FLOW HEATER

A flow heater has a housing with a base and cover. A heating plate is adjacent the channel, and fins in the channel contact the heating plate. An inner wall of the housing has a slanted section and a printed circuit board is arranged between the inner wall and the cover. A channel for liquid has first and second wedge-shaped sections that taper from an end of the heating plate adjacent to the inlet and the outlet to an opposite end. A middle section connects the wedge-shaped sections. The flow direction in the middle section is crosswise to the flow direction in the wedge-shaped sections. A wedge-shaped space is defined by the inner wall and the cover part, and the wedge-shaped space tapers in a direction opposite the direction in which the first and second wedge-shaped channel sections taper. The printed circuit board is arranged in the wedge-shaped space.

RELATED APPLICATIONS

This application claims priority to EP 23 181 991.3, filed Jun. 28, 2023, the entire disclosure of which is hereby incorporated herein by reference.

BACKGROUND AND SUMMARY

This disclosure relates to a flow heater for heating liquids of the type generally described in U.S. Publication No. 2022/0082297 A1.

Flow heaters are needed, for example, in automobiles to heat various liquids, in particular water and aqueous solutions. Constant goals in the development of flow heaters for automobiles are a compact design, low manufacturing costs, and a high efficiency.

This disclosure teaches a flow heater that achieves these goals to a greater extent.

A flow heater according to this disclosure comprises a channel for liquid to be heated that is arranged between a heating plate and an inner wall that has at least one section that is slanted with respect to the heating plate. Accordingly, the channel has a first wedge-shaped section adjacent to the inlet and a second wedge-shaped section adjacent to the outlet, both wedge-shaped sections tapering from an end of the heating plate adjacent to the inlet and the outlet to an opposite end. The wedge-shaped sections are connected by a middle section of the flow channel, in which the direction of flow is crosswise to the direction of flow in the wedge-shaped sections.

Along the length of the first wedge-shaped section of the channel liquid to be heated enters the middle section of the flow channel and flows in the middle section in a direction crosswise to the length of the first tapering section. Thus only a small fraction of the liquid to be heated reaches the end of the first wedge-shaped section. The rest of the liquid enters the middle section along the way. Likewise, the amount of liquid inside the second wedge-shaped section increases in a direction towards the outlet as liquid enters the second wedge-shaped section along the way. Such a channel allows very large amounts of liquid to be heated efficiently in a short time.

The compactness of design enabled by the channel arranged as explained above is further improved by arranging the printed circuit board slanted with respect to the heating plate in a wedge-shaped space defined by the inner wall section and a cover part of the housing. Thereby the length of the circuit board can be greater than the length of the housing. Moreover, by arranging small, flat components of an end section of the circuit board on an end section adjacent to the inlet and the outlet and large components, like capacitors, on an opposite end section, the volume enclosed by the housing can be used very efficiently resulting in a very compact flow heater.

DESCRIPTION

FIG.1shows a flow heater. The same flow heater is shown in a sectional view along line AA inFIG.2, in sectional view along line CC inFIG.3and schematically in a sectional view along line BB inFIG.3.

The flow heater comprises a housing have a base part1, a first cover part2, and a second cover part3. The housing may be cuboid shaped as shown in the figures. The base part1has two opposing short sides1a,1band two opposing long sides1c,1d, said two short sides1a,1band said two long sides1c,1dare arranged between both cover parts2,3.

The base part1is provided with an inlet4and an outlet5, e.g., in one of the short sides1aof the base part1. Liquid to be heated flows through a channel inside the housing from the inlet4to the outlet5. The sectional view ofFIG.2shows an end section6of the channel, which is adjacent to the outlet5, and the sectional view ofFIG.3shows another section7of the channel, said section being downstream of the inlet4. Sections6and7of the flow channel are arranged between and delimited by a heating plate8and a section of an inner wall9of the housing. This inner wall9is part of the base part1and may be integral with it.

As can be seen inFIGS.2and3, a section of the inner wall9is slanted with respect to the heating plate8. The end section6of the channel is wedge-shaped. The channel section6is tapering in a direction away from the outlet5and the channel section7is tapering away from the inlet4.

InFIG.4, the course of the channel is illustrated schematically with arrows. Liquid to be heated flows from the inlet4to the left inFIG.3and then along a wedge-shaped section which is not shown in the figures, but formed like end section6. Flow through this wedge-shaped section is indicated inFIG.4with a downward arrow10. Liquid flows from this wedge-shaped section into a middle section14of the channel that is delimited on one side by the heating plate8and on an opposite side by a section11of inner wall9. Flow in this section is illustrated inFIG.3by arrow12. Note that arrow12is shown outside of the housing for reasons of space, but that the middle section of the flow channel is of course inside the housing. The middle section14of the channel leads to the end section6of the flow channel shown inFIG.2and depicted by arrow13inFIG.3.

FIG.4is limited to details essential for understanding the course of the channel. Hence, printed circuit board16and other details shown inFIG.2are not shown inFIG.4.

The wedge-shaped section7downstream of the inlet4is also called the first wedge-shaped section and the wedge-shaped section6leading to outlet5is also called the second wedge-shaped section. Both wedge-shaped sections are connected by middle section14which may have a constant height as measured perpendicular to the heating plate8. The direction of flow in the wedge-shaped sections6is crosswise, e.g., perpendicular, to the direction of flow in the middle section14. Fins20that are in contact with the heating plate8are arranged in the channel, especially in the middle section14of the channel.

The fins20may be corrugated sheet metal connected to the heating plate8, e.g., by brazing. The heating plate8is provided with heating resistors, e.g., resistive tracks, arranged on a substrate. The substrate may be a metal plate covered by a dielectric layer on which resistive tracks are arranged as heating resistors, especially on a side of the substrate facing away from fins20.

The inner wall9delimiting the heating channel may have a middle section11parallel to the heating plate8and on both sides of this middle section11a slanted section as shown inFIG.2. Then the middle section14of the channel has a constant height, while the sections6,7on both sides of the middle section, are wedge-shaped. These wedge-shaped sections6,7of the flow channel taper towards the end of the heating plate8facing away from the inlet4and the outlet5.

Both cover parts2,3and the heating plate8are parallel to each other. Parallel here means that any deviation from a geometrical perfect parallel orientation is within manufacturing tolerances.

AsFIG.2shows, the slanted section9of the inner wall and the first cover part2of the housing define a wedge-shaped space15that tapers in a direction that is opposite to the direction in which the first and second wedge-shaped section6of the channel taper. Inside this wedge-shaped space15is a printed circuit board16with control electronics. This printed circuit board16is slanted with respect to the heating plate8and also slanted with respect to the cover parts2,3. Thereby, a longer printed circuit board16can be arranged in the housing as would be possible if it were oriented in parallel to the heating plate8and the cover parts2,3. Moreover, by the slanted arrangement of the printed circuit board16in the wedge-shaped space the distance from the printed circuit board16to the first cover2increases from an end of the printed circuit board16adjacent to the inlet4and the outlet5to an opposite end of the printed circuit board16. At the end of the printed circuit board16there is therefore enough space for mounting large components, like e.g., capacitors18, on the printed circuit board16, whereas the other end may be used for smaller components of the control electronics.

The printed circuit board16and the heating plate8enclose an acute angle which may be 3° to 10°, for example. As can be seen inFIG.2, there may be wedge-shaped gap19between the printed circuit board16and the slanted section of the inner wall9. This wedge-shaped gap19may taper in a direction opposite to the direction of tapering of the wedge-shaped space15, in which the printed circuit board16is arranged. Thus the gap19tapers towards the inlet4and the outlet5.

InFIGS.5and6, further embodiments of a flow heater are shown in a sectional view according toFIG.2. Identical and corresponding components of the flow heaters of all embodiments are designated with identical reference numerals in the various figures. The embodiments shown inFIGS.4and5differ from the embodiment explained mostly in the printed circuit board16. Whereas in the embodiment ofFIG.2the printed circuit board16is slanted with respect to the heating plate8, two separate, smaller circuit boards16a,16bare used in the embodiment ofFIG.4which are electrically connected by means of an electrical conductor21, e.g., a wire. In the embodiment shown inFIG.5, a single printed circuit board16is used that is arranged in parallel with the heating plate8. Large components of the control electronic, e.g., a capacitor18, are arranged on an end of the printed circuit16board facing away from the inlet4and the outlet5and on a surface of the printed circuit board16facing away from the first cover part2.

The embodiment shown inFIG.5refers to a flow heater, comprising a housing comprising a base part1and a cover part2, a channel for liquid to be heated, which extends from an inlet4to an outlet5, a heating plate8adjacent to the channel, fins20arranged in the channel in contact with the heating plate8, and a printed circuit board16arranged between an inner wall9of the housing and the cover part2, wherein the inner wall9has at least one section that is slanted with respect to the heating plate8, between the heating plate8and the inner wall9the channel has a first wedge-shaped section downstream of the inlet and a second wedge-shaped section6leading to the outlet5, both wedge-shaped sections tapering from an end of the heating plate8adjacent to the inlet4and the outlet5to an opposite end, wherein said wedge-shaped sections are connected by a middle section of the flow channel, in which the direction of flow is crosswise to the direction of flow in the wedge-shaped sections6, and wherein a fist printed circuit board16aand a second printed circuit board16bare arranged in a wedge-shaped space defined by the inner wall9and the cover part2, said wedge-shaped space tapering in a direction that is opposite to the direction in which the first and second channel sections taper. The first printed circuit board16aand the second printed circuit boards16bbeing arranged at different distances from the cover part2.

The embodiment shown inFIG.6refers to a flow heater, comprising a housing comprising a base part1and a cover part2, a channel for liquid to be heated, which extends from an inlet4to an outlet5, a heating plate8adjacent to the channel, fins20arranged in the channel in contact with the heating plate8, and a printed circuit board16arranged between an inner wall9of the housing and the cover part2, wherein the inner wall9has at least one section that is slanted with respect to the heating plate8, between the heating plate8and the inner wall9the channel has a first wedge-shaped section downstream of the inlet and a second wedge-shaped section6leading to the outlet5, both wedge-shaped sections tapering from an end of the heating plate8adjacent to the inlet4and the outlet5to an opposite end, wherein said wedge-shaped sections are connected by a middle section of the flow channel, in which the direction of flow is crosswise to the direction of flow in the wedge-shaped sections6, and wherein a printed circuit board16is arranged in a wedge-shaped space defined by the inner wall9and the cover part2, said wedge-shaped space tapering in a direction that is opposite to the direction in which the first and second channel sections taper. The printed circuit board is arranged adjacent to the cover2, in parallel with the cover2, and provided with components, e.g., a capacitor on a surface facing away from the cover2.

LIST OF REFERENCE SIGNS