avoided.

FIG. 3 illustrates the housing of the fluid heater 100 of FIG. 1 with a second variant of the displacer body arrangement. The latter consists of a tube 101; 201; 301; 401; 501; 601 that is radially clamped at the coils of the tubular heating elements 2. The two end faces of the tube 101; 201; 301; 401; 501; 601 are spaced apart from the respective housing end walls 12 of the preferably trough-like housing part 6. Initial filling of the rest chamber 25 created in this way takes place via the two annular openings 23 in the region of the housing end walls 12. During operation of the fluid heater 100, low transverse flow is possible, namely along the two housing end walls 12 and from the one annular opening 23 through the rest chamber 25 to the other annular opening 23.

In a sub-variant of the second variant, an end-face lid 26 is provided on the tube 401; 501 or an inner partition is provided inside the tube 101; 201; 301; 601 at any position along the coil axis 4 (both are not shown in FIG. 3). An opening is provided in the lid 26 or in the partition.

FIG. 4 illustrates the housing of the fluid heater 100 of FIG. 1 with a third variant of the displacer body arrangement. The latter consists of two cups 1; 701; 801 which are clamped radially to the coils of the respective tubular heating element 2. The bottoms 16 of the two cups 1; 701; 801 are adjacent to each other and have a small distance from each other. The end-face edges of the two cups 1; 701; 801 are spaced apart from the respective housing end wall 12 of the preferably trough-like housing part 6. The initial filling of each of the two rest chambers 25 created in this way takes place via the annular opening 23 formed between the edge of the cup 1; 701; 801 and the adjacent housing end wall 12. During operation of the fluid heater 100, a low transverse flow is possible directly along the two housing end walls 12 and between the bottoms 16 of the cups 1; 701; 801.

In a sub-variant of the third variant (not shown in FIG. 4), the two cups 1; 701; 801 abut on each other to minimize the transverse flow. Accordingly, the two bottoms 16 or else, in a deviating manner, the two edges of the cups 1; 701 can abut on each other.

In the following, more concrete embodiments of the present disclosure shall be described on the basis of the associated figures.

FIG. 5 illustrates the electric fluid heater 100 according to the disclosure with a first embodiment of a displacer body arrangement formed of two independent displacer bodies each being designed as a cup 1.

Two tubular heating elements 2 each having a plurality of coils are provided resulting in a circular-cylindrical inner region which extends along a coil axis 4. Arrangements of this type are basically known from prior art so that further explanations are not necessary.

The two cups 1 of the displacer body arrangement are inserted in a respective tubular heating element 2. Also, two cups of different length can be inserted, the longer cup thereof being inserted in both tubular heating elements 2.

The fluid heater according to FIG. 5 includes the trough-like housing part 6 on the lower side of which along the coil axis 4 the two ports 8 for the fluid, preferably a coolant, are formed to be spaced apart from each other. On an upper side, the trough-like housing part 6 is tightly sealed by a housing lid 10. Two end sections with electrical connections of each of the two tubular heating elements 2 extend in a sealed state through the housing lid 10 to the outside, in FIG. 5 only one end section with the electrical connection being shown.

Each cup 1 has a cover and a bottom 16, wherein a rounded region is formed on the cover adjacent to the bottom 16. The two cups 1 are identical and are inserted mirror-inverted to each other into the inner region of the coils so that the two bottoms 16 face each other and have a small distance from each other. Each of the two edges of the cups 1 abuts on a housing end wall 12 of the trough-like housing part 6. In particular due to the distance of the two bottoms 16 from each other, the illustrated displacer body arrangement extends over at least 90%, preferably over at least 95% of the distance of the two housing end walls 12 along the coil axis 4.

FIG. 6 illustrates the fluid heater of FIG. 5 in a cross-section with the viewing direction A-A (according to FIG. 5) along the coil axis 4. This results in a view to the bottom 16 of a cup 1 and along the flow region 18, 20 for the fluid at the outer circumference of the cups 1. It can be seen that the cup 1 has four longitudinal ribs 17 distributed along the circumference of its cover by which the cup 1 is held, such as clamped, in the coils of the tubular heating element 2, and that four longitudinal channels are maintained between the four longitudinal ribs 17. Each of the longitudinal channels forms an inner flow region 18 for the fluid through which the fluid can flow between the coils and the cover of the cup 1 and can absorb heat. Said inner flow regions 18 also help reduce the undesired heat input into the interior space of the respective cup 1. An outer flow region 20 is formed at the outer circumference of the coils.

According to the first principle of the disclosure, the cup 1 has four openings in the form of through-holes 22, which are arranged in the rounded region of the cover.

FIG. 7 illustrates one of the two cups 1 of the FIGS. 5 and 6. Only one through-hole 22 out of the four through-holes 22 in the rounded region of the cover can be seen. It is further shown that the cover of the cup 1 has the four longitudinal ribs 17, wherein an opening in the form of a slit 24 is provided at one of the longitudinal ribs 17. The total of five openings allows the fluid to penetrate from the flow region 18, 20 into the interior space of the cup 1, resulting in 90%, preferably 95%, of the interior space being separated by fluid-tight walls from the flow region 18, 20, thus allowing the fluid to penetrate into the rest chamber 25 formed in this way.

FIG. 8 illustrates a deviating embodiment of a displacer body arrangement which is formed by a tube 101 provided for insertion into the inner region of the coils of the two tubular heating elements 2 of FIG. 2 or 3. The tube 101 takes a cylindrical shape having five longitudinal ribs 17 unevenly distributed along the circumference and a corresponding number of inner flow regions 18.

The upper longitudinal rib 17 in FIG. 8 is manufactured to have an overlap so that a slit 17 can be formed there. Further, the end-face edges of the tube 101 are not in fluid-tight contact with the two housing end walls 12 (shown in FIG. 1) so that there also openings are formed allowing the interior space to form a rest chamber for the fluid.

The tube 101 of FIG. 8 can be installed with the slit acting as an opening in the first variant (according to FIG. 2) and with the closed slit of the second variant (according to FIG. 3).

FIG. 9 illustrates another embodiment of a one-part displacer body arrangement formed by a tube 201 for insertion into the inner region of the coils of the tubular heating elements 2 of the FIGS. 2 and 3. The tube 201 takes a cylindrical shape with eight longitudinal ribs 17 distributed around the circumference and a corresponding number of inner flow regions 18.

An inner flow region 18, which is deeper than the other inner flow regions 18, is provided between two (upper in FIG. 9) longitudinal ribs 17.

Since the end-face edges of the tube 201 are not in fluid-tight contact with the two housing end walls 12 (shown in FIG. 1), openings 23 are formed there allowing the interior space to form a rest chamber 25 for the fluid. Thus, the tube 201 of the second variant (according to FIG. 3) is installed.

The tube 201 of FIG. 9 can also be installed in the first variant (according to FIG. 2) after introducing openings into the cover.

FIG. 10 illustrates another embodiment of a one-part displacer body arrangement formed by a tube 301 for insertion into the inner region of the coils of the tubular heating elements 2 of the FIGS. 2 and 3. Similarly to the embodiment of FIG. 9, the tube 301 takes a cylindrical shape with eight longitudinal ribs 17 evenly distributed around the circumference and a corresponding number of inner flow regions 18.

Since the end-face edges of the tube 301 are not in fluid-tight contact with the two (shown in FIG. 1) adjacent housing end walls 12, openings are formed there allowing the interior space to form a rest chamber 25 for the fluid. Thus, the tube 301 of the second variant (according to FIG. 3) is installed.

The tube 301 of FIG. 10 can also be installed in the first variant (according to FIG. 2) after introducing openings into the cover.

FIG. 11 illustrates a further embodiment of a one-part displacer body arrangement formed by a tube 401 for insertion into the inner region of the coils of the tubular heating elements 2 of the FIGS. 2 and 3. The tube 401 corresponds to the tube 101 of FIG. 8, the difference being that it has a lid 26 formed by triangular or circle segment-shaped cover sections at each of the end faces. Due to the two covers 26, the interior space acting as rest chamber is sealed as far as possible according to the disclosure even if the two end faces have a significant distance from the respective housing end walls 12 (shown in FIG. 1).

The fluid can penetrate into and fill the rest chamber from a region between the end-face cover 26 of the tube 401 and the adjacent housing end wall 12, as the cover 26 has slits 24. The latter are arranged between triangular and/or circle segment-shaped sections of the cover 26.

The tube 401 of FIG. 11 can be installed in the above-mentioned sub-variant of the second variant (according to FIG. 3).

FIG. 12 illustrates another embodiment of a displacer body arrangement formed by a largely circular-cylindrical tube 501 for insertion into the inner region of the coils of the tubular heating elements 2 of the FIGS. 2 and 3. At the outer circumference, for each of the two tubular heating elements 2 there is provided a group of four longitudinal ribs 17 distributed along the circumference which do not extend over the total length of the tube 501 and act as a contact section. Thus, the cross-section of the inner flow region 18 is maximized.

At each of the end faces, the tube 501 has a lid 26. Thus, the interior space acting as a rest chamber is sealed as far as possible according to the disclosure even if the two end faces of the tubes 501 have a significant distance from the respective housing end walls 12 (shown in FIG. 1).

The fluid is allowed to penetrate into the interior space of the tube 501 through a respective opening in the form of a through-hole 22 in the lid 26 and through respective slits 24 provided on both sides of the longitudinal ribs 17.

The tube 501 of FIG. 12 can be installed in the above-mentioned sub-variant of the second variant (according to FIG. 3).

FIG. 13 illustrates a further embodiment of a one-part displacer body arrangement formed by a tube 601 for insertion into the inner region of the coils of the tubular heating elements 2 of the FIGS. 2 and 3. Just as the tube 301 of FIG. 10, the tube 601 includes eight longitudinal ribs 17 evenly distributed around the circumference and a corresponding number of inner flow regions 18. Deviating from this, the tube 601 is not continuously cylindrical, but a constriction 28 is provided in the middle, thus allowing a respective cup-shaped section of the tube 601 to be inserted into each of the two (shown in FIGS. 2 and 3) tubular heating elements 2.

The tube 601 of FIG. 13 can be installed in the second variant (according to FIG. 3) and, after introducing openings into the cover, also in the first variant (according to FIG. 2).

For the embodiments shown in the FIGS. 8 to 10 and in FIG. 13, an inner partition (not shown) may be provided in the tube 101; 201; 301; 601. Particularly when the end-face edges at the ends of the tube 101; 201; 301; 601 do not abut on the housing end walls 12, the transverse flow can be prevented in this way.

FIG. 14 illustrates another embodiment of a two-part displacer body arrangement for use in the fluid heater 100 of FIG. 1. Two cups 1 are provided according to FIG. 7, the bottoms 16 of which abut on each other.

The displacer body arrangement of FIG. 14 including the two cups 1 is installed in the sub-variant of the third variant mentioned with reference to FIG. 4.

FIG. 15 illustrates an embodiment of a displacer body arrangement formed by two cups 701 for insertion into the inner region of the coils of the tubular heating elements 2 of FIG. 4. The two cups 701 are nested at their respective circumferential edges. Thus, the two cups 701 jointly form a tubular displacer body arrangement having exactly one interior space.

The bottoms 16 are arranged adjacent to a respective housing end wall 12 (shown in FIG. 4).

Each cup 701 has four longitudinal ribs 17 evenly distributed around the circumference and a corresponding number of inner flow regions 18.

The fluid is allowed to penetrate into the interior space of the tube-shaped displacer body arrangement by an opening in the form of a through-hole 22 in each of the two bottoms 16 and by a plurality of slits 24 provided between the longitudinal ribs 17 (in the flow regions 18).

At least one slit 24 is provided in a cover of the cup 701 spaced from the edge thereof, and at least one slit 24 extends to the respective edge of the cup 701, whereby two slits 24 formed on different cups 701 may result in a longer slit of the displacement body arrangement.

The displacer body arrangement of FIG. 15 including the two cups 701 is installed in the sub-variant of the third variant mentioned with reference to FIG. 4.

FIG. 16 illustrates another embodiment of a two-part displacement body arrangement for use in the fluid heater 100 of FIG. 1 including two cups 801 for insertion into the inner region of the coils of the tubular heating elements 2 of FIG. 4. The two cups 801 are identical and are inserted mirror-inverted to each other in the inner region of the respective coil.

The two cups 801 abut on each other at their respective circumferential edges. Consequently, the two cups 801 jointly form a tubular displacement body arrangement having exactly one interior space.

The bottoms 16 are arranged adjacent to and spaced apart from the respective housing end wall 12 (shown in FIG. 4).

Each cup 801 has a plurality of longitudinal ribs 17 evenly distributed around the circumference and a corresponding number of inner flow regions 18.

The fluid is allowed to penetrate into the interior space of the tube-shaped displacement body arrangement by an opening in the form of a through-hole 22 in each of the two bottoms 16.

The displacer body arrangement of FIG. 16 including the two cups 801 is installed in the sub-variant of the third variant mentioned with reference to FIG. 4.

Deviating from the fluid heater 100 shown in FIGS. 1 to 6 having two tubular heating elements 2, as a matter of course also a housing extended along the coil axis 4 can be provided in which-similarly to the prior art according to WO 2011/054970 A2—the coils of three tubular heating elements 2 are arranged. Thus, the performance density according to the disclosure would concretely be an increase in performance as compared to WO 2011/054970 A2.

As a matter of course, there can also be provided a housing extended along the coil axis 4 in which the coils of four of more tubular heating elements 2 are arranged.

Also, plural illustrated and/or mentioned fluid heaters 100 with their respective ports 8 can be connected in series so as to multiply the performance of the fluid heater arrangement formed in this way.

LIST OF REFERENCE NUMERALS

• • 1; 701; 801 cup
  • 2 tubular heating element
  • 4 coil axis
  • 6 trough-like housing part
  • 6a mounting tab
  • 8 port
  • 10 housing lid
  • 10a high-voltage plug
  • 10b ground stud
  • 10c low-voltage plug
  • 11 electronics housing
  • 12 housing end wall
  • 16 bottom
  • 17 longitudinal rib
  • 18 inner flow region
  • 20 outer flow region
  • 22 through-hole
  • 23 annular opening
  • 24 slit
  • 25 rest chamber
  • 26 lid
  • 28 constriction
  • 100 electric fluid heater
  • 101; 201; 301; 401; 501 cylindrical tube
  • 601 tube