Instantaneous water heater and heating plate for an instantaneous water heater

Abstract

A flow heater comprising a heating plate (6) comprising a metal plate (6a), a heating conductor (6b), and an insulating layer (6c) between the heating conductor (6b) and the metal plate (6a), a housing (1) in which the heating plate (6) is arranged, the housing (1) surrounding a flow channel for liquid to be heated, which leads from an inlet opening (2) of the housing (1) to an outlet opening (3) of the housing (1), a circuit board (8) with control electronics, and an electrical connector (10) via which the heating conductor (6b) of the heating plate (6) is connected to the control electronics and which has a plastic body (11; 11a, 11b) from which a conductor (12) protrudes and is embedded in the circuit board (8), characterized in that the heating plate (6) is connected between a terminal part (13) of the electrical connector (10) and a conductor (12) protruding from the plastic body. (11;11a, 11b) protruding end section (12b) of the conductor (12) is clamped, wherein the clamping element (13) is designed as a sheet metal separate from the conductor (12) and a first end section of the sheet metal of the clamping element (13) or sheets of the clamping element (13) rests against the heating plate (6) and a second end section of the sheet metal (13) or sheets of the clamping element (13) is arranged in the plastic body (11; 11a, 11b).

Description

The invention relates to a continuous-flow heater and to a heating plate for a continuous-flow heater. A continuous flow heater having the features specified in the preamble of claim 1 is known from DE 10 2022 132 476 B3.The continuous-flow heater known from DE 10 2022 132 476 B3 contains an electrical connector, via which the heating plate is connected to a printed circuit board with control electronics. This connector has a plastic body from which both ends of a metal strip project. A first end portion of the metal strip is soldered to the heating plate and a second end portion of the metal strip plugs into the circuit board.EP 2 330 865 A1 discloses an electric heating device in which a printed circuit board is contacted in a clamping manner by a conductor designed as a claw.The object of the present invention is to show a way in which the production of a continuous-flow heater of the type mentioned at the beginning can be simplified.This object is achieved by a continuous flow heater having the features specified in claim 1 and by a heating plate according to claim 9.In a continuous-flow heater according to the invention, electrical contact with the heating plate is produced by the heating plate being clamped between a clamping part of the electrical connector and an end section of a conductor which protrudes from the plastic body of the electrical connector. Advantageously, a solder connection between the conductor leading to the printed circuit board and the heating plate can thus be avoided. This simplifies the production and allows any production tolerances to be compensated for using simple means. In addition, a longer service life of the continuous-flow heater can be achieved, since electrical contact by clamping is generally more stable and reliable than a soldered connection.The clamping part may be formed by the plastic body of the electrical connector. Greater clamping forces can be achieved by the clamping part containing sheet metal, for example by a separate clamping sheet being embedded in the plastic body or by a clamping section branching off from the conductor and the heating plate being clamped between this clamping section and an end section projecting from the plastic body. According to the invention, the clamping part is designed as a clamping plate which protrudes from the plastic body of the electrical connector. The clamping plate can be formed integrally with the conductor, but is a separate plate according to the invention.The conductor can be a sheet metal part which has been produced by a cutting method, for example laser cutting, water jet cutting, punching or fine cutting. Alternatively, the conductor can also be produced by original forming or layer-forming methods. The clamping plate can be manufactured in the same manner as the conductor.Further details and advantages of the invention are explained on exemplary embodiments with reference to the attached drawings. Identical and corresponding components are provided with corresponding reference numerals in the drawings of the different exemplary embodiments. The following are shown: FIG. 1 shows an exemplary embodiment of a continuous-flow heater according to the invention; FIG. 2 is a sectional view of FIG. 1 ; FIG. 3 shows a sectional detailed view of the heating plate with electrical connector; FIG. 4 shows a detailed view of the heating plate with electrical connector from below; FIG. 5 shows a detail view of the heating plate with electrical connector from above; FIG. 6 is a view of the electrical connector; FIG. 7 shows the conductor and the clamping plate of the electrical connector; FIG. 8 shows a further exemplary embodiment of an electrical connector; FIG. 9 shows the conductor and clamping plate of the connector shown in FIG. 8 FIG. 10 shows a further exemplary embodiment of an electrical connector with heating plate; FIG. 11 illustrates conductors and clamping plates of the connector shown in FIG. 10; FIG. 12 shows a further exemplary embodiment of an electrical connector with heating plate; FIG. 13 shows the clamping plates of the connector shown in FIG. 12 ; FIG. 14 shows a further exemplary embodiment of an electrical connector with a heating plate, which is not the subject matter of the claims; FIG. 15 shows the conductor and clamping plate of the connector shown in FIG. 14; and FIG. 16 is a side view of the embodiment shown in FIG. 14.The continuous flow heater shown in FIGS. 1 and 2 has a housing 1 with an inlet opening 2 and an outlet opening 3 and electrical connections 4, 5.The flow channel runs along a heating plate 6, which carries one or more electrical heating resistors, which are designed as heating conductor tracks. In order to improve the heat emission of liquid in the flow channel, the heating plate 6 can carry a corrugated ribbed plate 7 which projects into the flow channel. The heating plate 6 is connected to a printed circuit board 8 which carries control electronics. The heating plate 6 and the circuit board 8 are arranged one above the other and parallel to each other in the exemplary embodiment shown. However, it is also possible to arrange the printed circuit board 8 obliquely to the heating plate 6.FIGS. 3, 4 to 5 show in various views a section of the heating plate 6 with an electrical connector 10, via which the heating plate 6 is connected to the printed circuit board 8. FIG. 6 shows the connector 10 without heating plate.The heating plate 6 has a metal plate 6 a, for example made of steel or an aluminum-based alloy, and at least one heating conductor track 6 band an insulator layer 6 cbetween the metal plate 6 aand the heating conductor track 6 b.The electrical connector 10, via which the heating conductor track 6 bof the heating plate 6 is connected to the printed circuit board and thus to the control electronics, has a plastic body 11 from which at least one conductor 12 protrudes, which is plugged with an end section into the printed circuit board 8. This end section of the conductor 12 forms a plurality of press-fit contacts 12 a, for example two press-fit contacts 12 a. The other end section 12 bof the conductor 12 contacts the heating conductor track 6 bor one of the heating conductor tracks 6 bof the heating plate 6, and the clamping part 13 is designed in the exemplary embodiment shown as a clamping plate 13 which protrudes from the plastic body 11 of the electrical connector 10. In this exemplary embodiment, a first end section of the clamping plate 13 therefore bears against the heating plate 6, while a second end section of the clamping plate 13 is arranged in the plastic body 11Press-fit contacts are designed to establish an electrical connection in a metallized hole of a printed circuit board by means of a press fit. Press-in contacts must be deformed when press-in into a metallized hole. To facilitate this, the press-in contacts in the embodiment shown have a bulging central part and can be provided with a slot or an opening in the bulging central part. The press-in contacts can be coated with nickel and / or tin in order to facilitate a good electrical connection with low resistance.The plastic body 11 can have at its end facing the circuit board 8 one or more projections 16 for insertion into matching openings of the circuit board 8, for example a pin. Such a protrusion 16 facilitates the correct positioning of the circuit board 8 relative to the electrical connector 10 before end portions of the conductors 12, for example formed as press-in contacts 12 a, are pressed into matching openings of the circuit board 8.In the exemplary embodiment shown, the connector 10 has a plurality of conductors 12, for example two conductors 12. Opposite edges of the heating plate 6 can be seated in lateral grooves 15 of the plastic body 11 of the connector 10 and thus facilitate the mechanical connection between heating plate 6 and connector 10.As is shown in particular in FIG. 3, the conductor 12 and the clamping plate each rest with a bend 14 against the heating plate 6. The end section 12 bof the conductor 12 therefore has, like the end section of the clamping plate, a bulge facing the heating plate 6. This facilitates clamping of the heating plate 6.In the exemplary embodiment shown, the conductor 12 is formed as a continuous sheet metal strip, the two ends of which protrude from the plastic body 11. Instead of a continuous sheet metal strip, however, a composite conductor can also be used. The conductor 12 has a main section which runs transversely to the plane of the heating plate 6 and an end section 12 bprotruding from the plastic body 11 and extending along the heating plate 6 and bearing against the heating plate 6 by a bend 14.The connector 10 may be manufactured by overmolding the conductor 12 and the clamping plate with plastic. In order to facilitate the production of the electrical connector 10, the conductor 12 and the clamping plate can have a through opening 15 which, during the injection molding with plastic, enables a precise positioning by pins of a tool engaging in these openings, which are pulled out after the injection molding. These openings 15 can be seen in FIG. 7.FIG. 8 shows a further exemplary embodiment of a connector 10 by means of which the heating conductor track of the heating plate 6 of a continuous heater shown in FIGS. 1 and 2 can be connected to a printed circuit board. This connector 10 differs from the connector described above essentially only in that the conductor 12 and the clamping part 13, in the example shown as the clamping plate, are no longer arranged one above the other in the plastic body 11 according to FIG. 7, but rather the clamping plate has a section which is arranged laterally offset from the end section 12 bof the conductor 12 protruding from the plastic body 11 and which bears against the heating plate 6 as intended. Figure 9 shows the conductor 12 and the clamping part 13 of the connector 10 shown in Figure 8 in the spatial relationship they have in the connector 10 to each other.FIG. 10 shows a further exemplary embodiment of a connector 10 by means of which the heating conductor track of the heating plate 6 of a continuous heater shown in FIGS. 1 and 2 can be connected to a printed circuit board. This connector 10 differs from the above-described connector substantially only in that two clamping parts 13 designed as clamping plates are provided for each conductor 12 in order to clamp the heating plate 6 between it and the end section 12 bof the conductor 12. The conductor 12 is arranged between the two clamping parts 13. This makes it possible to prevent the spring force exerted by the clamping parts 13 from causing tilting moments.FIG. 12 shows a further exemplary embodiment of an electrical connector 10 with a section of the heating plate 6, and FIG. 13 shows a section of the conductor 12 and the clamping parts 13 of the connector 10 shown in FIG. 12.In the previously described exemplary embodiments of electrical connectors 10, the plastic body 11 thereof is integral. In the embodiment shown in FIG. 12, the plastic body of the connector 10 is a multi-part body. A first partial body 11 aof the plastic body abuts the heating plate 6. The clamping part or parts 13 designed as clamping plates and the end section 12 bof the conductor 12 or the conductors 12 abutting the heating plate 6 protrude from this first part body 11 a. A second part body 11 bis plugged together with the first part body 11 a. The end section 12 aand the end sections 12 aof the conductor 12 which are inserted into the printed circuit board protrude from this second part body 11 b.In the exemplary embodiment of FIGS. 12 and 13, the conductor 12 is a multi-part conductor. A part of the conductor 12 is embedded in the first sub-body 11 a, and a second part of the conductor 12 is embedded in the second sub-body 11 b. Both parts of the conductor 12 can be made of sheet metal. One of the two partial conductors, for example the partial conductor of the first partial body 11 a,thereby forms a resilient contact receptacle with two contact arms which are resiliently opposite one another, while the partial conductor of the other partial body 11 bconstitutes a contact tongue which is pushed into this contact receptacle and thus between these two contact arms which are resiliently opposite one another when the two partial bodies 11 a, 11 bare plugged together.FIGS. 14 and 16 show a further exemplary embodiment of an electrical connector 10 with a cutout of the heating plate 6 in different views. In this exemplary embodiment, the heating plate 6 is clamped between an end section 12 bof the conductor 12 protruding from the plastic body 11 and a clamping part 13 formed by the plastic body 11. To improve the mechanical load-bearing capacity, the clamping part 13 formed by the plastic body 11 can contain sheet metal, for example a clamping sheet 13 which is formed integrally with the conductor, as shown in FIG. 15, or a separate clamping sheet.The exemplary embodiment shown in FIG. 14 corresponds largely in its external appearance to the connector 10 shown in FIG. 10, but differs in the configuration of the clamping part 13.If the clamping part 13 is formed as part of the plastic body 11 of the electrical connector 10 and contains sheet metal to improve its load capacity, the plastic body 11 can cover an upper side of this sheet metal facing away from the heating plate 6 or even completely enclose the clamping sheet 13.List of reference characters1 Housing 2 Inlet opening 3 Outlet opening 4 Electrical connection 5 Electrical connection 6 Heating plate 6 aMetal plate 6 b Heizleiter conductor track 6 c Isolatorschicht layer 7 Corrugated ribbed sheet 8 Printed circuit board 10 Connector 11 Plastic body 11 aPartbody of the plastic body 11 bPartbody of the plastic body 12 Conductor 12 aPress contact 12 bEnd section of the conductor 13 Clamping part 14 Bend 15 Opening 16 Projection

Claims

Continuous-flow heater having a heating plate (6) which has a metal plate (6a), a heating conductor track (6b) and an insulator layer (6c) between the heating conductor track (6b) and the metal plate (6a), a housing (1) in which the heating plate (6) is arranged, wherein the housing (1) surrounds a flow channel for liquid to be heated which leads from an inlet opening (2) of the housing (1) to an outlet opening (3) of the housing (1), a printed circuit board (8) having control electronics, and an electrical connector (10) via which the heating conductor track (6b) of the heating plate (6) is connected to the control electronics and which surrounds a plastic body (11; 11 a, 11 b), from which a conductor (12) which plugs into the printed circuit board (8) projects, characterized in that the heating plate (6) is clamped between a clamping part (13) of the electrical connector (10) and an end section (12 b) of the conductor (12) which projects from the plastic body (11; 11 a, 11 b), wherein the clamping part (13) is formed as a metal sheet which is separate from the conductor (12) and a first end section of the metal sheet of the clamping part (13) or of the metal sheets of the clamping part (13) bears against the heating plate (6) and a second end section of the metal sheet (13) or of the metal sheets (13) of the clamping part is arranged in the plastic body (11; 11 a, 11 b).Continuous heater according to claim 1, characterised in that the plastic body (11) has a first part body (11a) which abuts against the heating plate (6) and a second part body (11b) from which the end section of the conductor (12) which is plugged into the printed circuit board (8) protrudes, wherein the first part body (11a) and the second part body (11b) are plugged into one another.Continuous heater according to one of Claims 1, characterized in that the conductor (12) is formed by a continuous sheet-metal strip, the sheet-metal strip (12) having a first end section (12a) which is plugged into the printed circuit board (8) and having a second end section (12b) which bears against the heating plate (6).Continuous heater according to one of the preceding claims, characterized in that the electrical connector (10) has two or more clamping parts (13), and the heating plate (6) is clamped between the clamping parts and the end section (12b) of the conductor (12).Continuous flow heater according to one of the preceding claims, characterized in that the plastic body (11; 11a, 11b) is inserted into a recess in the heating plate (6) and has a groove (15) on opposite sides, in which the heating plate (6) is seated.Continuous flow heater according to one of the preceding claims, characterized in that the conductor (12) forms one or more press-in contacts (12a) which plug into the printed circuit board (8).Continuous heater according to one of the preceding claims, characterized in that the conductor (12) bears with a bend (14) against the heating plate (6).Continuous flow heater according to one of the preceding claims, characterized in that the conductor (12) is a sheet metal part which has been produced by a cutting method.Heating plate for a continuous heater, having a heating plate (6) which has a metal plate (6a), a heating conductor track (6b) and an insulator layer (6c) between the heating conductor track (6b) and the metal plate (6a), and an electrical connector (10) for connecting the heating plate (6) to a printed circuit board (8), wherein the connector (10) has a plastic body (11) from which a conductor (12) projects which ends in a contact for insertion into a bore of a printed circuit board (8), characterized in that a clamping plate (13) projects from the plastic body (11; 11a, 11b), and the heating plate (6) projects between the clamping plate (13) and one of the plastic body (11; 11 a, 11 b), wherein the clamping part (13) is formed as a separate sheet from the conductor (12) and a first end portion of the sheet of the clamping part (13) or of the sheets of the clamping part (13) abuts the heating plate (6) and a second end portion of the sheet (13) or of the sheets (13) of the clamping part is arranged in the plastic body (11; 11 a, 11 b).

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