EP1731850B2 - Flangeless plastic boiler - Google Patents

Description

The present invention relates to a plastic boiler for heating a flowable medium, in particular for heating water according to the preamble of claim 1.

Such boilers are used in practice in coffee machines, espresso machines, etc. In the past, these boilers were made of metal. However, the use of metal resulted in high manufacturing costs due to the high cost of materials. In addition, metal is a complex material to be processed, which has further increased the production costs.

Therefore, plastic boilers have already been used in practice. From the European patent application 1 211 466, which forms the closest prior art, from which the present invention proceeds, such a plastic boiler can be removed. This known plastic boiler consists of a boiler shell and a boiler base. The heater is formed by a tubular heater, which is inserted in the boiler lower part by means of a large mounting flange made of metal. For the attachment of the mounting flange, a relatively large opening must be provided in the boiler lower part. This opening must again be sealed by suitable sealing means against leakage of located in the boiler, to be heated medium. Again, the use of a metal flange increases the manufacturing costs. Furthermore the manufacturing costs are increased by the special sealing measures necessary as a result of the large opening diameter.

The German utility model DE 75 12 731 U discloses a container made of plastic for a hot water heater with an electric radiator, in which in an area of the container wall an outwardly directed passage is formed through which the radiator is plugged and on the outside of a ring is pressed, the passage against the outer shell of the radiator, wherein the bearing surface between the passage and the ring tapers slightly conically outward. Between the radiator and the passage, a sealant such as an epoxy resin is applied, which forms a sealing bead surrounding the outer jacket of the radiator. The document DE 7512731U discloses the preamble of claim 1.

The published patent application of the British patent application GB 2 284 132 discloses a thermal switching device which is actuated by a relative expansion of parts of a heating element to an immersion electric heater for example, water heater, boiler or the like. The electric heater comprises a heating element such as a tubular heater having substantially unheated end portions fixed to a top plate, and a heated rear portion. The rear portion extends in the direction of the head plate at a distance L from the ends of the end portions, so that as soon as the heating element runs dry, ie without surrounding water, the rear portion moves by thermal expansion in the direction of the top plate, wherein a movable push rod with the rear portion so cooperates, that a switch at a predetermined movement of the rear portion for switching the heating element can be actuated.

It is an object of the present invention to provide a plastic boiler of the type mentioned, in which the heater can attach to the boiler in a simpler and thus more cost-effective manner compared to the prior art.

The above object is solved by the features of claim 1. Advantageous embodiments can be found in claims 2 to 10.

Due to the design of the heater in such a way that it has an unheated portion at least in the region of the mounting hole, and by the further embodiment of the mounting hole in the boiler housing in such a way that the inner diameter at least partially corresponds to the outer diameter of the heater at least partially, which consists Possibility to a separate mounting plate or a separate To dispense with mounting flange. At the same time, the diameter of the mounting hole is significantly reduced, so that the measures for achieving a sufficient seal compared to the prior art, in which a mounting flange made of metal for fixing the heater is used in the boiler housing, reduce.

To ensure that the heat generated by the heater does not damage the plastic walls of the boiler housing, it is further contemplated that the unheated portion of the heater continues on the inside of the boiler housing. In other words, the unheated portion of the heater continues into the interior of the boiler housing. Similarly, the unheated portion of the heater may continue on the outside of the boiler housing. Furthermore, it is advantageous if the length of the unheated portion of the heater in the direction of the inside of the boiler housing is greater than in the direction of the outside.

The heater can be fixed or attached in different ways in the mounting hole. If the heater is inserted into the mounting opening after the plastic boiler housing has been manufactured, there is the possibility that, depending on the configuration of the heating device, this can be done both from the outside of the container and from the inside of the container. If the assembly of the container inside made, which is particularly advantageous if the boiler housing is constructed of at least two housing sections, which are connected together in a separate assembly step, the mounting opening to the outside of the boiler housing can have a constriction whose inner diameter smaller is as the outer diameter of the heater and on which the heater is applied during assembly. The constriction has an inner diameter such that a connecting element of the heating device, such as a connecting bolt and the like, can still be passed through the constriction. As a result of this configuration, a defined axial position of the heating device is provided in a simple manner during installation by contacting the front side of the heating device facing the outside at the constriction.

Due to the high strength of some plastics, the wall thickness of the boiler housing can be chosen correspondingly low. In such a case, but also independently thereof, the resulting axial length of the mounting opening for a safe installation of the heater may not be sufficient. Therefore, the invention provides that the mounting opening is formed by an arranged on the boiler housing extension whose axial length is greater than the wall thickness of the boiler housing and extending from the wall of the boiler housing to the outside.

Of course, there is the possibility that an extension, both on the outside and inside of the housing is arranged. By using plastic for the boiler housing, this extension can easily be produced during an injection molding process for the boiler housing together with it in the injection molding process. Of course, there is also the possibility that the extension is made separately from the boiler housing and then attached by means of a suitable mounting method with the boiler housing to the mounting hole in the housing wall in such a way that the central longitudinal axis of the extension is aligned with the central longitudinal axis of the mounting hole.

In order to prevent the escape of the flowable medium located in the boiler housing from the mounting opening for the heating device, it is further provided that at least one sealing element is arranged between the inner wall of the mounting opening and the outer wall of the heating device. Here, the manufacturing process can be further simplified in that the sealing element is sprayed onto the outside of the heater.

Basically, it is possible to choose as a fastening means, the fit between the inner wall of the mounting hole and the outer wall of the heater so that the heater is fixed there after insertion into the mounting hole, ie, so that the fit is a stiff mating fit or a press fit , However, since the heater cyclically heats and cools, there is the possibility that this fit changes over the life of the heater or the time of use of the boiler. Therefore, it is provided that the fastening means, which fixes the heating device in the mounting opening, is formed by at least one clamping element. In this case, the clamping element fixes the heating device in the assembly opening by plastic deformation. For example, this can be done by the preferably made of metal clamping element has a C-shaped configuration, wherein the inner diameter of the fastener is selected so that the clamping element can be arranged during assembly of the heater in the mounting opening of the boiler housing, but then plastically so is deformed that it engages behind with its two free ends behind corresponding undercuts on the housing wall of the boiler or on a provided extension. It is also possible that the clamping element is formed by a completely closed ring, preferably made of metal, whose inner diameter corresponds at least approximately to the outer diameter of the extension. Again, the fixation of the ring and thus the fixation of the heater by plastic deformation of the ring, preferably by gripping the annular edges of undercuts done.

It should also be noted that the fastener can serve as a ground connection for the heater.

It is also possible that the fastening means is integrally formed on the housing and / or the extension of the mounting hole by preferably injection molding. Again, the fixation of the heater after its mounting in the mounting hole can be fixed by plastic deformation of the fastener.

Furthermore, there is the possibility that the fastening means to an insulating bead, preferably made of plastic, is attached, which closes the mounting opening relative to the outside of the boiler with mounted heater and / or the heater. As already explained in the above-described cases, the fixing of the heating device in the assembly opening takes place here as well by plastic deformation of the fastening means after insertion of the heating device into the assembly opening.

In addition to the mounting opening for the heating device, a mounting opening for the attachment of a control unit, which is in heat-conducting contact with a heated section of the heating device, can furthermore be provided. This makes it possible to provide a control or regulating process for the heater. In addition to this mounting opening for the control unit, it is of course also possible to provide further mounting openings in the boiler housing, in which additional control and / or regulating elements or measuring elements, such as pollution sensors, pressure sensors, etc., can be used.

The Wärmeleitkontakt can be made by thermal radiation or heat conduction. In the latter case, the heat-conducting contact is produced by a heat-conducting element, preferably a heat-conducting sheet.

The control unit can in turn be formed by a wide variety of components. Preferably, the control unit is formed by a PTC or an NTC element or by a fuse.

For fixing the control unit in the mounting opening, a latching operation and / or a fastening element can be provided. Basically, however, there is also the possibility that the control unit is already inserted into the injection molding machine during the injection molding process for the container housing, or parts thereof, to be introduced during the injection molding in the container wall and thus in the resulting mounting opening.

As already stated above, the boiler housing may be formed in one piece or constructed from two or more housing sections. A particularly simple manufacturing process and a simple assembly of the boiler as a whole is achieved in that the boiler housing consists of at least two parts, wherein preferably at least one mounting opening for the heater and / or the mounting opening for the control unit is provided in one of the two boiler housing parts. In this case, the two housing parts with the interposition of a seal cohesively, positively or non-positively connected to each other. A frictional connection is made by using one or more metal clamps, which on two flange portions over which the two housing parts rest against each other and receive at least one sealing element between them, are pushed in the assembly of the boiler. In this case, the metal clamp is designed such that it exerts an elastic clamping force on the two flanges. It is also possible that the two housing parts are interconnected by a latching connection or one or more snap hooks. Finally, alternatively, it may be provided that the one boiler housing part has one or more plastic pins on the flange, which passes through a through-passage on the flange of the other boiler housing part and which is then plastically deformed by heating at its upper free end similar to a rivet engages over the edges of the passage opening in the flange. Finally, the two housing parts can also be materially connected, for example by gluing or welding, together.

For the heater, a variety of solutions can be used. It is preferable for the present invention that the heater is a tubular heater.

Fig. 1

eine Seitenansicht auf einen erfindungsgemäßen Boiler;

Fig. 2

eine Vertikalschnittansicht durch den in Fig. 1 gezeigten Boiler entlang der Linie II-II in Fig. 1;

Fig. 3

eine horizontale Querschnittsansicht einer weiteren Ausführungsform des erfindungsgemäßen Boilers;

Fig. 4

eine detaillierte Querschnittsansicht auf eine in einer Montageöffnung des Boilergehäuses eingesetzte herkömmliche Heizeinrichtung;

Fig. 5

ein weiteres herkömmliches Ausführungsbeispiel für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 6

eine dritte herkömmliche Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 7

eine vierte herkömmliche Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 8

eine erfindungsgemäße alternative Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 9

eine sechste herkömmliche Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 10

eine siebte herkömmliche Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 11,

12 eine achte herkömmliche Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung;

Fig. 13,

14 eine weitere alternative Ausführungsform für eine Ausgestaltung der Montageöffnung in dem Boilergehäuse und für Anordnung der Heizeinrichtung in der Montageöffnung gemäß der Erfindung;

Fig. 15a-c

Teilquerschnittsansichten der Fügestellen eines erfindungsgemäßen Boilers, der aus zwei Gehäuseteilen aufgebaut ist; und

Fig. 16

eine Teilquerschnittsansicht des Boilergehäuses mit einer Montageöffnung für eine Steuereinheit.

Further advantageous embodiments and exemplary embodiments of the present invention will be explained below in conjunction with the drawing figures. It should be noted that the terms "left", "right", "top" and "bottom" used in the description refer to the drawing figures with normally readable reference numerals and figure names. Here is:

Fig. 1

a side view of a boiler according to the invention;

Fig. 2

a vertical sectional view through the in Fig. 1 shown boiler along the line II-II in Fig. 1 ;

Fig. 3

a horizontal cross-sectional view of another embodiment of the boiler according to the invention;

Fig. 4

a detailed cross-sectional view of a conventional heater used in a mounting opening of the boiler housing;

Fig. 5

another conventional embodiment for a configuration of the mounting hole in the boiler housing and for arranging the heater in the mounting hole;

Fig. 6

a third conventional embodiment for a configuration of the mounting hole in the boiler housing and for arranging the heater in the mounting hole;

Fig. 7

a fourth conventional embodiment for a configuration of the mounting hole in the boiler housing and for arranging the heater in the mounting hole;

Fig. 8

an alternative embodiment of the invention for a configuration of the mounting hole in the boiler housing and for arrangement of the heater in the mounting hole;

Fig. 9

a sixth conventional embodiment for a configuration of the mounting hole in the boiler housing and for arranging the heater in the mounting hole;

Fig. 10

a seventh conventional embodiment for a configuration of the mounting hole in the boiler housing and for arranging the heater in the mounting hole;

Fig. 11,

12 shows an eighth conventional embodiment for an embodiment of the mounting opening in the boiler housing and for arranging the heating device in the mounting opening;

Fig. 13,

14 shows a further alternative embodiment for an embodiment of the mounting opening in the boiler housing and for arranging the heating device in the mounting opening according to the invention;

Fig. 15a-c

Partial cross-sectional views of the joints of a boiler according to the invention, which is constructed from two housing parts; and

Fig. 16

a partial cross-sectional view of the boiler housing with a mounting opening for a control unit.

In Fig. 1 an inventive boiler 10 is shown in a side view. The housing 12 of the boiler 10 consists of an upper housing part 14 and a lower housing part 16, which are each made of plastic, preferably by a 2K method. The two housing parts 14, 16 are substantially pot-shaped rotationally symmetrical and geometrically similar to each other in such a way that their outer and inner shape coincides, but the upper housing part 14 has a greater depth or axial length than the lower housing part 16. Are the two housing parts 14, 16 joined to the boiler 10, they have, as shown in the Fig. 1 and 2 can be removed, the shape of a cylinder, the front ends 14a, 16a are slightly convex outwardly arched.

The two housing parts 14, 16 have at their unspecified free edges, where they are joined together to the boiler housing 12, each having a preferably completely circumferential flange 18, 20, on which they preferably rest against each other in the assembled state, as shown in the Fig. 15a to 15c is removable. The two flanges 18, 20 extend from the outside of the free wall end of the respective housing part 14, 16 at an angle of at least approximately 90 ° away from the housing wall to the outside. Both flanges 18, 20 have approximately in the middle of their unspecified contact surfaces a semi-cylindrical, also completely circumferential recess 18a, 20a, in which a sealing element 22 is inserted.

Like from the Fig. 15a to 15c can be removed, the two flanges 18, 20 and thus the two housing parts 14, 16 are connected to each other in very different ways. So is at the in Fig. 15a shown in the first alternative, a cross-sectionally C-shaped metal clamp 32 is provided, the complete, in sections, in two half-rings or in the form of the letter "C". viewed from above, the two flanges 18, 20 can embrace. The C-shaped metal clamp 32 is resilient, wherein the distance at the free ends of the "C" is smaller than the strength or height of the two superimposed flanges 18, 20. As a result, the clamp 32 for sliding on the two flanges 18, 20 are widened. The thus constructed elastic, in the direction perpendicular to the horizontal in the illustrated examples surfaces or contact surfaces of the two flanges 18, 20 acting compressive force serves to press the two flanges 18, 20 to each other and thereby in conjunction with the sealing element 22 a fluid-tight connection between the two housing parts 14, 16 to form.

At the in Fig. 15b shown alternative is on the flange 20 of the lower housing part 16, a preferably elastic, also at least partially circumferential snap hook 20b integrally formed, which engages over the flange 18 of the upper housing part 14. Due to the elasticity of this snap hook 20b, a compressive force is again built up perpendicular to the horizontally extending flange surfaces or contact surfaces, so that the two flanges 18, 20 are pressed against one another and form a fluid-tight connection between the two housing parts 14, 16 in conjunction with the sealing element 22 ,

Finally, at the in Fig. 15c Alternative shown, the two flanges 18, 20 and thus the two housing parts 14, 16 connected by a hot stamping. For this purpose, the flange 20 of the lower housing part 18 is provided with a plurality of spaced apart in the circumferential direction of the flange 20 to each other, provided substantially perpendicular to the flange or contact surface and in the mounted state in the direction of the flange 18 of the upper housing part 14 pins 20c. The axial length of the pins 20c is greater than the axial length of the passage openings 18b of the flange 18 of the housing top 14. After insertion of the pins 20c, the over the flange 18 of the Upper housing part 14 protruding end of the pins 20c plastically deformed by heating so that the resulting, unspecified flats over which also unspecified edges of the passage openings 18b of the flange 18 overlap. If the two flanges 18, 20 are pressed against each other during the heating and curing of the pins 20c, this also results in a resilient prestress which, in conjunction with the sealing element 22, permits a tight connection of the two housing parts 14, 16. It should also be noted that in place of a plurality of pins 20c, annular portions may also be provided on the flange 20 which engage correspondingly shaped slots on the flange 18.

In addition to the two housing parts 14, 16, the boiler 10 according to the invention has a heating device 40, which is formed by an electric tubular heater of known type. The tubular heater 40, which has a circular cross section, passes through with its two free terminal ends 42, the lower end wall 16 a of the lower housing part 16 each through a mounting opening 46. As from Fig. 2 As can be seen, the tubular heater 40 is spirally wound inside the boiler 10, wherein the spiral is at least approximately in a horizontal plane. In this case, the spiral winding is in the vicinity of the front end 16a of the lower housing part sixteenth

For explaining the structure of the mounting hole 46 and the arrangement of the heater 40 in this will be explained Fig. 3 Reference is made to one Fig. 1 and 2 similar Boiler 10 with a slightly different outer contour shows. At the in Fig. 3 illustrated embodiment, the boiler 10 is shown in a horizontal section, wherein the heater 40 also extends horizontally with its central longitudinal axis. In contrast to the embodiment of the Fig. 1 and 2 Here, the tubular heater 40 extends straight into the interior of the housing 12 of the boiler 10 inside.

The mounting opening 46 has, as well as the tubular heater 40, a circular cross-section. How out Fig. 3 can be removed, the mounting hole 46 is not only formed by a circular cross-section opening in the wall of the lower housing part 16, but it is additionally integrally formed on the mounting opening 46 an extension 48 on the outside of the housing wall in such a way that the central longitudinal axis of the extension 48 is aligned with the central longitudinal axis of the opening in the wall of the lower housing part 16. The extension 48 has a cylindrical outer contour.

How to continue Fig. 3 shows, the unspecified inner wall of the mounting hole 46 is located on the outer wall of the tubular heater 40 with two annular portions 46a, 46b. The two sections 46a, 46b are located respectively at the two front ends of the mounting opening 46, ie on the inside and the outside of the mounting opening 46. The space lying between the two sections 46a, 46b serves to receive a seal 50, which is prior to assembly the heater 40 may be inserted into this space or sprayed onto the heater 40 prior to its attachment in the mounting hole 46.

Out Fig. 3 In addition, it can be seen that the tubular heater 40 has a relatively long unheated connection end 42. This is formed by an elongated cylindrical connecting bolt 52 made of an electrically conductive material, which is arranged centrally in the interior of the tubular heater 40 and which is only relatively far in the interior of the boiler 10 with a heating coil 54 made of an electrical resistance heating wire. This ensures that the heat emitted by the heater 40 does not damage the mounting opening 46 or the housing sections located in the vicinity thereof. Here, the axial length of pointing into the interior of the boiler 10 portion of the unheated end 42 of the tubular heater 40 and the connecting bolt 52 is longer than the axial length of the outwardly facing portion of the unheated end 42 and the connecting bolt 52. This will, as already mentioned, a sufficient distance is provided between the heated portion of the heating device 40 beginning with the heating coil wire 54 and the wall of the lower housing part 16, so that damage to the wall of this housing part 16 or the mounting opening 46 and / or the seal 50 even in a drying cycle the heater 40 reliable is avoided. It should also be noted that the connecting bolt 52 on the outside of the mounting hole 46 spaced therefrom protrudes from the jacket tube 41 of the tubular heater 40, which allows a contact with an electric current source.

On the outer side of the extension 48, a support ring 56 is preferably placed or pushed and clamped from metal. The support ring 56, which may be a completely closed ring or a C-shaped ring, has an inner diameter which at least approximately corresponds to the outer diameter of the extension 48. The support ring 56 is plastically deformed after being pushed onto the extension 48 so that it compresses the extension 48 and thereby fixes the heating device 40 in the interior of the installation opening 46. In addition, the support ring 56 may serve to exert sufficient compressive stress on the seal 50 over the life of the boiler 10 of the present invention. This may be necessary because the extension 48 made of plastic and the tubular heater 40, the jacket tube 41 may be made of stainless steel, show a different thermal expansion. With an appropriate choice of material for the plastic boiler 10 and the heater 40 and a corresponding material pairing can also be dispensed with the support ring 56. With a corresponding design, this support ring 56 can also be used to ground the connection of the tubular heater 40.

In the 4 to 13 find different configurations for fixing the tubular heater 40 in the mounting hole 46 in a schematic representation. The individual embodiments will be described below, with only similar differences being described in similar embodiments. Of course, individual elements of an embodiment can be combined with elements of other embodiments:

In Fig. 4 a first conventional variant is shown, is held in the tubular heater 40 by means of a Isolierperle 58 preferably made of plastic in the mounting hole 46. The insulating bead 58 is pushed from the outside to the tubular heater 40 and preferably attached thereto. With the insulating bead 58 of the support ring 56 is firmly connected. The solid connection can be effected, for example, by casting the ring 56 in the casting process of the insulating bead 58. The function of the support ring 56 of this embodiment and its determination takes place in the same manner as in the support ring 56 in Fig. 3 ,

In the Fig. 5 The second conventional embodiment shown differs from that in FIG Fig. 4 shown in that the mounting hole 46 has on its outwardly facing end face a constriction 46c, whose inner diameter is approximately the diameter of the connecting bolt 52 of the tubular heater 40 corresponds. In this embodiment, the tubular heater 40 is inserted from the inside of the housing part 14 or 16 until the end face 40a of the jacket tube of the tubular heater 40 abuts against the constriction 46c. In this case, the connecting bolt 52 of the Rohrheizköpers 40 passes through the constriction 46c. Subsequently, the support ring 56 can be pushed onto the extension 48 from the outside and jammed there, as it is in connection with the Fig. 3 has been explained above.

In the Fig. 6 The conventional embodiment shown differs from the previous one in that the tubular heater 40 is inserted into the mounting opening 46 in such a way that the tubular heater 40 is overmolded during injection of the housing part 14 or 16, so that the mounting opening 46 forms in this injection process. In this case, the tubular heater 40 may be provided with an overmold seal 50 again. It is also possible that a corresponding support ring 56, as has been explained above, is provided. In order to increase the anchoring of the seal 50 to the tubular heater 40, a constriction 42 may be provided on the jacket tube 41 of the tubular heater 40.

In Fig. 7 a fourth conventional embodiment is shown, the essential difference from the previous embodiments comprises that the front end 40a of the jacket tube of the tubular heater 40 is widened and at the same time when injecting the housing parts 14 or 16 is inserted into the mounting hole 46. In other words, the flared end of the jacket tube of the tubular heater 40 is molded directly with plastic, so that the mounting hole 46 is formed during the injection process and the tubular heater 40 is integrated directly into the respective housing part 14 or 16 after the injection process. The frontal expansion of the jacket tube can form an acute or obtuse angle with the axis of the mounting hole. In the example shown in the Fig. 7 is the end-side widening funnel-like shape or the expansion of the jacket tube extends to the axial direction of the mounting opening at an acute angle in the direction of the boiler interior. D. h., The jacket tube has at its front end a larger diameter than the inner diameter of the mounting hole and tapers toward the boiler interior to the normal diameter of the jacket tube.

Further, the embodiment differs from the Fig. 7 from, for example, the Fig. 4, 5 or 6 on the container inner wall by a directed into the boiler interior extension 48 'in addition to the extension 48 which is directed to the boiler outer wall to the outside. As a result, the effective strength of the mounting opening is increased, which leads to an improvement in the attachment and support of the jacket tube of the tubular heater 40. It should be noted that it is also possible to enlarge one of the projections 48, 48 'such that the other extension can be reduced or omitted. Finally, the wall thickness of the boiler can be dimensioned so that none of the extensions is necessary.

It should also be noted that in the fourth embodiment, at or adjacent to the flared end, the tubular heater 40 may be additionally provided with one or more overmold seals similar to the gasket 50 discussed in the other embodiments. In order to reinforce the support of the tubular heater 40 in the mounting opening 46, one or more constrictions (s) (similar to the constriction 42, which may be used, for example, in FIG Fig. 6 is shown) and / or one or more expansion (s) (such as the expansion of the tubular casing of the tubular heater of the Fig. 12 ), which in the Fig. 7 are not shown in detail, may be provided on the jacket tube of the tubular heater 40. Another option is to provide an additional support ring, similar to the support ring 56 described above, on the extension 48.

In Fig. 8 an embodiment of the invention for a mounting hole 46 and for the embodiment of the attachment of the heater 40 is shown in this. This differs from that associated with the Fig. 4 described embodiment in that the extension 48 has at its pointing in the direction of the outside of the boiler 10 end a completely circumferential widening 48 a. In this expansion 48 a, the sealing element 50 is inserted in the form of an O-ring. The fastener is formed in this embodiment by a clamping sleeve 58, which, as shown in Fig. 8 shows, double-walled is formed in such a way that the clamping sleeve 58 can be pushed over the widening 48a of the extension 48 from the outside and the two double-wall forming portions 58a, 58b of the clamping sleeve 58, the wall of the expansion 48a between them. The two double-wall forming wall sections 58a, 58b of the clamping sleeve 58 are interconnected by an unspecified bottom, the round contour is adapted in cross-section to the contour of the expansion 48a of the extension 48, as is apparent from Fig. 8 is removable. The axial length of the clamping sleeve 58 is selected so that it protrudes beyond the end of the widening 48a of the extension 48 with the outer wall section 58a, which is axially longer than the inner wall section 58b. The free end of this wall portion 58a is then, as also out Fig. 8 can be removed, plastically deformed in such a way that the clamping sleeve 58 is fixed to the widening 48 a of the extension 48. On the free end of the tubular heater 40 and the casing tube 41 is a Erdungsspeednut 60 is pushed, as is apparent from Fig. 8 emerges, which serves as a ground connection. The jacket tube of the heater 40 is closed fluid-tight by an insulating bead 61.

This in Fig. 9 The sixth conventional embodiment for a mounting hole 46 is different from that in FIG Fig. 8 shown in that the widening 48a of the extension 48 is not continuous but discontinuous in the form of a substantially radially extending step. In the resulting gap between the outside of the jacket tube 41 of the heater 40 and the inside of the expansion 48a, a double-walled sealing member 62 is used, the opening formed by the two wall portions facing outward. How out Fig. 9 is removable, the sealing element 62 is adapted at its connecting portion or its bottom of the shape or the step of the expansion 48a. In the gap formed by the two wall sections of the double wall, a grounding sleeve 63 is inserted, wherein the outwardly facing end face of the grounding sleeve 63 is crimped in the direction of the jacket tube 41 of the tubular heater 40. On the outside, the widening 48a in the region of the jump from that portion of the extension 48 whose inside diameter at least approximately corresponds to the outside diameter of the jacket tube 41 of the heater 40, to the portion of the extension 48, which forms the widening 48a, a circumferential shoulder 48b. On this paragraph 48b of the support ring 56 is pushed or pressed. It should be noted that in the presentation of the Fig. 9 the insulating bead 61 which is in Fig. 8 is not shown, although it is present in the operational state of the boiler 10.

At the in Fig. 10 shown seventh conventional embodiment of the mounting hole 46 has the extension 48 has a larger inner diameter than the actual mounting hole 46 in the housing wall of the boiler 10. In this embodiment, the facing in the direction of the outside end face of the jacket tube 41 of the heater 40 with a widening 40a in provided the way that this over the edges of the mounting hole 46 also overlaps. In the between the inner wall of the extension 48, whose outer diameter is greater than the outer diameter of the expansion 40 a of the heater 40, existing space, the sealing element 50 is inserted. The sealing element 50 can in turn be inserted or sprayed onto the widening 40a of the jacket tube 41, the sealing element 50 also being widened during the production of the widening 40a. In the region of the widening 40a of the jacket tube 41, a sleeve 63 with a grounding flat plug is used, which serves as a ground connection for the heating device 40. On the outer side of the extension 48 of the support ring 56 is still provided.

The in the Fig. 11 and 12 The eighth conventional embodiment shown differs from that in FIG Fig. 10 only to the extent that the jacket tube 41 of the heater 40 at the extending from the wall of the housing 12 of the boiler 10 inwardly extending portion has a circumferential recess 40 b, in which the edge of the actual Mounting opening 46 engages. As a result, the heater 40 is axially fixed both in the outward direction and the inward direction.

In the Fig. 13 and 14 a further embodiment of the invention is shown, in which an extension 48 is provided not only on the outside of the housing 12 of the boiler 10, but also on the inside of the housing 12. This further extension 68 serves to receive or attach a double-walled sealing element 69, which overlaps the extension 68 on both sides. As in particular from Fig. 13 In the region of the extension 68 engages the inner portion of the double-walled sealing element 69, whereas in the region of the extension 48, the jacket tube 41 of the heater 40 has a widening 40a. On the outer extension 48 of the support ring 56 is placed and flanged. This in turn has a grounding flat plug.

In Fig. 16 is another preferably circular mounting opening 70 in the housing 12 of the boiler 10 and in one of the housing parts 14 or 16 reproduced. This mounting opening 70 serves to attach a control unit 72 in the housing wall. How out Fig. 16 The control unit 72, which preferably has a cylindrical outer contour, is fixed in the mounting opening 70, if necessary with the interposition of a sealing element (not shown), by preferably elastic snap-in lugs 70a which are integrally formed on the outer side of the mounting opening 70. The control unit 70 is in heat-conducting contact with the heating device 40 via a corrugated heat conduction plate 74, so that the control unit 70 can detect the temperature of the heating device 70. The corrugation of the Wärmeleitblechs 74 serves to compensate for the changes in length during its heating and cooling. It should also be noted that the heat conducting sheet 74 may be fixedly connected to the heater 40 and / or the control unit 72 by a welding or soldering operation.

Claims (10)

1. Boiler for heating a free-flowing medium, in particular for heating water, comprising
   a boiler housing (12) made of plastics material,
   a heating device (40), which projects into the interior of the boiler housing (12) via an assembly opening (46) in the boiler housing (12) and is fixed in the assembly opening (46) by fixing means, which are formed by at least one clamping element (56), and
   at least one sealing element (50), which is arranged between the internal wall of the assembly opening (46) and the external wall of the heating device (40), the internal diameter of the assembly opening (46) in the boiler housing corresponding at least approximately to the outer diameter of the heating device (40) at least in portions,
   characterised in that the heating device (40) comprises an unheated portion (42) at least in the region of the assembly opening (46), which portion continues on the inside of the boiler housing (12),
   the assembly opening (46) for the heating device (40) is formed by an extension (48) arranged on the boiler housing (12), the axial length of which extension is greater than the wall thickness of the boiler housing (12), and which extends outwards from the wall of the boiler housing (12), wherein the fixing means

   a) is formed by a clamping sleeve (58), such that the extension (48) has ,at its end facing towards the outside of the boiler (10), a completely circumferential expansion (48a), into which the sealing element (50) in form of an O-ring is inserted; wherein the clamping sleeve (58) is formed double-walled such that the clamping sleeve can be slid onto the expansion (48a) of the extension (48) from the outside and wherein the two portions (58a, 58b) of the clamping sleeve that form the double wall accommodate the wall of the expansion (48a) between them, wherein the two portions (58a, 58b) of the clamping sleeve that form the double wall are connected with one another through the bottom, whose round contour is adapted in its cross-section to the contour of the expansion (48a) of the extension (48), wherein the axial length of the clamping sleeve (58) is selected such that it protrudes with the outer wall portion (58a), which is axially longer than the inner wall portion (58b), beyond the end of the expansion (48a) of the extension (48), whereby the free end of this wall section (58a) is then plastically deformed in such a way that the clamping sleeve (58) is fixated at the expansion (48a) of the extension (48); or

   b) is formed by a support ring (56) such that in the region of the extension (48) a jacket tube (41) of the heater (40) has an expansion (40a), wherein the support ring (56) is mounted and crimped at the outer lying extension (48); and
   in that the fixing means can serve as an earthing connection, at least for the heating device (40).
2. Boiler according to claim 1, characterised in that the unheated portion (42) of the heating device (40) continues on the outside of the boiler housing (12), and in that the length of the unheated portion (42) of the heating device (40) is greater in the direction of the inside of the boiler housing (12) than in the direction of the outside.
3. Boiler according to any of the preceding claims, characterised in that the clamping element (56) is fixed in the assembly opening (46) for the heating device (40) by means of plastic deformation.
4. Boiler according to any of claims 1 to 3, characterised in that at least one further assembly opening (70) is provided for the attachment of at least one control unit (72), which is in heat-conducting contact with a heated portion of the heating device (40), the heat-conducting contact taking place by means of heat conduction via a heat-conducting element (74), preferably a heat-conducting sheet.
5. Boiler according to claim 4, characterised in that the control unit (72) is formed by a PTC element, a NTC element, a fuse or a regulator.
6. Boiler according to either claim 4 or claim 5, characterised in that the control unit (72) is held in the assembly opening (46) by a locking action and/or fixing elements (70a).
7. Boiler according to any of claims 1 to 6, characterised in that the boiler housing (12) consists of at least two parts (14, 16), the at least one assembly opening (46) being provided in one of the two boiler housing parts (14, 16).
8. Boiler according to claim 7, characterised in that the two housing parts (14, 16) are interconnected by the interpolation of at least one seal (22) at the abutting surfaces of the housing parts (14, 16) with material, positive or non-positive locking.
9. Boiler according to any of claims 1 to 8, characterised in that the heating device is a tubular heating element (40).
10. Boiler according to claim 1, characterised in that an additional extension (48', 68) is arranged at the assembly opening (46) on the inside of the boiler housing.

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